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Finometer TM User's Guide

FMS, Finapres Medical Systems BV

C

2002 FMS

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Finometer TM User's Guide

Version 1.10, dd: 2002.05.06

This document is for information purposes only.

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FMS, Finapres Medical Systems BV

C

2002 FMS

Customer support

The Finometer is manufactured by FMS, Finapres Medical Systems BV, at the location given below. The Finometer and its accessories are constructed of high quality materials and great care has been taken in its manufacture. We stand behind our product and will do what is in our power to have you as a satisfied customer and Finometer user. If the product fails to function properly, or when assistance, or service, or recalibration is needed, please contact: FMS, Finapres Medical Systems BV Simon Stevinweg 48 NL-6827 BT ARNHEM, The Netherlands phone fax email web : : : : +31 26 3849080 +31 26 3849081 [email protected] www.Finapres.com

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If accessories for Finometer are needed, such as extra cuffs, or further copies of this User Guide, please contact: Mr R Roelandt Decavee 12, B-1790 AFFLIGEM, Belgium phone fax email +32 53 685626 +32 53 685636 [email protected]

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Finometer contains no field serviceable parts. Servicing of any component of this device, therefore, is to be performed by FMS only. Unauthorized repairs or modifications may violate the conformity of Finometer with the requirements in the Medical Device Directive 93/42/EEC set forth by FMS.

Warranty

The Finometer system is guaranteed by FMS, Finapres Medical Systems BV for a period of one year after the date of purchase. During this warranty period FMS will, without charge for labor or parts, repair or replace defective parts. The warranty does not include the following: · · · · · ·

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Finger cuffs. Finger cuffs, however, are reusable items which can, given proper care and handling, often be used for several years. Transport costs and insurance of the shipment of the Finometer to FMS. Defects caused by repairs through unauthorized personnel, or the use of accessories not obtained from, or approved by FMS. Periodic check--ups, upon request of the user. Damage through misapplication, misuse, or failure to follow the instruction in this User's Guide, or in other accompanying documents. Accidents that affected Finometer or its accessories.

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Disclaimer

DISCLAIMER OF WARRANTIES AND LIMITATIONS fms makes no warranty or representation, either express or implied, with respect to the finometer device, its quality, merchantability, or fitness for a particular purpose. the equipment is provided as is, no oral or written information or advice given by either party or its employees shall create a warranty or make any modification, extension or addition to the warranty. fms shall not be liable for any direct, indirect, incidental or consequential damages, including lost profits and damages for personal injury or property damage, arising from or in connection with the licensed rights or its use whatsoever. in no case shall fms, finapres medical systems bv's liability exceed the purchase price for the device.

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Information in this document is subject to change without notice and does not represent a commitment on the part of FMS, Finapres Medical Systems BV.

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The BeatScope software is furnished under a license agreement. The software may be used only in accordance with that agreement. Beatscope includes the Finometer--to--PC link program: Finolink, which can also be used as a stand--alone program, and can be copied to any Windows PC and run. Finolink downloads data packets, unpacks these files, and allows limited remote control of Finometer. BeatScope, Finolink, Finometer, Modelflow, and Portapres are trademarks of FMS, Finapres Medical Systems BV. Finapres is a trademark of Ohmeda Monitoring Systems. No part of this publication may be reproduced, transmitted, transcribed, stored in a retrieval system, or translated into any language in any form by any means, for any purpose other than the purchaser's personal use only after prior written permission of FMS, Finapres Medical Systems BV

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Dear Finometer user

This guide has been written to ease you into doing measurements with Finometer. With its Start display and three built--in instruments it might appear that you are in for a steep learning curve. We hope that you will find this as untrue as it was for the young person on the facing page. The Start display (page 44) appears when Finometer electrical power is turned on. It is the super device since it allows the starting of each of the three instruments of Finometer. As further options, you may output one of two analog calibration waveforms or view a series of instruction or help slides on how to wrap cuffs, apply the finger hydrostatic height correction sensors, and more. Start any instrument or action by pressing the corresponding button twice. Finometer--research (page 49) is a finger arterial pressure measurement instrument with configurability and many options. It was designed principally as a noninvasive hemodynamics monitor for research, displaying arterial pressure, rate and flow. It has the remote control functions: start/stop a measurement, start/stop Physiocal, and start/stop a return-to--flow calibration. It will also store externally supplied markers. It has three external analog signal inputs and may even be run from an external pressure wave without starting finger pressure. Finometer--clinique (page 81) is a finger arterial pressure measurement instrument with a fixed display of pressure and heart rate, and operation is via a limited number of function keys. It was designed principally for clinical monitoring of finger pressure. It has no remote control option and does not sample and store external analog signals. It does, however, produce the same file as does Finometer--research, and off--line evaluation of the data is not in any way limited. Finometer--classico (page 91) is an upper arm cuff inflate/deflate controller and Korotkoff phase marking instrument. Inflation and deflation rates are setable. Together with a stethoscope it facilitates auscultatory blood pressure measurements and with the mark facility for the Korotkoff phases a full record of each measurement is output. Exiting an instrument is by pressing simultaneand ously the two front panel buttons marked , which returns you to the Start display. Suggested reading is to first turn to chapter 1 with warnings and cautions. Next, try out the quick start guide of chapter 2 which describes in order every step to perform a finger blood pressure measurement for the first time. Soon thereafter, wrapping a finger cuff and entering patient data will quickly become routine, and starting a measurement is a one button operation. If you find anything missing in this User's Guide--it is in its first version--please contact us as we may be able to provide the missing information.

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Dear Interactive Guide user

The Interactive Finometer User's Guide has been designed to easily find a topic of interest and to follow its information trail. Interactive User's Guide screen layout. The page layout consists of two parts: At the left there is a colored control column with often a small figure at the top and a set of browse buttons below. At the right there is a text page with an occasional embedded figure or table or animated cartoon (section 4.2). In a text page blue colored items are clickable to reach an associated topic. In the table of contents everything is clickable. Return to where you came from by clicking the go back button. Figures. Click on the stamp sized figure upper left to display it in full size. Click again and the text page reappears. Or use the show figure and hide figure buttons. Paging. Jump to a page by clicking the page button and typing your page number. Further use the previous page and next page buttons. Searching. A word or a phrase is found by clicking the search text button and typing your word or phrase. For its next occurrence click search again . Acrobat cannot always find ligatures. Search for `Modelflow' via `Model'. Contents. The table of contents presents an overview of sections principally ordered according to the various instruments or user (interfaces 3.4) present in the Finometer device. Jump to it by clicking the contents button. The table of contents is followed by a list of figures and a list of tables. There is no button to jump to these lists directly. Glossary. The glossary is one of the appendices and explains terms used in connection with Finometer and finger blood pressure measurement. The terms are listed in the index under "Glossary" Index. At the end of this Guide you find an alphabetical index of words of phrases. To ease searching there are multiple entries with somewhat differing terms so that you may find: Analog I/O calibration waveforms Calibration signals square wave pressure wave Start display calibration signals all leading to the same page. Jump to the index by clicking the index button. Close document. Click close document to close the Interactive User's Guide but not the reader (Acrobat 4.0 or higher). To close the reader click the × at the upper right, or type <Alt><F4>.

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Contents

Customer support Dear Finometer user Dear Interactive Guide user 1 Uses, warnings, cautions, protective measures 1.1 When to use Finometer? 1.1.1 Noninvasive 1.1.2 Modelflow 1.2 When not to use Finometer 1.3 Avoiding injury to patient and personnel

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3 6 7

15 16 16 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 32 32

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2 To a quick start 2.1 Setting up Finometer 2.2 A first measurement 2.3 Accessing the packet file 2.4 Sampling external signals 2.5 External offset and sensitivity 2.6 Save & recall the configuration 3 Introduction 3.1 What is Finometer? 3.2 Methodology 3.3 Features 3.4 User interfaces 3.5 Derived parameters--beat--to--beat 3.6 Bias and precision 3.6.1 Arterial pressure 3.6.2 Cardiac output

4 Help slides 4.1 Cuff selection & handling slide 4.2 Cuff and frontend mounting slide 4.3 Difficult situations 4.3.1 Cold fingers 4.3.2 Arm arterial sclerosis 4.3.3 Costo--clavicular cutoff 4.3.4 Cyanotic finger tips 4.4 Height sensor nulling & placement slide 4.4.1 Nulling 4.4.2 Sensitivity 4.5 The Finometer front panel buttons slide 4.6 Waveform modeling & level correction slide 4.7 Level calibration by return--to-flow slide 4.8 Finometer instrument selection slide 5 The Start display 5.1 The Finometer selftest 5.2 The calibration signals 5.3 Off--line downloading of stored packet files 5.4 Failure to start--rebuilding the index 6 The Finometer--research instrument 6.1 Entering patient data--research 6.2 Layout of the Research display 6.3 The error message display--research

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49 51 52 53

6.4 6.5 6.6 6.7 6.7.1 6.7.2 6.8 6.9 6.10 6.11 6.12 6.13 6.14 7

Files downloading and remote control The Help card The Describe subject card Setting a subject's data Thermodilution cal Aortic diameter cal The pressure--volume diagrams The Select trends card Cardiac oxygen supply/demand The Select A/D signal card The Physiocal card The Return--to--flow--cal card The Derived variables card

54 55 56 57 57 57 58 59 60 61 62 63 64

8.4 8.5 8.6 8.7 8.8 8.9

Show trends The control buttons during off-line idling Layout of the Clinique display The control buttons during a measurement Scale compression Performing a return--to--flow calibration

85 86 87 88 89 90 91 93 94 95 96 97 99 100 101 103 104 105 106 107 108 109 110 111 112 113

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Configuring the Research instrument 7.1 Transducer check--buffer pressure 7.2 Transducer check--height nulling 7.3 Transducer check--height calibration 7.4 Transducer check--finger cuff 7.5 Transducer check--arm cuff 7.6 Pressure reconstruction 7.7 External signal input 7.8 Which channel to choose? 7.9 Setting date and time 7.10 Miscellaneous--finger switching 7.11 Miscellaneous--display units selection 7.12 Miscellaneous--the beeper 7.13 Miscellaneous--saving a configuration 7.14 Miscellaneous--loading a configuration 8 The Finometer--clinique instrument 8.1 Entering patient data--clinique 8.2 The error message display--clinique 8.3 Files downloading from a remote PC

65 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84

9 The Finometer--classico instrument 9.1 Setting the in-/deflate and readout parameters 9.2 The Classico calibration waveform 9.3 The normal Riva-Rocci/Korotkoff measurement 9.4 The Classico random zero measurement A Specifications A.1 Unpacking--The Finometer components A.2 Patient safety measures A.3 Protective measures A.4 Analog Input/Output A.5 Environmental specifications A.6 Electrical specifications A.7 Mechanical specifications A.8 Instrumental information A.9 Instrumental accuracy A.10 Connecting external equipment A.11 Remote control A.12 Safe data storage--Data durability A.13 Unpacking--The data packets A.14 Cleaning

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B C D

Error messages Derived parameters Glossary

114 116 117

E F

Literature references Index

126 128 138

Colophon

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Figures

1 1 A novice Finometer operator studies the button--screen interaction. The Interactive User's Guide screen layout and buttons. The buttons and blue colored clickable items in the text (not present in this figure) facilitate reaching the nooks and crannies of this guide. The frontend cable connector. The analog input/output (I/O) box. The front end (top) with rear mounted telephone receptacle to receive the height sensor electrical connector and, separately, the height sensing system (bottom). The pillbox is the reference sensor to be attached at heart level. The Finolink option select (top) and download (bottom) display. Reading an external signal on input--4 of the analog I/O box (upper panel) and adjusting its offset to zero (lower panel). Adjusting (here) channel 1 sensitivity by bringing it down. Saving a configuration under Blue. The three user interfaces. The upper two are finger pressure devices, the bottom interface is to the Riva--Rocci/ Korotkoff device. 3.2 6 Some parameters derived from the current pressure and simulated flow waveforms, timed at the begin upstroke instant. The start display: two inventions founding Finometer. Cuff size selection. Cuff position on a finger. Click on figure to start a movie on finger cuff positioning. Height correction system nulling and sensor placement. Finometer front panel layout and description of the functions of the buttons. The arm cuff is inflated via the socket labeled i. Arm cuff pressure is sensed via socket s Transfer functions (left) and effect of level correction (right). Finger pressures, FAP, (left panels) and reconstructed brachial pressures, reBAP, (right panels) compared to intrabrachial artery pressures, BAP. Program selection options. The three softkey selectable Finometer instruments. The Finometer Start display with the [Help slides] button highlighted.

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4.1 4.2 4.3 4.4 4.5 4.6

2.1 2.2 2.3

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21 4.7 22 4.8

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23 24 25 4.9

2.6 2.7 3.1

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5.1 30

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5.2

5.3 5.4

6.1 6.2 6.3 6.4 6.5 6.6

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6.10

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Start display showing all deviations from normal that can be detected in the Finometer hardware selftest. The two analog calibration signals available in Finometer. Start display when Finometer has been approached for off--line files downloading by the Finolink program. Finometer--research selected in the Start display. First or opening display after starting Finometer--research. The Finometer--research display layout. An error message. Finometer--research display with off--line files downloading in progress. The first help paragraph is always displayed initially since it says how to stop a measurement run. The {Describe subject} card shown before proper subject data are entered and confirmed. The subject data have been modified but not confirmed. The blue message instructs you to press the [Describe subject] button to confirm the changes. The great effect of age on aortic nonlinearity is shown in these two highlighted diagrams. The relationship between the settings on the {Select trends} card and both trend display panels.

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6.14 51 52 53 54 7.1 55

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57 7.4 58 7.5 59

A measure for cardiac time-tension is displayed in m Hg. The Finometer internal finger plethysmogram is shown on a time scale of 0.5 s per division, with zero in the middle, on a ±2.5 V full scale. A Physiocal procedure is in progress. The Physiocal side of the {Physiocal & RTF--cal} card with Physiocal turned off. The RTF--cal side of the {Physiocal & RTF--cal} card with ramp inflate selected. Twelve pressure and flow derived variables presented as 8--beat running averages updated every 1 second. Opening display of the {Configure} card, with sections, subsections perhaps, and instructions in blue. Arm cuff air buffer pressure check. The hydrostatic height sensing system check display panel. Height on the tab card is in cm. In the left information display the Hite: value is shown in mmHg. The hydrostatic height sensing system check display when the sensors are held apart 50 cm vertically. Checking the finger cuff pressure transducer.

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7.8 7.9 7.10

7.11 7.12 7.13 7.14 7.15 8.1 8.2 8.3 8.4

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8.5

Connecting piece (top) is a Kuhnke socket (order nr 50.064), 6 × 1 mm air hose, and Luer assembly, the screen display (bottom) shows when performing an arm cuff transducer test. Changing from finger to brachial pressure waveform reconstruction to no reconstruction. Selecting channel 1 for external input. Setting a channel's sensitivity. Date and time on the {Configure} card are related to Date: and clock-TIME on screen. Changing the finger switching interval. Selecting the SI unit system and hPa for pressure. The system beeper turned off. Saving a Finometer--research configuration under Blue. Loading a the Red Finometer-research configuration. Finometer--clinique selected in the Start display. Entering patient data in Finometer--clinique Finometer--clinique displaying an error message. Off--line files downloading display of Finometer--clinique. Patient data was being entered when the Finometer was approached by Finolink for off--line downloading. Display after pressing the [Show trends] button.

8.6 8.7

71 8.8 72 73 74 8.9 75 76 77 78 79 80 9.4 81 82 83 9.5 A.1 D.1 D.2 D.3 D.4 D.5 D.6

8.10 9.1 9.2 9.3

84 85

Showing the yellow idling control buttons. Finometer--clinique display during a measurement, showing its layers. The display is off--colored to emphasize the layers. Showing the blue control buttons during a measurement with the Clinique instrument and the waveform at high speed. Note the begin upstroke markers. Trend display just before (upper) and after (lower) reaching the end demonstrating scale compression. Display after a return--to--flow calibration took place. Finometer--classico selected in the Start display. The Classico setup tab cards stacked. The Classico calibration waveform has 50 mmHg steps and runs between 50 and 250 mmHg. The Classico normal Riva--Rocci/ Korotkoff display. The Classico random zero display. The Finometer ready for a measurement. Some derived parameters. A finger cuff. The Modelflow model. Nonlinear curves. Square wave calibration. Transfer functions.

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94 95 96 99 118 119 121 121 124 125

Tables

3.1 3.2 3.3 6.1 7.1 Differences (mmHg) between FinAP and BAP. Differences (mmHg) between reBAP and BAP. Differences ( /min) between Modelflow and thermodilution C.O.. The Finometer internal analog signals. The Finometer internal analog signals. C.1 32 32 33 61 74 Finometer derived parameters. All parameters when displayed are 8--beat averages. Indexed parameters have a darker shade. The clinique waveform display shows beat--to--beat heart rate in Yellow.

116

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1 Uses, warnings, cautions, protective measures

This chapter lists a number of important precautions that we urge you to study before starting to measure a patient for the first time. Listed are situations where, from extensive experience with Finapres and Finometer, the device can be used and situations are listed when Finometer preferably should not be used. It tells you about precision, which is limited, and about precautions you may take to optimize safety for the patient. 1.1 1.2 1.3 When to use Finometer? 16 When not to use Finometer 17 Avoiding injury to patient and personnel

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1.1 When to use Finometer?

Use Finometer when there is a need for a noninvasive hemodynamic monitor providing an almost complete, noninvasive characterization of the arterial circulation and its beat--to--beat variability in pressure and flow, and in various parameters derived from these continuous signals, such as systolic, diastolic and true mean pressure, pulse interval, heart rate, and left ventricular ejection time, stroke volume, cardiac output, systemic peripheral resistance, and a form of time-tension index. reconstruction procedures run fully automatically as the default setting of Finometer, although they can be de--selected. We have demonstrated in practice that accuracies of finger blood pressure after reconstruction are within the AAMI requirements of ±5 ± 8 mmHg against intrabrachial blood pressures (for references see page 126). Application of Finometer in clinical practice seems not limited by inaccuracies or by risk to the patient.

1.1.1 Noninvasive

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1.1.2 Modelflow

In addition, Finometer includes the patented Modelflow method to derive continuous cardiac output from finger pressure using a model. Compared to carefully executed thermodilution cardiac output estimates the bias is near zero but precision is limited (to 20%) until it has been calibrated with another method. In tracking changes from control in percent before, or in /min cardiac output after calibration, however, the Modelflow method (at 8% precision) is as precise as or better than triple random thermodilution estimates.

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The Finometer is a noninvasive instrument to measure blood pressure on the finger of a human. Since it is noninvasive, application is associated with little risk. Noninvasive methods are usually associated with reduced accuracy. In Finometer, however, the brachial artery pressure wave is reconstructed in waveform and level. For this purpose patented methods and algorithms are included, using an upper arm cuff return--to--flow systolic pressure determination, to substantially reduce inaccuracies. The

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1.2 When not to use Finometer

When 100% availability of arterial pressure is required in critically ill patients since treatment depends on it, and other means are available, Finometer is not the preferred choice. Still, in two studies we found that the overall percentage availability of Finapres in the operating room during coronary artery bypass grafting 22 and of Portapres in 24 hour ambulatory recordings 11 was equal to that of the intraarterial lines. The finger is a distal measuring site and smooth muscle in the arteries and arterioles of the circulation of hand and finger can come to full contraction. An extreme example of this is Raynaud's phenomenon. Measures have been built into Finometer to alert the user to such conditions developing. When full contraction does occur finger pressure measurement is no longer possible, and cannot be restored quickly.

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1.3 Avoiding injury to patient and personnel

· (US) Federal law restricts this device to sale by or on the order of a physician. This device is intended for use by trained health care professionals. The physiological parameters provided by this device have clinical significance only if determined by a physician and should not be used as the sole means for determining a patient's diagnosis. Explosion hazard exists when operated in the presence of flammable gases and liquids. Protection against the ingress of liquids is limited. Do not apply electrical power to the device when liquids did enter as this may cause internal short circuits and unpredictable external electrical currents. Always use a grounded 3--wire electrical cable and connector to plug into the power line. Closely follow the instructions on the Finometer on screen help slides. In particular selecting a proper sized cuff and the correct placement of a cuff on a finger are critical for success. Do not wrap finger cuffs around a toe or the wrist of an infant. Accuracy of measurement on a toe has not been established. An inflated finger cuff applied to the wrist causes congestion of blood in the distal circulation of the hand, which may become painful and restricts distal oxygenation. The zero adjustment or nulling of all pressure transducers built--in is automatic, except for the pressure transducer of the height correction system for which nulling has to be performed manually (see section 4.4 on page 39). It is the responsibility of the operator to periodically check the zeros and sensitivities of the transducers. Finometers leave our premises with carefully calibrated transducers. Immediately after transport, and at any time that the instrument is dropped or otherwise damaged the zeros and calibrations should be rechecked. These checks are quick and easy to perform (see section 7.1 and following sections, beginning on page 67). For safe and reliable operation and optimal accuracy only use FMS cuffs and only use data downloading software approved by FMS, Finapres Medical Systems BV. Externally generated analog signals coming from other devices, such as respiratory signals and ECG's can be connected to the Finometer for recording. Furthermore, personal computing equipment can be interfaced to the digital I/O port of the Finometer for downloading of signals and data, and for remote control. Connected equipment has to meet the IEC specifications (IEC 601 for electromedical devices or IEC 950 for data processing devices). The configuration has to meet the IEC system standard (IEC 601-1--1). He who connects such additional devices is responsible for adherence to the IEC 601--1--1 standard. Complete specifications of Finometer are listed in appendix A beginning on page 97.

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2 To a quick start

This chapter describes step by step how to make a first measurement with Finometer, how to obtain the resulting packet file, and how to sample an external signal during a finger pressure measurement. 2.1 2.2 2.3 2.4 2.5 2.6 Setting up Finometer 20 A first measurement 21 Accessing the packet file 22 Sampling external signals 23 External offset and sensitivity 24 Save & recall the configuration 25

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2.1 Setting up Finometer

Before you start a first measurement please read the "Warnings, cautions and protective measures" chapter on page 15. Then do the following (Omit all steps marked with I/O dealing with the analog I/O box if you have no immediate interest): 1.

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Connect the power cable at the rear of the Finometer. Plug the power cable into a grounded AC power outlet. Switch Finometer on, the switch is at the rear. You should see a display like that shown on this User's Guide front cover. Observe the error message that may show up above the Finometer picture on screen, see figure 5.2 on page 45. Disregard any gray colored ones. There should be no yellow or red colored errors. Contact FMS if there is, see page 3. Take the Finometer frontend box and cable, figure 2.3 on page 21, and insert the big connector straight into the receptacle at the Finometer front bottom left, facing page upper panel. The red dot should point upwards. The connector must go in straight and smoothly and must be seated firmly. By pulling at the cable try to

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pull the connector out. This should fail. I/O Take the analog I/O box, facing page, and connect it to Finometer at the rear. The chassis connector part that fits is marked "Analog I/O". I/O In the Start display start the Square wave cal calibration signal by pressing its button twice, once to select and once more to activate. You should see a display as shown in figure 5.3 upper panel on page 46. I/O Connect an oscilloscope in turn to each of the 4 analog output BNC connectors. They are the bottom four connectors in the lower figure on the facing page, marked output 1 through output 4. Check that the signal on the oscilloscope screen matches that on the Finometer Start display. Start the Finometer-clinique instrument by pressing its button twice. You should see a display like in figure 8.2 on page 82. The Clinique instrument starts a square wave calibration signal which will run until a measurement is started.

Your system is set up. It is time to turn to your patient.

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2.2 A first measurement

Next, attach to your patient two sensor systems, the finger cuff and the hydrostatic height sensing system (Omit all steps marked with I/O dealing with the analog I/O box if you have no immediate interest): 1. Strap the frontend box to a subjects hand or wrist. The cable should run away from the fingers and along the arm. Select a properly sized finger cuff, see figure 4.2 on page 35. Wrap the cuff as shown in figure 4.3 on page 36. Note that finger cuffs have a conical form. Gently try to remove the finger cuff by pulling. This should fail. Connect the hydrostatic height sensing system, see facing page top panel. Insert its electrical connector at the rear end of the frontend box in the telephone chassis part, facing page bottom panel. Null the hydrostatic height correction system. Follow the instructions of figure 4.5 on page 39. Position and attach both height sensors as shown in figure 4.5, the pillbox sensor at heart level. In the Clinique display note that the button marked [Gender] is highlighted. Press the button until the correct gender is shown. 8. Press once so that the button marked [Age] or until the correct is highlighted, then age is shown. For the moment, disregard the buttons marked [Height] and [Weight]. Press start/stop once to start a measurement. Note that the on screen control buttons change color and change function. Continue the measurement for some minutes and move the hand gently in height. If the height correction system was connected and properly nulled you should observe no effect. If not connected a substantial level shift should show in the curve displayed. I/O Connect the oscilloscope to analog output 1. A finger blood pressure waveform should show. I/O On analog output 2 the height correction signal should show if this system was connected and properly nulled. Gently move the hand in height and observe the changed height level. Press start/stop once to stop the measurement. Press and simultaneously until a message appears asking you to confirm exiting the Clinique instrument. Press start/stop to confirm. You will be returned to the Start display.

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You have just successfully completed your first measurement with Finometer.

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2.3 Accessing the packet file

Each Finometer--research or Finometer--clinique finger blood pressure measurement automatically results in a packet file, of 1 kB per second of measurement. This file is stored internally in Finometer. The Finolink program allows access to and downloading of such files from a remote PC. The Finolink program is described in its chapter in the Beatscope 1.1 User's Guide. To download a packet file:

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Get the so--called "null modem" cable coming with Finometer. Any other such cable will do too. Connect it to Finometer at the rear. The proper chassis connector is marked "RS232". Connect the other end to your Personal computer. Use a free COM port. Usually a PC has two COM ports. Finolink can be configured to use any available port. Start Finolink by double clicking on its icon. The display on the facing page is shown. Select the button marked `Download' and click on it. The second display on the facing page should show. Click on `Configure', then `Serial port', and select the desired COM port. Click on `Select'.

Click on `Connect' and Finolink will start downloading the file name directory in Finometer. Wait until finished. 8. Click on `Time' to sort the list on time. Possibly click a second time to reverse sort order and to have the most recent file at the top. 9. Click on the top file to select it. 10. Click on `Local files' to select a destination directory. 11. Click on `<' to start the file transfer. Wait until finished. 12. Quit Finolink. The file just made has been transferred to your PC in the subdirectory of your choice. The file name follows the date/time convention explained in section 7.9 on page 75 that is generated automatically. A packet file can be renamed with Finolink before it reaches the PC, or afterwards but not inside the Finometer to assure greatest data integrity. Finolink can also unpack the packet file to the earlier FAST system's header, results and samples files. This facilitates the continued use of your own software in the manner you are used to.

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2.4 Sampling external signals

Assume a comparison is to be made between a finger and an intraarterial blood pressure recording. For this purpose both signals need to be sampled simultaneously. Finometer records its plethysmographic waveform on channel 4, but there is no interest in this signal for the present study. Connect the intraarterial blood pressure signal to input--4 of the analog I/O box. The following steps remove the plethysmogram from channel 4 and replace it with the desired external input--4 signal (Note: The plethysmogram is still present internally and is still evaluated, it is just not stored in the packet file.): 1. 2.

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5. 6. 7. 8.

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9. If not already done switch on the Finometer. From the Start display select Finometer--research by pressing the [Finometer--research] button twice, once to select, once to activate. Press the [Configure] button. The arm cuff air pump will start automatically and continue until the full buffer pressure is reached. until the section external signals Press

3.

is highlighted. to reach the Channel-nr column. Press Press or until channel number 4 is highlighted. Press to reach the Source-mV column. Press to select external for that channel. Note that the signal channel display just above the Source mV--meter, facing page top display, changed to show Ext 4. At the same time the calibration waveform is removed from the analog output 4 BNC connector and replaced by the digitized input--4 signal. Connect your signal source to input--4 on the analog I/O box, assuming the box is still connected from the previous recording, section 2.1. The green lettering on black background Source mV--meter (facing page top display) indicates the voltage read on channel 4. The input signal must be within ±5 V.

4.

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2.5 External offset and sensitivity

The external signal may not comply with the Finometer internal standard sensitivity of 100 mmHg/V and offset equal to 0 V. To remedy there are two possible ways to go. Both routes can be taken as long as the input signal amplitude remains within ±5 V. The first is simplest. Just accept any offset and sensitivity that the external signal source has, but record a calibration signal, and use the recorded signal to calibrate afterwards in software yourself. The other route is to let Finometer digitally preprocess the input signal by adjusting zero offset to 0 V, and sensitivity to 100 mmHg/V, the values used in Finometer. In that case follow these steps: 1. Apply a voltage to the input--4 BNC connector that represents a pressure of 0 mmHg. 2. 3. 4. once to reach the Offset-mV column. Press Press or until the Source mV--meter reads 0, see figure 2.5. Next, apply a known voltage to the input--4 BNC connector, here for example 1.033 V, equivalent to 100 mmHg, see figure top panel, here performed on channel 1. once to reach the "Sensitiv-0 00 " column. / Press Press or until the mV--meter reads 1000 mV, see figure bottom panel. The sensitivity is now reduced to 9670 00 or 0.967. / In case the input signal polarity is reversed with positive pressures producing negative voltage excursions, change the polarity in the left most column and repeat adjusting offset and sensitivity.

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2.6 Save & recall the configuration

After the effort to setup external channels you may want to store (to later reload) this information in the case that the set up is stable and will be used frequently. Do the following: 1. 2.

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At the next occasion reload the blue configuration as follows: 1. 2. 3. 4. 5. Press the [Configure] button. several times to select the miscelPress laneous section. Press once to reach the Load config select column. to select the Blue configuration color. Press Press the [Configure] button to load this configuration.

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Press the [Configure] button. several times to select the miscelPress laneous section. Press twice to reach the Save config select column. Press to select a configuration color, say Blue. Press the [Configure] button to save this configuration, as suggested by the blue instruction on screen. The configuration is saved under Blue on disk and can be recovered at another occasion.

You are now ready for another finger pressure measurement recording an external pressure on channel 4. Press start/stop to start.

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3 Introduction

This introduction presents a general description of Finometer in terms of methods used--with literature references, features, available derived parameters from the blood pressure and flow waveform, and bias and precision of the principal parameters: blood pressure levels and cardiac output. 3.1 3.2 3.3 3.4 3.5 3.6 What is Finometer? 27 Methodology 28 Features 29 User interfaces 30 Derived parameters--beat--to--beat Bias and precision 32

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3.1 What is Finometer?

Finometer, like Finapres TM is a noninvasive hemodynamic cardiovascular monitor based on the measurement of finger arterial pressure. It is the successor to the TNO Finapres--model--5 which has been the basis of many methodological papers and space flight models, and of the Ohmeda Finapres 2300e, no longer available. Finometer has more options than its predecessors, and can be used as a noninvasive hemodynamic monitor for trending of many arterial hemodynamic parameters. Yet, once set up it is still possible to wrap a finger cuff and start a measurement by pressing the start/stop button.

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3.2 Methodology

The Finometer succeeds the popular Finapres TM device which was marketed by Ohmeda for many years. Whereas Finapres meant finger arterial pressure, Finometer means Finapres with bias and precision and tracking against intrabrachial artery pressures improved so that it approaches an intraarterial brachial measurement in accuracy. To achieve this goal Finometer includes the methodological advances developed and published by TNO in cooperation with the Academic Medical Center of the University of Amsterdam, the University of Florence Italy, and the Erasmus University of Rotterdam over several years. Some technology developed for the Portapres ambulatory finger blood pressure recorder is also included. For references see appendix E on page 126.

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Continuous monitoring of the finger arterial pressure waveform with the volume--clamp method of Pe´z 17 and the Physiocal criteria of na Wesseling 23, as in Finapres. Reconstruction of brachial artery pressure waveform and level from finger pressure via generalized waveform inverse modeling 6, 7. Automatic individual Riva--Rocci arm cuff return--to--flow pressure level calibration. 2 Stroke volume and cardiac output monitoring with the Modelflow modeling method, 21 simulating a nonlinear, self adaptive, three--element arterial model fed with a finger pressure wave to output an aortic flow waveform similar to ones measured with US Doppler or EM flowmetry.

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3.3 Features

· Three instruments embedded in one hardware environment: - Research interface offering finger arterial pressure recording with flexible displays and all options; - Clinique interface offering finger arterial pressure recording with fixed display and a few options; - Classico interface offering upper arm auscultatory blood pressure with computer controlled cuff inflate and deflate and three types of read out. Three finger cuff sizes, fitting most patients above the age of 6 years. Low sensitivity to motion artifact. Automatic hydrostatic height correction that can adjust finger pressures to heart level. 26 cm (10 inch) diagonal, bright color TFT-LCD display featuring excellent viewing angle, crisp, highly visible waveforms, selectable trend displays, and large numerical readouts. On screen, off--line graphics help pages showing front panel operation, cuff application and hydrostatic height sensing. On screen, on--line operator manual available. Front panel mark button with markers entered in the data file for easy reference. 24 hour internal storage of all recorded data available for remote downloading to a PC, with provided Finolink software. On--line real time remote downloading of the da· · · · · · · ta stream with Finolink. Remote control of important Finometer--research instrument functions via Finolink. Sampling (at 200 Hz) of maximally four externally provided analog signal inputs. Four analog signal outputs. Square wave and pressure wave calibration signals available on the four analog signal outputs. Displays configurable in medical units (mmHg) and SI units (pascal). Once configured the configuration can be stored for easy recovery. Upper arm Riva--Rocci cuff with automatic fast inflation and slow, linear deflation and return-to--flow systolic pressure detected by the finger cuff distal to the arm cuff, with the systolic pressure level used to calibrate finger pressure. Calibrated reconstruction of continuous brachial artery from the finger arterial pressure wave. Cardiac output computed continuously from arterial pressure by simulating a nonlinear, self-adaptive model of human arterial circulation. Fourteen beat--to--beat derived parameters computed from pressure and modelled flow waveforms are stored and available for trending. User's Guide available in paper and interactive form. Flexible postprocessing with the BeatScope software package.

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3.4 User interfaces

Three user interfaces are available in the Finometer by simple softkey selection. These user interfaces configure the display for the convenience of the user. 1. Finometer--research instrument offering full display programmability, consisting of three preprogrammed configurations (full featured Finometer, original Finapres, slave monitor using externally supplied analog pressure waveforms) and 2. two user programmed configurations. Configurations are color coded. Finometer--clinique instrument with fixed displays and limited features and supreme ease of operation. Finometer--classico instrument providing a Riva--Rocci auscultatory blood pressure device with automatic fast upper arm cuff inflation and controlled linear deflation.

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3.5 Derived parameters--beat--to--beat

Default, the pressure waveform is processed with two automatic generalized procedures. These procedures reconstruct a brachial artery pressure (reBAP) from finger pressure (FinAP): 1. 2.

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generalized finger to brachial waveform filtering, 6 and generalized level correction. 7

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Furthermore, an individual patient level adjustment called "calibration" can automatically be obtained by a return--to--flow systolic pressure measurement. 2 Highest precision in blood pressure readings is obtained only after this calibration. Default, 1 the following parameters are derived from the reconstructed brachial artery pressure waveform: · · SYS systolic pressure as the maximum pressure in arterial systole, DIA diastolic pressure as the low pressure just before the current upstroke, MAP mean arterial pressure as the true integrated mean pressure between the current and the next upstroke, IBI pulse interval as the time between the current and the next upstroke, HR pulse rate derived from the pulse interval,

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1

LVET left ventricular ejection time as the time between the current upstroke and the dicrotic notch, SV stroke volume as the true integrated mean of the simulated flow waveform between the current upstroke and the dicrotic notch, CO cardiac output as the product of stroke volume and heart rate, TPR total systemic peripheral resistance as the ratio of mean arterial pressure to cardiac output, assuming zero venous pressure (at the right atrium), D/SPTI diastolic to systolic pressure time index ratio as an index of cardiac oxygen supply and demand, always computed off a reconstructed aortic pressure waveform, PS*HR time--tension index (rate pressure product) as an index of cardiac oxygen demand, computed as the product of systolic pressure and pulse rate, dp/dt maximal steepness of the current upstroke always computed on the finger pressure waveform, Zao ascending aorta characteristic impedance at the current diastolic pressure, Cwk total arterial compliance at the current diastolic pressure.

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When the default reconstruction option is de--selected all parameters except two (D/SPTI and dp/dt) are obtained directly from finger arterial pressure. The return--to--flow calibration procedure is then unavailable. Stroke volume and cardiac output are not affected.

3.6 Bias and precision

Bias is the mean difference between value pairs obtained with two different methods of measurement of a parameter and precision is the standard deviation of the differences. Level systolic diastolic mean bias +4 +1 +1 (precision) (7) (5) (5) be-

3.6.1 Arterial pressure

Finger arterial pressure (FinAP) shows waveform distortion and pressure decrements when compared to brachial artery pressure (BAP) leading to bias and imprecision. Compared to intrabrachial artery pressure the bias and precision are: Level

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Table 3.2 Differences (mmHg) tween reBAP and BAP.

requires bias to be less than 5 mmHg and precision to be better than 8 mmHg. Clearly, waveform reconstruction reduces finger pressure uncertainty. 2 We have no data accumulated according to the BHS protocol in comparison with Riva--Rocci/ Korotkoff upper arm auscultatory pressure levels. Since auscultatory pressures differ systematically from intrabrachial levels (our reconstruction goal), we cannot expect that reconstructed brachial artery pressure levels will meet BHS auscultatory criteria closely.

bias +1 -8 -10

(precision) (11) (8) (7) (mmHg) be-

systolic diastolic mean

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Table 3.1 Differences tween FinAP and BAP.

Numbers vary somewhat per study but the ones listed are probably a fair resume. 12 After waveform reconstruction and Riva--Rocci return--to--flow level calibration a reconstructed brachial artery pressure (reBAP) results with reduced errors: The results are within the AAMI specification 1 which

3.6.2 Cardiac output

The Modelflow method used in the operating room with intraradial artery pressure has +0.3 /min bias and 20% precision compared to thermodilution cardiac output. It can thus not replace thermodilution as a monitor of absolute levels of cardiac output. Once calibrated its bias is zero and precision is 8%. 13

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bias as is calibrated +0.3 -0.1

(precision) (1.0) (0.5)

a triple random thermodilution or any other clinical method presently in use. In addition, using noninvasive finger pressure instead of intraradial or intrabrachial pressure does not appear to reduce Modelflow tracking precision. 9

Table 3.3 Differences ( /min) between Modelflow and thermodilution C.O.. Thus, in tracking percentage changes it can replace

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4 Help slides

Full screen help slides in Finometer are reachable from the Start display. Press the Help slides associated button twice, then repeatedly to view the slides in order: 1. 2. 3.

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4. 5. 6. 7.

the cuff sizing slide (section 4.1) shows how to select a properly sized cuff for a finger; the cuff wrapping slide (section 4.2) shows the correct manner to wrap a FMS finger cuff, plus three ways of incorrect wrapping; the height sensing slide (section 4.4) presents the two simple steps towards a well nulled system, and shows proper sensor placement; the front panel slide (section 4.5) explains the functions of the Finometer control buttons; the correction slide (section 4.6) presents the finger to brachial inverse modeling methods through generalized filter and correction equation; the calibration slide (section 4.7) presents the effect of an individual patient return--to--flow systolic calibration in reducing bias and improving precision; the available software slide (section 4.8) explains briefly which instruments can be selected to run in Finometer.

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The Start display (figure left) honors two pioneers of blood pressure measurement: Landois, who demonstrated for the first time the importance of the pulsatile component present in the blood pressure which had been masked in earlier methods by sluggish instrumentation, and Riva--Rocci who invented the arm cuff method which has proven so simple and reliable. The ideas of reliable cuff measurement and of faithful recording of pulsatility are present in Finometer. For historical notes honoring Professor Jan Pe´z, 17 the inventor of the na servo--plethysmomanometer device, which lies at the root of Finapres, Portapres, and now the Finometer, see Wesseling. 20 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 Cuff selection & handling slide 35 Cuff and frontend mounting slide 36 Difficult situations 37 Height sensor nulling & placement slide 39 The Finometer front panel buttons slide 40 Waveform modeling & level correction slide 41 Level calibration by return--to--flow slide 42 Finometer instrument selection slide 43

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4.1 Cuff selection & handling slide

The finger cuff is the sensory organ of Finometer. It is in contact with the patient's finger to detect the smallest changes in finger artery size, at high speed, and to control cuff pressure to oppose even subtle changes in arterial pressure dynamically. Handle these sensors with care and they will provide years of useful service.

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Selection of a proper size cuff is easy if finger circumference can be measured in centimeter. A table lookup refers to the proper size. Otherwise you might use the indications of a proper fit that are shown in the slide. To prevent damage to a finger cuff:

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is disconnected from the frontend. Even though Finometer automatically deflates when the finger cuff unwraps, the bladder may still become damaged. · Do not apply air pressure to a finger cuff when it is not wrapped around a finger or other solid object. This may damage the finger cuff bladder. · Do not flatten finger cuffs by in-- or outward bending since this may damage the electrical connections, the bonding of materials, and the electrical shielding. Finger cuffs are preformed around a conical mandrel during manufacture and best remain in this shape. · Do not attempt to repair a defective finger cuff since this will substantially affect measurement accuracy.

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Do not remove the finger cuff from a finger before the measurement is stopped and the air hose

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4.2 Cuff and frontend mounting slide

Finger cuff positioning is shown in the figure in four ways, three of which are incorrect. It is important · · · ·

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This is the mounting order that seems to work best: 1. Strap the frontend box to the back of the hand or the wrist. Place the finger cuff as shown in the slide. The index, middle and ring finger are often your best choice. Measurements on a thumb are possible when the shape of the thumb is acceptable. Lead the cable and air hose between two fingers to the frontend box. Match the red dots on the frontend receptacle and the cable connector and insert the connector as deeply as it will go. Firmly insert the Luer attached to the air hose to achieve a tight seat.

that the conical cuff matches the conical finger, that both knuckles are covered equally, that the cuff mounted plethysmograph sees the finger arteries well, and that the cuff leaves no undue space between it and the finger.

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Figure 4.4 Click on figure to start a movie on finger cuff positioning.

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4.3 Difficult situations

Obtaining finger pressure readings can be difficult at times, when patients feel uncomfortable, sense a cold draft, are nervous, are cold, are in pain, or underfilled, or under light anaesthesia. wards each other and let them slap on the opposite sides of the back. This forces blood into the hands. Repeat several times. Blow warm air onto the back of the neck. Have the person wear a sweater, have no arms, shoulders, neck exposed. Avoid air conditioning with cold air drafts coming from any side.

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4.3.1 Cold fingers

Differing somewhat per study, 95 to 100% success in recording acceptable blood pressures is usually obtained in nonanesthetized patients. Special measures have to be taken to get readings in the remaining few percent. Here are the actions that we found to have success, in no particular order:

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4.3.2 Arm arterial sclerosis

Arteriosclerotic plaques in subclavian, brachial and radial arteries do not occur with great frequency, even in elderly patients. In cases when the finger pressure wave appears damped or has unexpectedly low systolic and diastolic levels, or when a return--to--flow systolic calibration procedure causes level corrections greater than +15 mmHg over and above the level correction already applied automatically, it is recommended to switch to the other arm to see if conditions improve. When a finger pressure curve is seriously damped a message will appear immediately above the pressure pulse display, alerting to this condition.

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Take the patient's hand in your own warm hand, speak a few comforting words, explain about the device and how it behaves. Try the right (dominant) hand; it tends to have a higher pressure in the finger. Wrap a warm--colored towel loosely around the hand with the cuff. Place the hand simultaneously on a warmed pad or rubber flask filled with warm water. Cover the other hand as well. Raise the hand above the head for at least one minute. One minute is the time constant for arterial smooth muscle tone to relax. Then lower the hand to heart level and start a measurement. Let your patient stand up and spread out their arms. Then make a forceful horizontal circular motion where you start with your arms spread out, to move them rapidly (centrifugal force) to-

4.3.3 Costo--clavicular cutoff

Infrequently, in some patients the subclavian artery may become compressed between the ribs and the clavicle. The result of this compression is a damped pulse or a completely occluded artery and no pulse

at all, in which case Finometer cannot start. When a patient reports about frequent occurrences of numbness or tingling sensations in the fingers this is often an indication that such compression can be present. The condition is easily remedied by changing the position of the arm until a pulse is palpated at the wrist.

4.3.4 Cyanotic finger tips

Using finger cuffs cyanotic finger tips often become visible after several minutes of monitoring. Obviously, venous congestion distal of a finger cuff does occur and the venous blood visible in the plexuses appears as a blue or a pink coloring of the skin. A pink color is seen at a high degree of arterialization of the congested blood. In addition, numbing of tactile sense is occasionally reported by some patients. Upon removal of the cuff, reddening of the skin under the cuff always occurs. All phenomena disappear within a few minutes after the measurement is stopped, suggesting that the method can be tolerated for very long periods without harm. No obvious swelling of the fingertip is observed and no long term effects have been reported. Keeping the fingers and hand warm during the measurement improves finger tip arterialization tending to change finger tip color to pink and reducing the rate of occurrence of numbing the tactile sense. The theory of this is as follows: The arteries un-

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der the finger cuff are dynamically unloaded and the arterial walls float steady at their unstressed (slightly smaller than normal) diameter. The unloaded arteries still have about 60% of their original distended diameter. The veins under the cuff are collapsed and block venous return flow. The finger tip distal of the cuff thus contains a pool of blood in arteries, arterioles, capillaries, venules and veins all at arterial pressure. During systole blood flows in through the open arteries under the cuff filling the distal circulation and raising the pressure. Since this blood is arterial it partially refreshes the congested venous blood. In diastole some congested blood leaves the distal finger tip through the still open arteries in a retrograde direction. This process is more thorough the easier the blood can fill and empty the finger tip circulation. When in-- and outflow is so easy that it reaches the venous blood in the small veins below the skin the finger tip is seen to color pink. When in-- and outflow is compromised due to arteriolar constriction the finger tip colors blue. Relaxed arterioles can be seen frequently during normal sleep. Gravenstein, et al. 8 reported a substantial capillary oxygen pressure remaining in the finger tip distal of a Finapres cuff of from 49 to 58 mmHg compared to about 80 mmHg normally and Pulse Oximeter saturation of about 93% with much variability. Interspersing regular rest periods of 30 s every 5 minutes during 30 minutes of monitoring did not improve capillary oxygen partial pressures.

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4.4 Height sensor nulling & placement slide

Blood pressure is referred to heart level since Hales. The upper arm Riva--Rocci cuff is almost always near heart level, but a finger cuff is not. Thus, to sense the position of the finger with respect to the heart, a height correction system is included in Finometer. It has a sensor to be placed at heart level and another at the finger. The height of the liquid column between the sensors is measured by a pressure transducer and automatically subtracted from the finger pressure. Sensor placement and sensor nulling require some attention. tem may also show drift. This drift may have varying causes and cannot be adjusted in the field. It can, however, be checked as follows. 1. From the Finometer--Start display start the Finometer--research instrument by pressing [Finometer--research] twice, it is the left most button under the display. Press [Configure] once, it is the right most button under the display; if [Configure] is not shown you are doing a measurement and cannot check height. or to select "transducer check". Press Press and to select "height". This card shows a display of relative transducer height expressed in cm. Follow the blue instructions displayed on the card.

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2.

4.4.1 Nulling

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3. 4.

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Height system nulling normally is automatic from its previous value. This null is essentially stable but may show some drift with time. It is best, therefore, after the Research or Clinique instrument has been selected and activated, to check the height null before starting a measurement. Follow the instructions on the help slide (facing). Furthermore, renulling is required if the height correction unit was removed and reinserted or if another height correction unit is connected. An on screen message alerts the operator to it. See the depicted procedure.

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If the sensors are held 100 cm apart vertically, and the indicated height is only 90 cm, the system has a 10% error. This unit should be replaced. In the case that no replacement is available, it is best to keep the hand close -- within 20 cm -- to heart level. In that case a hydrostatic height difference of no greater than 20 cm is associated with an error of less than 2 cm (10% of 20 cm) water column or 1.5 mmHg in blood pressure for the defective unit, which is often acceptable.

4.4.2 Sensitivity

The sensitivity (the gain) of the height correction sys-

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4.5 The Finometer front panel buttons slide

Finometer embodies three instruments in one device, the Research, the Clinique, and the Classico instruments (section 3.4 on page 30). The Clinique instrument has a simplified interface without tab cards. The descriptions below and facing, therefore, apply only partially to the Clinique instrument. The Research and Classico instruments, however, do have tab cards to select options, to enter patient information, to configure displays. Their function is as follows: · the selection/confirmation buttons immediately below the display jump to the associated on screen tab card or button, and double arrow buttons move the between on screen tab cards or buttons, the and arrow buttons move between columns on a tab card, they thus have no function in the Clinique instrument, the and arrow buttons move between dis· · played selection or change a displayed value, the mark button places a marker in the results file and in the trend display, the start/stop button starts or stops a measurement.

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The mark button also serves to null the height correction system when no measurement is ongoing. It is recommended, however, to use the {Configure} card in the Research instrument since it additionally allows the checking of system sensitivity, see section 7.3 on page 69. A special extra function is activated by pressing the and buttons simultaneously. This allows to EXIT the currently running instrument and to return to the Start display.

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4.6 Waveform modeling & level correction slide

Finger blood pressure pulsations are tens of milliseconds delayed with respect to intrabrachial ones since they travel farther. In addition, their levels are generally lower, and the waveforms appear more distorted 7. When we studied these distortions in detail it appeared that they can be explained by a generalized "forward (i.e. brachial to finger)" transfer function or linear filter effect 6. Clearly, low frequencies in the brachial pulse, those below 2.5 Hz, are attenuated and higher frequencies are amplified, in particular those near 8 Hz. This is shown in the figure, left panel thin curve. Although this transfer function is not the same for each subject the differences are so small that the distortion can be explained with little error by a single generalized transfer function. To correct distortion we thus could design a "reverse (i.e. finger to brachial)" or inverse filter with a shape such that the natural, forward transfer function is precisely compensated. This inverse filter's response is shown as the thick line in the figure. It emphasizes lower frequencies and has an anti-resonance near 8 Hz. The original and the resulting inverse filtered finger pressure pulses are shown in the figure, right panel upper two boxes. The delay in the finger pressure we did not compensate. After inverse filtering both waveforms are nearly identical in shape, but the pressure levels are not compensated well. Thus, we also studied the differences in the systolic, diastolic and mean pressure levels 7. It appeared that pulse pressure was correct on average after inverse filtering but that all pressure levels were high. Using the inverse filtered systolic and diastolic levels we next developed a generalized level correction equation to return level differences to near zero on average, although not too well individually, and to slightly reduce the standard deviation of the differences 7. The effect of generalized level correction on the pressure pulses is shown in the figure, right panel bottom box. In this particular case correction is nearly perfect but this is not always so.

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4.7 Level calibration by return--to--flow slide

The level of the finger pressure waveform after generalized correction, statistically, is not or is only marginally within AAMI requirements 1, section 3.6.1 on page 32. That situation can be improved by performing an individual upper arm cuff systolic calibration 2. For this purpose an arm cuff is wrapped on the ipsilateral arm and automatically inflated and deflated by a computer system upon operator command. When arm cuff pressure is suprasystolic no pulsations can be sensed in the finger. The first pulsation that passes under the arm cuff signals return to flow. It is sensed in the finger and detected by software. Arm cuff pressure is read at that instant and the reconstructed brachial pressure of the previous section is further shifted in level by an individual amount thereby improving bias and precision substantially, page 32. It is not clear at present if and when this calibration needs to be repeated although there are indications that the inverse filter and generalized level correction take care of the variability over time in finger pressure levels with respect to brachial. If this were true under all conditions a return to flow systolic calibration would not need to be repeated. Presently, however, we recommend that the calibration procedure is repeated at each major change in hemodynamics.

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4.8 Finometer instrument selection slide

In the Start display softkeys allow selection of one of three instruments by pressing its associated button twice, once to select and once to activate. Once an instrument is running return to the Start display is and simultaneously. When in by pressing a measurement, however, stop it first by pressing the start/stop button. The distinguishing features of each instrument are described briefly on the slide, on page 6 and in section 3.4.

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5 The Start display

When Finometer is turned on the Start display shows up after a few seconds (facing page). The TNO logo (see under FMS and TNO in the Glossary D on page 117) is shown upper left, a copyright note upper right. The copyright note also presents the software build date as year and day--number of the year: (C) 2001.083 TNO, meaning the 83--rd day of the year 2001. At the screen bottom six soft keys are available, operated by the hardware buttons just below, from left to right: [Finometer research], [Finometer clinique], [Help slides], [Square wave cal], [Pressure wave cal], and [Finometer classico]. The [Help slides] button is preselected. When you are new to finger pressure measurement with Finometer please take some time to scan these slides, or this guide from page 34. To activate the help slides press or . Exit by pressing any other button, start/stop or press the [Help slides] button once, then press for example start/stop . From the Start--display the four analog output BNC--type connectors located on the analog input/output (I/O) box can be supplied with a calibration waveform to calibrate subsequent analog or digital recording channels. See page 46.

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A Finometer software instrument (Research, Clinique or Classico) is selected by pressing one of the below screen buttons twice. Try and press the [Finometer research] button twice to start the Finometer--research instrument. Once its display has been built up press the and buttons simultaneously to return to the Start display. Finally, it is possible to off--line download the packet files stored in Finometer. To do this you have to run the supplied so--called "null modem" cable between the serial I/O port marked "RS232" on your Finometer and a COM port on a Windows PC. On the PC execute the Finolink program, select the COM port to which you connected and you have access to all the data files stored in the Finometer without deleting any files on the Finometer. For further details on the Finolink program please refer to the Beatscope 1.1 User's Guide, and for Finometer file storage and recovery to page 54. 5.1 5.2 5.3 5.4 The Finometer selftest 45 The calibration signals 46 Off--line downloading of stored packet files Failure to start--rebuilding the index 48

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47

5.1 The Finometer selftest

The Finometer performs selftests to check if the embedded computer is still running and if essential hardware is in operating order. The result of these tests is not shown unless an error is detected. In the figure (facing page) all errors are listed. Gray errors can be corrected easily, yellow errors are serious hardware errors but affect only upper arm cuff operations, red errors are serious hardware errors. If a red or yellow error occurs, or if a gray error persists you should contact FMS immediately (see page 3). Frontend not connected: If the frontend cable connector is not inserted in its receptacle (see figure 2.1 on page 19) this gray error appears. The error should disappear after the connector is inserted and seated firmly. Height sensor absent: If the hydrostatic height sensor's electronic connection (see figure 2.3 on page 21) is disconnected the gray error appears. Reconnect and the error should disappear. Height sensor not nulled: When the hydrostatic height sensor is not present at start up Finometer assumes that a new unit will be used. In that case it asks the operator to renull manually. Armcuff xdcr out of order: Arm cuff pressure is transduced by a semi--conductor pressure transducer within the device. It is automatically nulled. When this automatic null is not achieved the yellow error is signalled. Return--to--flow systolic calibration of finger pressure is not possible. Buffer xdcr out of order: The arm cuff is inflated from an air buffer. Pressure in this buffer is measured by a semi--conductor pressure transducer. Upon failure of the transducer this yellow error appears. Internal ground fault: Finometer cannot perform normally. Power supplies not well: Finometer cannot perform normally. A/D converter not well: Finometer cannot perform normally.

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5.2 The calibration signals

The square wave calibration signal has been designed to allow for checking the · · · · ·

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sensitivity, zero offset, signal polarity, recording speed, and dynamic response characteristics

case for an ECG recording channel, a rising baseline and drooping topline should then be observable at this slow speed waveform. Such a recording channel is not suitable for blood pressure signals. The same calibration square wave is present at the analog outputs after selecting the Research and Clinique instruments. Before a measurement with these instruments is started the calibration square wave is automatically supplied to the four analog output connectors, and automatically removed when a measurement is started or a channel is configured as an external input channel, see section 7.7 on page 73. The pressure wave calibration is a single, exactly repeating finger artery pulsation, recorded in a young adult subject. Its systolic pressure level is 1295 mV, diastolic is 710 mV, pulse interval is 930 ms (exact) and calculated heart rate 64.5 BPM. These values are also displayed on screen. The signal amplitude is specified in millivolt (mV) and for Finometer 1000 mV corresponds to 100 mmHg. Thus S/D is 129.5/71 mmHg. Your pulse wave detection software should be able to closely approach these values if the recording channel has adequate dynamic response, no offset, and correct timing and sensitivity.

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of a subsequent analog recording channel and to manually adjust sensitivity and offset or to automatically program such adjustments at a later time. The signal moves between three levels: 0, +1, and +2 V, spending 60% of the period at zero and 40% of the period at either positive voltage level. Check polarity on this 40/60% property. Five cycles of exactly 1 s duration, or 1 Hz, or 60 BPM are generated first. All these numbers are displayed on screen. Check the recording channel's rise time and overshoot at this 1 Hz frequency. Rise time should preferably be less than 5 ms, overshoot ideally 0%. Next a single 10 s square wave is generated. This is well suited to manually adjust your recording channel's zero offset and sensitivity, providing ample time for an operator. If a recording channel is AC coupled, as may be the

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5.3 Off--line downloading of stored packet files

Each finger arterial pressure measurement that is made with the Finometer Research or Clinique instruments is stored in a revolving store on disk. In a full revolving store a newly arriving packet automatically overwrites the oldest packet present. A revolving store, therefore, does not have to be erased. Finometer's store can hold maximally 4096 files of maximal total duration of 24 h, in 512 byte packets of 0.5 s storage each. If these packet files are needed for later analysis they can be downloaded off--line by Finolink as long as not overwritten by new packets. To perform off--line downloading the Finolink program must be started on a Windows personal computer linked to Finometer via the so--called "nullmodem" cable supplied with the device. There is no other way to download files. In the Research and Clinique instruments both on-line (while a measurement is running) and off--line downloading are possible. In the Start display only off--line operation is possible and measurements cannot be started while downloading. If an analog output calibration signal has been started, however, it will continue. For further details on downloading see · · · section 2.3 on page 22, section 6.4 on page 54, section 8.3 on page 84.

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5.4 Failure to start--rebuilding the index

When the power plug was accidentally pulled during a measurement the system does not have time to update the pointer index file (a directory like structure) and to properly terminate files. At the next Finometer power--up this is detected by the software. The situation is quite similar to improperly terminating Windows. The system detects which files are OK and which need reconstruction or recovering. You select the action to be taken and are asked permission before any operation is started. If you decide not to act because you want to contact FMS first (page 3), simply press the mark button and the Finometer will go into a state of hibernation. Switch power off and on to wake up.

page 48 previous page next page ... hr 23 ...... Pointer file reconstructed.

Progress is shown by typing a . for each minute of data packets reconstructed. Thus, per hour reconstructed 60 . are typed. Your interrupted data file is also recovered (as far as it was written to internal memory) and properly terminated. The total operation takes approximately 10 min. After successful completion of either process return is to the Start display to start a measurement. The recommended approach is to first try [F1]. This operation is fast and when successful does the trick. When the recovery operation shows errors try [F2] which will almost always work. Try [F3] if nothing else works but the next time you do a measurement you overwrite even recent earlier files. After this action is successful you may, therefore, want to try [F2] again since no data file is yet erased, and still keep previous files. In summary, [F1] is fast and usually successful. [F2] can always be done but is time consuming. [F3] is also fast but destroys data files unless reconstructive action is taken.

This screen is shown initially:

Pointer file corrupted... [F1] to recover lost file [F2] to reconstruct pointer file [F3] to start new empty pointer file [mark] to escape ^^Which? [F1] pressed: will recover lost file... [start/stop] to confirm, [mark] to escape? [start/stop] pressed: recovering lost file... ... Lost data recovered.

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When you go for reconstruction you will see appear:

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6 The Finometer--research instrument

The Finometer--research instrument was designed with a researcher in mind who is in need of full control of all the options that Finometer offers. Even remote control of some functions is available. Yet, relative simplicity of operation is maintained by grouping various options logically on Tab cards on screen. For example, the entering of patient information is grouped on the second tab card from the left and data entry is not more and keys to select and complex than selecting an information column on the card and pressing the change a value. On--line context sensitive help is available. Press the [Help] button and the relevant help text appears. Press the [Help] button a second time and a table of contents is shown. Use the and keys to highlight a topic, then press the [Help] button once more to move to that help paragraph. Five of the 15 derived parameters can be trended on screen of which three of the pressure parameters are fixed. Convenient vertical and time scales can be selected by the pressing of a few buttons. Twelve derived parameters are displayed numerically on the right most tab card, with values updated every second of time. Four signal channels can be viewed, one at a time, with selectable vertical and time scales. A special calibration tab card shows information on Physiocal (left side) and on return--to--flow calibration (right side), and pushing a button turns either one off or on. When not in a measurement, all pressure transducers in Finometer can be checked interactively for zero and sensitivity. Furthermore, once you configured the screen display to your needs the configuration can be stored by moving to the configuration tab card and saving under a "color". Loading a configuration is just as easy. Running the Finolink program on a remote PC it is possible to place the Finometer near the patient with the display closed. Connected via a serial cable an almost complete copy of the Finometer--research display can be viewed on the PC screen. From the remote PC you may start and stop a measurement, turn Physiocal off and on, start and stop a return--to--flow systolic calibration, place markers in the Finometer packets and download this file at the same time. After selecting and activating the Research instrument in the Start display a first screen is shown always with the second tab card from the left {Describe subject} preselected. This should be interpreted as a reminder of the importance of entering correct patient data first. Treatment of the Finometer--research tab card system, however, is in the left to right order in which the cards appear on screen. The left most is the {Help} card.

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In the accompanying texts the notation that is followed is: a front panel button is marked by [ ], an on screen tab card is marked by { }. When a button is pressed its action is immediate. When by exception action is not immediate but a confirmation is needed this is always indicated by a message in blue lettering displayed on the tab card. For example, when entering patient data on the {Describe subject} card, a message appears: Press [Describe] to confirm changes. Correct patient data is essential since the SV/CO/TPR values depend critically on it. Confirm, therefore, any changes made.

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6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 6.10 6.11 6.12 6.13 6.14

Entering patient data--research 51 Layout of the Research display 52 The error message display--research 53 Files downloading and remote control 54 The Help card 55 The Describe subject card 56 Setting a subject's data 57 The pressure--volume diagrams 58 The Select trends card 59 Cardiac oxygen supply/demand 60 The Select A/D signal card 61 The Physiocal card 62 The Return--to--flow--cal card 63 The Derived variables card 64

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6.1 Entering patient data--research

After starting Finometer--research the most noticeable line displayed is: "Enter Age and gender". Knowing the exact age and gender of the subject is important information for an optimal pattern recognition, but is essential for setting up the Modelflow simulation with correct model parameter values to compute cardiac outflow.

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subject descriptive data by reselecting the {Describe subject} card and changing the settings. In that case part of the packet file will contain stroke volume and cardiac output data computed with an incorrect patient description. In subsequent evaluations with our Beatscope software this is detected and you are asked if you want to recompute the results. To change any of the displayed values:

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Although to enter this information at the start is not enforced, the first display screen draws attention to the missing subject information and induces an operator to enter the patient data first. When a rapid start is required or when the information is not available Finometer software assumes the current values to be acceptable. In the case that no gender is selected gender is shown as decide and an intermediate setting is assumed. In the Finometer--research instrument it is possible at any time during the measurement to adjust the

1. 2. 3. 4. 5.

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or to move to the desired parameter press column on the tab card, press or to change the value of the parameter, press or to move to the other parameters, and change their values, press the [Describe subject] button below the screen to enter the data, check in the right model information display panel the entries Pat: BSA:

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6.2 Layout of the Research display

The Research screen has five horizontal layers, from the top: · · · · ·

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the software identifier and status line, the (flow--)derived parameter trend display layer, the pressure parameter trend display layer, the miscellaneous information layer, the tab card program control layer.

scale spans 1 s. The middle panel is a trend display of the three pressure levels (S/D--M) measured on the processed pressure waveform at the left. The vertical and time scales are selectable, see section 6.9 starting on page 59. The dual numeric display shows the eight--beat running average systolic and diastolic levels. The miscellaneous information layer left panel shows todays date, the beeper state, the unit system, the active finger cuff (1 or 2), the time lapsed and the total measurement time available on this finger before the next finger switch (here 3/30 min). Also shown are the current file name and size, and the finger height (here -15 mmHg, which is below the heart). The middle panel shows one of the four sampled signals that are also stored on internal memory. Normally they are finger arterial pressure (FinAP), finger hydrostatic height (Height), arm cuff pressure (Armcuf), and finger plethysmogram (Pleth). An internal signal can be replaced by an externally supplied signal for display and storage, if so configured, see section 7.7 on page 73. The right panel lists patient information and model parameter values. The three Modelflow parameters are framed in white. BSA (body surface area) is according to Dubois and Dubois. The tab card instrument control layer is treated in following sections.

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The status line shows the TNO logo, the time, and a copyright note. When an error occurs time is replaced by an error message which remains for 10 s. During a measurement the copyright note is replaced by the Physiocal state. The time display shows clock time and time lapse since the start of the current measurement or when off--line the idling period. Clock time can be adjusted via the {Configure} card date and time section, see section 7.9 on page 75. The derived parameter layer left panel shows the Modelflow curve. The vertical scale is from -250 to +1000 ml/s. The horizontal scale is 1 s, with 0.1 s tick marks. The middle panel is a trend display of two selectable derived parameters, section 6.9 starting on page 59. The dual numeric display shows two trended parameters as eight--beat running averages. The pressure parameter layer left panel shows the processed pressure waveform. The vertical scale is the same as in the trend panel. The horizontal

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6.3 The error message display--research

Normally the top status line shows clock time and time lapse since measurement start in green letters on a black background. When an error occurs the time display is replaced by an error message in red color. Typically, an error message signals a condition in which Finometer cannot function properly and from which it cannot recover automatically. The measurement is stopped and the error message is displayed 10 s. At the start 3 beeps are sounded, followed by another 3 beeps after 5 s. After another 5 s the message disappears and another start can be attempted. In the case shown the finger cuff air hose got dislodged and must be reinserted. After the forward slash (/), the procedure where the error was detected is named. The message is also stored in the last packet of this measurement's file on disk. Here are some of the error messages: Connect frontend/startAutolock

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Check air supply/steadyPressure Check armcuff air supply/fillRivabuffer Unstable pressure/steadyPressure No plethysmogram/failAutolock Finger too thin/checkFrontgainDn Check cuff cable/centerPlet Connect cuff cable/checkLEDcurrent Faulty finger cuff/setLEDcurrent cuff--LED problem/checkLEDcurrent Error messages, unlike alerts or alarms, represent situations that are not considered dangerous. They have to do with dislodged connectors, contracted finger arteries, or worn cuffs. For a list of annotated error messages see "Error messages" on page 114

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6.4 Files downloading and remote control

Each finger arterial pressure measurement that is made with the Finometer--research or clinique instruments is stored in a revolving store on disk. In a full revolving store a newly arriving packet automatically overwrites the oldest packet present. A revolving store, therefore, does not have to be erased. The files can be downloaded off-line by a remote PC with program Finolink. Files downloading can be done while the Finometer is doing a measurement. This is called on-line downloading. For on--line downloading you must start the Finolink program and click its "Monitor" button, see figure 2.4 on page 22. This is completely invisible to the Finometer operator. Off--line files downloading was discussed briefly in section 2.3 on page 22. Any measurement file present can be selected for off--line downloading. It requires full control over the Finometer packet store so that no new packets can be stored. Thus, off-line files downloading and doing a finger blood pressure measurement are mutually exclusive. A warning is issued in that case that a measurement cannot be started, see facing page. To start either form of downloading: 1. 2. Get a "null-modem" cable. There is one supplied with your Finometer. Plug one end of the cable into the Finometer 3. serial I/O connector marked "RS232", located at the rear. Plug the other end into one of the PC serial ports possibly labelled COM1:, etc. In the case that the supplied cable is of insufficient length you may extend it with ordinary (non-null-modem) serial cable. Start Finolink on the PC by double clicking on its icon, or go via Beatscope. If not done configure the COM port number: click on `Configure', the `Serial port', and select the desired COM port. Click on `Select'. For on--line downloading click on "Monitor". A display is shown quite similar to the Finometer-research display. If the Research instrument is running on Finometer you can control four of its actions remotely: · start and stop a measurement run, · start and stop a return--to--flow upper arm cuff cycle, · turn Physiocal off and on, · place a marker. For details see the Beatscope 1.1 User's Guide Finolink chapter. These four items allow the remote operations that might be needed in case the subject and the Finometer are not in the same room as the experimenter.

4. 5.

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6.

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6.5 The Help card

The Finometer--research instrument has more than 100 help paragraphs built--in. They explain some of the methodology and ways to control the Research instrument. 1. Press the [Help] button once to bring up the {Help} card to display the first help paragraph, see facing page. or to display the previous or Press the next help paragraph. Keep the or depressed to leaf through the paragraphs in greater steps. Press the [Help] button again to display a table of contents. or to highlight a topic of interest. Press Press the [Help] button once more to jump to the selected topic. Press one of the other Tab selection buttons then 8. press the [Help] button again to display help for that {Tab card}. Some {Tab cards} have subsections. Move to the subsection and then press the [Help] button to display more detailed help.

Throughout these help paragraphs [] {} () <> signify signify signify signify Finometer front panel buttons, tab cards, miscellaneous information, literature references.

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2. 3. 4. 5. 6. 7.

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Thus: [Help] -- a button, {Configure card} -- a tab card on screen, (Files downloading) -- some miscellaneous information, <Langewouters> -- a literature reference.

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6.6 The Describe subject card

Finometer provides for finger arterial blood pressure measurement but the reason we searched for a noninvasive method to give us calibrated phasic blood pressure waves around 1975 was that we needed it as input to a pressure pulse contour algorithm to compute cardiac stroke volume and output. Later, as a successor to pulse contour methods, we developed the Modelflow method for computing a cardiac flow curve. One of the reasons that Modelflow shows better precision than earlier pulse contour methods is that it uses a patented, nonlinear, self-adaptive simulation model based on aortic hemodynamic properties measured never before with such precision by Langewouters. 15 Langewouters showed that human aortic properties were substantially nonlinear and that nonlinearity depended strongly on a subject's age and gender, and slightly also on height and weight. Hence the importance of entering the patient parameters from the start, so that the Modelflow method will be better in estimating and trending stroke volume and cardiac output. It would be expected that properties also depended on degree of arterio-sclerosis but it appeared from Langewouters' studies that the stiffening of the arterial wall in sclerosis is compensated by an enlarged diameter in such a way that hemodynamically they are behaving almost identically. In the Research instrument it is also possible to enter these patient data at a later time while doing the measurement, but this means that if stroke volume and cardiac output are needed they must be recomputed, with the correct patient data for the entire file, in off--line analysis using the original pressure waveforms. The Beatscope software alerts the user to this situation and will perform this analysis when so instructed.

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6.7 Setting a subject's data

To set any of the values gender, age, height or weight: 1. 2. 3.

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6.7.1 Thermodilution cal

If, during a measurement, a thermodilution cardiac output estimate is 4.5 l/min and Modelflow indicates 5.0 l/min, then set Calib-% to: (4.5/5.0) × 100 = 90%. 1. 2. 3. or to move to the Calib-% column press on the tab card, press several times to change the value from 100 to 90, accept the changed value by pressing [Describe subject].

4. 5. 6.

press or to move to the desired parameter and column on the tab card, press or to change the value of the parameter, press or to move to the other parameters and change their values, note that in the right model information panel the entries Pat: BSA: have not yet changed. press the [Describe subject] button just below the screen to enter the data, check that the entries Pat: and BSA: did change.

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The fifth parameter that can be adjusted on this tab card is Calib-%. Entering gender and age sets the aortic cross--sectional area, A, to an average value for the population of that age and gender, with fine adjustments for height and weight possible. In contrast to the other aorta parameters, the `A`-parameter has a rather poor precision of somewhat less than 20%. Unfortunately, the absolute level of the stroke volume and cardiac output computed is directly proportional to A. A 10% wider aorta than the population means a 10% greater cardiac output for the same pressure level and waveform. The `A'-factor should be calibrated out, but this requires an extra measurement, for example by thermodilution or US Doppler aortic diameter.

6.7.2 Aortic diameter cal

If an US scan measures a thoracic aortic diameter at the current pressure of 29.3 mm, but in the left model information panel the diameter shown is 25.4 mm, then: 1. 2. 3. or to move to the Calib-% column press on the tab card, press or until Dao: shows the same value, accept the changed value by pressing [Describe subject].

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6.8 The pressure--volume diagrams

The small diagrams shown on the {Describe subject} card at the far right serve to show the importance of entering proper age and gender. The resultant aortic pressure--volume diagram is shown in black and the associated pressure--compliance diagram in purple color. Pressure ticks on the horizontal axis are at 50 mmHg increments; pressure span is 0 to 200 mmHg. Both curves are clearly nonlinear. The compliance curve for the young adult is rather wide, peaks at 50 mmHg to decline moderately at higher pressures. For the elderly subject the compliance peaks at 10 mmHg, peaks higher, and decreases more quickly with increasing pressure. The importance of this nonlinearity can perhaps best be clarified with a numerical example. Given aortic compliance we can compute the volume pressed into the aorta by measuring its associated pressure rise. If this compliance is 2 ml per 1 mmHg pressure increment then a pressure rise of 40 mmHg during the systolic pressure upstroke means a stroke volume of 40 × 2 is 80 ml. The aorta's compliance at low distending pressure is, as indeed shown, substantial but at higher distending pressures compliance progressively decreases. Typically, for a 50 year old patient aortic compliance could be 3 at 50 mmHg distending pressure, 1.1 at 100 mmHg and 0.5 at 150 mmHg. Thus the same 40 mmHg pulse pressure equates to 120, 44 and 20 ml stroke volume depending on pressure. Moreover, the numbers change with the patient's age and nonlinearity is more severe in the elderly. Aortic compliance is no solid physiological basis for a pulse contour method unless carefully modelled. 16

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6.9 The Select trends card

The fundamental Finometer signal is pressure. It is always displayed in the lower trend panel and cannot be deselected. On display are the pressure pulsation left, the systolic, diastolic, and mean level trends at selectable sensitivity, and S/D numerically in selectable units (mmHg, hPa or kPa). The vertical scale for the pulse display and for trending are always the same, see facing page top diagram. Depending on configuration (see section 7.6 on page 72) direct finger arterial pressure or a processed, reconstructed pressure pulse are displayed. This is indicated above the pressure trend panel. Default it is Brachial from FIN before RTF-cal initially. The currently configured unit of measurement is also shown, here the mmHg. Any two of fifteen available parameters can be selected for trending in the upper trend panel. All are derived from pressure: MAP, CO, SV, TPR, HR, IBI, LVET, D/SPTI, PS*HR, CI, SVI, PRI, dp/dt, Zao, Cwk. Trends and numeric displays show 8--beat running average values. The numeric values are updated in pairs once every other second. Their meaning and computation details are described in section 3.5 on page 31. There are four time scales: spanning 6 and 30 min, 2 and 8 h full scale. Only the most recent period data are shown. Thus, when viewing the past it appears as increasingly compressed with further averaging applied. To select a time scale: 1. 2. 3. Press the [Select trends] button once. until the Time scale select column is Press highlighted. Press or until the desired time scale is displayed. The selection effect is immediate.

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The time span displayed offers the most recent window on a possibly larger recording. The displayed period since measurement start is shown below the time axis in both trend panels. The relationships between the selection columns on the {Select trends} card and the derived parameter and display scales is shown on the facing page. To select any parameter or scale: 1. 2. 3. Press the [Select trends] button once. or until the desired select column is Press highlighted. Press or until the desired parameter or display scale is shown. The selection effect is immediate.

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6.10 Cardiac oxygen supply/demand

The build-up of tension in muscle is associated with great oxygen consumption. The shortening of muscle and ejection of blood consumes much less. Thus, the height of the generated systolic pressure points to the level of cardiac oxygen demand per beat. The higher the heart rate is, the more often this amount of oxygen is demanded per minute. Thus, PS*HR is considered an index for cardiac oxygen demand per min. Finometer computes this index for display, trending and output. The product of systolic pressure and heart rate is expressed in meters--mercury--per--minute and selected as the right trended parameter, facing page. The unit of m Hg/min is equivalent to k--mmHg/min, thus 7.57 m Hg/min as displayed means 7570 mmHg/min. With the perfusion of cardiac muscle mainly taking place in diastole and being proportional to diastolic pressure (diastolic pressure time index) on the one hand, and cardiac effort and hence oxygen demand principally proportional to systolic pressure maintained in systole (systolic pressure time index) on the other, their ratio (DPTI/SPTI) is considered an index of cardiac oxygen supply/demand. This index we labeled D/SPTI, expressed in %. Levels below 50% are often associated with ST-segment depression. For the computation of D/SPTI in Finometer a reconstructed aortic pressure waveform is used obtained by inverse filtering, and independent of the choice of pressure reconstruction that is made. Inverse filtering is the process whereby a waveform passing by in real time is subjected to an inverse transfer function. The effect is the same as applying an inverse transfer function in off--line computer analysis but is achieved in a different way. The inverse finger to aorta transfer function in Finometer is experimental in that it is obtained over a somewhat smaller population than usual. Its shape, however, is essentially identical to ones published in literature.

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6.11 The Select A/D signal card

The waveform display in the signal information panel is like an oscilloscope. It displays one of the four Finometer original signals as in the table below, or external signals when they are connected and chosen for sampling. At the same time these signals are stored in the packet files and output via the analog I/O box. For the oscilloscope, the channel, its vertical sensitivity, zero line position and time scale can be selected. The left vertical scale shows which internal signal or external channel number is viewed. Thus the oscilloscope display, the analog output signal, and the packet stored signal are identical. Channel

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beled Ext 1..4. Each pixel represents several samples. All samples are taken and a vertical line is drawn between the minimum and the maximum value. Thus no fast oscillations are missed. To display a channel: 1. 2. 3. Press the [Select A/D signal] button. to highlight the Channel select column. Press Press or to select one of the channels [1..4]. Note that it is possible to select dsp off in which case the display area is blanked. Press to reach time axis setup column T [s/div]. The fastest speed is 0.5 s/div. A division is marked with a black dot and is about 1 cm wide. to set the position of the zero. Three Press choices are: at top, middle, bottom. Press to set full scale (FS) sensitivity. The effect of all selections can be seen immediately.

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4. Label FinAP Height Armcuf Pleth Signal Finger pressure Finger hydrostatic height Arm cuff pressure Finger plethysmogram 1 2 3 4 Table 6.1

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5. 6. 7.

The Finometer internal analog signals.

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Note that the reconstructed brachial artery pressure (reBAP) is not shown here, is not stored in the packets, and is not available as an analog output. reBAP is reconstructed later in Beatscope from FinAP with the same algorithms as are used in Finometer. When an external analog signal is selected it is preprocessed for offset and sensitivity, displayed, and la-

A typical setting for the channel 1 display (FinAP) to judge waveform quality is: · · · · channel = 1 time scale = 1 s/div Zero at bottom FS = 2.5 V 250 mmHg

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6.12 The Physiocal card

This tab card has a left or Physiocal--side, a middle diagram panel used by both sides, and a right or RTF--cal--side. Emphasized here (facing page) is the Physiocal side. It shows that Physiocal was turned off possibly to perform a Valsalva maneuver without having it interrupted by a Physiocal. The off state is also shown top right in the Finometer display:

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Physiocal off ! Physiocal is normally on. When Physiocal remains off for more than a few minutes the top right display will flash reminding you. To switch Physiocal states: 1. From its present state press or or press the [Physiocal & RTF-cal] button. Either action switches state. Press any one of these buttons again and switch Physiocal state once more, and so forth. From any situation in the Finometer--research instrument press the [Physiocal & RTF-cal] button once to select it and once more to switch Physiocal states.

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The Physiocal side presents Physiocal diagnostics information: · Physiocal excellent. This is the best grade

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available. The other levels are great, good, useful, sufficient, adequate, inadequate, very inadeq, uncertain. setp 334 indicates a good size finger on which measurements are made easily. But any servo setpoint level is in principle acceptable. pleth 90 indicates a good size artery on which measurements are made easily. This number may be seen to vary from 4 to 400 between subjects. The larger the better. gain 106 indicates a well performing servo loop. Gain preferably is some 20 to 50% greater than pleth. If much greater then an oscillation may have occurred on which the servo system automatically reduces gain, which results in a larger gain number. shape 4 indicates well formed plethysmograms. Values may range from 0 to 16. Lower values are better. state LOG indicates the state of the adaptive servo control system. Possibilities are L/S, O/F, G/Q. The dual diagram in the middle panel shows the finger arteries pressure--volume curve in black and a Marey oscillogram in blue. The horizontal scale has 100 mmHg tick marks, the vertical scale is arbitrary.

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6.13 The Return--to--flow--cal card

That no RTF has been done yet can be seen just above the pressure trend panel where is written Brachial from FIN before RTF-cal. To perform a return--to--flow systolic calibration take the following steps: 1.

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Wrap the upper arm cuff provided with your Finometer (it should have two air hoses) tightly on the arm where finger pressure is measured. Return--to--flow will be detected automatically by the finger cuff. Insert the tube sockets into the Finometer front side, either way is right, see figure 4.6 on page 40. Press the [Physiocal &RTF-cal] button. to activate the RTF--cal side. Press Press to select a cuff inflation type. A step inflation is often found more pleasant since it is quick and reduces congestion distal of the upper arm cuff. In about 50% of the subjects pooling is so small that finger pressure after stepwise inflation drops to values too low to be measured

with Finometer. In such cases select a ramp inflation, and/or hold the hand below heart level. 6. Wait at least two minutes since the previous RTF--cal. This can be monitored on the tab card as Ago 10 min 7. During the 30 s before inflation starts ask the patient to be quiet, without movement or talking. 8. Press the [Physiocal &RTF-cal] button. This starts inflation. Inflation is smooth and deflation linear. To emergency--stop press this button again. 9. While deflation progresses observe the middle panel. A first RTF level is detected after which a reinflate takes place. Both RTF levels detected are displayed in yellow. 10. Upon successful completion the RTF and Tot = RTF + cor level shifts will be computed and updated. Positive values mean up--shifts of finger pressure.

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6.14 The Derived variables card

The {Derived variables} card replaces the {Configure} card during a measurement run. On this card there is nothing to control or adjust. Configuration of options is not possible during a run. On the {Derived variables} card 12 variables are displayed numerically, lined up in four columns, from the left:

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pressure levels derived from the processed waveform, time intervals derived from the unprocessed waveform, flow related values derived from the computed flow waveform, flow related values indexed for body surface area (BSA) according to Dubois and Dubois.

ery 1 s. The units are added, and depend on the unit system originally configured. The colors of the values correspond to the trend colors. In fact, all derived variables colors are fixed and the same and coordinated throughout the displays, (appendix C on page 116). The symbols indicating the variables are shortened to 2 characters due to lack of space. Some unusual ones: PI is pulse interval (IBI), ET is left ventricular ejection time (LVET), RI is peripheral resistance index (PRI). The big white arrows indicate corresponding parameters. The values are not identical at all times since the big numbers displays are updated less frequently. These are 12 parameters, selected from the pool of beat--to--beat derived variables available and considered most useful for normal monitoring. More exotic ones can be displayed with the {Select trends} card, see page 59.

All values are 8--beat running averages updated ev-

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7 Configuring the Research instrument

The {Configure} card is only available off--line and used to check the calibration of pressure transducers, and to set various process parameters in order to adapt to various tasks and situations. The possibilities are grouped into five sections: transducer check: The Finometer has pressure transducers whose zeroing is automatic but whose sensitivities need to be checked. Erroneous sensitivities cannot be adjusted in the field. These four sensitivities can be checked: 1. the upper arm air supply buffer can be checked to reach the appropriate level; 2. the hydrostatic height sensor zero and sensitivity can be checked and the zero offset can be nulled; 3. the finger cuff pressure transducer can be checked for sensitivity and linearity against a calibrating manometer; 4. the arm cuff pressure transducer can be checked similarly. pressure reconst: Pressure reconstruction is the conversion from finger pressure to brachial artery pressure. Its details can be chosen under Configure. external signals: Finometer allows the sampling of external analog signals to be stored simultaneously with finger pressure. In addition, finger pressure itself can be replaced by an external analog pressure signal, optionally recorded at another anatomical site. date and time: For accurate event recording all clocks should be synchronized. Finometer clock date and time can be set under Configure. miscellaneous: Five personal, color coded Finometer configurations can be stored and recalled; finger switching intervals can be set (not in the present nullseries); the internal beeper can be turned off or on; the system of display units (mmHg, hPa, or kPa) can be chosen. 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 Transducer check--buffer pressure 67 Transducer check--height nulling 68 Transducer check--height calibration 69 Transducer check--finger cuff 70 Transducer check--arm cuff 71 Pressure reconstruction 72 External signal input 73 Which channel to choose? 74 Setting date and time 75

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7.10 7.11 7.12 7.13 7.14

Miscellaneous--finger switching 76 Miscellaneous--display units selection Miscellaneous--the beeper 78 Miscellaneous--saving a configuration Miscellaneous--loading a configuration

77 79 80

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7.1 Transducer check--buffer pressure

To check arm cuff buffer pressure: 1. 2. 3. 4.

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cycle should be nearly 1 min. If the pump cycle is much shorter an air leak may be present. The upper arm cuff is inflated from this air buffer. This allow a smooth and controlled, almost pleasant inflation. Although buffer pressure is higher, actual arm cuff pressure is limited to 300 mmHg, both by a hardware circuit and a software guard. In the case that a higher arm cuff pressure is reached circuitry tries to reduce arm cuff pressure to zero immediately and to switch off the pump. When this process is insufficiently effective, or when the procedure takes too much time (in compliance with CEI IEC 601-2--30) a visual warning is displayed, accompanied by 30 beeps. In that case you are to remove the upper arm cuff at once.

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If not already done, switch Finometer on. Select and start the Finometer--research instrument. Press the [Configure] button once to select it. or to highlight section transducPress er check Press to reach the Select xdcr column. Press or to highlight Buffer. The display on the facing page should now show.

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A simulated mercury column indicates arm cuff air buffer pressure. In rest, buffer pressure cycles between 750 and 800 mmHg by automatic switching of the air pump. This can be heard. A pump on/off

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7.2 Transducer check--height nulling

In the white field at the left the current height difference value is displayed in cm. On the left information panel Hite: is also shown in mmHg. Both indicate 0. Note the blue text on the card, explaining what to do to zero the system and to check its sensitivity. Height correction nulling is normally automatic from the stored value of a previous run. It is only when the frontend or height system became disconnected that a manual re-null is required. Nulling can be carried out only when Finometer does not measure finger pressure. Nulling can be done in two ways. The quick way is to hold both sensors together (as shown in section 4.4 on page 39) and press the mark button. The more involved way is by using the {Configure} card: 1. 2. 3. 4. 5. Press the [Configure] button once to select it. or to highlight section transducPress er check Press to reach the Select xdcr column. Press or to highlight Height. The display on the facing page should now show. Hold both sensors together (see section 4.4 on page 39) and press the [Configure] button. Height should now read 0 cm.

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7.3 Transducer check--height calibration

To check the height sensor system sensitivity: 1. 2. 3. 4.

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mm. If the sensors are held 100 cm apart vertically, and the indicated height is only 90 cm, the system has a 10% error. This unit should be replaced. There are no field serviceable parts here. In the case that no immediate replacement is available, it is best to keep the hand close -- within 20 cm -- to heart level. In that case a hydrostatic height difference of no greater than 20 cm is associated with an error of less than 2 cm (10% of 20 cm) blood column or 1.5 mmHg in blood pressure for the defective unit, which is often acceptable, and 90% of the height error is still corrected. The height correction system removes the hydrostatic errors that are caused by small shifts in finger position that otherwise go unnoticed. Since a 1.3 cm shift in finger height already causes and error of 1 mmHg the importance of this system is clear.

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Press the [Configure] button once to select it. Press or to highlight section transducer check Press to reach the Select xdcr column. Press or to highlight Height. The display on the facing page should now show. Hold both sensors together (see figure 4.5 on page 39) and verify that height reads 0 cm. Hold both sensors 50 or 100 cm or any known vertical distance apart, and verify that the Height indicator reads the same distance. In the left information display, for a 50 cm distance, Hite: should indicate -50 × 0.78 which is -39 mmHg.

The factor 0.78 arises from the density ratios of blood ( = 1.06) and mercury ( = 13.6), adjusted for the fact that one column is measured in cm, the other in

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7.4 Transducer check--finger cuff

The Finometer generates setable air pressure at the frontend box so you don't need another source of air pressure: 1. 2. 3. 4. 5. Press the [Configure] button once to select it. or to highlight section transducPress er check Press to reach the Select xdcr column. Press or to highlight Finger. Press to reach the setable air pressure column equipped with the simulated mercury column. The display on the facing page top panel should now show, but with null selected. Verify that the numeric display shows Finger 0 mmHg. This nulling is automatic. If a 0 is not shown there may a fault in the system. Insert a Luer into the frontend air outlet and run an air hose to your calibrating manometer. Press twice to set a 100 mmHg air pressure, indicated as Finger 100 mmHg, see facing page bottom panel. If a lower pressure is shown there may be a leakage in the air system just connected. Check that your calibrating manometer also indicates 100 mmHg or its equivalent 133 hPa, or 13.3 kPa. Differences should be less than 3 mmHg or 4 hPa or 0.4 kPa. 10. Linearity can be checked by measuring at each 50 mmHg level increment up to 250 mmHg maximal pressure. When Finometer is set to generate a certain pressure, such as 100 mmHg, its built--in servo system attempts to reach that pressure. This attempt will be unsuccessful when there is a leak in the system and Finometer indicated pressure will then be less than the set level. If, in an airtight system, the calibrating manometer and the Finometer indicated pressures differ by more than 3 mmHg then either one or both transducers have a sensitivity error. If you are certain of your own calibrating manometer then the Finometer transducer requires servicing. This cannot be done in the field and the frontend has to be returned to FMS, Finapres Medical Systems BV (see page 3). If, however, your calibrating manometer also has a 1% error the errors of both transducers add and you should allow for a 6 mmHg difference between the two. Handle transducers carefully, do not expose to extreme pressures or drop tests and mechanical shocks. With some care solid state transducers keep their calibration for the life of the device.

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7.5 Transducer check--arm cuff

The arm cuff transducer is located in the main instrument behind the air hose receptacle marked `s' in figure 4.6 on page 40, bottom left. 1. 2. 3. 4. 5. Press the [Configure] button once to select it. Press or to highlight section transducer check to reach the Select xdcr column. Press Press or to highlight Armcuf. Press to reach the setable air pressure subsection with the simulated mercury column. The display on the facing page top panel should now show, except with null selected. Get the air hose and connector assembly shown in the facing page upper panel. Insert the Luer into the frontend air outlet and the other side into the main instrument receptacle marked `s', front side, bottom left. Verify that the numeric displays show Finger 0 mmHg and Armcuf 0 mmHg. This nulling is automatic. If a 0 is not shown there may a fault in the system. four times to set a 200 mmHg air pres9. Press sure, indicated as Finger 200 mmHg, see facing page bottom panel. If a lower pressure is shown there may be a leakage in the air system just connected. 10. Check that the Armcuff transducer also indicates 200 mmHg. Differences should be less than 6 mmHg since each transducer may have a 1% of 300 mmHg full scale error. The arm cuff pressure transducer can also be checked with the Finometer--classico instrument, see section 9.2 on page 94. This is theoretically a better way since the transducer is then checked directly against your calibrating manometer and not indirectly against the finger pressure transducer. This concludes the section on transducer check.

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7.6 Pressure reconstruction

The Finometer--research device allows to select the details of finger--to--brachial waveform reconstruction as follows: 1. 2. 3. 4. 5. 6. 7.

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to highlight do not, see figure top Press panel. Press the [Configure] button to confirm.

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Press the [Configure] button once to select it. or to highlight section pressure Press reconst Press twice to reach the Filter column. Press or to highlight to brachial. This is also the default setting. Press and to reach the Level cor column and select yes. Press and to reach the Level CAL column and select yes. Press the [Configure] button to confirm.

You have now set Finometer to no reconstruction at all. Finger arterial pressure will then be displayed as with a Finapres device, see figure bottom panel. Without finger--to--brachial waveform filtering no level correction or calibration is defined. The four reconstruction options are: 1. 2. 3. 4. Waveform filtering to brachial artery pulsations only. 6 Waveform filtering plus level correction. 7 Waveform filtering plus level calibration. 2 Full brachial artery pressure reconstruction. Full reconstruction includes the generalized waveform filter, the generalized level correction and a further individual level calibration from a return--to--flow systolic determination added.

You have now set Finometer to what is already its default: full reconstruction. You may select any combination of filtering and level correction and calibration, but to level correct filtering must be selected: 1. Press twice to reach the Filter column.

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7.7 External signal input

Finometer--research normally records four internal analog signal but each one can be replaced with an external signal. Channels 2, 3 and 4 can sample any signal (always at 200 Hz sample rate). When channel 1 is configured "external" the normal Finometer finger pressure measurement cannot be started. Instead the external signal is analyzed after pressing start/stop . It must be an arterial pressure waveform of proper calibration: 1. Connect the external pressure signal to the analog I/O box input--1 BNC connector, see figure 2.2 on page 20 and section 2.4 on page 23 for instructions. Press the [Configure] button once to select it. Press or to highlight section external signals Press to reach the Channel-nr column. Press or to highlight 1=pressure. Press and to select external. The message Set pressure reconstruction... 7. 8. 9. is displayed, see facing page top panel. Defer this to last. Apply a zero pressure signal to input--1. If the Source-mV voltmeter does not read 0 then: to reach the Offset-mV column. Press Press or until the Source-mV reads 0, facing page, bottom panel. A 1 mmHg offset shows up as 10 mV. Next, apply a known fixed pressure to input-1, say 100 mmHg. The Source-mV voltmeter should now indicate 1000 mV, see figure 7.9 upper panel. The Source-mV shows 1033 mV, however, which is interpreted by Finometer as 103.25 mmHg, an error of +3.25%. Press to reach the Sensitivity- 0 00 column. / Press until the Source-mV reads 1000, see figure 7.9 lower panel. The channel is now ready for recording. Move to pressure reconst to set the anatomical recording site and the required pressure reconstruction, section 7.6 on page 72.

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7.8 Which channel to choose?

To Finometer--research you may connect up to four (4) external signals for input, sampling and simultaneous internal storage in the packet file. Except for input--1 which is always treated as a pressure signal, these channels are not analyzed, they are just recorded. Think of ECG leads, 2 respiratory signals, tilt table tilt angle, rectified MSNA recordings or rectified EMG, Doppler flow velocity, ergometer exertion level, an analog marker signal, etc. The sample rate is 200 Hz. The input voltage range is from -5.12 to +5.12 V with a resolution of 2.5 mV. Milli--volt amplitude signals, therefore, should be amplified first. Each one of the following four Finometer internal signals normally stored can be replaced with an external analog signal. Channel 1 2 3 4 Table 7.1 Label FinAP Height Armcuf Pleth Signal Finger pressure Finger hydrostatic height Arm cuff pressure Finger plethysmogram Consider which of these internal signals to best omit. Normally one would be least interested in the plethysmographic signal of channel 4 since it is near zero most of the time, then least in the only sporadically (during a return--to--flow calibration) nonzero arm cuff pressure signal of channel 3, then least in the height signal of channel 2 whose value is already used internally to correct the finger pressure for hydrostatic level errors. Replacing the finger pressure signal of channel 1 with an external signal, however, results in pulse feature detection and Modelflow cardiac output computation being performed on the externally provided pressure waveform. Even though, for example, the arm cuff pressure is replaced by an external signal, Finometer still has the arm cuff pressure signal available internally and will read its value at the instants of return--to--flow systolic detection as usual. In other words, the normal functioning of Finometer--research is not affected by configuring the signal channels 2 to 4 externally, as long as channel 1 is configured as internal.

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The Finometer internal analog signals.

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An ECG sampled at 200 Hz is undersampled for fine diagnostic purposes. For heart rate variability computations 200 Hz suffices if (parabolic) interpolation is used to refine the R wave fiducial point (see page 359 of 19).

7.9 Setting date and time

To set the date and time: 1. 2. Press the [Configure] button once to select it. Press or to highlight section date and time. In six columns from left to right the current date and time are shown updated each second, facing page. thrice to reach the Hour column. Press Press once to change 16 to 17 h going from summer (daylight saving time) to winter (standard) time. Press or to move to another column. Press or to change its value. Changes take effect immediately and are reflected in the on screen date and time displays. as follows: year mo da hh mm ss 2000 10 22 16 44 33 0OC22P16.445 Of the year only the last digit is used (0); the month is translated to a two character mnemonic: (JA FE MR AP MY JN JL AU SE OC NO DE); the date is taken in full; next follows a unique file type identifying character, which is a P for a Finometer packet file; this character is followed by the hour; the first two digits of the extension is the minute; the last digit is seconds divided by 6. Note that 33 divided by 6 is 5, and seconds 30 to 35 also produce a 5. When off--line downloading a file with Finolink you are thus able to see on which date and time a file was generated. Finolink also shows the patient description to more easily recognize a patient file from the directory listing.

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Date and time are used internally in the Finometer software as a file signature. For this purpose the date and time at the start of a measurement are taken and combined into a signature string which is stored in each packet of a file on disk. Further, date and time are used to construct an 11 character file name

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7.10 Miscellaneous--finger switching

In the present Finometer devices switching between cuffs is not available. In the software it has, however, been prepared: 1. 2. 3.

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test the proper functioning of finger switching. Automatically timed finger switching can be suppressed in the 10 s just before the actual switch instant by pressing mark . A warning message and beep alert the operator to a coming switch. After a period of uninterrupted monitoring on the same finger of 1 h the Cuff: message will change from dark gray to orange color. After 12 h of uninterrupted monitoring Finometer will stop the measurement and this cannot be prevented by the operator. Twelve hours of monitoring on a single finger has not been seen to do harm. 18 Frontend cuff switching may reduce irritation at the finger in awake patients, see a note on cyanotic finger tips in (section 4.3.4 on page 38). Pressures may differ between fingers. 11

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Press the [Configure] button once to select it. or to highlight section miscelPress laneous. Press five times to reach the Switching column. Press or to highlight off. Press the [Configure] button to activate. Finger switching is now inactive. or to highlight 60 min, see facing Press page. Press the [Configure] button to activate. Finger switching will now occur every 60 min. or to highlight now. Press Press the [Configure] button to activate. Finger switching will immediately occur to move monitoring to the other finger. Can be used to

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7.11 Miscellaneous--display units selection

The Finometer--research instrument can display its results in two unit systems: a "medical" unit system (MU) and the "SI" unit system. In the SI unit system pressures can be displayed as hPa or kPa: 1. 2.

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The m for volume and acronym units such as lpm and bpm are used in both systems without change. The total peripheral resistance (TPR or SVR or Rp ) of a patient is a quantity that cannot be measured directly but is derived from the simultaneous measurement of pressure (p) and flow (q) by division: Rp = p/q. In medical units pressure is expressed as mmHg and flow as m /s. Thus the medical unit for Rp is mmHg.s/m . On the display and in the output results file pressure is in mmHg and cardiac output in /min. Peripheral resistance, however, is often expressed in CGS (the now obsolete centimetergram-second system) units. In this system pressure is expressed in dyn/cm2 and flow in cm3 /s, and consequently resistance in dyn.s/cm5 . To convert from mmHg to dyn/cm2 use 4000/3. To convert from /min to cm3 /s use 1000/60. Thus, to compute Rp from pressure and cardiac output divide the numbers and multiply by 4000/3 × 60/1000 = 80. For example, mean arterial pressure is 100 mmHg and cardiac output is 4 /min. Resistance then is 100/4 × 80 = 2000 dyn.s/cm5 .

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Press the [Configure] button once to select it. or to highlight section miscelPress laneous. Press four times to reach the Display column. Press or to highlight hPa (SI). The display changes immediately according to the new choice, see facing page. or to highlight mmHg (MU), to Press restore the default unit.

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The world wide measurement unit system since 1960 is the Syst`me International d'Unit´s or SI system. In e e this system the mmHg was accepted only temporarily. Thus the official unit of pressure since 1960 is the pascal (Pa). The conversion factor from mmHg to pascal is 133.3224 or very nearly 400/3 and to hectopascal (hPa) it is nearly 4/3. Finometer internally uses the mmHg. The factor of 400/3 is used for conversion to pascal units.

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7.12 Miscellaneous--the beeper

Finometer has a built--in beeper which produces a repetition of brief sounds at 2047 Hz for 80 ms. To turn it off: 1. 2. 3.

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left information display under Beep: off. The beeper is used principally to alert the operator to developing error states. Three beeps are then given. Confirmation of certain selections is also associated with beeps. Typically the beeper would be turned off when the operator is not in the same room, or during night time monitoring, or when a subject should not be distracted from his/her task.

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Press the [Configure] button once to select it. or to highlight section miscelPress laneous. Press three times to reach the Beeper column. Press or to switch states on--off or off--on. The resulting beeper state is also shown in the

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7.13 Miscellaneous--saving a configuration

Preparation of a configuration might typically involve a physiologist with Finapres experience who wants Finometer to mimic an Ohmeda 2300e Finapres, no warning beeps, displays in SI and kPa, view trends of heart rate and stroke volume, and to work with young adults. He wants to save this configuration for later use. He achieves this as follows:

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10. 11. 12. 13. 14. 15. 16. 17.

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Press the [Describe subjects] button once to select it. or several times to reach the Age Press column and press until 25 is shown. Press the [Describe subjects] button once to confirm. Press the [Select trends] button and set the Left signal to SV, stroke volume. Set the Right signal to HR, heart rate. Press the [Configure] button once to select. or to highlight pressure reconst. Press

twice to reach the Filter column. Press Press to highlight do not. Press the [Configure] button to confirm. Selecting no filtering automatically disables Level cor and Level CAL. or to highlight miscellaneous. Press Press five times to reach the Switching column. Press or to highlight off. Press once, then twice to highlight kPa (SI). once, then to highlight off for Press the beeper. Press to reach the Safe config column. Press or to highlight Blue. Press the [Configure] button to activate and to save all your settings and selections under the Blue color.

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7.14 Miscellaneous--loading a configuration

On another day a Red configuration must be loaded: 1. 2. 3. 4. Press the [Configure] button once to select. Press or to highlight miscellaneous. Press once to reach the Load config column. Press or until Red is highlighted. 5. Press the [Configure] button to load the Red configuration.

After a colored configuration has been loaded the startup or `white' configuration can only be restored by exiting from and restarting Finometer--research.

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8 The Finometer--clinique instrument

The principal objectives of the Finometer--clinique instrument are simplicity of control and operation, and stability of display. Instrument control, therefore, is by six buttons below the display screen. Each button has one function during off--line idling when no measurement is done and another function during a measurement. During idling buttons are yellow colored and during a measurement they are blue colored for distinction. Displays have fixed scales and present fixed signals. The essentials of Finometry, however, remain the same. Thus, the Clinique instrument has brachial artery waveform reconstruction by default, and includes a return--to--flow calibration. Modelflow cardiac output is computed for later analysis, but not displayed. Entering correct patient data, therefore, is again essential since the SV/CO/TPR values and their correct trending depend critically on it. The Clinique instrument's first screen display (figure 8.2 on page 82) reminds the operator of this requirement by providing a series of four buttons to enter patient data and by highlighting the second button from the left, labeled [Gender [up]|[dn]]. Further buttons set [Age-y], [Height-cm], and [Weight-kg]. Finometer--clinique uses the same software procedures as Finometer--research. Thus it is guaranteed that the same pressure waveform analysis generates the same beat--to--beat derived parameters with both instruments, that the same error messages are generated, that the packet file is identical. On--line and off--line files downloading are identical also. In contrast with the Research instrument, however, no remote control of the Clinique instrument is possible. A measurement start/stop, Physiocal off/on, or a return--to--flow procedure cannot be controlled from a remote PC, and external markers cannot be entered via the serial interface. 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 Entering patient data--clinique 82 The error message display--clinique 83 Files downloading from a remote PC 84 Show trends 85 The control buttons during off--line idling 86 Layout of the Clinique display 87 The control buttons during a measurement 88 Scale compression 89 Performing a return--to--flow calibration 90

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8.1 Entering patient data--clinique

Enter the patient descriptive data before a measurement starts to get correct, scalable cardiac output values and trending: 1. If not highlighted press the [Pat-f/m] button or to move to this button. once or use Its current setting is shown just above the button on screen in white on a dark gray background. Here, facing page, it is decide. Press or to change the setting of the parameter from decide to male or female. The Pat: parameter in the right information is highlighted and the display changes in accord with the changed setting. to move to Press the [Age-y] button or use this button. Press or to change the value of the Age parameter. Press the [Height-cm] button once. Press or to change the value of the Height parameter. Press the [Weight-kg] button once. or to change the value of the Weight Press parameter. Check that the entries in the right information display panel have obtained the correct value. All four patient descriptive data have now been entered. Do this before a measurement starts since these buttons are not available during a measurement. Although cardiac output is computed it is not displayed. Thus, there is no need for and no way to set cardiac output calibration in Finometer--clinique. But calibration can be linearly scaled in post-processing, without deteriorating tracking precision. This is true only, however, when the patient descriptive data were set correctly. For example, when during a head--up tilt uncalibrated Modelflow stroke volume drops from an initial 120 to 80 ml when tilted up, but a thermodilution estimate shows initial stroke volume to be 96 ml, the scaling factor is 96/120=80%. After calibration the initial Modelflow stroke volume of 96 ml now drops to 64 ml when tilted up. This drop is 33% in both cases. The 33% is only correct if age and gender, height and weight were set correctly.

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8.2 The error message display--clinique

Normally the top status line shows clock time and time lapse since measurement start in green letters on a black background. When an error occurs the time display is replaced by an error message in red color. Typically, an error message signals a condition in which Finometer cannot function properly and from which it cannot recover automatically. The measurement is stopped and the error message is displayed during 10 s. At the instant that the error occurs 3 beeps are heard, followed by another 3 beeps after 5 s. After another 5 s the message disappears and another measurement start can be attempted. In the case shown the finger cuff air hose got dislodged and must be reinserted. After the forward slash (/), the procedure that detected the error is named. The error message is also stored in the last packet of this measurement's file on disk. Here are some of the error messages that may show: Connect frontend/startAutolock

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Check air supply/steadyPressure (facing page) Check armcuff air supply/fillRivabuffer Unstable pressure/steadyPressure No plethysmogram/failAutolock Finger too thin/checkFrontgainDn Check cuff cable/centerPlet Connect cuff cable/checkLEDcurrent Faulty finger cuff/setLEDcurrent cuff--LED problem/checkLEDcurrent Error messages represent situations that are not considered dangerous. They have to do with dislodged connectors, or with contracted finger arteries, or worn cuffs. They do not represent alarm conditions such as may be present when the hemodynamic parameters of a patient move out of a preset safe range. For a more complete list of error messages, causes and possible actions see appendix B on page 114.

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8.3 Files downloading from a remote PC

Each finger arterial pressure measurement that is made with the Finometer--clinique instrument is stored in a revolving store on disk. In a full revolving store a newly arriving packet automatically overwrites the oldest packet present. A revolving store, therefore, does not have to be erased. These files can be downloaded off--line after the measurement by a remote PC with program Finolink. Files downloading can also be done while the Finometer is doing a measurement. This is called on--line downloading and regards only the currently generated file. For on--line downloading you must start the Finolink program and click its "Monitor" button, see figure 2.4 on page 22. Finometer will allow this and cooperate fully behind the screens, and without a distracting message. It has no effect on the measurement. Off--line files downloading was discussed briefly in section 2.3 on page 22. In this case any measurement file in store can be selected for downloading. This requires full control over the Finometer packet store so that no new packets can be stored. Thus, off-line files downloading and doing a finger blood pressure measurement are mutually exclusive. A warning message is issued that a measurement cannot be started, see facing page. To start either form of downloading: 1. 2. Get a "null-modem" cable. There is one supplied with your Finometer. Plug one end of the cable into the Finometer serial I/O connector marked "RS232", located at the rear. Plug the other end into one of the PC serial ports possibly labelled COM1, etc. In the case that the supplied cable is of insufficient length you may extend it with ordinary (non--null--modem) serial cable. Start Finolink on the PC by double clicking on its icon, or go via Beatscope. If not yet done configure the COM port number: click on `Configure', the `Serial port', and select the desired COM port. Click on `Select'. For on--line downloading click on "Monitor". A display is shown on the PC that is quite similar to the Finometer--research display. With the Clinique instrument running on Finometer you cannot remote control some of its functions as was possible for the Research instrument, see section 6.4 on page 54.

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8.4 Show trends

When a measurement is finished the trend display continues to be displayed for a brief period. After this period a message is shown prominently "Start a measurement", to indicate that the device a ready for another measurement, see figure 8.6 on page 86. The trend display just overwritten by this message, however, is still available in the background. It is recalled by pressing the [Show trends] button once to highlight the button and a second time to activate.

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8.5 The control buttons during off--line idling

When no measurement is in progress Finometer is idling and called off--line. The on screen buttons are colored yellow and the control buttons below the screen from left to right have the following functions: [Show trends] Press this button twice to redisplay the trend panel when it was replaced by the message "Start a measurement". [Pat-f/m] Press to set a patient's gender. This is very important for cardiac output computation precision. When pressed a dark gray window is opened presenting the presently selected or to change the selection. gender. Press [Age-y] Press to set a patient's age. This is very important for cardiac output computation precision. When pressed a dark gray window is opened presenting the presently set age. Press or to change the age. [Height-cm] Press to set a patient's height. This is important for cardiac output computation precision. When pressed a dark gray window is opened presenting the presently set or to change the height. height. Press [Weight-kg] Press to set a patient's weight. This is important for cardiac output computation precision. When pressed a dark gray window is opened presenting the presently set or to change the weight. weight. Press [use FinAP] Used to select either unprocessed finger artery pressure (FinAP) or reconstructed brachial artery pressure (reBAP) for display and derived parameters computation. First the [use FinAP] button is pressed to select it, then a second time to activate it. This causes the display labeling to change. The button text changes to [use reBAP]. Press once again to return to the default reBAP based display. The action of these buttons is immediate. No confirmation needs to be given. Once a measurement is started by pressing the start/stop button these functions are no longer available and remain fixed during the measurement. The height system can be nulled when still off-line by following the instructions in section 4.4 and figure 4.5.

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8.6 Layout of the Clinique display

The status line shows the TNO logo, the time display and a copyright note. During a measurement the copyright note is replaced by the Physiocal state. The time display left shows the system clock time and right shows the time lapse since the start of the current measurement or off--line idling period. The system clock time can be adjusted in Finometer--research, see section 7.9 on page 75. When an error occurs the time display is replaced by an error message. The pressure parameter layer left panel shows a trend display of the three pressure levels (S/D-M). The white dot is mean pressure. The blue dot is heart rate. The vertical scale is fixed and the same for all four derived parameters. The time scale is compressed automatically each time it reaches the end, see figure 8.9 on page 89. The quadruple numeric display at the right shows from above the eight-beat running averaged systolic, diastolic and mean levels and heart rate updated each second, computed on finger (FinAP) or reconstructed brachial artery pressure (reBAP). The waveform and information layer left panel shows the selected unprocessed finger (FinAP) or processed reconstructed brachial artery pressure (reBAP) waveform. The yellow trace is beat--to--beat heart rate, except during a return--to--flow procedure when it is replaced by arm cuff pressure. The vertical scale is fixed and the same as that in the trend panel. The time scale is nearly 100 s. With the [Hi speed waveform] button the time axis is expanded 10× and the waveform has the begin upstroke instants marked, see figure 8.8 on page 88. The information panel lists from the top: · · · · · · · · · · · todays date (Date: Apr 06) beeper on/off state (Beep: on) present date/time filename (Filename:) current file size (Size: 177 k) patient gender and age (Pat: male 50) patient height (H-cm: 175) patient weight (W-kg: 75) active cuff, minutes on this cuff and switch period (C2: 3/off) finger hydrostatic height (Hite: -5 mmHg) total level correction shift (Shft: 18 mmHg) Physiocal quality factor (QF: great)

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The program control buttons are treated in later sections.

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8.7 The control buttons during a measurement

When a measurement has begun the control buttons below the screen have the functions shown just above each button on the display screen. From left to right: [Stop plotting] Press this button to stop the trend plot. The trend plot is halted although the finger pressure measurement continues. The button text changes to: [Start plotting]. Press again and the trend plot is cleared and a new trend plot started. These actions have no effect on the measurement, or on the result packet file, which both continue normally. [---] Not presently used. [Hi speed waveform] Press this button to increase the plot speed of the waveform display. The plot clears and starts at the left side at a 10 times increased velocity, see facing page. When reaching the right side, plotting returns automatically to normal speed. Keep the button depressed to continue high speed plotting. [Turn off Physiocal] Press this button to suppress the Physiocal procedure. This is then marked in the status line upper right section. The button text changes to [Turn on Physiocal]. Use this button to display uninterrupted Valsalva and other short term maneuvers. Turn Physiocal back on as soon as possible. Physiocal should not be off for more than a few minutes preferably. [Start RTF calibrate] Press this button to start a return--to--flow systolic calibration of reconstructed brachial artery pressure. The procedure is started and the button text changes to [Stop RTF]. In the case that something is wrong the procedure can be broken off by pressing the button again. After a procedure completes another cannot be started until at least 2 min have passed. During these two minutes the button is blanked: [---]. A typical procedure is described in section 8.9 on page 90. [Turn off beeper] Press this button to turn off the beeper. The beeper is silenced and the button text changes to [Turn on beeper]. Press again to turn the beeper back on. This is accompanied with a beep. The action of these buttons is immediate. No confirmation needs to be given.

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8.8 Scale compression

In the Finometer--clinique instrument vertical and time scales cannot be freely chosen. The vertical scales are fixed. The time scale of the waveform display is expanded by pressing the [Hi speed waveform] button. The time scale of the trend display is compressed automatically as follows:

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end of the display area is reached. The clearing and compression cycle repeats with 30 min, 1 h, 2 h, etc. as full scale values.

The rationale is that a short experiment is shown at maximal time resolution. A more extended test such as a tilt table test which may last one hour is also shown in full with its maximally possible resolution. In case a series of short tests must all be displayed at maximal resolution the plotting can be stopped by pressing the [Stop plotting] button once to highlight and once more to activate. Press this button now labeled [Start plotting] again and the display is cleared and started at highest resolution on a time scale from 0 to 7.5 min. This starting and stopping has no effect on the measurement, or on the result packet file, which both continue normally.

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After measurement start the display is cleared and the time scale is set to run from 0 to 7.5 min full scale. Trend data is written every 1 s until the end of the display area is reached. Now the display is cleared and the time scale is set from 0 to 15 min full scale. The data already accumulated is averaged by two and redisplayed, filling the display from 0 to 7.5 min. The remaining space from 7.5 to 15 min is filled with trend data written every 2 s, again until the

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8.9 Performing a return--to--flow calibration

The display, facing page, represents the state after the return--to--flow calibration procedure took place. To perform a return--to--flow systolic calibration take the following steps: 1. Wrap the upper arm cuff provided with your Finometer (it should have two air hoses) tightly on the arm where finger pressure is measured. Return--to--flow will be detected automatically by the finger cuff. Insert the tube sockets into the Finometer front side, either way is right, see figure 4.6 on page 40. Wait until the [Start RTF calibrate] button shows up. During the 30 s before inflation starts ask the patient to be quiet, without movement or talking. Press the [Start RTF calibrate] button to start inflation. The waveform display is cleared and restarted. During the RTF procedure beat--to--beat HR is replaced by arm cuff pressure, initially in blue, later in yellow color. The ramp inflation is smooth and deflation linear. To emergency--stop press the [Stop RTF] button as indicated in the waveform panel. 8. While deflation progresses observe the waveform panel. A first RTF level is detected after which a reinflation takes place for a second detection. 9. Upon successful completion the two RTF arm cuff pressure levels detected are displayed as RTF=success(144 & 134). 10. The level shift will be updated and displayed in the information panel as Shft: 18 mmHg. Positive values mean up--shifts of finger pressure. 11. The [Start RTF calibrate] button is blanked. To repeat the procedure wait at least 2 min until the button reappears. After a 5 s priming period at 20 mmHg, the Clinique instrument always does a ramp inflate and no choice is offered. When the arm cuff pressure trace turns yellow this indicates that the return--to--flow detection is working. The two arm cuff pressure levels at which detection of return--to--flow took place are stored in the packet file at their instants of detection. Any specific return--to--flow error messages are displayed in the waveform panel, replacing the Press [stop RTF] alert.

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9 The Finometer--classico instrument

The Classico instrument uses part of the Finometer hardware to control upper arm cuff inflation and linear deflation to the specifications as set up by the operator. When the cuff is inflated and deflated you do your Korotkoff sound detection as usual and (mentally) record the associated cuff pressures. Cuff pressure is displayed on a simulated mercury column and a digital readout is also available. When the mark button is pressed the instantaneous cuff pressure is stored, or rather the value averaged over the 1 s before the marker. Upon termination the list of marked values is displayed. Three forms of blood pressure reading are provided: the normal mercury sphygmomanometer type readout, the blinded London School of Hygiene type readout, and the Hawksley Random Zero type readout. For epidemiological purposes the London School of Hygiene sphygmomanometer was developed, featuring blinded detection and cuff pressure storage at three phases of the Korotkoff sounds, followed by measured readout on three mercury columns. This system is programmed in the Classico instrument. Press the mark button at each detected phase and read pressure levels from a list displayed upon termination.

The LSH instrument was shown later to provide biased results for two reasons. First, the instrument read systematically low. Second, it was thought that observers were late in pressing the buttons since there were no mercury column oscillations alerting the observer. 5 Classico does not have the first error and tries to compensate for the second by recording the cuff pressure that effectively existed 0.5 s earlier.

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The successor of the LSH instrument was the Hawksley Random Zero sphygmomanometer. In this instrument a random zero offset was created, to be subtracted later once the memorized pressures were noted down. This system is also programmed in the Classico instrument. Zero offsets are chosen in the range from -15 to +15 mmHg and, if the mark button is pressed at the Korotkoff detection instants, the offset cuff pressures are recorded and automatically corrected upon display of the list of marked values. Thus no computations need to be done.

The Hawksley Random Zero instrument had various subtle mechanical errors which rendered it inaccurate. 3 These are not present in the Classico instrument due to its electronic nature.

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The Classico instrument in its three modalities has, as yet, not been tested for bias and precision and should not, therefore, be used for blood pressure epidemiology.

9.1 9.2 9.3 9.4

Setting the in-/deflate and readout parameters The Classico calibration waveform 94 The normal Riva--Rocci/Korotkoff measurement The Classico random zero measurement 96

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9.1 Setting the in-/deflate and readout parameters

The Classico instrument offers automatic fast inflation to a preset level, or slower manual inflation by pressing the button. There are a slow and a fast linear deflation at setable rates. Finally, three types of readout are offered: normal, random zero, and blinded. All settings are stored and the next time you start Classico it will preload your latest settings.

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The fast deflate rate is often used after systole has been detected. Keep depressed during deflation to activate.

Readout: To set a readout type: 1. 2. Press the [Setup read] button. or to highlight a readout type. Press

Inflation: To set inflation: 1. 2. 3. 4. 5. Press the [Setup inflate] button. to reach the Inflate column. Press Press or to highlight to preset level. Press to reach the Preset level column. Press or to increase or decrease the level (range 20 to 300 mmHg). The top status line presents clock time and time lapse since start, and any error messages that occur. Below it, the summary panel shows the current settings of the instrument. The narrow mercury column left indicates the pressure in the air buffer. The mercury column at the right shows arm cuff pressure. It has a resolution of 1 mmHg, as does the digital readout. Measurement results can be downloaded to a PC with Finolink. Finometer must first be set to run the Finometer--classico instrument. Finolink then recognizes this instrument automatically. Once set up Finolink automatically requests and receives the results of each new measurement. Results are fully documented with date and time, all the settings for that measurement, and all marked arm cuff pressure levels. It is, therefore, necessary that you press the mark button at the Korotkoff phases you detect. A total of 10 markers can be stored per measurement.

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Deflation: To set deflation: 1. 2. Press the [Setup deflate] button. Press to reach the Slow deflate rate column. Press or to increase or decrease the rate in mmHg/s (range 1.5 to 7.5 mmHg/s). Press to reach the Fast deflate rate column. Press or to change that rate in mmHg/s (range 5 to 20 mmHg/s).

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9.2 The Classico calibration waveform

The calibration waveform steps pressures up from a 50 mmHg initial level in 50 mmHg increments until the 250 mmHg level is reached, then switches to 50 mmHg decrements until the 50 mmHg level is again reached, then deflates. For patient safety the calibration cycle does not automatically repeat. At each level the pressure is maintained during 10 s. With a calibrating manometer connected you may verify Finometer--classico's calibration. To calibrate: 1. Get several 50 cm long sections of 6×1 mm plastic tubing, a T or Y air hose connector, and two Kuhnke sockets, see figure 7.6 on page 71, and assemble. Insert one Kuhnke socket in the arm cuff inflate 8. 9. 3. outlet marked "i", see figure 4.6 on page 40. Insert the other Kuhnke socket in the arm cuff sense outlet marked "s". These two steps connect the inflate and sense ports as would normally be achieved with a two-tubed arm cuff. Connect the third air hose to your calibrating manometer. Press the [Setup inflate] button. to reach the Inflate column. Press Press or to highlight to calibration levels. Press the start/stop button. Compare the pressure levels on screen with those on your calibrating manometer. They should be within ±3 mmHg. When the difference is greater please contact FMS, see page 3.

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9.3 The normal Riva--Rocci/Korotkoff measurement

The Classico normal RRK measurement includes controlled inflation and deflation of the arm cuff, optional mark button cuff pressure storage, and display of a list of marked levels upon termination of the measurement. Up to ten instants can be stored. To perform a measurement:

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Wrap the upper arm cuff provided with your Finometer (it should have two air hoses) tightly on either arm. Insert the tube sockets into the Finometer front side, either way is right, see figure 4.6 on page 40. Setup the various inflate, deflate and readout parameters according section 9.1 on page 93. Note in the Summary panel that Inflate to 170 mmHg was chosen. This causes a step-wise cuff inflation which is often found more pleasant by the patient since it reduces distal venous congestion. Reduced congestion enhances Korotkoff sound generation as well, and reduces effects of an auscultatory gap. Note in the Summary panel that slow deflation

has been set to 2 mmHg/s and fast deflation to 10 mmHg/s. 6. Note in the Summary panel and on the {Setup read} card that Read column normally has been chosen. 7. Press the start/stop button to start inflation. Inflation is smooth and deflation begun immediately. To emergency--stop and deflate press the start/stop button again. 8. Optionally press the mark button at the instants of detection of the various Korotkoff phases. 9. Press the start/stop button after the last Korotkoff sound was heard. 10. A list of maximally 10 cuff pressure levels is now displayed, recorded just 0.5 s before the instants when the mark button was pressed. This finishes a normal auscultatory sphygmomanometric blood pressure measurement. The blinded measurement runs identical except no display of arm cuff pressure is shown and the sphygmomanometer remains frozen. For blinded measurements you must press the mark button to record the detection instants.

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9.4 The Classico random zero measurement

The random zero measurement includes controlled inflation and deflation of the arm cuff, optional mark button cuff pressure storage, and display of a list of marked levels after termination of the measurement. Up to ten instants can be stored. To perform a measurement:

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Wrap the upper arm cuff provided with your Finometer (it should have two air hoses) tightly on either arm. Insert the tube sockets into the Finometer front side, either way is right, see figure 4.6 on page 40. Setup the various inflate, deflate and readout parameters according section 9.1 on page 93. Note in the Summary panel that Inflate with [up] key was chosen. This causes a smooth ramp cuff inflation. Use palpation of the radial pulse to determine the moment to stop inflation. Note in the Summary panel that slow deflation has been set to 2 mmHg/s and fast deflation to 15 mmHg/s. Note in the Summary panel and on the {Setup read} card that Read column random zero has been chosen.

Press the start/stop button to start inflation. Inflation is first to 20 mmHg, then to 30 mmHg. At that time the button may be depressed to increase cuff pressure. To emergency--stop and rapidly deflate the cuff press the start/stop button again. 8. Automatic deflation begins immediately when the button is released. Press again to further inflate as needed. 9. While deflation progresses observe the simulated mercury column and press the mark button at selected Korotkoff phases. 10. Press the start/stop button after the last Korotkoff sound was heard. 11. A list of cuff pressure levels is now displayed recorded at instants when the mark button was pressed. These levels are already corrected for random zero offset. 12. Assume you remember reading S/D as 147/85. Now subtract 11 mmHg as instructed in the display. The result is 136/74. When you pressed the mark button the instrument recorded 146/86 and duly subtracted 11 mmHg to display 135/75. 7. This completes a random zero blood pressure measurement.

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A Specifications

This device fulfills the provisions of the EC directive 93/42/EEC (Medical Device Directive), and the European Standards EN 60601--1, EN 60601--1--1, and EN 60601--1--2.

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Manufacturer: FMS, Finapres Medical Systems BV Simon Stevinweg 48 NL-6827 BT ARNHEM, The Netherlands phone fax email web

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: : : :

+31 26 3849080 +31 26 3849081 [email protected] www.Finapres.com

Important note: Specifications are subject to change without notice. A.1 A.2 A.3 A.4 A.5 A.6 A.7 A.8 A.9 A.10 A.11 A.12 A.13 Unpacking--The Finometer components Patient safety measures 100 Protective measures 101 Analog Input/Output 103 Environmental specifications 104 Electrical specifications 105 Mechanical specifications 106 Instrumental information 107 Instrumental accuracy 108 Connecting external equipment 109 Remote control 110 Safe data storage--Data durability 111 Unpacking--The data packets 112 99

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A.14 Cleaning

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A.1 Unpacking--The Finometer components

Each Finometer consists of the units listed below: · Main unit. A box holding the principle electronic and pneumatic components, the embedded computer, the front panel control buttons (section 4.5), and the display. A three-pronged grounded power cord is included. Frontend. A box to be worn on the back of the hand or the wrist and containing connectors for the finger cuff and the height correction system (section 2.2). Height system. A liquid filled tube with sensors at both ends measuring their relative vertical distance (section 4.4). Analog Input/Output box. Eight BNC connectors provide for four--channel analog signal input and output (section 2.1). Six finger cuffs. Two each of three sizes of finger cuff: white, S--size, small; beige, M--size, medium; blue, L--size, large (section 4.1). Arm cuff. A normal upper arm blood pressure cuff with two air hoses to be wrapped around the same arm as the finger cuff and used to accomplish the return--to--flow calibration of reconstructed brachial artery pressure. Serial I/O cable. A null modem cable to connect Finometer to a remote PC's COM port for data downloading and remote control, using Finolink software (section 2.3). Calibrating air hose. A length of 6 mm outer diameter, 1 mm wall thickness plastic tube equipped with Kuhnke socket and Luer (figure 7.6), used to calibrate Finometer transducers. Finolink. A Windows software program to download data from Finometer to a remote PC, offering a remote monitor screen and some remote control of Finometer functions. Finolink may unpack Finometer--type packed data files. Finometer User's Guide. The document you are presently reading. FMS Finger Pressure Reference Guide. A document containing background information on finger arterial pressure measurement. Beatscope. The Beatscope Windows software program is present on CD-ROM to view waveforms and beat--to--beat derived data on a PC screen.

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The guides are available on CD-ROM as PDF files in printable format and in interactive screen display format. Use Acrobat version 4 or later for viewing. Further copies are obtainable from FMS (page 3). Upon unpacking a quick inspection of proper functioning is obtained by following the instructions in chapter 2 on page 19. Transducer calibration may be checked with the procedures described in section 7.1 beginning on page 67. Please contact FMS (page 3) immediately in case of malfunction.

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A.2 Patient safety measures

· The data produced by Finometer or BeatScope software is intended as an adjunct in patient assessment and should not be used as the sole means for determining a patient's diagnosis. Finometer is a finger blood pressure monitor. Do not use the finger cuffs on other members of the body, such as a toe or the wrist of an infant. Performance on a toe is undocumented. Use on the wrist of a neonate or small infant substantially reduces flow to the hand, causes venous congestion and can be maintained only for very short periods of not more than one (1) min. Finometer can only be used on adult humans and on children of 6 years or older. 14 Performance on younger children is undocumented. To maintain the designated operator and patient safety only use accessories, such as finger and arm cuffs, that are provided by FMS, Finapres Medical Systems BV. (U.S.A.) Federal law restricts this device to sale by or on the order of a physician. To maintain the designated operator and patient safety, peripheral equipment that is connected to Finometer or one of its components, must be certified according to EN 60601--1 for electromedical equipment. Use Finometer only with a properly grounded AC power outlet. Obey the voltage rating mentioned at the rear panel near the line power connector.

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A.3 Protective measures

Finometer electrical circuits do not touch the skin and are not in galvanic contact with body fluids. Finger cuff pressure is zero during idling and not higher than intraarterial blood pressure during a measurement. Such pressures can be tolerated for at least 12 hours of continuous monitoring. The highest pressure that can be reached is 350 mmHg which is practically painless and does no harm but should not be applied continuously for many hours. Still, further measures are taken for the safety and comfort of the monitored patient and for the safety and convenience of the operator.

Electrical protective measures

· · · · Low finger cuff LED voltage (approximately 1.4 V) and power dissipation (approximately 50 mW) reduce electrical hazard and prevent undue heating which might cause skin irritation. An electrical short circuit in the cuff or in the instrument cuts off cuff pressure within 1 s. An interrupted frontend or cuff cable cuts off cuff pressure within 1 s. A self test of essential instrumental functions and parameters is performed every second of time.

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Finger cuff pressure protective measures

· · · · Compressed air fed to the Frontend unit is pressure regulated to 350 mmHg (0.5 bar). A watch dog timer cuts off cuff pressure and resets the Finometer built--in computer and software in case of internal computer malfunction. A finger cuff pressure greater than 250 mmHg sustained for 2.5 s cuts off cuff pressure. During the start procedure finger cuff pressure is limited to a maximum of 295 mmHg to last less than 2 s.

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Arm cuff pressure protective measures

· An arm cuff pressure greater than 300 mmHg sustained for 5 s cuts off the cuff pressure pump and rapidly

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· ·

deflates the arm cuff. A return--to--flow procedure typically does not take more than 30 s, and cannot be repeated within 2 min. During a return--to--flow procedure the arm cuff is fully deflated automatically if detection of return--to-flow fails within 1 min.

General system protective measures

· · · · A watch dog timer cuts off cuff pressure and resets the Finometer built--in computer and software in case of internal computer malfunction. If finger cuff pressure oscillates during a measurement the software takes action to remove the oscillation, although such oscillations present no hazard or discomfort to the patient. When fully contracted finger arteries are detected during the start procedure, allowing no pressure monitoring, Finometer issues an error message to the display, and shuts off cuff pressure. Increases in the contractional state of the finger arteries can be followed by inspection of the Physiocal and servo control parameter display. A quality factor expresses from `excellent', via `great', `good', `useful', `sufficient', and `adequate', to `uncertain' the state of the finger arteries below the cuff. This information is stored every 0.5 s in the data file on disk.

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A.4 Analog Input/Output

I/O voltage range I/O Resolution Input zero offset Output zero offset Internal impedance input Internal impedance output Output current Output approximation -5 to +5 V 2.5 mV < ±5 mV ±1% of value or ±20 mV, which ever is greater 200 k <1 max 2 mA channel 1 & 2: linear interpolation channel 3 & 4: staircase

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A.5 Environmental specifications

Operating temperature Storage temperature Humidity Ambient pressure 10 to 40 C -20 to 70 C 5 to 90% non--condensing 700 to 1100 hPa

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A.6 Electrical specifications

Power requirements (optionally) Main unit fuses (two) (optionally for 110 V) Power cord Protection against electric shock (EN 60601--1) Protection against the ingress of objects or water Power dissipation 220--240 V, 50/60 Hz, 100 VA 100--120 V, 50/60 Hz, 100 VA IEC 127, 0.8 A slow blow IEC 127, 1.6 A slow blow IEC 320 to local mains plug Degree: type B applied part, Type: Class I equipment IP20 In Main unit: < 100 W, in Frontend unit: 1 W, in finger cuff: < 50 mW 3.6 V non--rechargeable Lithium, type Sonnenschein SL--389 energy content: 1 Ah expected life time: 20 year

CMOS back--up battery

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A.7 Mechanical specifications

Finometer main unit weight depth width height Frontend weight depth width height Arm cuff bladder size weight Analog I/O connector box d×w×h Finger cuff weight Note: all specifications rounded upwards.

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11.5 kg 45 cm 40 cm 16/41 cm (closed/open) 900 g (plus cables) 7 cm 5 cm 3 cm Speidel & Keller 12 × 28 cm (width × length) 270 g (with two rubber tubes) 15 × 9 × 4 cm 18 - 23 g (depending on size)

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A.8 Instrumental information

Product category Product type Measurement method Finometer finger blood pressure measuring device, with Finolink and BeatScope PC--based software Model 1 Arterial volume--clamp method of Pe´z 17; Physiocal na criteria of Wesseling 23; brachial waveform reconstruction of Bos, Gizdulich and Wesseling 2 ,6 ,7; Modelflow method of Wesseling 21; see appendix E and the patent literature. maximally 350 mmHg maximally 300 mmHg range ± 128 mmHg On a built--in 88 MB hard disk for 24:00:00 hours, 4096 measurements maximally 10 inch VGA 640 × 480 × 16 TFT--LCD RGB, 15 pin female, D--type Serial port, 9 pin male, D--type Centronics printer port, 25 pin female, D--type 4 input, 4 output, 15 pin male, D--type, ±5 V max. Pressure regulated at 350 mmHg; maximum pressure: 380 mmHg; maximum air flow: 70 /h @ 200 mmHg Buffer pressure regulated at 800 mmHg; maximum buffer pressure: 1150 mmHg; maximum arm cuff pressure: 300 mmHg

Finger cuff pressure Arm cuff pressure Height sensing Data storage

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Display VGA connector RS--232C connector LPT (not used) Analog signal I/O connector Finger cuff pump system

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Arm cuff pump system

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A.9 Instrumental accuracy

Finger cuff pressure accuracy Arm cuff pressure accuracy Height accuracy Rate accuracy Interbeat interval accuracy 1% of full scale (max 3 mmHg), zeroing automatic 1% of full scale (max 3 mmHg), zeroing automatic 2% of full scale (max 3 mmHg), zeroing manually (Rate [BPM] / 60)%, thus 1% at 60 BPM 10 ms (peak, non--accumulating)

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A.10 Connecting external equipment

External analog signal sources may be connected to the analog input/output (I/O) box for sampling, and a personal computer may be connected to the serial RS232 connector for remote data downloading. Connecting such equipment represents a hazard to the patient and operator as well since this equipment may fail or may not be designed for medical usage. Specifications have been written by the IEC for such peripheral equipment to meet when connected indirectly, here via Finometer, and/or directly via sensors or electrodes to a patient. They are the European EN 60601 standard for electromedical devices and the IEC 950 standard for data processing devices. The department of Medical or Clinical Physics of your hospital can advise you on how to achieve a safe, interconnected system. Please note that the configuration when within the EC has to meet standard EN 60601--1--1. He who interconnects such devices is responsible for adherence to the EN 60601--1--1 standard.

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A.11 Remote control

The Finometer offers two built--in instruments to measure finger blood pressure: the Finometer-research and the Finometer--clinique instruments (section 4.8). The Research instrument is designed for investigators that appreciate Finometer for the safety from its noninvasive character, generally know well what they are doing, and might apply Finometer to subjects under circumstances such as in an experimental laboratory or a human centrifuge. The Clinique instrument is designed in situations when minimal control is needed but constancy of displays and the ability to view and appreciate the patient data presented at a glance, and operation by personnel not specifically trained for this equipment.

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ment mentioned in section A.10 on page 109. The Beatscope/Finolink software exactly reproduces the screen interface present on Finometer allowing full remote observation of the waveforms and data generated, with a delay not greater than 1 s of time. In addition, the following actions can be remotely controlled from the PC by mouse or PC keyboard interaction: · · · · Start or stop a measurement; Turn Physiocal off/on; Start or stop an RTF calibration; Record a marker signal.

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For situations when a subject has been instrumented by an investigator but must be left alone for experimental reasons, Finometer--research offers limited remote control over its operation. Only via an externally connected personal computer running the Beatscope or Finolink software is this control possible. Note the requirements for connecting such equip-

It is recognized that these are the actions that may be required during an experiment. They are the same actions that are available from the Finometer keyboard, and can be corrected, redressed, annulled and overridden from this Finometer keyboard or from a remote PC acting in parallel. Note that the packet data generated by Finometer is downloaded simultaneously by the PC and displayed.

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A.12 Safe data storage--Data durability

The data packets that Finometer generates when measuring blood pressure are stored on a built--in storage device which presently is an ordinary PC harddisk. On this storage medium an area is devoted uniquely to the storage of data packets. The size of this area is such that exactly 24 hours of storage is provided. Since packets have a size of 512 byte and since two packets are generated each second of time the data rate is 1024 byte/s or 1 kB/s. To store 24 hours of data the total file size is 24×60×60×1 kB = 86.4 MB. Upon receiving your Finometer this file has been created and holds just empty data packets. With your first measurement data packets are stored consecutively starting at position 0. When a measurement is terminated a final packet is written with special termination information. Each packet of a measurement has a unique identifier code identical for each packet. Each packet, in addition, has a CRC, a cyclic redundancy check (see Glossary D), to facilitate the checking of the integrity of the packet. This checking can be used when storing data, when transmitting it, etc. The system of storage is fully self contained. By inspecting the packets in a file it can be determined where each file begins and ends, and the identifier code further allows to determine which file is the most recent. That process is time consuming, however, since an 86 MB file has to be read sector by 512 byte sector. The storage system, therefore, separately maintains an index or pointer file indicating at which position a measurement starts and stops, and the most recent position written. If this pointer file becomes corrupted it can be recreated (section 5.4). When 24 hour of data packets has been written there is no more room left and the earliest packet written, the one at position 0, is overwritten with new data and the original file at that position is no longer complete. This fact is also recorded in the pointer file. Thus needed data must be downloaded regularly to a PC using Beatscope or Finolink software. This can be done during the measurement or afterwards. The advantages of this system are: · The storage medium (the harddisk) never fills to completion and consequently does not have to be erased and does not require any maintenance. The storage is very reliable such that power failures do not cause the system to crash with all data lost. The wear on the storage medium is minimal since packets are always stored consecutively without reference to file directories. The pointer system can recover itself when corrupted. Each packet can be checked separately for integrity. The system operates unattended. When the stored data is not needed no operator attention is asked.

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A.13 Unpacking--The data packets

Finometer produces data packets when measuring finger pressure, which are stored internally and are downloadable to a PC with the Finolink software and/or Beatscope. Both on--line (when measuring) and off--line downloading is possible. Each Finometer generated packet is a "molecule" of measurement data of 512 byte size covering a 0.5 s measurement period. Thus data is stored at a rate of 1kB/s. A packet includes a measurement identifying signature, a serial number, instrument diagnostics data, heart beat derived data, four signals sampled at 200 Hz, a marker, finally, a CCITT cyclic redundancy check (CRC) allowing verification of the integrity of each packet.

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A packet file thus contains all the information that used to be stored in the FAST system and in the subsequent Beatscope system in header, samples and results files. But packet files are more compact and can be further compressed to ZIP files, by factors often greater than 3. A total compression factor of 5 or more is achievable. Thus a standard CD-ROM may hold as much as 24 days of 24 hour of continuous monitoring. Beatscope reads and unpacks packet files transparently and is able to display all stored data. In case you don't use Beatscope, however, you may still recover the header, samples, results and ASCII extended results files with Finolink. Finolink works without a license. Start Finolink and use it to unpack the Finometer packet files. For details see the Beatscope 1.1 User's Guide Finolink chapter. The header file and the ASCII results files that are available after unpacking are readable with a text editor. It is best NOT to use proportional fonts since information is lined up in columns. The ASCII results file can be imported directly into a spreadsheet. The results and the samples files, however, are binary files and cannot be viewed directly except with Beatscope.

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Normally, the four signals stored are: finger cuff pressure (FinAP), hydrostatic finger height (Height), upper arm cuff pressure (Armcuf), and servo system error signal (Pleth). These signals are listed in table 6.1. When the latter three have been replaced by externally applied analog signals (page 73) this is signalled in the packets, and Beatscope knows what to do. The first (FinAP) can also be replaced by an external signal but it must be an arterial pressure wave. In that case the external pressure signal is analysed for beats and processed as finger cuff pressure would be. This fact is also stored in each packet.

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A.14 Cleaning

The Finometer housing is made of materials that do not easily attract dust. If cleaning is needed: · · · · Always first unplug the power cord. Wipe clean using a soft, slightly moist cloth. Never apply any liquids directly to the device or its associated units such as frontend or analog I/O box. Do not immerse the device or its units in a liquid. Never use alcohol, refined petrol, thinner or any other chemical agents that could damage the Finometer housing. Do not allow water or any other liquid to enter the Finometer or its units.

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Use the same cautions when cleaning the height correction system, arm cuff and finger cuff. Should water accidentally enter a finger cuff or air hose, then try to shake it out and allow enough time to dry.

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B Error messages

· Setup errors: - Configuration not found, save one first. You tried to load a configuration color that was not first saved. All colors were factory pre-saved. Move to the configuration save column, highlight the required color and press the [Configure] button. This error should not occur. - Version incorrect, save anew. You used an older version configuration file on newer software. Please setup this configuration again and save. This error should not occur. Startup errors: - Cannot start w/o frontend. - Check air supply. No air is supplied to the finger cuff. Check if airhoses are disconnected, are kinked or stepped on. - Check cuff cable. Possibly a finger cuff cable hardware error. Try another finger cuff. - Connect cuff cable. Finger cuff cable not properly connected to frontend. - Connect frontend. - Cuff artifact. An externally caused cuff pressure instability. Restart. - cuff-LED problem. The LED driver servo could not set a proper LED current. Try another finger cuff. - Faulty finger cuff. A finger cuff hardware error. Try another finger cuff. - Finger too thin. Too much light passes through the finger. Remove the finger cuff. Wrap a dark colored thin cloth or plastic sheet around the finger then reapply the finger cuff. - Gain switch malfunction. A hardware error. If it occurs repeatedly please contact FMS, see page 3. - No plethysmogram. No plethysmogram was observable, possibly due to full finger artery contraction. Try to warm the hand, see section 4.3 on page 37. - Nonstop switch malfunction. A hardware error. If it occurs repeatedly please contact FMS, see page 3. - Pointer file not updated, this file lost. A hardware error. For recovery turn Finometer off, then on; see section 5.4. - Unstable pressure. The finger cuff air pressure servo could not stabilize pressure in the required amount of time. Check if air hoses are disconnected, are kinked or stepped on. Run time errors: - Mean pressure too high. The mean finger cuff pressure was too high for 1 s. This may be an

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artifact but could be a potentially serious error. Try once more. - Measured 12 h on this finger. An uninterrupted measurement of 12 h on a single finger possibly approaches a safe limit. Wrap the cuff on another finger or allow a rest period of at least 5 min. Restart. - Premature operator stop. You stopped the measurement while it was in startup. Restart. - Pressure low--check air hose. The finger cuff air hose may have become dislodged. Reinsert firmly. Restart. - Pressure too low. The run time finger cuff pressure reached unphysiologically low levels. This may be a movement artifact. Restart. - Reconnect front end. The frontend cable was removed during a run. Reinsert the connector firmly, see section 2.1 on page 20. Restart. - Reconnect height sensor. The hydrostatic height correction system was disconnected while measuring rendering erroneous finger pressures. Reconnect and restart - Semaphore overrun. A hardware error. If it occurs repeatedly please contact FMS, see page 3. - Unacceptable plethysmogram. The plethysmogram values moved out of range. This may be a movement artifact. Restart. Arm cuff errors: - Arm cuff overinflated. An arm cuff pressure of greater than 300 mmHg was maintained too long. Usually a serious hardware error. Please immediately contact FMS, see page 3. - Arm cuff still inflated. After an arm cuff over pressure situation deflation to zero pressure has taken too long. Remove arm cuff immediately. Usually a serious hardware error. Please contact FMS, see page 3. - Calibration cycle compleat. An arm cuff calibration cycle went up and came down, then stopped. This is not an error but a safety measure. Restart for another cycle. - Check arm cuff air supply. The arm cuff air buffer does not reach proper pressures. There may be a leak or the pump malfunctions. Please contact FMS, see page 3. - Connect both cuff tubes to Finometer. - Cuff deflation not linear. May be due to artifact. If the error is systematic it is a hardware error. Please contact FMS, see page 3. - Deflation stopped, cuff pressure<20 mmHg. A Classico measurement stops when cuff pressure moves below 20 mmHg. This is not an error. Usually the operator would have stopped the measurement manually. - Measurement stopped, taking too much time. Inflation to a high pressure and deflation at a very slow rate may take longer than normal. A safety measure.

C Derived parameters

Symbol SYS DIA MAP IBI HR LVET SV CO TPR

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Color Red Red White Gray Red Gray White Cyan Yellow --

Meaning systolic pressure as the maximum pressure in arterial systole diastolic pressure as the low pressure just before the current upstroke mean arterial pressure as the true integrated mean pressure between the current and the next upstroke pulse interval as the time between the current and the next upstroke pulse rate derived from the pulse interval left ventricular ejection time as the time between the current upstroke and the dicrotic notch stroke volume as the true integrated mean of the simulated flow waveform between the current upstroke and the dicrotic notch cardiac output as the product of stroke volume and heart rate total systemic peripheral resistance as the ratio of mean arterial pressure to cardiac output, assuming zero venous pressure (at the right atrium) systolic pressure time index, the area under the reconstructed aortic pressure waveform in systole, between begin upstroke and the dicrotic notch, not separately available diastolic pressure time index, the area under the reconstructed aortic pressure waveform in diastole, between the dicrotic notch and begin upstroke of the next beat, not separately available diastolic to systolic pressure time index ratio as an index of cardiac oxygen supply and demand, always computed off a reconstructed aortic pressure waveform time--tension index (rate pressure product) as an index of cardiac oxygen demand, computed as the product of systolic pressure and pulse rate maximal steepness of the current upstroke always computed on the finger pressure waveform ascending aorta characteristic impedance at diastolic pressure total arterial compliance at diastolic pressure

SPTI

DPTI

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D/SPTI PS*HR dp/dt Zao Cwk

Green Magenta Blue Green Magenta

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Table C.1 Finometer derived parameters. All parameters when displayed are 8--beat averages. Indexed parameters have a darker shade. The clinique waveform display shows beat--to--beat heart rate in Yellow.

D Glossary

A/D converter see "converter A/D". baroreflex sensitivity Expresses the change in interbeat interval, in ms, for a simultaneously occurring change in blood pressure, in mmHg. It is thought to principally represent the sensitivity of vagal heart rate control upon blood pressure changes and to a lesser degree on sympathetic control. Its value in normal subjects tends to depend on blood pressure, on heart rate, and subject age. The measurement can be performed in various ways, evoked or spontaneous, sequential or spectral. The distribution of a number of BRS observations is almost always log--normal and non--parametric statistics are called for. If a mean value is computed the best approach usually is to take the geometric mean. Beatscope A computer program available from FMS featuring "click and go" connection of a PC to Finometer (or to Portapres), display of waveforms and derived parameter trends, extraction of data epochs to separate files for analysis with spreadsheets, Matlab, computation of descriptive statistics and production of publishable graphics. bias The mean difference between the results of measurements of the same parameter with two methods in several subjects. The method under test may show biased results with respect to a reference measurement. For example, finger diastolic pressure shows a negative bias with respect to intrabrachial artery pressure. BNC connector A coaxial type connector designed originally for high frequency signals but also used with advantage to pass low frequency signals such as ECG, EEG, BCG, BAP, EMG, respiration in a continuously shielded manner. Easy to connect and disconnect. COM port A communications port of a PC which is available under most operating systems and which passes data serially, and asynchronously, in start/stop mode. These ports follow the RS-232 standard in personal computers. converter A/D Converts an analog voltage signal to a digital data stream. Measures the value of an analog, continuously variable signal at fixed increments of time converting its instantaneous value to a number which can be handled by a digital computer. The numbers are usually stored in a file on harddisk and when displayed interconnected with straight lines restore the impression of the original continuous signal. At the sample rate used in Finometer of 200 Hz the fixed time increment is 0.005 s or 5 ms. converter D/A Changes a stream of numbers at fixed increments of time usually to a step wise varying analog signal for plotting and viewing. The two Finometer analog output ports labelled output 1 and output 2 use linear interpolation, not step wise variation, for a smooth output signal. This requires special analog output circuitry and causes a 5 ms delay since the line can be "drawn" to the next point only

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when it is known. cyclic redundancy check A system used to secure communication of data streams in packets between computers and allowing to test after transmission of the packet if transmission occurred without error. In case of an error a repeat transmission can be requested. Finometer applies a CCITT (the telecommunications standards committee) CRC for all its data packets. It is generated and added to each packet before storage to disk or transmission over a port to an external device such as a personal computer. When Finolink is used for communication this program checks the CRC and in case an error is detected requests re-transmission by Finometer until the packet is received correctly. D/A converter see "converter D/A".

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Figure D.1

Some derived parameters.

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deflation rate The speed with which a Finometer arm cuff is deflated expressed in mmHg/s. Deflation is linear for the Finometer, controlled by a servo system. For best precision a slow deflation is chosen. For return--to--flow calibrations at normal blood pressures the deflation rate is near 2 mmHg/s, for higher blood pressures it is slightly faster. derived parameters Measurements made on the pressure or flow pulsation available in Finometer. The pressure pulsation (figure D.1), default, is the reconstructed brachial artery (reBAP) pulse, but the original finger pressure (FinAP) pulse may optionally be chosen. The flow pulse used is generated by the Modelflow algorithm and does not depend on brachial pressure reconstruction. Derived parameters de-

scribe a patient's state. Finometer provides for many such parameters mostly measured on a beat--to--beat basis. downloading The process by which data is received from another (central) computer system and loaded into local store. In Finometer's context downloading is performed by a PC running Finolink software to obtain packet files from a Finometer. The process is initiated from and controlled by Finolink. Finometer takes care that the requested packet is transmitted over the cable. Finapres Finapres TM, acronym for FINger Arterial PRESsure, was the first commercially available device to measure finger blood pressure continuously according to the volume--clamp method of Pe´z na and the Physiocal criteria of Wesseling. Portapres

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and Finometer are successors of Finapres. Finapres is no longer marketed.

reconstruction, return--to--flow calibration and Modelflow cardiac output computation. These methodologies are described in corresponding papers in the scientific literature and implemented. They aim at improved accuracy of measurement. Many derived parameters are computed on the pressure and flow waveforms and can be selected for display and trending. FMS FMS, Finapres Medical Systems BV. A company established under the law of the Netherlands with its seat in Arnhem, to manufacture, market, sell and service Finapres based devices and software. FMS is a spin off of TNO TPD Biomedical Instrumentation at the Academic Medical Centre in Amsterdam. The current product line consists of Portapres, Finometer, Beatscope, and WinCPRS, the latter in collaboration with AA Oy in Finland. frontend A small box to be mounted near the patient's cuffed finger containing amplifiers, a pressure transducer and a fast air pressure control valve, implementing the volume--clamp method of Pe´z. The na hydrostatic height correction system is also operated from the frontend box. generalized A method or result valid for a population of subjects on average with little interindividual spread. The transfer function from intrabrachial to finger pressure, for example, is nearly identical for most subjects, and independent of clinical condition and, therefore, generally correct. heart rate variability A term to describe variations of both instantaneous heart rate and RR inter-

Figure D.2

A finger cuff.

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finger cuff A conical shaped inflatable cuff, with an extremely thin bladder, coming in three sizes fitting most fingers from the age of 6 years. On the inside an infrared plethysmograph is mounted to monitor the size of the arteries under the cuff (figure D.2). Finolink A Windows software program provided by FMS to be used to download the packet files generated by Finometer. Downloading with Finolink can be done off--line (when Finometer is not connected to a patient performing a measurement) or on--line. When off--line downloading each and every file can be selected for downloading. When on--line only the file and packets currently being generated and stored can be downloaded. Finometer The commercial successor of Finapres but with many extras such as hydrostatic finger to heart level compensation, brachial artery pressure

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vals. Heart rate variability represents a marker of autonomic activity which has a significant relationship with cardiovascular mortality. HRV can be measured in many different ways, in the time domain and in the frequency domain, and many computed parameters increase in value with the duration of the record. In 1996 a report was published by an international Task Force, bringing order in this complex matter and recommending that at least four measures be computed in the time domain: SDNN as an estimate of overall HRV; HRV triangular index as another estimate of overall HRV, based on the RR interval histogram; SDANN as an estimate of long--term components of HRV; RMSSD as an estimate of short--term components of HRV. NN represents consecutive intervals between sinus beats. hydrostatic height A vertical column of liquid has a higher pressure at the bottom than at the top. Thus, finger pressure measured with the arm hanging down is higher than when the finger is at heart level. The effect is substantial. A 1.3 cm difference in height causes a 1 mmHg difference in pressure. The hydrostatic height correction system measures the relative vertical positions of hand and heart and automatically compensates for any measured difference. This removes a major source of uncertainty in finger blood pressure measurement. I/O Input/Output. A general term denoting the transfer of information between two (computer) systems. A person may input information to a computer by typing on an attached keyboard. A computer outputs information by displaying it on a screen.

I/O analog Input and/or output of analog signals to and from a system such as Finometer. It is performed with A/D and D/A converters and the information transferred is an analog signal such as a voltage proportional to a blood pressure pulsation. I/O parallel Input/output of digitally coded information when not bits but words are transferred over a number of parallel wires, usually between two computers or between a PC and the computer embedded in Finometer. Parallel I/O is often transferred via printer ports. Potentially faster than serial I/O. I/O serial Input/output of digitally coded information as a modulated voltage bit stream over a single wire usually between two computers or between a PC and the computer embedded in Finometer. Serial I/O is transferred via a COM port and is subjected to strictly standardized protocols. inflation rate The speed in mmHg/s with which an upper arm cuff is inflated. Finometer uses a special pneumatic circuitry to allow full arm cuff inflation in only one or two seconds. Such fast yet smooth inflation limits the pooling of blood in vessels distal of the cuff and thus is often considered more pleasant than slow inflation. In addition it provides for clearer Korotkoff sounds and reduces the auscultatory gap. level correction A procedure that shifts finger pressure usually in an upwards direction to approach brachial artery pressure levels more closely, thus correcting for the pressure decrement that generally exists between brachial and finger blood pressures. The amount of correction depends on the relative levels of

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systolic and diastolic pressure. light emitting diode An electronic component that transmits almost monochromatic light when an electrical current is passed through it. Finometer finger cuffs contain an LED that transmits light in the infrared. Infrared light is invisible.

the area under the flow pulse in systole. Cardiac output is the product of stroke volume and heart rate. Total systemic peripheral resistance equals the sum of Z0 and Rp . In Finometer TPR is computed and averaged differently and displayed in different units. Modelflow provides close tracking of changes in cardiac stroke volume and output. Entry of patient gender, age, height and weight are required for best precision.

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Figure D.4 Figure D.3

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Nonlinear curves.

The Modelflow model. nonlinear A relationship is nonlinear when the plot of a dependent variable against an independent variable is curvilinear. For example aortic volume, V, when plotted against blood pressure is nonlinear since aortic volume does not increase linearly with increasing pressure but at higher pressures increases less and less. Compliance, C, plotted against pressure is also highly nonlinear. Furthermore, aortic nonlinearity is age dependent as can be seen by comparing the curves for an elderly (upper left) and a young adult subject in the above diagrams D.4.

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Modelflow A method and algorithm to compute an aortic flow curve from an arterial pressure pulsation by simulating a nonlinear, self--adaptive model of the aortic input impedance. The three--element model (figure D.3) is well known from physiology for its ability to compute stroke volume. The aortic characteristic impedance, Z0 , and Windkessel compliance, Cw , are nonlinearly depending on arterial pressure, p, the peripheral resistance, Rp , adapts to changes in mean flow, q . Stroke volume is computed by taking ¯

nulling Reducing the zero offset of a transducer to null. Devices such as semiconductor pressure transducers convert pressure into voltage, and do that linearly. However, at zero applied pressure there may already be a positive or negative voltage output also called zero offset. This should be removed (nulling) and is done by first measuring and then subtracting the zero offset such that the resultant output is 0 V at 0 mmHg. null modem cable A computer is designed to communicate in serial fashion over a COM port with passive, non--computer attached devices such as printers or a modem. If computers want to communicate to each other instead of to a passive device they get confused unless they are connected via a `null-modem' cable. This applies to the Finometer embedded computer when it needs to communicate with a PC.

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measurement information. Each packet is given a cyclic redundancy check value (CRC) as soon as it is assembled. Thus at any storage or transfer action the packet's integrity can be verified. Packets are grouped into files. A measurement file consists of a number of packets with each packet having a sequential number and the file being terminated with a last packet containing extra information not present in a normal packet. Pe´z method The Czech professor of Physiolona gy Dr Jan Pe´z working in Brno, invented the volna ume--clamp method whereby the volume of the arteries under a finger cuff, as observed by a photo--electric plethysmograph, is dynamically held constant by precisely measured counter pressure in the finger cuff during the pulsation, using a pneumatic servo system. photocell An electronic component or device which responds to light by generating an electrical current. In a Finometer cuff a photocell is mounted which is principally sensitive in the infrared to observe changes in light from an LED proportional to changes in arterial volume. Physiocal Acronym for Physiologic Calibration. The algorithm that calibrates the finger arterial size at which finger cuff air pressure equals finger arterial blood pressure. During a Physiocal cuff air pressure is held at varying levels and the plethysmogram is observed that is caused by the pulsating intraarterial pressure. The amplitude and shape of the plethysmogram determine the volume--clamp level. plethysmogram A graphic representation of vol-

off--line A device is called `off--line' when it is operating independently of a central computer. For Finometer we use the expression when it is not connected to a patient performing a finger pressure measurement. offset A steady, systematic difference or shift between the actual value and the reference or ideal value. on--line The opposite of `off--line'. Finometer is on--line when connected to patient and performing a measurement. packet For Finometer a packet is 512 byte of data in a predefined format and representing 0.5 s of

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ume changes with time of a part of the body such as a finger or arm. In Finometer the finger arterial volume changes (finger plethysmogram) are recorded in the infrared. Red blood cells absorb infrared light strongly. A larger vascular volume contains more red cells and absorbs more infrared. Thus, a more distended blood vessel is recorded as a decreased brightness. precision The amount of scatter in the difference between values of a variable such as blood pressure measured by two independent methods. For example, when blood pressure is measured intraarterially in the brachial artery and noninvasively in the finger the systolic levels may differ each beat. The difference can be expressed statistically as the mean difference and the standard deviation of the difference. The mean difference is also called bias. The standard deviation is also called precision.

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receptacle Usually the chassis mounted part of a connector to receive the cable mounted part of the connector. return--to--flow A method, different from Korotkoff sounds but similar to palpation, to detect the instant that cuff pressure equals intraarterial systolic pressure. The term originates from the detector used, an ultrasound Doppler flow meter. In Finometer the finger pressure distal of the occluding cuff is monitored for return of pressure pulsations. revolving store A storage area or buffer in computer memory or on harddisk which is addressed in a circular fashion starting at the beginning, moving towards the end, then restarting at the beginning, and so forth. In Finometer, such a storage area is reserved on harddisk. It consists of 24 × 60 × 60 × 2 packets of 512 byte size to a total size of 172800 packets or 88,473,600 byte. Finometer maintains an index into the store holding the starting points of each separate file. When this pointer file is disturbed, for example by switching the power off during a measurement, it has to be recreated. This is a time consuming process. Because the store is a revolving store which overwrites itself, it does not have to be erased. Hence, there is no need for erasure facilities. rise time The time it takes for a pulse to rise from bottom to top or, more precisely, from 10% up to 90% up. The rise time of a finger pressure pulse is typically 100 ms or 0.1 second. When it is much slower than 100 ms the operator is alerted. Slow rise times may occur due to proximal plaques or other hemodynamic obstructions.

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random zero A zero offset of unknown and random value is introduced to the mercury column of the Hawksley Random Zero sphygmomanometer. This causes the readout of cuff pressure to be in error. At the completion of a measurement the zero offset is measured separately and subtracted from the readouts to obtain correct measurement values. The procedure reduces operator bias and digit preference. In the Finometer--classico instrument, when set to `random zero readout' the zero offsets range in value between -15 and +15 mmHg. Their randomness or unpredictability is guaranteed by using a digital random number generator. After the measurement the zero offset is subtracted automatically from any marked cuff pressures.

RS-232 An international standard for asynchronous serial communication of digital information over a COM port. Among other things it sets communication rates expressed in baud or in BPS for bit per second, number of start and stop bits and parity checking. All this is automatically set up between Finometer and a PC running the Finolink software. RTF calibration A technique used in Finometer to compare the return--to--flow systolic pressure with the waveform filtered finger pressure. An optimal pressure increment or decrement is computed to make reconstructed brachial pressure levels nearly identical to intrabrachial levels. sensitivity One pressure transducer may react to a 1 mmHg pressure variation by changing its output by 8, another by 15 mV. Thus sensitivity is 8 or 15 mV/mmHg. For Finometer it is a requirement that sensitivity is exactly 10 mV/mmHg or 1 V per 100 mmHg. Finometer pressure transducer sensitivity can be checked but if it deviates more than the specification it cannot be adjusted in the field but must be returned to the manufacturer. It is believed that the semiconductor pressure transducers in Finometer maintain their calibration over many years. serial I/O see "I/O serial". square wave A waveform that changes stepwise in time from a low to a high level. A square wave is well suited as a calibration signal since many properties of a recording system can be tested with it. Finometer outputs a square wave on all four analog output connectors when it is not performing a measurement Figure D.5 Square wave calibration.

(when it is off--line). For best performance it moves between three (0, 1 and 2 V) not two levels, and at the two frequencies, 1 and 0.1 Hz (figure D.5). TNO The Dutch Organization for Applied Scientific Research. TNO operates a number of Institutes. TPD is the TNO institute of Applied Physics having its seat in Delft, The Netherlands. Biomedical Instrumentation (BMI) is a division of TPD and is located at the Academic Medical Center of the University of Amsterdam. The Finapres, the Portapres, the Modelflow method, the Beatscope software, and the Finometer were developed at BMI and are now available from FMS, Finapres Medical Systems BV. transducer A device or component that changes one mode of physical power into another. Finometer can be called a transducer. It changes blood pressure into air pressure and further into an electrical voltage that can be amplified, filtered, sampled digitally, displayed, etc.. transfer function A mathematical equation describing how frequencies in one waveform, for example the brachial pressure waveform, are amplified or

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the arterial walls in the finger under the cuff. waveform filtering Applying a frequency dependent filter to a waveform to change its shape in a predetermined way. Waveform filtering is used in Finometer to change a finger to a brachial artery blood pressure waveform. This includes amplifying frequencies below 2.5 Hz by a factor slightly greater than one and attenuating frequencies near the 8 Hz resonance peak that occurs in the transmission path between brachial and finger artery sites. Waveform filtering is akin to applying a transfer function to a signal but it is done in real time almost without delay and does not use Fourier transforms. Wesseling criteria Noninvasive blood pressure measurements with an occluding cuff require a criterion to detect when cuff pressure equals an intraarterial pressure level. For the oscillometric method of Marey, MAP is the cuff pressure at maximum cuff pressure oscillations. The volume--clamp method of Pe´z na dynamically unloads finger arterial volume, and the Wesseling criteria establish the (setpoint) volume at which finger cuff pressure equals intraarterial blood pressure. Since this setpoint volume is under sympathetic influence the calibration has to be repeated regularly. Physiocal is the computer implementation of these criteria. zeroing see "nulling".

Figure D.6

Transfer functions.

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attenuated in another related waveform such as the finger pressure. The brachial to finger pressure transfer function (thin line in figure D.6) shows attenuation for low and amplification for higher frequency components, in particular near the frequency of 8 Hz. unloading Removing the load of a construction or component. Arterial walls carry the load of the blood pressure that tries to expand the arteries from the inside. By applying a counter pressure from the outside the arterial wall can be unloaded. The counter pressure then carries the load. If blood pressure has a pulsatile component on top of a mean distending pressure then unloading can be done statically, only compensating for the mean pressure, or it can be done dynamically, thus also countering the pulsatile component. Finometer does a dynamic unloading of

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E Literature references

1. AAMI: American national standard ANSI/AAMI SP10--1992: Electronic or automated sphygmomanometers. Association for the Advancement of Medical Instrumentation, 1993, Arlington, VA. 2. Bos WJW, van Goudoever J, van Montfrans GA, van den Meiracker AH, Wesseling KH: Reconstruction of brachial artery pressure from noninvasive finger pressure measurement. Circulation 1996; 94:1870--1875. 3. O'Brien E, Mee F, Atkins N, O'Malley K: Inaccuracy of the Hawksley random zero sphygmomanometer. The Lancet 1990; 336:1465--1468.

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brachial to finger pulse wave distortion and pressure decrement. Cardiovasc Res 1997; 33:698-705. 8. Gravenstein JS, Paulus DA, Feldman J, McLaughlin G: Tissue hypoxia distal to a Pe´z finger na blood pressure cuff. J Clin Monit 1985; 1:120-125. 9. Harms MPM, Wesseling KH, Pott F, Jenstrup M, van Goudoever J, Secher NH, van Lieshout JJ: Continuous stroke volume monitoring by modelling flow from non-invasive measurement of arterial pressure in humans under orthostatic stress. Clin Sci 1999; 97:291--301. 10. Imholz BPM, Wieling W, Langewouters GJ, van Montfrans GA: Continuous finger arterial pressure: utility in the cardiovascular laboratory. Clin Autonomic Res 1991; 1: 45--53. 11. Imholz BPM, Langewouters GJ, van Montfrans GA, Parati G, van Goudoever J, Wesseling KH, Wieling W, Mancia G: Feasibility of ambulatory, continuous, 24-hour finger arterial pressure recording. Hypertension 1993; 21:65--73. 12. Imholz BPM, Wieling W, van Montfrans GA, Wesseling KH: Fifteen years experience with finger arterial pressure monitoring: assessment of the technology. Cardiovasc Res 1998; 38:605--616.

4. Castiglioni P, Parati G, Omboni S, Mancia G, Imholz BPM, Wesseling KH, DiRienzo, M: Broadband spectral analysis of 24 h continuous finger blood pressure: comparison with intra-arterial recordings. Clin Sci 1999; 97:129--139. 5. Fitzgerald DJ, O'Malley K, O'Brien E: Inaccuracy of London School of Hygiene sphygmomanometer. BMJ 1982; 284:18--19. 6. Gizdulich P, Imholz BPM, van den Meiracker AH, Parati G, Wesseling KH: Finapres tracking of systolic pressure and baroreflex sensitivity improved by waveform filtering. J Hypertens 1996; 14:243-250. 7. Gizdulich P, Prentza A, Wesseling KH: Models of

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13. Jansen JRC, Schreuder JJ, Mulier JP, Smith NT, Settels JJ, Wesseling KH: A comparison of Modelflow cardiac output derived from the arterial pressure wave against thermodilution in cardiac surgery patients. Br J Anaesth 2001; 87:212--222. 14. de Jong-de Vos van Steenwijk CCE, Wieling W, Johannes MD, Harms MP, Kuis W, Wesseling KH: Incidence and hemodynamic characteristics of near-fainting in healthy 6 to 16 year old subjects. JACC 1995; 25:1615--1621. 15. Langewouters GJ, Wesseling KH, Goedhard WJA: The static elastic properties of 45 human thoracic and 20 abdominal aortas in vivo and the parameters of a new model. J Biomech 1984; 17:425-435.

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of two prototype devices producing noninvasive, pulsatile, calibrated blood pressure measurement from a finger. J Clin Monit 1985; 1:17--29. 19. Task Force: Heart rate variability. Standards of measurement, physiological interpretation, and clinical use. Eur Heart J 1996; 17:354--381. 20. Wesseling KH: A century of noninvasive arterial pressure measurement: from Marey to Pe´z and na Finapres. Homeostasis 1995; 36:50--66. 21. Wesseling KH, Jansen JRC, Settels JJ, Schreuder JJ: Computation of aortic flow from pressure in humans using a nonlinear, three-element model. J Appl Physiol 1993; 74:2566--2573. 22. Wesseling KH, Smith NT: Availability of intraarterial pressure waveforms from cathetermanometer systems during surgery. J Clin Monit 1985; 1:11--16. 23. Wesseling KH, de Wit B, van der Hoeven GMA, van Goudoever J, Settels JJ: Physiocal, calibrating finger vascular physiology for Finapres. Homeostasis 1995; 36:67--82.

16. van Lieshout JJ, Wesseling KH: Continuous cardiac output by pulse contour analysis? Br J Anaesth 2001; 86:467--469 (Editorial II). 17. Pe´z J: Photoelectric measurement of blood na pressure, volume and flow in the finger. Digest 10th Int Conf Med Biol Engng. Dresden, 1973; p 104 (abstract). 18. Smith NT, Wesseling KH, de Wit B: Evaluation

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F Index

24 h measurement store 111 a A/D converter--Glossary 117 Accessing files 22, 111 Accuracy 108 Analog I/O blood pressure signal 21 BNC connectors 21 calibration selection 46 calibration signal 19 calibration signal properties 46 calibration waveforms 46 configurability 73, 74 connector 20 external input 23 external pressure wave 73 external signals 23 external signal safety 18, 109 height signal 21 off--line calibration 46 sampling rate 29, 74 specifications 103 Analog input 103 Analog output 103 Arm cuff over pressure protection 67, 101 Arm cuff wrapping 63 Arteriosclerosis 37 Auscultation 91 Availability of finger pressure 17 Averaging 52, 59, 64, 87, 89, 91 Avoiding injury 18, 109, 110 b Baroreflex sensitivity--Glossary 117 Battery 105 Beatscope 5, 22, 29, 44, 51, 56, 84, 100, 111, 112 Beatscope--Glossary 117 Bias and precision arterial pressure 32 cardiac output 32 Classico 91 definition 32 Bias--Glossary 117 Bibliography 126 BNC connector--Glossary 117 Brachial pressure reconstruction derived parameters 31 level calibration 42 level correction 41 setting up 72 Browsing with mouse and buttons 7 BRS--Glossary 117 Buffer 67 Button functions of Interactive User's Guide 7 c Calibration arm cuff transducer 71, 94 buffer pressure 67 Classico waveform 94 external signal 73 finger pressure transducer 70 Finometer pressures 28 height transducer 69

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Modelflow 16, 82 Modelflow by aortic diameter 57 by thermodilution 57 not possible 45 physiologic 62 pressure level 42, 72 pressure transducers 18, 65 pressure wave 46 return--to--flow 31, 32, 63, 88, 90 return--to--flow display 90 service 3 signal during downloading 47 signals 29, 44, 46 signal selection 46 slide 42 square wave 46 transducer stability 70 use other arm 37 Cannot start 48 Cautions 17 CE marking 97 CGS unit system 77 Chapter classico instrument 91 clinique instrument 81 customer support 3 Dear Guide user 7 derived parameters 116 disclaimer 5 error messages 114 glossary 117 help slides 34 introduction 26 literature references 126

quick start 19 research configuration 65 research instrument 49 specifications 97 start display 44 warnings 16 Classico instrument auscultation 95 blinded readout 95 calibration 94 display layout 93 Hawksley Random Zero 96 introduction 91 London School of Hygiene 95 random zero 96 results download 93 Riva--Rocci/ Korotkoff 95 setup deflate 93 setup inflate 93 setup readout 93 Cleaning 113 Clinique instrument control idling 86 measuring 88 off--line 86 describe subject 82 display compression 89 display layout 87 error message display 83 files downloading 84 height nulling 86 hidden Modelflow 81 introduction 81 return--to--flow 90

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setting patient data 82 show trends 85 status line 87 Clock setup 75 Cold fingers 37 COM port--Glossary 117 Configuration date and time 75 display units 77 external signal channel 74 external signal input 73 finger switching 76 load 80 miscellaneous 76 overview 65 pressure waveform reconstruction 72 save 79 system beeper 78 time and date 75 transducer check arm cuff 71 buffer pressure 67 finger cuff 70 height calibration 69 height nulling 68 Connecting external equipment 109 Control buttons 21, 40, 88 Clinique 86, 88 Finometer 40 remote 18, 54, 81, 84, 109, 110 Research 52 servo system state 62, 102 tab cards 52 Converter A/D--Glossary 117

Converter D/A--Glossary 117 Costo--clavicular cutoff 37 CRC--Glossary 118 Cuff application 36 Cuff sizing 35 Customer support 3 Cyanotic finger tips 38 Cyclic redundancy check--Glossary d D/A converter--Glossary 118 Data file erasure 111 Date and time 75 Deflation rate--Glossary 118 Derived parameters 31, 116 Derived parameters--Glossary 118 Describe subject Clinique 82 Research 51, 56, 57 Dimensions 106 Disclaimer 5 Display layout Classico 93 Clinique 87 Research 52 Downloading 22, 44, 109, 110, 111 Downloading Clinique 84 Finolink 5 off--line 47, 54, 84 on--line 54, 84 Research 54, 110 Start display 47 Downloading--Glossary 118

118

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e ECG 74 Electrical hazards 109 Electrical safety 101 Electrical specification 105 Environmental specification 104 Error message list of 114 Error message display Classico 93 Clinique 83 Research 53 EXIT 40 External signals analyze pressure waveform 74 channel select 74 offset 73 polarity 73 sampling 23 sensitivity 73 f Failure 48 Features 29 Files downloading 111 Files downloading, see Downloading FinAP 31, 32, 52, 61, 74, 86, 87 Finapres cuff 38 Finometer mode 30, 72, 79, 80 Ohmeda Model 2300 27 oxygen saturation 38 trade mark 5 Finapres and Finometer 28 Finapres--Glossary 118

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Finger cuff over pressure protection 101 Finger cuff--Glossary 119 Finger switching pressure differences 76 Finolink 107, 112 Finolink approved software 18, 110 Classico download 93 Clinique download 84 file name 75 off--line download 47 packets 54 remote control 29 Research download 54 setting up 22, 110 Start display 44 trade mark 5 Finolink--Glossary 119 Finometer application safety 16 cannot start 48 derived parameters 31 description 27 ease of use 6 EXIT 40 features 29 instruments 30 level calibration 42 level correction 41 methods 28 three built--in instruments 6 trade mark 5 user interfaces 30 Finometer and Finapres 28 Finometer component parts 99 Finometer in a system 109

Finometer--Glossary 119 FMS 3 FMS--Glossary 119 Frontend--Glossary 119 g Generalized--Glossary 119 General system protection 102 Glossary A/D converter 117 baroreflex sensitivity 117 Beatscope 117 bias 117 BNC connector 117 BRS 117 COM port 117 converter A/D 117 converter D/A 117 CRC 118 cyclic redundancy check 118 D/A converter 118 deflation rate 118 derived parameters 118 downloading 118 Finapres 118 finger cuff 119 Finolink 119 Finometer 119 FMS 119 frontend 119 generalized 119 heart rate variability 119 HRV 119 hydrostatic height 120 I/O 120

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I/O analog 120 I/O parallel 120 I/O serial 120 inflation rate 120 LED 121 level correction 120 light emitting diode 121 Modelflow 121 nonlinear 121 nulling 122 null modem 122 off-line 122 offset 122 on-line 122 packet 122 Pe´z method 122 na photocell 122 Physiocal 122 plethysmogram 122 precision 123 random zero 123 receptacle 123 return-to-flow 123 revolving store 123 rise time 123 RS-232 124 RTF 123 RTF calibration 124 sensitivity 124 serial I/O 124 square wave 124 TNO 124 transducer 124 transfer function 124 unloading 125

waveform filtering 125 Wesseling criteria 125 zeroing 125 h Hawksley Random Zero 91 Heart rate variability 74 Heart rate variability--Glossary 119 Height correction 39 Height system nulling 39, 40 sensitivity 39 Help slides 34 Hibernate 48 HRV 74 HRV--Glossary 119 Hydrostatic height system 69 Hydrostatic height--Glossary 120

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Introduction Classico 91 Clinique 81 Finometer 26 Research 49 Start display 34 k Korotkoff

91

l LED--Glossary 121 Level calibration 42, 72 Level correction 41, 72 Level correction--Glossary 120 Light emitting diode--Glossary 121 Litterature 126 Loading a configuration 25, 80 London School of Hygiene 91 m Mark button 40 Mechanical specification 106 Medical unit system 77 Methods in Finometer 28 mmHg 77 Modelflow bias and precision 32 calibration from aortic diameter 57 calibration from thermodilution 57 Clinique 81 flow curve 52 from external signal 74 head--up tilt 82 linear scaling 82

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i I/O analog--Glossary 120 I/O parallel--Glossary 120 I/O serial--Glossary 120 I/O--Glossary 120 IEC standard 601 109 IEC standard 950 109 Impedance internal 103 Inflation rate--Glossary 120 Input 103 Inspection incoming 99 Instruction slides 34 Instrumental accuracy 108 Instrumental specification 107 Instruments 30

methodology 28 not displayed 81 patient data 51, 56 trade mark 5 Modelflow--Glossary 121 n Nonlinear--Glossary 121 Nulling--Glossary 122 Null modem 22, 44, 109, 110 Null modem--Glossary 122 o Off-line--Glossary 122 Offset--Glossary 122 On-line--Glossary 122 Ordering parts 3 Output 103 Over pressure arm cuff 67, 101 finger cuff 101 p Package checklist 99 Packet file A/D signals 61 accessing 5, 22 Clinique trend plot 88 contents 111, 112 date and time 75 display compression 89 downloading 44, 47, 84, 111 erasing data 111 erasing memory 47, 54 error message 53, 83

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identical 81 index 111 internal signal not stored 23 naming convention 75 return--to--flow data 90 size 111 stop plotting 88 unpacking 22, 112 Packet--Glossary 122 pascal 77 Patient data Clinique instrument 82 Research instrument 51 Patient safety 100, 109 Patient sensors 21 Pe´z method--Glossary 122 na Peripheral resistance 77 Photocell--Glossary 122 Physiocal 28 Physiocal Clinique 88 diagnostics 62 displayed 61 grading quality 62 off/on 54, 62, 110 Research 62 Physiocal--Glossary 122 Plethysmogram--Glossary 122 Pointer file corrupted 48, 111 recreation 48, 111 Power dissipation 105 Precision--Glossary 123 Protective measures 18, 109, 110

q Quick start accessing files 22 equipment setup 19 external signals 23 loading a configuration 25 patient sensors 21 saving a configuration 25 r Random zero--Glossary 123 Readout Classico blinded 95 calibration 94 markers 95, 96 normal 95 random zero 96 reBAP 31, 32, 72, 86, 87 Receptacle--Glossary 123 References 126 Remote control 18, 54, 81, 84, 109, 110 Repairs 3 Research instrument calibration by aortic diameter 57 calibration by thermodilution 57 cardiac oxygen 60 context sensitive help 55 control 52 derived parameters display 52 derived variables card 64 describe subject 51 describe subject card 56 display layout 52 error message display 53 files downloading 54

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help notations 55 help paragraphs 55 introduction 49 miscellaneous information 52 notation 49 opening display 51 Physiocal card 62 pressure-compliance diagram 58 pressure-volume diagram 58 pressure parameters display 52 remote control 54, 110 return--to--flow card 63 select A/D signal card 61 select trends card 59 setting patient data 57 status line 52 Return-to-flow--Glossary 123 Return--to--flow Clinique 90 Research 63 Revolving store--Glossary 123 Rise time--Glossary 123 RS-232--Glossary 124 RTF calibration--Glossary 124 RTF--Glossary 123 s Safe data storage--Data durability 111 Safety arm cuff pressure 101 avoiding injury 18, 109, 110 electrical 101 finger cuff pressure 101 general system 102 patient 100

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Saving a configuration 25, 79 Screen layout of Interactive User's Guide 7 Self test 45 Sensitivity--Glossary 124 Serial I/O--Glossary 124 Serial port downloading 54, 84, 109 I/O 44, 109, 110 RS-232 54, 109, 110 selecting 22 specification 107 Service 3 SI unit system 77 Slides available instruments 43 buttons 40 cuff application 36 cuff size 35 Finometer control 40 front panel layout 40 height sensing 39 help 34 Software License rights 5 Specification accuracy 108 analog I/O 103 derived parameters 116 electrical 105 environmental 104 instrumental 107 mechanical 106 Sphygmomanometer 91 Square wave--Glossary 124 Standard EN 60601--1--1 109

Start display available options 44 calibration signals 46 off--line downloading 47 selftest 45 State of servo control 102 Status line Classico 93 Clinique 83, 87 Physiocal 88 Research 52 Suggested order of reading 6 SVR 77 Systemic vascular resistance 77 Syst`me International d'Unit´s 77 e e t Tab card Derived variables 64 Describe subject 56 Help 55 Physiocal 62 RTF cal 63 Select A/D signal 61 Select trends 59 Technical support 3 Three built--in instruments 6 Time and date 75 TNO--Glossary 124 Total systemic peripheral resistance TPR 77 Trademarks FMS 5 Trademarks Ohmeda 5 Transducer check arm cuff 71

77

buffer pressure 67 finger cuff 70 height calibration 69 height nulling 68 overview 65 Transducer--Glossary 124 Transfer function--Glossary 124 u Units pressure 77 resistance 77 Unit system--CGS 77 Unit system--medical 77 Unit system--SI 77 Unloading--Glossary 125 Unpacking--The data packets

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Unpacking--The Finometer components Upstroke 31, 87, 88 User's Guide button functions 7 how to browse it 7 screen layout 7 w Warnings, cautions, protective measures Warranty 4, 5 Waveform filtering 72 Waveform filtering--Glossary 125 Weight 106 Wesseling criteria--Glossary 125 z Zeroing--Glossary 125

99

16

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Colophon

Title: Finometer TM User's Guide Text: Karel H Wesseling Design: PRAGMA ADE Ridderstraat 27, NL - 8061 GH HASSELT, THE NETHERLANDS Software: Context Illustrations: Allard P Wesseling Novice Finometer operator: Mischa R Guelen Copyright: FMS, Finapres Medical Systems BV Simon Stevinweg 48, NL-6827 BT ARNHEM, The Netherlands Date: 2002.05.06

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