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External Fetal Monitoring

· Computer assisted auditory & visual assessment of fetal heart rate (FHR) and uterine contractions (UC) · Components:

­ Tocotransducer: placedover fundus ­ Ultrasound transducer: placed over fetal back

External Fetal Monitoring

· · · · · · · Advantages Dilation/ ROM not needed Nonninvasive Easy to apply Continuous tracing of FHR Frequency of UCs easily assessed FHR changes detected early. No complications associated with use.

External Fetal Monitoring

Disadvantages · Reliable tracing difficult if patient obese or active · May pick up artifact · FHR may be lost if fetus active or changes position · FHR may only be picked up when woman on back · No information about intensity of the contractions; fundus must be palpated to assess intensity. · Cannot determine baseline tone of uterus

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Internal Fetal Monitoring

· Intrauterine pressure catheter (IUPC) with pressure gauge on one end ­ Inserted via cervix into amniotic fluid in uterus ­ Intrauterine pressure measured in mm Hg ­ Must be 2-3 cm dilated with ruptured membranes · Fetal Scalp Electrode (FSE) spiral electrode ­ Inserted via cervix; attached to presenting part giving direct EKG. ­ Must be 2 cm dilated with ruptured membranes ­ Thick fetal hair may make insertion difficult

Internal Fetal Monitoring

Advantages · Freedom of movement without altering quality of tracing · Accurately measures about intensity of Ucs and baseline tone( in mm Hg) · FHR variability can be assessed · Can cultures of amniotic fluid through lumen · Can instill fluid into uterus; amnioinfusion · Not usually subject to artifact

Internal Fetal Monitoring

Disadvantages · Requires partial dilation of cervix · Requires skilled to apply scalp electrode and insert IUPC. · Insertion of IUPC and FSE uncomfortable · Requires sterile, disposable equipment · IUPC may be impossible to insert if fetus at low station · Complications: scalp abscess or laceration, uterine perforation, separation of a low-lying placenta, bleeding

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Monitor Strip Literacy

Two sections:

­ Upper is where FHR appears ­ Lower is where uterine activity appears

Monitor Strip: Fetal Heart Graph

Longitudinal · Divided into 10 sec intervals by light line. Every 6th line dark. Time between two dark lines = 1 min Horizontal · Divided horizontally by lines with a column of numbers ranging from 30 to 240. These numbers to determine the FHR and represent beats per minute.

Monitor Strip: Contraction Graph

Longitudinal · Divided vertically by lines. Time between two dark lines = 1 min. Time between two light lines = 10 sec Horizontal · Column of numbers from 0 to 100; determine the intensity of UCs when a pressure catheter is used

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Uterine Contractions

Four Phases of UC pattern Increment: the building up phase; longest part Acme: peak; shortest & most intense part Decrement: letting up phase; diminishing of contraction Nadir: resting phase; facilitates uteroplacental reoxygenation

Uterine Contractions

Duration: length of UC, measured from beginning of increment to end of decrement Frequency: from onset of one UC to onset of the next UC Intensity: the strength of the contraction during acme, measured by palpation as mild, moderate, or strong or by IUPC

Montevideo Units

· Way to describe uterine intensity when IUPC is used · To calculate:

­ Baseline uterine pressure subtracted from the peak contraction pressure for each UC recorded in a 10 min tracing ­ These adjusted pressures are added together and the sum is the number of MVUs

· Average is 180 to 240

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EFM-Fetal Heart Rate

· External

­ Ultrasound transducer placed over fetal back detects fetal heart movement. ­ Maternal obesity, fetal or maternal movement may interfere

· Internal

­ Fetal scalp electrode inserted through cervix and attached to epidermis of presenting part giving direct EKG. ­ Must be dilated to at least 2 cm with ruptured membranes. ­ Thick fetal hair may make insertion difficult on cephalic presentation

EFM-Fetal Heart Rate

· Baseline FHR

­ Average heart rate between UCs; measured in bpm. ­ Normal range is 120-160

· Short-term variability

­ Change in rate between one beat and the next creating a jagged appearance ­ Interplay of fetal sympathetic/parasympathetic NS ­ Decreased by fetal tachycardia, prematurity, fetal heart and CNS anomalies and fetal sleep ­ Normal is 2 to 3 bpm; classified as present or absent ­ Can only be evaluated by internal monitoring?

EFM-Fetal Heart Rate

· Long-term variability ­ Rhythmic fluctuations occurring 2 to 6 times per minute; wave-like ­ Determined by interplay between fetal SNS/PNS ­ Increased by fetal movement ­ Decreased by fetal sleep or hypoxia and subsequent acidosis ­ Average or moderate is 6 to 25 bpm ­ Minimal or decreased = < 6 ­ Marked or increased = > 25

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Fetal Tachycardia

Baseline increase > 160 May result from: · Hypoxia · Drugs · Prematurity · Maternal fever · Fetal infection · Fetal tachyarrhythmia · Maternal hyperthyroidism · Fetal movement

Fetal Bradycardia

Decrease in baseline FHR < 120 BPM May result from: · Fetal hypoxia: · Drugs · Umbilical cord compression · Maternal hypotension · Fetal cardiac arrhythmias · Maternal hypothermia

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FHR Periodic Changes

· Periodic FHR Changes: deviations from baseline occurring with UCs · Episodic FHR changes: deviations from baseline occurring independently from UCs · Accelerations:transient increases in FHR ­ Episodic (spontaneous): symmetric, uniform, not r/t UCs, occur in response to fetal movement, indicate fetal well-being ­ Periodic: occur with UC

Periodic Accelerations

· · · · Begins with UC; returns to baseline at end of UC Height of acceleration reflects intensity of UC Occurs repeatedly throughout labor Occur most frequently in following situations:

­ ­ ­ ­ ­

Preterm labor Term breech During vaginal examinations During abdominal palpation Active fetus

· No treatment required

Early Decelerations

· FHR decrease: begins onset of UC and returns to baseline by end of UC with lowest point of deceleration at UC acme · Uniform shape inversely mirrors contraction · Cause: fetal head compression and vagus nerve stimulation · Rarely falls below 110 BPM · Associated with vaginal exams, FSE application, CPD, after AROM, vetex positions · No intervention required

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Late Decelerations

· Begins after UC onset and returns to baseline after end of UC · Uniform shape · Cause: uteroplacental insufficiency · Considered ominous · Nursing interventions: ­ Oxygenate: O2 by mask at 8-10 LPM ­ Rotate: Lateral position to improve perfusion ­ Hydrate: Increase IV fluid rate ­ Discontinue oxytocin if infusing ­ Call healthcare provider

Variable Decelerations

· Variable in duration and intensity · Variable in relation to UCs (variable in onset and return to baseline) · Variable shape, usually "U", "V" or "W" · Variable in depth · Variable in duration · Begin and resolve abruptly · Caused by compression of umbilical cord · Often seen in late labor

Variable Decelerations

· Classified as mild, moderate or severe based on lowest FHR reading and duration of deceleration ­ Mild: decelerates to any level for < 30 sec with abrupt return to baseline ­ Moderate: decelerates no lower than 80 BPM for any duration with abrupt return to baseline ­ Severe: decelerates < 60 BPM for > 60 sec with slow return to baseline ( ominous; indicate fetal asphyxia) · Nursing interventions: relieving cord compression through repositioning, vaginal exam for prolapsed cord, oxygen by mask, assist with amnioinfusion

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