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SHOCK Definition

· Clinical syndrome, systemic imbalance between oxygen supply and demand · Inadequate blood flow to body organs and tissue causing life-threatening cellular

dysfunction

Pathophysiology

· Stimulus leads to alteration in hemodynamics within the body · Body responds by maintaining perfusion to vital organs, heart and brain · Results in inadequate tissue and cellular perfusion; if not reversed, body develops acidosis and if untreated, progresses to organ hypoxia, ischemia and death

Pathophysiology cont.

· Alteration in hemodynamics results in a drop in arterial blood pressure by one of these mechanisms · Decrease in cardiac output (ability of heart to supply adequate circulation) · Decrease in circulating blood volume · Increase in size of vascular bed

Hemodynamic terms

· Stroke Volume (SV): amount of blood pumped into aorta by contraction of left ventricle · Cardiac Output (CO): amount of blood pumped into aorta by contraction of left ventricle in one minute · Mean arterial pressure (MAP): product of cardiac output and systemic vascular resistance

Stages of Shock

Early reversible and compensatory shock · Mean arterial pressure drops 10 -15 mm Hg · Decrease in circulating blood volume (25-35%) 1000ml · Sympathetic nervous system stimulated; release of catecholamine

Stages of Shock cont.

· To maintain blood pressure: increase in heart rate and contractility; increase in peripheral vasoconstriction · Circulation maintained, but can only be sustained short time without harm to tissues · Underlying cause of shock must be addressed and corrected or will progress to next stage

Stages of Shock cont.

Intermediate or progressive shock · Further drop in MAP (20%) · Increase in fluid loss (1800 ­ 25400 ml) · Vasoconstriction continues and leads to oxygen deficiency · Body switches to anaerobic metabolism forming lactic acid as a waste product.

Stages of Shock cont.

· · · · · Body increases heart rate and vasoconstriction. Heart and brain become hypoxic More severe effects on other tissues which become: ischemic and anoxic State of acidosis with hyperkalemia develops Needs rapid treatment

Stages of Shock cont.

Refractory or irreversible shock · Tissues are anoxic, cellular death widespread · Even with restoration of blood pressure and fluid volume there is too much damage to restore homeostasis of tissues · Cellular death leads to tissue death; vital organs fail and death occurs

Effects of Shock on Body Systems

· · · · Cardiovascular Initially: slight tachycardia, normal blood pressure Progresses to weak, rapid pulse with dysrhythmias Progressive decrease in systolic and diastolic blood pressures with narrowing of pulse pressure; blood pressure becomes inaudible

Effects of Shock on Body Systems cont.

· Respiratory · Initially: Increased respiratory rate, but gas exchange is impaired; leads to anaerobic metabolism and development of acidosis · Acute Respiratory Distress Syndrome (ARDS): complication of decreased lung perfusion

Effects of Shock on Body Systems cont.

· · · · · · Gastrointestinal and Hepatic GI organs become ischemic, with blood circulation shunted to heart and brain Complications Stress Ulcers: GI mucosa becomes ischemic, prone to rapid ulceration Paralytic Ileus: decreased gastrointestinal motility with decreased blood flow Altered liver metabolism: initially glucose made available, then hypoglycemia, fat breakdown leads to ketones and metabolic acidosis

Effects of Shock on Body Systems cont.

· · · · · · · Neurologic Develops cerebral hypoxia Restlessness initially, then altered level of consciousness, lethargy, coma Renal: Decreased kidney perfusion leads to oliguria (urine output < 20 ml/o) Skin temperature, thirst Skin: cool, pale, hypothermic Thirsty from dehydration

Types of Shock (categorized according to underlying causes)

· · · · · Hypovolemic Decrease in intravascular volume > 15% Most common: occurs with other types of shock Common stimuli: hemorrhage, burns, severe dehydration, third spacing Progresses through stages of shock without restoration of fluid volume

Types of Shock cont

· Cardiogenic · Pumping ability of heart compromised to a degree that cannot maintain cardiac output and adequate tissue perfusion · Common stimuli: myocardial infarction, cardiac arrest · Develops left and right sided heart failure · Cyanosis occurs with this type of shock

Types of Shock cont

· · · · · · Obstructive Heart or great vessels obstructed; venous return or cardiac pumping action impeded Common stimuli: pulmonary embolism, pneumothorax Distributive (Vasogenic) Widespread vasodilatation Decreased peripheral resistance

Types of Shock cont

· Septic Shock · Leading cause of death in intensive care units · Common stimuli: Gram negative bacterial infections (pseudomonas, E coli); Gram positive bacterial infections (staphylococcus and streptococcus) · Increased risk: clients with chronic illness, poor nutritional status, invasive procedure or tubes, such as foley catheters

Types of Shock cont

· · · ·

· Course

Septicemia develops (pathogens and their toxins in the blood) Endotoxins disrupt circulation Normal coagulation mechanisms Inflammatory response triggered

Types of Shock cont

· Phases of Septic Shock · Warm Phase (early): skin flushed, warm due to vasodilatation · Cold Phase (late): skin cool due to fluid deficit with shock

Types of Shock cont

· Neurogenic Shock · Imbalance between parasympathetic and sympathetic nervous stimulation of vascular smooth muscle, resulting in sustained vasodilatation · Common stimuli: head injury, spinal cord trauma, insulin reactions, anesthesia

Types of Shock cont

· · · · · · · Anaphylactic Shock Result of widespread hypersensitivity (anaphylaxis) Vasodilatation occurs leading to hypovolemia and altered cellular metabolism Sensitized in past, re-contact with the allergen (medication, bee sting, food allergen) Allergic reaction with large amounts of histamine released Histamine leads to increased permeability and massive vasodilatation, Develops respiratory distress with bronchospasm and laryngospasm

Collaborative Care

· Focus on treating underlying cause to stop progress through stages of shock · Rapid shock identification; rapid diagnosis of cause; rapid aggressive treatment: better outcome for client · Goal: improving arterial oxygenation and tissue perfusion · Determine type of shock

Diagnostic tests and purpose used with clients in shock

· · · · · Blood hemoglobin and hematocrit: hypovolemic shock Arterial Blood Gases: identify body compensatory mechanisms, such as acidosis Electrolytes BUN and creatitine, osmolality: renal function Blood cultures: identify causative organism in septic shock; treatment

Diagnostic tests and purpose used with clients in shock cont

· White blood count and differential: septic shock · Cardiac enzymes: diagnosis of cardiogenic shock (Cardiac enzymes are: lactate dehydrogenase (LDH); Creatine phosphokinase (CPK); serum glutamic-oxaloacetic transaminase (SGOT): · Other tests may be ordered

Medications

· Inotropic agents: improve cardiac contractility · Vasoactive agents: drugs causing vasoconstriction or vasodilatation according to client symptoms · Other meds according to cause such as antibiotics, steroids

Oxygen Therapy

· Patent airway and adequate oxygenation critical interventions · Monitor with ABG, pulse goniometry (more accurate in early stage) · Mechanical ventilation assistance may be needed

Fluid Replacement

· Essential for hypovolemic shock; also with other types as symptoms indicate · Types of Intravenous Fluids · Crystalloid: Dextrose or electrolyte solutions Increase intravascular and interstitial fluid volume:Isotonic .9% NaCl, lactated Ringers Hypotonic (5% dextrose in water, .45% NaCl) · Colloids: Do not diffuse easily through capillary walls Fluids stay in vascular compartment; increase osmotic pressure : albumin, plasma protein and dextran. · Blood and Blood ProductsTreatment of hemorrhage Restore coagulation properties

Nursing Process with Clients in Shock:

· Nurse assesses and analyzes client situation and any change in condition · Notification of physician: early treatment before shock is advanced and less responsive to treatment · Care of client in shock: constant assessment with modification of treatment · Transfers to intensive care unit for hemodynamic monitoring and respiratory support · Complexities of changing status of fluid, acid-base, cardiovascular function · Support of client and family

Common Nursing Diagnoses

· Decreased Cardiac Output · Altered Tissue Perfusion · Anxiety

Information

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