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Chapter 39

Care of Patients with Shock

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Shock

Widespread abnormal cellular metabolism that occurs when the human need for oxygenation and tissue perfusion is not met to the level needed to maintain cell function.

“Whole-body” response. Shock is a “syndrome.” Any problem that impairs oxygen delivery to

tissues and organs can start the syndrome of shock and lead to a life-threatening emergency.

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Classification of Shock by Functional Impairment

Hypovolemic shock Cardiogenic shock Distributive shock Obstructive shock

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Classification of Shock by Origin of the Problem

Hypovolemic Cardiogenic Basogenic Septic

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Processes of Shock

Initial stage (early shock) Nonprogressive stage (compensatory

stage) Progressive stage (intermediate stage) Refractory stage (irreversible stage)

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Review of Oxygenation and Tissue Perfusion

Total blood volume Cardiac output Size of the vascular bed

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Hypovolemic Shock

Occurs when low circulating blood volume causes a mean arterial pressure decrease; the body’s oxygen need is not met

Commonly caused by hemorrhage (external or internal) and dehydration

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Cardiogenic Shock Actual heart muscle is unhealthy, and

pumping is directly impaired. Myocardial infarction is the most common

cause of direct pump failure.

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Distributive Shock Blood volume is not lost but is distributed

to the interstitial tissues where it cannot circulate and deliver oxygen

Caused by loss of sympathetic tone, blood vessel dilation, pooling of blood in venous and capillary beds, capillary leak

Neural-induced distributive shock Chemical-induced distributive shock

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Chemical-Induced Distributive Shock

Anaphylaxis Sepsis Capillary leak syndrome

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Obstructive Shock Caused by problems that impair the ability

of the normal heart muscle to pump effectively

Heart is normal, but conditions outside the heart prevent either adequate filling of the heart or adequate contraction of the healthy heart muscle

Pericarditis Cardiac tamponade

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Stages of Shock

Initial stage Nonprogressive stage Progressive stage Refractory stage

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Initial Stage of Shock

Baseline MAP decreased by less than 10 mm Hg

Heart and respiratory rate increased from the baseline or a slight increase in diastolic blood pressure

Adaptive responses of vascular constriction and increased heart rate

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Nonprogressive Stage

MAP decreases by 10 to 15 mm Hg. Kidney and hormonal adaptive

mechanisms activated. Tissue hypoxia in nonvital organs. Acidosis and hyperkalemia. Stopping conditions that started shock and

supportive interventions can prevent shock from progressing.

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Progressive Stage of Shock

Sustained decrease in MAP of more than 20 mm Hg from baseline.

Vital organs develop hypoxia. Life-threatening emergency. Immediate interventions are needed. Conditions causing shock need to be

corrected within 1 hour of the onset of the progressive stage.

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Refractory Stage of Shock

Too much cell death and tissue damage result from too little oxygen reaching the tissues.

Body can no longer respond effectively to interventions, and shock continues.

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Multiple Organ Dysfunction Syndrome

Sequence of cell damage caused by the massive release of toxic metabolites and enzymes.

Metabolites released from dead cells. Microthrombi form. MODS occurs first in the liver, heart, brain,

and kidney. Myocardial depressant factor from the

ischemic pancreas.

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Health Promotion and Maintenance

Primary prevention of hypovolemic shock Secondary prevention of hypovolemic

shock

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Physical Assessment/Clinical Manifestations

Cardiovascular changes Pulse Blood pressure Oxygen saturation Skin changes Respiratory changes Renal and urinary changes Central nervous system changes Musculoskeletal changes

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Assessment

Psychosocial assessment Laboratory tests

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Nonsurgical Management

Goals of shock management are to maintain tissue oxygenation, increase vascular volume to normal range, and support compensatory mechanisms

Oxygen therapy IV therapy Drug therapy

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Drug Therapies

Vasoconstrictors, such as dopamine, epinephrine, norepinephrine, phenylephrine

Agents that enhance contractility Agents that enhance myocardial perfusion

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Sepsis and Septic Shock

Complex type of distributive shock—usually begins as a bacterial or fungal infection and progresses to a dangerous condition over a period of days

Sepsis—widespread infection coupled with a more general inflammatory response, known as systemic inflammatory response syndrome (SIRS), that is triggered when an infection escapes local control

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Severe Sepsis

Progression of sepsis with an amplified inflammatory response

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Septic Shock

Stage of sepsis and SIRS when multiple organ failure is evident and uncontrolled bleeding occurs.

Even with appropriate intervention, the death rate among patients in this stage of sepsis exceeds 60%.

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Septic Shock (Cont’d)

Etiology and genetic risk Incidence/prevalence Health promotion and maintenance

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Septic Shock: Clinical Manifestations

Cardiovascular changes Respiratory changes Skin changes Renal urinary changes Psychosocial assessment Laboratory tests

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Septic Shock: Interventions

Oxygen therapy Drug therapy Blood replacement therapy

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Community-Based Care

Home care management Health teaching