SHOCK   22A

A young woman is brought to the emergency department by ambulance after a severe motor vehicle accident. She is unconscious. Her blood pressure is 64/40 mm Hg and heart rate is 150 beats/min. She has been intubated and is being hand ventilated. There is no evidence of head trauma. The pupils are 2 mm and reactive. She withdraws to pain. Cardiac examination reveals no murmurs, gallops, or rubs. The lungs are clear to auscultation. The abdomen is tense, with decreased bowel sounds. The extremities are cool and clammy with thready pulses.

What are the salient features of this patient’s problem? How do you think through her problem?

Salient features: Trauma; tachycardia and hypotension; altered mental status; tense abdomen in the setting of trauma suggesting internal bleeding; cool extremities suggesting high systemic vascular resistance; suspicion of hypovolemia because of blood loss

How to think through: Because of the urgency and confusion that accompany a presentation such as this, reliance on protocols is essential and unequivocally improves outcomes. Begin with the ABCDE algorithm, with primary and secondary head-to-toe evaluations. In this case, the evaluation according to protocol reveals hypotension and evidence of poor perfusion—the definition of “shock”—and a rigid abdomen with no other obvious sources blood loss. What are the immediate management priorities? (Intravenous access with rapid fluid resuscitation, blood type and cross-match, central line and arterial line placement, initiation of pressor agents.) What are the immediate diagnostic priorities? (Electrocardiography [ECG], chest radiography, abdominal imaging.) How might the tense abdomen explain the patient’s blood pressure? (Blood loss in the peritoneal space with compression of the inferior vena cava limiting venous return.) To avoid focusing on hypovolemic shock as the only cause, what else might cause or contribute to shock in this patient? (Traumatic aortic dissection, cardiac tamponade, tension pneumothorax, other bleeding source, underlying adrenal insufficiency.) What are the other major classes of shock? (Cardiogenic, obstructive and distributive [septic, anaphylactic, and neurogenic].) What end-organ effects of poor perfusion can one evaluate and monitor during resuscitation? (Mental status; urine output; ECG evidence of cardiac ischemia and arrhythmia; peripheral perfusion with pulses, skin temperature, color, and capillary refill.)

SHOCK   22B

What are the essentials of diagnosis and general considerations regarding shock?

Essentials of Diagnosis

Hypotension; tachycardia; oliguria; altered mental status; cool, clammy extremities

Peripheral hypoperfusion and impaired oxygen delivery

General Considerations

Can be classified as hypovolemic, cardiogenic, obstructive, and distributive (including septic, anaphylactic, and neurogenic)

    Hypovolemic results from decreased intravascular volume

    Cardiogenic results from cardiac failure with inability of heart to maintain tissue perfusion

    Obstructive results from acute decrease in cardiac output

    Distributive causes include sepsis (most common), anaphylactic, and neurogenic; a reduction in systemic vascular resistance (SVR) results in inadequate cardiac output and tissue hypoperfusion despite normal circulatory volume

       Septic may be caused by gram-negative or gram-positive bacteria

       Anaphylactic is caused by an IgE-mediated allergic response

       Neurogenic caused by spinal cord injury or epidural anesthetic agents

SHOCK   22C

What are the symptoms and signs of shock?

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