American Board of Surgery Qualifying Exam (ABS QE) Practice Test

Which of the following is a characteristic of hemorrhagic shock?

1. Increased central venous pressure (CVP)

2. Increased pulmonary capillary wedge pressure (PCWP)

3. Decreased cardiac output (CO)

4. Decreased systemic vascular resistance (SVR)

The correct answer is: Decreased cardiac output (CO)

Hemorrhagic shock is a critical condition resulting from significant blood volume loss, leading to inadequate tissue perfusion and oxygen delivery. One of the hallmark characteristics of this condition is the decreased cardiac output. As blood volume decreases due to hemorrhage, the heart has less preload, leading to reduced stroke volume and, consequently, diminished cardiac output. This reduction in cardiac output is a compensatory response to maintain blood pressure and perfusion to vital organs through various mechanisms, including increased heart rate and vasoconstriction. However, if the loss of blood volume is severe, these compensatory mechanisms may eventually fail, leading to systemic hypotension and organ dysfunction. In contrast, in cases of hemorrhagic shock, central venous pressure and pulmonary capillary wedge pressure are typically low due to reduced blood volume returning to the heart. Systemic vascular resistance may initially increase as the body attempts to maintain blood pressure through vasoconstriction, rather than decrease. Therefore, the decrease in cardiac output is a definitive reflection of the inadequate volume and perfusion caused by hemorrhagic shock, making it the correct characteristic to identify.