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

What is a characteristic feature of neurogenic shock?

1. Increased central venous pressure (CVP)

2. Decreased pulmonary capillary wedge pressure (PCWP)

3. Increased cardiac output (CO)

4. Increased systemic vascular resistance (SVR)

The correct answer is: Decreased pulmonary capillary wedge pressure (PCWP)

Neurogenic shock is characterized primarily by a loss of sympathetic tone due to spinal cord injury or central nervous system damage. This loss of sympathetic tone leads to widespread vasodilation, which results in decreased systemic vascular resistance. As a consequence of this vasodilation, there is often a decrease in blood pressure, and the body compensates through other mechanisms. A decrease in pulmonary capillary wedge pressure (PCWP) occurs because the reduction in systemic vascular resistance and the resulting vasodilation lead to reduced preload on the heart. This reduction indicates that less blood is returning to the heart, which aligns with the characteristics of neurogenic shock. In contrast, the other options describe physiological responses that do not align with the mechanisms at play in neurogenic shock. Increased central venous pressure or increased cardiac output is not typical due to the vasodilation and hypotension that characterize this condition, further supporting that decreased PCWP is a key feature.