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

What is a characteristic hemodynamic finding in hypovolemic shock?

1. High PCWP

2. Low CO

3. High mVO2

4. Normal SVR

The correct answer is: Low CO

In hypovolemic shock, one of the primary characteristics is a low cardiac output (CO). This occurs because hypovolemic shock is typically a result of significant fluid loss, whether from hemorrhage, dehydration, or other causes. The decrease in circulating blood volume leads to a diminished return of blood to the heart, which in turn reduces the amount of blood the heart can pump out with each contraction, resulting in a low cardiac output. In this state, the body attempts to compensate through mechanisms such as increased heart rate and vasoconstriction, but these compensatory responses may not be sufficient to restore normal perfusion, especially if the hypovolemic state is severe. The low cardiac output is critical in understanding the severity and physiological consequences of hypovolemic shock, emphasizing the need for rapid fluid resuscitation and addressing the underlying cause of the fluid loss. In contrast, other options involve different physiological responses that do not align with the characteristics of hypovolemic shock. For example, high pulmonary capillary wedge pressure (PCWP) would not typically be seen because this finding is more associated with fluid overload states, high mixed venous oxygen saturation (mVO2) would suggest good perfusion and oxygen utilization which