Which statement best describes the hemodynamics of hypovolemic shock?

Which statement best describes the hemodynamics of hypovolemic shock?

• A. Low preload, low Stroke Volume, low Cardiac Output; high Systemic Vascular Resistance
• B. High preload, high Stroke Volume, high Cardiac Output; low SVR
• C. Low preload, high Stroke Volume, high Cardiac Output; high SVR
• D. High preload, low Stroke Volume, low Cardiac Output; low SVR

Answer: (A)

Hypovolemic shock centers on a loss of circulating blood volume, which lowers venous return to the heart. That reduced venous return decreases preload (the filling of the ventricles). Because stroke volume is largely determined by preload, stroke volume falls. With a lower stroke volume, cardiac output drops even if the heart rate rises somewhat. To compensate and maintain arterial pressure, the body constricts systemic vessels, so systemic vascular resistance increases. This combination—low preload, low stroke volume, low cardiac output, and high systemic vascular resistance—best describes the hemodynamic pattern in hypovolemic shock. The other scenarios imply either a higher preload or a lower vascular resistance, which don’t fit the volume-depleted state.

Hypovolemic shock centers on a loss of circulating blood volume, which lowers venous return to the heart. That reduced venous return decreases preload (the filling of the ventricles). Because stroke volume is largely determined by preload, stroke volume falls. With a lower stroke volume, cardiac output drops even if the heart rate rises somewhat. To compensate and maintain arterial pressure, the body constricts systemic vessels, so systemic vascular resistance increases. This combination—low preload, low stroke volume, low cardiac output, and high systemic vascular resistance—best describes the hemodynamic pattern in hypovolemic shock. The other scenarios imply either a higher preload or a lower vascular resistance, which don’t fit the volume-depleted state.