In hypovolemic shock, which hemodynamic change is most characteristic?

• A. Increased preload
• B. Decreased preload with reduced cardiac output
• C. Increased cardiac output due to tachycardia
• D. Unchanged preload and cardiac output

Answer: (B)

In hypovolemic shock, loss of circulating blood reduces venous return to the heart, so preload (the filling of the ventricles before contraction) falls. With less end-diastolic filling, stroke volume drops according to the Frank-Starling mechanism, leading to a decrease in cardiac output. Although tachycardia may occur as a compensatory response, it cannot fully offset the reduced preload to maintain normal cardiac output. Therefore, the most characteristic hemodynamic change is decreased preload with reduced cardiac output.