In hypovolemic shock, which parameter is most directly reduced?

In hypovolemic shock, which parameter is most directly reduced?

• A. Cardiac output
• B. Afterload
• C. Preload
• D. Heart rate

Answer: (C)

In hypovolemic shock, the primary issue is a loss of circulating blood volume, which directly lowers venous return to the heart. This reduces preload, the amount the ventricles fill with blood at the end of diastole (end-diastolic volume/atrial pressure). With less filling, the ventricles stretch less and generate a smaller stroke volume (via the Frank-Starling mechanism), leading to a drop in cardiac output. While heart rate often increases as compensation and afterload may rise due to vasoconstriction, the immediate, most direct change from the volume loss is a decrease in preload.

In hypovolemic shock, the primary issue is a loss of circulating blood volume, which directly lowers venous return to the heart. This reduces preload, the amount the ventricles fill with blood at the end of diastole (end-diastolic volume/atrial pressure). With less filling, the ventricles stretch less and generate a smaller stroke volume (via the Frank-Starling mechanism), leading to a drop in cardiac output. While heart rate often increases as compensation and afterload may rise due to vasoconstriction, the immediate, most direct change from the volume loss is a decrease in preload.