What is the initial compensatory method during shock?

• A. Increase in systemic vascular resistance
• B. Decrease in heart rate
• C. Increase in cardiac output
• D. Decrease in stroke volume

Answer: (C)

During the early phase of shock, the body rapidly activates the sympathetic nervous system to preserve tissue perfusion. The fastest and most direct way to maintain blood flow to organs is by increasing cardiac output, which is achieved by raising heart rate and contractility (and supporting stroke volume when preload allows). Cardiac output is the amount of blood the heart pumps per minute, and boosting it helps keep mean arterial pressure and tissue oxygen delivery from falling.

Vasoconstriction to raise systemic vascular resistance also occurs, but it serves to support blood pressure rather than directly boost the blood flow the tissues receive. Heart rate and contractility-driven increases in cardiac output are the primary immediate compensations to maintain perfusion in early shock. Decreasing heart rate or stroke volume would worsen perfusion, so they are not the initial protective changes.