Which medication class would suppress the compensatory tachycardia in an elderly patient experiencing hemorrhagic shock?

• A. Blood thinners
• B. Beta blockers
• C. Thiazide diuretics
• D. Calcium channel blockers

Answer: (B)

Compensatory tachycardia in hemorrhagic shock is driven by the body's sympathetic response, which increases heart rate to maintain cardiac output. This effect on the heart is mainly through beta-1 receptors; when adrenaline and noradrenaline stimulate these receptors, the heart beats faster and stronger.

A beta-blocker directly blocks those receptors, so it blunts the heart’s response to sympathetic stimulation. By reducing heart rate (and contractility), it stops the reflex tachycardia that would otherwise try to compensate for low blood volume. In the context of the question, this makes beta-blockers the class that would suppress that compensatory tachycardia.

The other options don’t target this mechanism. Blood thinners affect clotting, not heart rate. Thiazide diuretics act on fluid balance and can even provoke reflex changes that don’t specifically suppress the tachycardia. Calcium channel blockers can slow heart rate by affecting calcium entry, but they aren’t the most direct or reliable way to blunt the sympathetic drive to the heart, and they carry additional risks in shock.