Hypovolemic shock is primarily caused by loss of circulating blood volume due to what?

• A. Tobacco use
• B. Loss of whole blood, dehydration
• C. Heart failure
• D. Vasodilation

Answer: (B)

Hypovolemic shock happens when there isn’t enough blood in the vessels to fill the heart and supply organs, so preload drops and cardiac output falls. The main ways this happens are loss of circulating blood volume from hemorrhage (loss of whole blood) and loss of body fluids from dehydration (including fluid losses from vomiting, diarrhea, sweating, or burns). That combination directly reduces the volume the heart can pump.

Tobacco use doesn’t acutely reduce circulating volume. Heart failure causes the heart to pump poorly (cardiogenic shock), not simply a lack of volume. Vasodilation changes how vessels distribute blood (distributive shock) and isn’t the primary mechanism of hypovolemia.