Burn injuries can lead to hypovolemic shock primarily due to loss of which fluid component?

• A. Plasma
• B. Red blood cells
• C. Whole blood
• D. Platelets

Answer: (A)

Burn injuries cause hypovolemic shock mainly because inflammatory processes make capillaries highly leaky, so plasma — the liquid part of blood — escapes into the interstitial space and is lost through evaporative losses. This rapid loss of plasma reduces the intravascular volume (the amount of fluid circulating in the vessels), lowering preload and cardiac output and leading to shock. The cells in blood—red blood cells, platelets, and even whole blood—aren’t lost in the same dramatic way during the early phase of burn shock, so they don’t drive the initial volume depletion.