Which classification of shock is defined by systemic vasodilation and relative hypovolemia due to sepsis?

• A. Hypovolemic shock
• B. Obstructive shock
• C. Distributive shock
• D. Cardiogenic shock

Answer: (C)

Distributive shock is defined by systemic vasodilation with relative hypovolemia, which is what happens in sepsis. In sepsis, inflammatory mediators cause the blood vessels to dilate across the body and increase capillary permeability, so fluid leaks into the interstitial space. Even if the total body fluid is normal, the amount effectively circulating to maintain perfusion drops, lowering preload and impairing tissue perfusion. This is different from hypovolemic shock, where there is an actual loss of intravascular volume; obstructive shock, due to a blockage that impedes blood flow; and cardiogenic shock, from the heart’s inability to pump effectively. In septic shock, the hallmark is the vasodilatory, distributing effect that creates relative hypovolemia.