Which category of shock is characterized by low systemic vascular resistance due to sepsis or anaphylaxis?

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

Answer: (C)

Distributive shock is defined by a pronounced decrease in systemic vascular resistance due to widespread vasodilation from inflammatory mediators. In sepsis, cytokines and other substances cause blood vessels to dilate and capillaries to leak, lowering afterload and often producing hypotension even when there’s adequate or increased blood volume. In anaphylaxis, the same idea applies: massive release of histamine and other mediators causes rapid vasodilation and fluid leakage, leading to low SVR and shock.

This contrasts with hypovolemic shock, where the primary issue is a loss of circulating volume leading to reduced preload; cardiogenic shock, where pump failure reduces cardiac output and often raises systemic vascular resistance as a compensatory mechanism; and obstructive shock, where an obstruction limits heart filling or outflow, with the hemodynamics driven more by impaired forward flow than by vasodilation. Thus, the category characterized by low systemic vascular resistance due to sepsis or anaphylaxis is distributive shock.