In an anaphylactic reaction, hypotension is mainly due to which mechanism?

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Multiple Choice

In an anaphylactic reaction, hypotension is mainly due to which mechanism?

In anaphylaxis, the main driver of hypotension is the loss of circulating blood volume due to increased capillary permeability. Mediators such as histamine make the capillary walls more permeable, causing fluid and proteins to leak from the intravascular space into the interstitial tissues. This plasma shift reduces venous return and overall circulating volume, leading to a drop in blood pressure. Widespread vasodilation from the same mediators also lowers pressure, but the primary mechanism for the acute fall is the capillary leak. Decreased heart rate is not typically the cause; the heart often compensates with a faster rate.

In anaphylaxis, the main driver of hypotension is the loss of circulating blood volume due to increased capillary permeability. Mediators such as histamine make the capillary walls more permeable, causing fluid and proteins to leak from the intravascular space into the interstitial tissues. This plasma shift reduces venous return and overall circulating volume, leading to a drop in blood pressure. Widespread vasodilation from the same mediators also lowers pressure, but the primary mechanism for the acute fall is the capillary leak. Decreased heart rate is not typically the cause; the heart often compensates with a faster rate.

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