What vital sign is most affected during anaphylaxis?

During anaphylaxis, the vital sign most notably affected is blood pressure. Anaphylaxis is a severe allergic reaction that leads to the release of various mediators from mast cells and basophils, resulting in widespread vasodilation. This sudden widening of blood vessels causes a rapid decrease in blood pressure, leading to a condition called anaphylactic shock, which can be life-threatening.

While heart rate, temperature, and respiratory rate may also change during anaphylaxis, the most critical and immediate concern is the drop in blood pressure. This is due to the loss of vascular tone and increased permeability of blood vessels, which can result in fluid leakage from the bloodstream. Therefore, monitoring blood pressure is crucial in the management of anaphylaxis to ensure the patient receives prompt and appropriate treatment to stabilize their condition.