During general anesthesia, the earliest and most common clinical sign of anaphylaxis is often:

Explanation

While all listed options can be signs of anaphylaxis, under general anesthesia, cutaneous signs like urticaria and angioedema may be masked by drapes or surgical fields, or their onset may be delayed. Sudden and profound hypotension, often refractory to initial fluid boluses, is frequently the earliest and most prominent sign of anaphylaxis during general anesthesia, followed by or concurrent with bronchospasm and tachycardia. The vasodilation and increased capillary permeability lead to a rapid decrease in systemic vascular resistance and intravascular volume, causing severe hypotension.