The mechanism of death in anaphylaxis is initiated by dramatic release of histamine from mast cells caused by the inciting agent. Histamine release has physiologic effects on multiple organ systems. The most striking effects are increased permeability of the blood vessels causing swelling of the upper airway and pulmonary edema. These effects cause severe difficulty breathing and a choking sensation, compounded by spasm of the bronchial muscles. Vasodilation may cause crampy abdominal pain and headache. The difficulty breathing causes profound anxiety, often described as a “sense of impending doom.” Loss of consciousness occurs as a result of hypoxia after a period of several minutes.
Death anaphylaxis medical expert witness specialties include forensic pathology, allergy, EMT, and emergency medicine.