Emergency Medical Technician (EMT) Intermediate Practice Exam

Angioedema in the context of anaphylactic shock is primarily caused by the release of histamine and other mediators from mast cells and basophils during an allergic reaction. When an individual experiences anaphylaxis, a significant amount of histamine is released into the bloodstream. This histamine release leads to an increase in vascular permeability, which in turn allows fluid to leak into tissues, resulting in swelling of the face and neck, characterized by angioedema. While direct trauma, infections, and food allergies can cause swelling or inflammation, they do not specifically lead to the pronounced and systemic swelling associated with anaphylaxis. Trauma may cause localized edema, infections can result in inflammatory responses, and food allergies can trigger anaphylaxis but not the mechanism of swelling itself. The critical factor in anaphylactic shock is the overwhelming release of histamine, making it the primary cause of angioedema in this context.