Angioedema is the oedema of the deep dermis and subcutaneous tissues.
It is usually an acute but sometimes a chronic mast cell–mediated reaction caused by exposure to a drug (eg, angiotensin-converting enzyme inhibitors), venom, dietary, pollen, or animal dander allergens, or it can be idiopathic.
Angioedema can also be a genetic or an acquired disorder characterized by an abnormal complement system response.
SYMPTOM are swelling, often of the face, mouth, and upper airways, which can be severe.
PATHOPHYSIOLOGY:
Angioedema is swelling (usually localized) of the subcutaneous tissues due to increased vascular permeability and extravasation of intravascular fluid. Known mediators of increased vascular permeability include the following:
Mast cell–derived mediators (histamine, leukotrienes, prostaglandins)
Bradykinin and complement-derived mediators
Mast cell–derived mediators tend to also affect layers superficial to subcutaneous tissue, including the dermal-epidermal junction. There, these mediators cause urticaria and pruritus, which thus usually accompany mast cell–mediated angioedema.
BRADYKININ-MEDIATED ANGIOEDEMA: the dermis is usually spared, so urticaria and pruritus are absent.
In some cases, the mechanism and cause of angioedema are unknown. Several causes (eg, calcium channel blockers, fibrinolytic drugs) have no identified mechanism; sometimes a cause (eg, muscle relaxants) with a known mechanism is overlooked clinically
Diagnosis is by examination
Treatment is with airway management as needed, elimination or avoidance of the allergen, and drugs to minimize swelling.