ANAPHYLAXIS / ANAPHILACTOID REACTION

Anaphylaxis is an acute multi-system severe type I hypersensitivity allergic reaction. The term comes from the Greek words ἀνά ana, means against, and φύλαξις phylaxis, means protection.

Signs & Symptoms
Cardiovascular:
Hypotension, tachycardia, dysrhythmias
Pulmonary:
Bronchospasm, cough, dyspnea, pulmonary edema, laryngeal edema, hypoxemia.
Dermatologic:
Urticaria, facial edema, pruritus.
Neurologic:
Sense of impending doom.

Diagnosis
Serum Tryptase level (released with histamine from mast cells). Draw levels at 1 & 24 hours after event. (Nl <25 mcg/L).

Treatment
Discontinue offending agent.
FiO2 100%.
Epinephrine (mainstay of therapy, mast cell stabilization, hemodynamic support, bronchodilator).
IV 50-100 mcg, may need repeat dosing.
If no IV access, 200-500 mcg IM or SQ (may repeat x 1).
Fluid resuscitation.

Secondary treatment:
Diphenhydramine 50 mg.
Albuterol MDI/Neb as needed for bronchospasm.
Catecholamine infusion.
Conside alpha-agonist after second dose of epinephrine.
Intravenous steroids (dexamethasone 20 mg or methylprednisolone 100 mg).