Intraoperative anaphylaxis: what is the initial management and epinephrine dosing in an adult?

• A. Discontinue the suspected antigen, administer 100% oxygen, and give epinephrine promptly (IV bolus 10–100 mcg titrated; IM 0.3–0.5 mg in adults if IV not feasible), with aggressive fluid resuscitation and airway support.
• B. Discontinue antigen, give antihistamines only, no epinephrine.
• C. Administer corticosteroids alone as treatment.
• D. Continue exposure to antigen and observe the patient.

Answer: (A)

Intraoperative anaphylaxis is a life-threatening emergency where reversing bronchospasm, airway edema, and profound hypotension must be done immediately. The first moves are to stop exposure to the triggering agent, give 100% oxygen, and treat with epinephrine right away because it tackles all the key problems at once: it constricts dilated vessels to raise blood pressure, relaxes bronchial smooth muscle to relieve bronchospasm, and stabilizes capillary leaks to reduce edema, while supporting cardiac output. After securing oxygen, you’ve got to administer epinephrine promptly and escalate support as needed.

If an IV line is available, give a small intravenous bolus of epinephrine, 10 to 100 micrograms, and titrate to the patient’s response. If intravenous access isn’t readily feasible, administer intramuscular epinephrine at 0.3 to 0.5 mg of a 1:1000 solution. Aggressive fluid resuscitation with crystalloids is important to maintain circulating volume, and be prepared for airway management and ventilatory support as edema and bronchospasm may jeopardize ventilation. If the patient remains hypotensive after the initial bolus doses, consider an epinephrine infusion and continue to titrate to effect.

Other treatments like antihistamines or corticosteroids are not replacements for epinephrine in the acute phase; they can be used as adjuncts after stabilization but do not reverse the shock and airway compromise quickly enough. The triggering antigen should be discontinued to stop ongoing exposure.