Paradoxical Effect of Epinephrine Administration During Anaphylaxis

Abstract

Bradycardia is an unexpected effect of epinephrine administration. Clinical factors that predispose to this paradoxical reaction are infrequently appreciated by healthcare providers and patients administering epinephrine. Three patients presented here were referred for outpatient Allergy evaluation following episodes of anaphylaxis. History of anaphylaxis was the presenting concern in all cases. The cause of anaphylaxis was identified as tree nut (n=1) and unknown (n=2). Peak tryptase levels were 2.6ng/ml (tree nut anaphylaxis), 26.2ng/ml, and 72.6ng/ml (normal <11.5 ng/ml). Management of anaphylaxis was complicated with bradycardia ensuing within 15 minutes of epinephrine administration. Heart rate nadir was 33-42 bpm. EKGs showed no underlying conduction abnormalities. Glucagon (n=1) and atropine (n=2) were administered with resolution of arrhythmia shortly. Chart review was significant for use of non-selective beta-blockers (NSBB; oral: n=2; ophthalmic: n=1) at the time of reaction. NSBB use was for anxiety (n=1), headache prophylaxis (n=1), and glaucoma (n=1). Discussion with patients' care providers was undertaken to assess alternatives to beta-blocker use. Paradoxical bradycardia following epinephrine administration is well-documented but rare. NSBB use can be a likely modifiable factor. Once paradoxical bradycardia is recognized, discussion with other healthcare team members may prevent future episodes by finding alternatives to NSBBs where permitted, or having risk-benefit discussions when beta-blocker use is mandated. Allergists are in a unique position to educate patients and other providers about potential adverse effects of epinephrine.