Multiphasic Anaphylaxis: Frequency and Implications
Emergency physicians are frequently called upon to treat patients with anaphylaxis. It has been recommended that patients whose signs and symptoms resolve after successful treatment be observed in the ED for a prolonged period or admitted to the hospital. This recommendation is based upon documented cases of biphasic anaphylaxis where patients have recurrent symptoms up to 24 hours (or more) after successful treatment.1 In a recent retrospective study, Brady et al sought to determine the rate of clinically significant recurrence of symptoms in patients treated in the ED for anaphylaxis. The authors reviewed charts from a 4.5 year period that included 67 patients with severe anaphylaxis. Clinically significant recurrence was determined by reviewing medical records from the primary institution and surrounding institutions and examining the state death registry corresponding to the study period.
Of the 67 patients treated, 62 had complete resolution of their symptoms in the ED. Of those 62, 46 patients were observed in the ED and released. Two of those patients experienced a biphasic recurrence, each of whom had hymenoptera envenomations. Both had prompt resolution of symptoms in the ED, and both had mild biphasic symptoms (urticaria only). None of the 19 patients who were admitted to the hospital had recurrence of symptoms. In this series, the rate of biphasic anaphylactic reactions was 3%. (Brady WJ, et al. Multiphasic anaphylaxis: An uncommon event in the emergency department. Acad Emerg Med 1997;4:193-197.)
COMMENT BY GLENN C. FREAS, MD, JD, FACEP
This study is useful in two ways. First, it clearly describes the authors’ experience with anaphylaxis and the rate of recurrence. Second, the authors succinctly examine other recent studies on multiphasic anaphylaxis. Combining all of the results from this and other studies, it appears difficult to justify an approach that recommends admitting all patients with severe anaphylactic reactions who promptly respond to therapy in the ED. With the exception of one study, there were no life-threatening biphasic reactions beyond eight hours from initial resolution of symptoms.
The authors summarize some useful considerations in selecting which patients can be safely discharged after an appropriate period of observation in the ED and which patients should be admitted for prolonged observation. They are quick to point out that these factors have not been prospectively studied, by them or others, to validate admission criteria for anaphylaxis.
Nonetheless, the presence of one or more of the following may be adequate justification for keeping patients for prolonged observation/admission: slow response to initial therapy/ongoing severe symptoms, past history of severe anaphylaxis, significant comorbidity, advanced age, use of beta-adrenergic blocking agents, and poor or uncertain access to medical care for prompt follow-up.
Reference
1. Douglas DM, et al. Biphasic systemic anaphylaxis: An inpatient and outpatient study. J Allergy Clin Immunol 1994;93:977-985.
Subscribe Now for Access
You have reached your article limit for the month. We hope you found our articles both enjoyable and insightful. For information on new subscriptions, product trials, alternative billing arrangements or group and site discounts please call 800-688-2421. We look forward to having you as a long-term member of the Relias Media community.