363: COMPARING EPINEPHRINE 0.3 MG AND 0.5 MG AS AN INITIAL DOSE IN COMPLETE RESOLUTION OF ANAPHYLAXIS

Introduction: Anaphylaxis is an acute, systemic allergic reaction that can be fatal if not treated appropriately. Current guidelines recommend epinephrine 0.01 mg/kg for pediatric patients weighing 30 kg or less and a single dose maximum of 0.3 mg to 0.5 mg for adults. Studies have shown that more than 13% of patients presenting to the ED with anaphylaxis required more than one dose of epinephrine to achieve anaphylaxis resolution. No study to date has compared 0.3 mg and 0.5 mg epinephrine as an initial dose in preventing progression of recurrent symptoms or protracted anaphylaxis. We hypothesize that an initial dose of 0.5 mg of epinephrine when compared to 0.3 mg will lead to reduced redosing of epinephrine for anaphylaxis resolution. Methods: This is a single-center, retrospective, observational study of patients who presented to the UC Davis Medical Center emergency department and received an initial dose of 0.3 or 0.5 mg of epinephrine for treatment of anaphylaxis from January 2010 to January 2022. The primary endpoint is the frequency of redosing epinephrine to achieve resolution of anaphylaxis using 0.3 mg or 0.5 mg epinephrine as an initial dose. Secondary endpoints include the number of patients requiring hospital admission, the number of patients who required epinephrine infusion, incorrect administrations of epinephrine, and the average total milligrams of epinephrine used. Results: 187 patients met the inclusion criteria of anaphylaxis. Of patients receiving 0.3 mg of epinephrine as an initial dose, 34/97 (35%) patients required redosing while 6/69 (9%) of patients receiving 0.5 mg required redosing. Patients were significantly more likely to be redosed when receiving an initial dose of 0.3 mg (p < 0.001). Of the 187 patients, 36 required hospital admissions with 7 requiring epinephrine infusions. There were no incorrect administrations of epinephrine reported. The average total milligrams of epinephrine used was 0.5 mg. Conclusions: This study identified that 26% more patients required redosing when using 0.3 mg compared to 0.5 mg of epinephrine as initial dose. This highlights opportunities for change in current standards of care when it comes to initial management of anaphylaxis in the emergency department.