Epinephrine use and outcomes in anaphylaxis patients transported by emergency medical services

Background: Anaphylaxis is a potentially life-threatening allergic reaction that may require emergency medical system (EMS) transport. Fatal anaphylaxis is associated with delayed epinephrine administration. Patient outcome data to assess appropriateness of EMS epinephrine administration are sparse. Objectives: The objectives of this study are to (1) determine the frequency of epinephrine administration in EMS-transported patients with allergic complaints, (2) identify predictors of epinephrine administration, and (3) determine frequency of emergency department (ED) epinephrine administration after EMS transport. Methods: A cohort study was conducted from over 5 years. A total of 59187 EMS transports of an Advanced Life Support (ALS) ambulance service were studied. Results: One hundred and three patient transports for allergic complaints were analyzed. Fifteen patients received EMS epinephrine, and epinephrine was recommended for 2 additional patients who refused, for a total of 17 (17%) patients for whom epinephrine was administered or recommended. Emergency medical system epinephrine administration or recommendation was associated with venom as a trigger (29% vs 8%; odds ratio [OR], 4.70; 95% confidence interval [CI], 1.28-17.22; P =.013), respiratory symptoms (88% vs 52%; OR, 6.83; 95% CI, 1.47-31.71; P = .006), and fulfillment of anaphylaxis diagnostic criteria (82% vs 49%; OR, 3.50; 95% CI, 0.94-13.2; P = .0498). Four (4%) patients received epinephrine after ED arrival. Conclusion: Low rates of epinephrine administration were observed. The association of EMS administration of epinephrine with respiratory symptoms, fulfillment of anaphylaxis diagnostic criteria, and low rate of additional epinephrine administration in the ED suggest that ALS EMS administered epinephrine based on symptom severity. Additional studies of EMS anaphylaxis management including ED management and outcomes are needed.