Characteristics of Central Ohio 911 Calls for Allergic Reaction and Anaphylaxis

RATIONALE: Emergency Medical Services(EMS) dispatchers are often the first healthcare contact in the event of anaphylaxis, playing a critical role in recognition and early epinephrine administration. The purpose of this study was to describe the clinical presentation of patients accessing EMS through 911 in Central Ohio to better understand the characteristics of this population.

METHODS: We performed a retrospective review of 911 calls over a six-month period during 2016-2017 where the responding EMS dispatcher’s clinical impression was allergic reaction or anaphylaxis. Using a modified Delphi approach, the calls were reviewed for demographic and clinical information. We calculated frequencies for categorical measures and medians for continuous measures.

RESULTS: Of 146 calls, 45.2% were male, median age was 29 years. Calls were most commonly placed by the patient(27.4%) and from home(56.9%). Allergy histories included peanut(5.6%), milk(1.4%), egg(0.7%), tree nut(4.8%), shellfish(2.1%), medication(3.5%), stinging insect(2.1%) and other(8.9%). Suspected allergens for the current reaction included peanut(4.1%), milk(1.4%), egg(0.7%), tree nut(6.2%), shellfish(2.7%), medication(27.4%), stinging insect(2.1%) and other(15.8%). Eleven percent administered epinephrine prior to calling. Only 12.3% of reactions were classified as meeting the definition of anaphylaxis.

CONCLUSIONS: The majority of 911 calls with concern for acute allergic reactions did not have prior history. Few calls met the definition of anaphylaxis based on call information, which could be due to a lack of information provided by the caller or acquired by the dispatcher. This highlights the importance of educating EMS dispatchers on the nuanced history needed to recognize anaphylaxis.