April 26, 2019
Anaphylaxis is a life-threatening allergic reaction requiring prompt treatment with epinephrine. Current guidelines for anaphylaxis management include epinephrine as first-line treatment but also antihistamines and steroids. Although prompt use of epinephrine has been well supported, studies so far have not established the role of antihistamines and steroids.
In a cross-Canadian study recently published in The Journal of Allergy and Clinical Immunology: In Practice, Gabrielli and colleagues assessed the pre-hospital management of anaphylaxis. They compared the effect of epinephrine to antihistamines and steroids on negative outcomes of anaphylaxis, which include intensive care unit/hospital ward admission, multiple doses of epinephrine in the Emergency Department (ED), and intravenous fluids given in the ED.
The Cross-Canada Anaphylaxis Registry enrolled cases of anaphylaxis presenting to EDs in 5 Canadian provinces (Quebec, Ontario, British Columbia, Alberta, and Newfoundland and Labrador) over a 6-year period. A standardized questionnaire, documenting symptoms, triggers and management, was completed by a health-care professional.
The study assessed 3,498 cases of anaphylaxis presenting to 9 EDs across Canada from April 2011 to October 2017. In the pre-hospital setting, antihistamines were the most commonly administered medication (46%), followed by epinephrine (31%), and steroids (2%). Admission to the intensive care unit/hospital ward was associated with pre-hospital treatment of anaphylaxis with steroids. Pre-hospital treatment with epinephrine and antihistamines decreased the likelihood of receiving multiple doses of epinephrine in the ED.
The study showed for the first time that, in the pre-hospital setting, the use of antihistamines in conjunction with epinephrine may reduce the risk of uncontrolled anaphylactic reactions, while the findings did not support the use of steroids. The use of steroids in the pre-hospital setting was associated with negative outcomes. The authors advise that current anaphylaxis management algorithms should be modified, at least in the pre-hospital setting, to exclude steroids and to administer antihistamines only in conjunction with epinephrine, in all cases of anaphylaxis.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.