Prevalence of anaphylaxis among adults admitted to critical care for severe asthma exacerbation.

Background: In asthmatics, making a diagnosis of anaphylaxis could be challenging as respiratory symptoms are a common feature of both conditions. Identifying anaphylaxis is important to providing appropriate care. A prior study showed that anaphylaxis is sometimes misdiagnosed as acute asthma in children. We sought to identify the percentage of adults admitted to the intensive care unit (ICU) with asthma exacerbations who met criteria for anaphylaxis.

Methods: Retrospective chart review of adults admitted with acute asthma to the ICU at Jacobi Medical Center, a Level 1 trauma centre in Bronx, New York. Study period was January 2012 to December 2014. Using the criteria outlined in the World Allergy Organization's Anaphylaxis Guidelines, we identified patients who met criteria for anaphylaxis.

Results: 105 patients were identified: 17 were excluded because their main reason(s) for admission was not asthma. 7 (8%) of the 88 cases eligible for the study met diagnostic criteria for anaphylaxis while 3 (3.4%) were highly likely to have had anaphylaxis. The baseline characteristics of the seven patients were similar to that of the overall population studied. They however had shorter onset of symptoms (median (IQR): 3.5 (2-6) vs 24 hours (12-72), p<0.001), were more likely to have been intubated (71%vs31%, p=0.04), received intramuscular epinephrine by the emergency medical services or in the emergency room (86%vs42%, p=0.04) and received antihistamines (28.6%vs1.2%, p=0.02). None of these seven patients died. Only one of the seven patients was prescribed an epinephrine pen injector and referred to an allergist at discharge.

Conclusion: In this single-centre retrospective review, 3.4% of adults admitted to the ICU for acute severe asthma also met criteria for anaphylaxis.