Background: Food allergy is the commonest cause of anaphylaxis. Changes in posture during acute reactions can trigger fatal outcomes, but the impact of allergic reactions on the cardiovascular system in non-fatal reactions remains poorly understood. Objective: To systematically evaluate changes in cardiovascular function during acute allergic reactions to peanut. Methods: Participants underwent double-blind placebo-controlled food challenge to
peanut as part of a clinical trial. Changes in hemodynamic parameters (heart rate, stroke volume, blood pressure, peripheral blood flow) and electrocardiogram during food challenges were assessed using continuous monitoring. ClinicalTrials.gov Identifier: NCT02665793 Results: 57 adults (median age 24 (IQR 20-29) years, 53% female) participated; 22 (39%) had anaphylaxis. Acute reactions were associated with significant changes in stroke volume (mean decrease 4.2%, 95%CI 0.8 to 7.6; p=0.03), heart rate (mean increase 11.6%, 95%CI 8.4 to 14.8; p<0.0001) and peripheral blood flow (mean increase 19.7%, 95%CI 10.8 to 28.6; p<0.0001), irrespective of reaction severity. These changes were reproduced at subsequent repeat peanut challenge in 26 participants, and could be reversed with administration of intravenous fluids which resulted in faster resolution of abdominal symptoms. Conclusions: In this first detailed human study of cardiovascular changes during food-allergic reactions, we found evidence for significant fluid redistribution, independent of reaction severity. This provides a sound rationale for optimizing venous return during significant allergic reactions to food. Finally, these data provide a new paradigm for understanding severity in anaphylaxis, where poor outcomes occur due to a failure in compensatory mechanisms.
Ruiz-Garcia et al 5 Clinical Implication: Significant changes in cardiovascular function, including decreased stroke volume, occur during peanut-induced allergic reactions in adults irrespective of severity; these changes (and associated symptoms such as
abdominal pain) can be reversed through early fluid resuscitation