Cardiovascular responses during IgE-mediated peanut allergic reactions

Abstract

INTRODUCTION: The pathophysiology of IgE-mediated food allergy is poorly described and this impairs our ability to develop new treatments or predict reaction phenotype. Data from case series and animal models suggest there may be significant cardiovascular changes during severe reactions. The aims of this thesis were to describe the local and systemic cardiovascular (CVS) changes during IgE-mediated reactions to peanut, and evaluate whether local vascular responses to skin prick test can predict threshold or severity of reaction.

METHODS: Fifty-seven peanut-allergic adults underwent continuous, non-invasive cardiac monitoring during double-blind placebo-controlled food challenges. CVS parameters during a 10-minute epoch at time of objective symptoms were compared to a 10-minute epoch at baseline. Comparisons were also made to equivalent data at the placebo reaction, and a further repeat open challenge in the same participants. Skin blood flow and titrated skin prick testing (SPT) were performed at each challenge.

RESULTS: A significant increase in peripheral blood flow (median 20%, IQR [-2.2 to 46.7%]), decrease in stroke volume (mean -2.3ml/beat/m2, 95% CI [-0.3 to -4.2]) and increase in heart rate (mean 7.7bpm, 95% CI [5.6 to 9.8]) were observed during reactions irrespective of reaction severity, which were reproduced at open challenge. Changes in heart rate variability were also noted, consistent with increased sympathetic activity, however these were not observed at repeat challenge. Titrated SPT (as a measure of local cutaneous vascular response) was found to predict reaction threshold at challenge. Time to resolution of peanut SPT wheal was associated with several measures of reaction severity at challenge.

CONCLUSION: There is a significant reduction in stroke volume during IgE-mediated reactions to peanut. This is likely to be caused by peripheral vasodilatation leading to reduced venous return, and was seen in both mild and severe reactions. This finding highlights the importance of adequate fluid resuscitation in the management of IgE-mediated allergic reactions to food.