Rationale: Intramuscular (IM) epinephrine (adrenaline) is the treatment of choice for anaphylaxis but little data exists on the cardiovascular effects of IM epinephrine during anaphylaxis, as such episodes typically occur outside a medical facility.
Methods: Seven peanut-allergic adults who experienced anaphylaxis (and received IM epinephrine) during double-blind, placebo-controlled food challenges to peanut (as part of the TRACE Peanut Study) were evaluated using continuous 12-lead ECG and non-invasive haemodynamic monitoring. Heart rate (HR), stroke volume (SV), systolic and diastolic blood pressure (sBP, dBP), cardiac output (CO), total peripheral resistance (TPR), PR, QRS and QTc intervals were measured. Skin blood flow was measured using laser Doppler.
Results: Administration of 0.5mg epinephrine IM resulted in a significant improvement in symptoms, but did not result in consistent and clinically relevant effects on measures of cardiovascular physiology or ECG between individuals. There was a small increase in HR (median 4.4 bpm, P=0.03) and QTc interval (14.8ms, 4-22.9ms, P=0.02) but the clinical relevance is unclear. No significant changes were found for the other parameters studied. No participant required a second dose of epinephrine.
Conclusions: These preliminary data suggest a limited and inconsistent effect of a single dose of IM epinephrine on cardiovascular measurements during food-triggered anaphylaxis. The data are limited by the small sample size and nature of the reactions experienced, with no participant having refractory anaphylaxis. Further work is needed to identify determinants of a prompt physiological response to epinephrine during allergic reactions.