“Anaphylaxis—we know it, we see it, and we even cause it, so we have to be the ones to prevent and treat it,” Anne Ellis, MD, MSc, FRCPC, told an audience of allergists at the ACAAI annual meeting. Allergists have the tools to manage it effectively, so they must be the experts.
Ellis, of Queens University in Ontario, Canada, is the winner of the ACAAI Bernard Berman Memorial Lecture. In it, she reviewed the pathophysiology of anaphylaxis, subcategorized as non-immunologic or immunologic, the latter of which can be subcategorized into IgE mediated and non-Ig mediated. In anaphylaxis, there is a release of histamine and other mediators (PAF, leukotrienes, and prostaglandins), which results in smooth muscle spasm, vascular permeability, vasodilation, myocardial depression, and activation of vagal effector pathways. She stressed the role of PAF as an important mediator and encouraged her colleagues not to focus only on histamine.
Ellis’ research has elucidated variants in the clinical course of anaphylaxis. Most cases begin within minutes of exposure to an antigen. However, some cases can be late onset, up to one hour after exposure; biphasic, including a second related episode; or protracted. In her studies, the longer it took to control a case of anaphylaxis, the more likely a biphasic episode was.
“Get things better fast,” she said, as early intervention will help prevent biphasic anaphylaxis. When considering whether to release a patient home, Ellis said that healthcare practitioners should consider these findings.
Some allergists have argued that biphasic reactions do not occur, she noted. However, that is due to biphasic reactions that do not occur during food challenges, as clinicians are ready for reactions and treat immediately. Biphasic reactions are happening in the field, she said, and research is exploring why they happen.
While reviewing administration guidelines, Ellis offered tips and areas for caution. Most clinicians should be using intramuscular epinephrine, with intravenous administration reserved for emergency physicians and anesthesiologists. Epinephrine can be repeated every three to five minutes if symptoms are still present. Ellis said there is “no downside” to continuing to dose them. In addition, she cautioned against sitting patients up, rather keeping them in a recumbent position with the legs elevated. Administration should be accompanied by oxygen and a lot of IV fluids.
“Early treatment is good, but primary and secondary prevention are better,” she concluded.