Anaphylactoid Reaction to Cisatracurium May Be Explained by Atracurium Metabolites

In Response: We appreciate the comments of Rieder et al. These colleagues suggest acrylate metabolites as potential mediators of histamine release following atracurium or cisatracurium administration. We refrained from discussing this mechanism because we deemed it highly speculative and clearly beyond the scope of a case report. Rather, it was the objective of our report to shed light on the persisting difficulty to discriminate between different types of anaphylactoid reactions in the acute clinical setting. This appeared necessary because previous case reports uniformly advocated IgE mediated reactions as the underlying mechanism (1–4), although they only relied on substitute methods rather than on direct IgE determination. Thus, the pathobiologic mechanism of our cases remains undetermined. Jens Krombach, MD Walter Buzello, MD