Two cases of circulatory collapse due to suspected remimazolam anaphylaxis

Abstract

Background: Remimazolam was approved in Japan in January 2020. We report two cases of circulatory collapse due to suspected remimazolam anaphylaxis during anesthetic induction. Case presentation: Case 1: A 74-year-old male was scheduled for debridement and skin grafting for a severe burn injury. We induced anesthesia with 4 mg of remimazolam and 20 mg of ketamine. The patient subsequently developed treatment-resistant severe hypotension. Case 2: A 59-year-old male was scheduled for laparoscopic-assisted sigmoid colectomy. We induced anesthesia with 9 mg of remimazolam. Within a few minutes, the patient developed treatment-resistant severe hypotension. As serum tryptase was elevated in both cases and only intravenous administration of adrenaline was effective, we considered the circulatory collapse might be due to anaphylaxis. Conclusion: We experienced two cases of circulatory collapse due to suspected remimazolam anaphylaxis during anesthetic induction. The prevalence of remimazolam anaphylaxis is not yet known, and further research is needed.