Remimazolam anaphylaxis during anesthesia induction

Anaphylactic shock is a potentially lethal complication during anesthesia and requires appropriate management to save the patient's life. We report a 32-year-old man who developed anaphylaxis during induction of general anesthesia with remimazolam for hand surgery. He received general anesthesia with midazolam 4 weeks before. This time facial flushing followed by a decrease of peripheral oxygen saturation (SpO₂) and blood pressure occurred 2 min after starting continuous remimazolam infusion at 6 mg/kg/h. Hypotension and SpO₂ were recovered by repeated administration of adrenaline. Despite no increase of serum tryptase levels, intradermal allergy tests 4 weeks postoperatively revealed that remimazolam and midazolam were positive, suggesting remimazolam as a causative agent for anaphylaxis. In the previous surgery, midazolam, which has a similar structure to remimazolam, may have caused sensitization. This is probably the first case report of anaphylaxis caused by remimazolam.