Abstract
BACKGROUND: Anaphylaxis is an immediate allergic reaction. However, in some cases, there is a delay between the administration of the causative agent and the onset of anaphylaxis. CASE PRESENTATION: A 41-year-old woman was scheduled for laparoscopic myomectomy under general anesthesia combined with epidural anesthesia. Midazolam was administered, and an epidural catheter was inserted. Seven minutes after the induction of general anesthesia (17 min after midazolam administration), the patient developed tachycardia, hypotension, and redness of the face and trunk. Her hemodynamic status improved after administration of phenylephrine and elevation of both legs, and the surgery was completed. Increased blood histamine and tryptase levels were observed 30 min after the onset of hemodynamic signs. Based on the above, anaphylaxis was diagnosed. Skin tests later showed that midazolam was the causative agent. CONCLUSIONS: A case of perioperative anaphylaxis caused by midazolam, which was used before the induction of general anesthesia, was described.