[Awareness during anesthesia with sevoflurane: a case report]

We report a case of a patient who experienced awareness during general anesthesia with sevoflurane. A 71-year-old man, weighing 57 kg, was operated on for a malignant tumor of the parotid gland. He was given 2 mg diazepam orally as a premedication. General anesthesia was induced by thiamylal 200 mg, fentanyl 50 microg, and up to 5% of sevoflurane. Muscle relaxation was obtained with vecuronium 6 mg, and the patient was intubated. After induction, fentanyl 150 microg was added, but no other intravenous anesthetics or muscle relaxants were used. The end-expiratory concentration of sevoflurane was maintained at 0.8% to 1.7% before the start of surgery, and 1.5% to 2.9% during surgery. The operation lasted for 10.4 hours. His left eye was guarded by ointment but kept open for observation by the surgeon of facial movement following muscle stimulation. The surgical course, emergence, and the postoperative course were uneventful. On the fifth postoperative day, the patient started to describe his visual memory during the operation, although he did not remember any pain or discomfort. We believe that visual input through his open eyes, the effect of cranial bone oscillation by the surgery, and the idiosyncrasy of the patient contributed to his intraoperative recall.