[Plasma concentration of propofol was 4.4 microg x ml(-1), 4.5 hours after completion of its administration].

Propofol is one of the most commonly used intravenous anesthetic drugs because its distribution, metabolism and excretion are rapid. Recovery from anesthesia using propofol infusion is generally smooth. We have therefore taken this opportunity to report on a case of delayed recovery from anesthesia in a 58-year-old man who underwent removal of a light maxillary sinus mucocele. General anesthesia was performed with propofol 3-7 mg x kg(-1) x hr(-1) associated with intermittent injection of fentanyl, total of 450 microg. He was not obese, and his preoperative liver function was within normal limits. Any intracranial hematomas, brain edema, cerebral infarction, acid-base abnormalities, hypo- and hyperglycemia and hypothermia were not detected in the early postoperative period. The administration of naloxone hydrochloride and flumazenil failed to improve delayed recovery from anesthesia. It was 16 hours after the end of operation and the administration of propofol had been completed before the trachea could be extubated. His plasma concentration of propofol was 4.4 microg x ml(-1), 4.5 hours after administration. In this patient we could not prove a metabolic abnormality with propofol, but it was strongly suspected.