Epidural fentanyl delayed emergence from anesthesia

An 83-year-old man (158 cm, 42 kg) was scheduled for cholecystectomy. He had a history of hypertension and atrial fibrillation. The patient received no premedication. An epidural catheter was inserted via the T9-10 interspace and 2% mepivacaine 7 ml was injected, producing a sensory block from T4 to T12. Anesthesia was induced with propofol and remifentanil, and was maintained with propofol, remifentanil, and nitrous oxide in oxygen. Rocuronium was given to provide neuromuscular block. Just before the completion of surgery, a bolus epidural injection of 2% mepivacaine 2 ml with fentanyl 50 microg was performed. Then epidural solution of ropivacaine 0.1% with fentanyl 6.25 microg x ml(-1), and droperidol 25 microg x ml(-1) was infused at 4 ml x hr(-1). Soon after the surgery, the patient developed atrial fibrillation that was treated with external electrocardioversion with 100 watt x sec. After the restoration of sinus rhythm, anesthetics were discontinued. The patient did not emerge from anesthesia though he breathed spontaneously Doxapram was slightly effective, but he did not respond to the verbal command. Epidural infusion was stopped and the patient was transferred to the ward. The patient fully recovered from anesthesia after 2 hours. Epidural infusion was restarted 17 hours later, and the patient fell asleep. He woke up after stopping epidural infusion. Epidurally administered fentanyl must have been the cause of delayed recovery from anesthesia. He could have been highly sensitive to fentanyl. Patient controlled epidural anesthesia may have been useful for this patient.