[Case of delayed awakening after remifentanil leakage out of a vein]

We report a case of delayed awakening with characteristic repeated loss of consciousness after remifentanil infusion complicated by leakage from an intravenous catheter. A 30-year-old male underwent microlaryngeal surgery for a vocal cord polyp. During anesthetic induction, infiltration from an intravenous (IV) line in the left forearm was observed 10 min after initiating a continuous infusion of remifentanil 0.5 microg x kg-1 x min -1. A second peripheral IV catheter was placed in the right forearm and general anesthesia was induced with remifentanil infusion at 0.3 microg x kg-1 x min- 1, propofol 120mg, fentanyl 100 microg, and rocuronium 70 mg. Anesthesia was maintained with remifentanil 0.05-0.3 microg x kg-1 x min -1and sevoflurane (1.5% in oxygen) for the 4 min of surgery. A few minutes after tracheal extubation, the patient developed respiratory arrest and loss of consciousness. We immediately ventilated him with a bag-valve-mask and administered naloxone 0.04 mg. Thereafter, he repeatedly awoke and was drowsy three times over the next 5hr. It was followed by an uneventful postoperative period. No remarkable deficit was observed in the patient. Blood gases, electrolytes, glucose values, and body temperature were within normal ranges throughout the perioperative period. Brain computed tomography, mag- netic resonance imaging, and electroencephalography showed no abnormalities. It was considered that the incidental subcutaneous remifentanil accumulation may have caused the respiratory suppression and delayed awakening.