We report a case of delayed loss of consciousness and respiratory depression caused by accidental remifentanil infiltration. A healthy 61-year-old female underwent a tooth extraction and cystectomy for a periapical cyst under general anesthesia. The anesthesia was induced via the intravenous injection of propofol (100 mg), rocuronium (50 mg), and remifentanil (0.2 mcg/kg/min), followed by tracheal intubation, and was maintained via the inhalation of oxygen (2 L/min), air (2 L/min), and sevoflurane (1.5-2%) and the intravenous administration of remifentanil (0.1-0.2 mcg/kg/min). The operative time was 2 h and 29 min, and sevoflurane and remifentanil administration were stopped 5 minutes after the end of the operation. At that time, her forearm and upper arm were swollen. The patient’s tidal volume during spontaneous breathing was 7 mL/kg. About 11 min after tracheal extubation, she showed clear consciousness and sufficient breathing. During transfer from the operation room, she lost consciousness and her SpO2 fell to below 90%. We immediately returned her to the operating room and performed manual ventilation with a mask. Her blood gases, electrolytes, and glucose values were within the normal ranges. Neuromuscular monitoring showed a TOF count of 4 and a TOF ratio of 92%. She was intubated and transferred to the ICU and was monitored until the following morning. Seventeen hours after surgery, her consciousness and respiration had recovered completely, and the tracheal tube was extubated. Accidental remifentanil infiltration may have caused a delayed loss of consciousness and respiratory depression.
