Bispectral index decreased to zero for a patient undergoing orthotopic liver transplantation

provided the original work is properly cited. CC A 56-year-old man (height, 165 cm; weight, 75 kg) suspected of having herbal-related fulminant hepatitis was admitted for emergency orthotopic liver transplantation (LT). His medical history was unremarkable, except for hypertension. Upon admission to our hospital, the patient was alert with a Glasgow Coma Scale (GCS) score of 15 (4/5/6) that gradually decreased to 10 (3/2/5) by 28 h after admission. After transfer to the intensive care unit (ICU), intubation was performed and a propofol infusion was started at 4 mg/kg/h. The patient’s vital signs were stable, and mechanical ventilatory support was performed with air in O2 (FiO2 0.5). Before surgery, the patient’s Model for EndStage Liver Disease score was 21, and the Child-Pugh score was class C. The patient’s pupils were 3 mm/3 mm in diameter (left/ right), and brain computed tomography (CT) and magnetic resonance imaging (MRI) revealed no remarkable findings. Upon arrival to the operating room, the right radial artery was cannulated and arterial blood pressure, electrocardiography, heart rate, pulse oxygen saturation, end-tidal CO2 concentration, and bispectral index (BIS) were monitored continuously. The preoperative BIS value was 43. Anesthesia was induced and maintained with a 4-6 vol% of desflurane and a 5-15 ng/ml of target effect site-controlled remifentanil infusion. Mechanical ventilatory support was maintained with air in O2 (FiO2 0.5). A Swan-Ganz catheter was inserted into the right internal jugular vein to monitor cardiac output and pulmonary arterial pressure. Prior to the skin incision, the patient’s vital signs were stable, and his BIS value was 14. Approximately 1 h after the skin incision, the patient’s BIS values decreased rapidly to zero. The suppression ratio was 100, and there was an absence of electric activity on electroencephalography. The patient’s pupils remained 3 mm/3 mm (left/right) in diameter. His vital signs were stable, and his body temperature was 35.2C. The BIS sensors were checked for proper placement. An arterial blood gas analysis was performed to evaluate for metabolic disturbances, but the results did not show any abnormal findings. During surgery, the patient’s vital signs were generally stable (Table 1). We tried to maintain the mean arterial pressure at > 60 mmHg and body temperature at 34-35C. Despite efforts to increase the BIS level, the patient’s BIS values remained at zero until the end of the surgery for a total duration of 10 h 50 min. The surgical procedures were completed uneventfully with a total anesthetic time of 13 h 10 min. The patient was transferred to the ICU with the endotracheal tube still in place. The patient was sedated using a propofol infusion. After 24 h, the propofol infusion was discontinued, and the patient awoke with a GCS score of (4/E/5) and pupil size of 3 mm/3 mm (left/right). Afterwards, the sedation agent was switched to fentanyl. After being sedated for 52 h, the patient had awakened with an alert mental status of GCS score of 15 (4/5/6) and no neurologic deficits. Brain CT and MRI scans 3 days after surgery revealed no interval changes. Adequate spontaneous respiration was maintained, and the possibility of brain death was excluded. Extubation was performed on the fourth postoperative day after the patient could communicate. Liver function after transplantation recovered sequentially, and the patient was discharged without any complications. The presence of a BIS value of zero during surgery is a sign