Validation of the Bispectral Index Monitor During Living Donor Liver Transplantation

Forty two American Society of Anesthesiologists physical class III-IV patients aged 20-50 years with severe liver dysfunction (Child-Pugh Class C) due to liver cirrhosis undergoing living donor liver transplantation in the Mansoura University Liver Transplantation Program from 2007 to 2010 were included in this prospective, observational study after obtaining approval of the local ethical committee and an informed written consent from all participants. The etiology of liver cirrhosis was hepatitis C, Budd Chiari syndrome, hepatocellular carcinoma and autoimmune in all patients.

Anesthetic technique was standardized for all patients. All patients received preoperative intravenous 40 mg of pantoprazole. Patients were monitored with three leads electrocardiography, pulse oximeter, and noninvasive blood pressure. BIS recording electrodes (Aspect Medical Systems. Inc., One Upland Road, Norwood, MA 02062 USA) were applied to the forehead of each patient according to the manufacturer recommendations. The BIS monitor was masked with opaque sheet and BIS data was recorded prior to induction of general anesthesia then continued throughout the procedure. All information obtained from the BIS monitor was continuously downloaded to a computer for offline analysis. The patient's management was not guided by the changes in BIS readings. Before induction of anesthesia, all patients were premedicated with 1-2 mg of intravenous midazolam.

Independent anesthetists, who were not involved in the collection and analysis of the patient's data, provided the perioperative anesthetic management. After preoxygenation, anesthesia was induced with lidocaine 0.75 mg/kg, propofol 1.5-2.0 mg/kg and fentanyl 2µg/kg. Rocuronium 1-1.2 mg/kg was given to suppress the first response on the train-of-four (TOF) stimulations of the ulnar nerve. After tracheal intubation, the lungs were ventilated with an inspired fraction of oxygen (FiO2) of 0.4 to maintain an arterial carbon dioxide tension at 35-45 mm Hg and monitoring of end-tidal carbon dioxide and sevoflurane concentration, direct arterial pressure monitoring through a radial artery catheter and a tympanic membrane temperature were implemented.

A 7.5 Fr continuous thermodilution fiberoptic pulmonary artery catheter (CCO/SvO2) Edwards Life Science, Irvine, CA, USA) was floated through the right internal jugular vein to the right pulmonary artery using waveform and fluoroscopic guidance to measure cardiac output using Angstrom AS5 Monitor (Datex - Ohmeda AS5, Microvitec Display LTD, Bolling Road, Bradford, UK). The final position was confirmed by fluoroscopy and when PAOP less than pulmonary artery diastolic pressure (PADP).

Anesthesia was maintained with 0.5-1.5 minimum alveolar concentration (MAC) of sevoflurane and continuous intravenous infusion of fentanyl (1-3 µg/kg/h) titrated to maintain the mean arterial blood pressure (MAP) and heart rate (HR) within 20% of their baseline values. Rocuronium 0.1-0.3 mg/kg/h was used to maintain suppression of the second twitch in the TOF.