Bispectral index and cerebral oximetry in low-flow and high-flow rate anaesthesia during laparoscopic cholecystectomy – a randomized controlled trial

INTRODUCTION: The need to reduce pollution emissions in the operating room and to reduce treatment costs motivates more frequent use of general anaesthesia with a small or minimal fresh gas flow rate. Nevertheless, the reduction of the delivery of fresh gases should not influence the quality and safety of the anaesthesia. MATERIAL AND METHODS: A total of 105 elective laparoscopic cholecystectomy patients were included in the study. There were 72 female (68.6%) and 33 male (31.4%) patients. Patients were randomized by a ‘closed envelope’ method into two groups. Group I included patients with low-flow anaesthesia and group II included patients with high-flow anaesthesia. In all patients the cerebral oximetry was measured separately for each cerebral hemisphere; the bispectral index (BIS), heart rate, blood pressure, end-tidal carbon dioxide concentration and haemoglobin oxygen saturation were monitored. RESULTS: Heart rate, blood pressure, end-tidal carbon dioxide concentration and saturation were similar in both groups and the differences between them were statistically insignificant. The BIS values were similar in both groups and indicated that patients who underwent low-flow anaesthesia were not exposed to a higher risk of awakening during the procedure than the high-flow anaesthesia patients. The changes in brain oximetry values were similar in both low-flow and high-flow anaesthesia. CONCLUSIONS: Use of both low-flow and high-flow rate general anaesthesia provided patients undergoing laparoscopic cholecystectomy proper oxygenation of the central nervous system, adequate sleep depth and haemodynamic stability.