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 motivatesmore frequent use of general anaesthesia with a small or minimal fresh gas flow rate. Nevertheless, the reduction ofthe 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. Therewere 72 female (68.6%) and 33 male (31.4%) patients. Patients were randomized by a ‘closed envelope’ method intotwo 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 bispectralindex (BIS), heart rate, blood pressure, end-tidal carbon dioxide concentration and haemoglobin oxygen saturationwere monitored. Results: Heart rate, blood pressure, end-tidal carbon dioxide concentration and saturation were similar in both groupsand the differences between them were statistically insignificant. The BIS values were similar in both groups and indicatedthat patients who underwent low-flow anaesthesia were not exposed to a higher risk of awakening during theprocedure than the high-flow anaesthesia patients. The changes in brain oximetry values were similar in both lowflowand high-flow anaesthesia. Conclusions: Use of both low-flow and high-flow rate general anaesthesia provided patients undergoing laparoscopiccholecystectomy proper oxygenation of the central nervous system, adequate sleep depth and haemodynamic stability.