Propofol requirement during propofol and butorphanol anesthesia with and without nitrous oxide in short duration intracranial surgeries: A bispectral index guided study

Abstract

Introduction: Propofol is a preferred agent in neurosurgical anesthesia because of its favorable effects on cerebral hemodynamics and excellent recovery profile. Butorphanol is a synthetic opioid which is 5-8 times more potent than morphine and is known to provide stable hemodynamics during various surgical procedures. Owing to its unfavorable effects on cerebral metabolism and hemodynamics nitrous oxide has a debatable role in neurosurgical anesthesia. But studies on exact dose requirement during propofol induction and maintenance anesthesia along with butorphanol with and without the use of N2O during craniotomies are lacking. So we aimed at studying the requirement of propofol (used along with butorphanol) with and without the use of nitrous oxide in intracranial surgeries using bispectral index (BIS) monitoring. Material and methods: Fifty ASA grade I/II patients (16-60 years) scheduled for elective intracranial surgeries (≤ 4 hour duration) were included and were randomly allocated into two groups, group P and PN. All received IV midazolam and butorphanol at a dose of 30 μg/kg each. Anesthesia was induced with propofol and maintained on propofol with oxygen in air (1:1 ratio) in group P and nitrous oxide in oxygen (2:1 ratio) in group PN patients. BIS score of ≤ 40 at the time of endotracheal intubation, 50-60 during maintenance and ≥ 70 at extubation was maintained. The overall and maintenance dose requirement of propofol and the recovery profile were studied. Results: The overall and maintenance propofol doses were significantly higher in group P than group PN (100.02 ± 20.28 μg/kg/min Vs 79.62 ± 13.13μg/ kg/min; p<0.001) and (90.82 ± 19.13 Vs 71.26 ± 11.78 μg/kg/min; p<0.001) respectively. The recovery profiles were identical between groups. Conclusion: When used along with butorphanol the overall and maintenance doses of propofol without the use of nitrous oxide are 100.02 ± 20.28 μg/ kg/min and 90.82 ± 19.13 μg/ kg/min respectively which is more (p<0.001) than the dose required in combination with nitrous oxide (79.62 ± 13.13 and 71.26 ± 11.78 μg/kg/min respectively). © 2012 Dube SK, et al.