Southern African Journal of Anaesthesia and Analgesia. Vol 22, No 1 (2016):32-36

A prospective, randomised, controlled clinical trial to evaluate the effect of nitrous oxide on propofol requirement in elective craniotomy in which entropy was used to measure depth of anaesthesia.
P Nanda, P Prakash, KJ Choudhury, VP Singh, S Prakash

Background: Propofol is known to have a favourable effect on cerebral haemodynamics. The role of nitrous oxide (N2O) in? neurosurgical anaesthesia is still being debated. The primary aim of this study was to assess the dose-sparing effect of N2O on? propofol infusion maintenance dosing.Method: Fifty American Society of Anesthesiology (ASA) grade I and II adults scheduled for elective craniotomies for supratentorial? tumours were enrolled in the study. The patients received a standard anaesthetic comprising a fentanyl 2 ? 1/4 g/kg bolus prior? to propofol induction. Anaesthesia was maintained with an infusion of fentanyl (2 ? 1/4 g/kg/hour), atracurium and propofol. The? patients were randomised into two groups. Group A received 67% N2O. Group B did not receive N2O concomitantly with the? propofol infusion. Entropy was used to guide the titration of the propofol infusion in both groups.Results: The propofol maintenance dose requirements were 47% lower in Group A (54.30 ?? 11.47 ? 1/4 g/kg/minute) vs. Group B? (102.30 ?? 14.00 ? 1/4 g/kg/minute), (p < 0.001).Conclusion: The use of supplemental N2O significantly decreased propofol infusion rate requirements, compared with the? propofol infusion alone, in ASA I and II patients undergoing elective supratentorial tumour excision.Keywords: anaesthesia depth, entropy, intracranial surgery, nitrous oxide, propofol

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