oa Southern African Journal of Anaesthesia and Analgesia - 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 : research

Volume 22, Issue 1
  • ISSN : 2220-1181
  • E-ISSN: 2220-1173



Propofol is known to have a favourable effect on cerebral haemodynamics. The role of nitrous oxide (NO) in neurosurgical anaesthesia is still being debated. The primary aim of this study was to assess the dose-sparing effect of NO on propofol infusion maintenance dosing.

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 μg/kg bolus prior to propofol induction. Anaesthesia was maintained with an infusion of fentanyl (2 μg/kg/hour), atracurium and propofol. The patients were randomised into two groups. Group A received 67% NO. Group B did not receive NO concomitantly with the propofol infusion. Entropy was used to guide the titration of the propofol infusion in both groups.
The propofol maintenance dose requirements were 47% lower in Group A (54.30 ± 11.47 μg/kg/minute) vs. Group B (102.30 ± 14.00 μg/kg/minute), (p < 0.001).
The use of supplemental NO significantly decreased propofol infusion rate requirements, compared with the propofol infusion alone, in ASA I and II patients undergoing elective supratentorial tumour excision.

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