The sevoflurane-sparing effect of nitrous oxide: a clinical study.

Abstract

We studied the sevoflurane-sparing effect of nitrous oxide in a prospective randomised study. Forty-two ASA I-II patients scheduled for elective knee arthroscopy under general anaesthesia were randomly assigned to a fresh gas flow consisting of oxygen in air or oxygen in nitrous oxide 1:2. All patients received a standardised anaesthesia consisting of induction with fentanyl and propofol and maintenance with sevoflurane adjusted according to clinical signs. The sevoflurane consumption was studied by means of weighing the vaporiser before and after every anaesthesia. The mean sevoflurane consumption was reduced from 0.62 to 0.25 g/min, a 60% reduction, by the use of oxygen in nitrous oxide 1:2 in the fresh gas flow. The emergence was faster for the patients receiving nitrous oxide. No major differences were observed during recovery. Nitrous oxide was found to be cost-effective for use during short ambulatory knee arthroscopy.