The effect of adding nitrous oxide on MAC of sevoflurane combined with two target-controlled concentrations of remifentanil in women

Andrea Albertin, A. Casati, P. C. Bergonzi, E. Moizo, F. Lombardo, G. Torri

Research output: Contribution to journalArticlepeer-review

Abstract

Background and objective: The aim of this prospective, randomized, double-blind study was to determine the effects of adding nitrous oxide on sevoflurane requirement for blunting sympathetic responses after surgical incision combined with two different target-controlled concentrations of remifentanil (1 and 3 ng mL-1) in female. Methods: 102 female patients, aged 20-50 yr, ASA I, undergoing general anaesthesia for elective abdominal surgery were enrolled and randomly allocated to receive sevoflurane anaesthesia alone (Group A, n = 53), or with the addition of 60% nitrous oxide (Group N, n = 49). Patients of both groups were further assigned to receive a target-controlled remifentanil infusion with an effect-site concentration of either 1 ng mL-1 (Group N1, n = 27; Group A1, n = 30), or 3 ng mL-1 (Group N3, n = 22; Group A3, n = 23). Sympathetic responses to surgical incision were determined after a 20-min period of stable end-tidal sevoflurane and target-controlled remifentanil concentrations. Predetermined end-tidal sevoflurane concentrations and minimum alveolar concentration (MAC) for each group were determined using an up-and-down sequential allocation technique. Results: The MAC of sevoflurane was 3.96% (95% confidence interval, CI95: 3.69-4.23%) in Group A1 and 1.2% (CI95: 0.9-1.3%) in Group N1 (P <0.01), while in Groups A3 and N3 the MAC of sevoflurane was 0.36% (CI95: 0.24-0.47%) and 0.18% (CI95: 0.1-0.3%), respectively (P <0.05). Conclusion: Adding 60% nitrous oxide reduces the MAC of sevoflurane by 70% when using a remifentanil concentration of 1 ng mL -1 and 50% when using a remifentanil concentration of 3 ng mL -1.

Original languageEnglish
Pages (from-to)431-437
Number of pages7
JournalEuropean Journal of Anaesthesiology
Volume22
Issue number6
DOIs
Publication statusPublished - Jun 2005

Keywords

  • Anaesthetics, inhalation, nitrous oxide, sevoflurane, minimum alveolar concentration
  • Analgesics, opioid, remifentanil
  • Stress, sympathetic response

ASJC Scopus subject areas

  • Anesthesiology and Pain Medicine

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