Breathing pattern during isoflurane anaesthesia with or without nitrous oxide

Br J Anaesth. 1986 Jun;58(6):586-92. doi: 10.1093/bja/58.6.586.


Tidal volume, respiratory timing and occlusion pressure were studied in spontaneously breathing patients during isoflurane anaesthesia and in the presence of surgery. In one group of patients, end-tidal concentrations of 1.5% and 2.5% isoflurane in oxygen were used and in the other group equivalent depths of anaesthesia were obtained with 0.75% and 1.75% end-tidal isoflurane plus 67% nitrous oxide in oxygen. During the deeper anaesthesia, the duration of the respiratory cycle decreased significantly in both groups. In the group breathing nitrous oxide, the greater isoflurane concentration caused a significant reduction in ventilation. Airway occlusion significantly decreased the duration of the inspiratory period in both groups, indicating that the presence of nitrous oxide was not necessary for this effect.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Anesthesia, Inhalation*
  • Female
  • Humans
  • Isoflurane / pharmacology*
  • Male
  • Methyl Ethers / pharmacology*
  • Middle Aged
  • Nitrous Oxide / pharmacology*
  • Oxygen
  • Pulmonary Ventilation / drug effects
  • Respiration / drug effects*
  • Tidal Volume


  • Methyl Ethers
  • Isoflurane
  • Nitrous Oxide
  • Oxygen