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MAC-AWAKE OF ISOFLURANE, ENFLURANE AND HALOTHANE EVALUATED BY SLOW AND FAST ALVEOLAR WASHOUT

GAUMANN, D. M. ; MUSTAKI, J.-P ; TASSONYI, E.

In: BJA: British Journal of Anaesthesia, 1992, vol. 68, no. 1, p. 81-84

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    Titre
    • MAC-AWAKE OF ISOFLURANE, ENFLURANE AND HALOTHANE EVALUATED BY SLOW AND FAST ALVEOLAR WASHOUT
    Auteur
    • GAUMANN, D. M.. Department of Anaesthesiology, University Hospital of Geneva, 1211 Geneva 4, Switzerland
    • MUSTAKI, J.-P. Department of Anaesthesiology, University Hospital of Geneva, 1211 Geneva 4, Switzerland
    • TASSONYI, E.. Department of Anaesthesiology, University Hospital of Geneva, 1211 Geneva 4, Switzerland
    Type de document
    • Postprint
    Langue
    • Inglese
    Publié dans
    • BJA: British Journal of Anaesthesia, 1992, vol. 68, no. 1, p. 81-84. Oxford University Press
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:304500
    Summary
    End-tidal anaesthetic concentrations at first eye opening in response to a verbal command during recovery from anaesthesia (MAC-awake), were measured for isoflurane (n = 16), enflurane (n = 16) and halothane (n = 14). MAC-awake was measured during either slow or fast alveolar washout. Slow washout was obtained by decreasing anaesthetic concentrations in predetermined steps of 15min, assuming equilibration between brain and alveolar partial pressures. Fast alveolar washout was obtained by discontinuation of the inhalation anaesthetic, which had been maintained at 1 MAC for at least 15 min. Mean MAC-awake obtained with slow alveolar washout was similar for isoflurane (0.25 (SD 0.03) MAC), and enflurane (0.27 (0.04) MAC) and significantly greater than values obtained by fast alveolar washout (isoflurane: 0.19 (0.03) MAC; enflurane: 0.20 (0.03) MAC). The MAC-awake of isoflurane and enflurane was significantly less than that of halothane, which was 0.59 (0.10) MAC as evaluated by the slow and 0.50 (0.05) MAC as evaluated by the fast alveolar washout method. Recovery time from anaesthesia with fast alveolar washout was 8.8 (4.0) min for halothane, which was not different from isoflurane (15 (2.5) min), but significantly shorter than for enflurane (22 (10) min), reflecting differences in the anaesthetic concentration gradient between MAC and MAC-awake values. These data do not support the hypothesis of a uniform ratio between MAC and MAC-awake values