CHANGES IN RESPIRATORY PATTERN DURING INDUCTION OF ANESTHESIA WITH SEVOFLURANE - COMPARISON OF NASAL AND THE ORAL BREATHING

In order to test the hypothesis that the effects on ventilation of nas al inhalation of sevoflurane during induction of anaesthesia differ fr om those of oral inhalation, 20 patients underwent inhalation inductio n of anaesthesia with sevoflurane 5% either through the nasal route or the oral route. In 10 patients who breathed through the nose (N-group ), there was an immediate decrease in tidal volume with no change in r espiratory duration whereas no similar change was observed in the 10 p atients who breathed through the mouth (O-group). The time from the st art of sevoflurane inhalation to the onset of sleep was significantly shorter in the O-group compared with the N-group [86.2+/-4.4 (mean+/-S E) vs. 115.0+/-8.4sec, P<0.01].