SINGLE-BREATH INHALATION INDUCTION OF SEVOFLURANE ANESTHESIA WITH ANDWITHOUT NITROUS-OXIDE - A FEASIBILITY STUDY IN ADULTS AND COMPARISON WITH AN INTRAVENOUS BOLUS OF PROPOFOL

The induction characteristics of sevoflurane in nitrous oxide and oxyg en were compared with sevoflurane in oxygen alone and a propofol infus ion. A vital capacity technique was used for the us induction groups u sing a Mapleson A system and a 4-litre reservoir bag. Four end-points of anaesthesia were recorded: time to cessation of finger tapping, tim e to loss of eyelash reflex, time to jaw relaxation and time to regula r settled breathing after laryngeal mask airway insertion. We also rec orded sequential blood pressure and pulse rate, the incidence of adver se airway events and the acceptability of the induction technique. Pro pofol had a faster time to cessation of finger tapping (p < 0.05) and jaw relaxation (p < 0.01). These differences disappeared with the fina l induction stage and sevoflurane in nitrous oxide and oxygen had the faster time to regular settled breathing, though this did not reach st atistical significance. Cardiovascular stability was good and comparab le in all groups. There were few adverse airway events in any group an d none caused oxygen saturation to fall below 96%. There tvas more exc itation in the gaseous induction groups, though this did not interfere with induction. Patient satisfaction with induction was high.