Single‐breath inhalation induction of sevoflurane anaesthesia with and without nitrous oxide: a feasibility study in adults and comparison with an intravenous bolus of propofol

Abstract

SummaryThe induction characteristics of sevoflurane in nitrous oxide and oxygen were compared with sevoflurane in oxygen alone and a propofol infusion. A vital capacity technique was used for the gaseous induction groups using a Mapleson A system and a 4-litre reservoir bag. Four end-points of anaesthesia were recorded: time to cessation of finger tapping, time to loss of eyelash reflex, time to jaw relaxation and time to regular settled breathing after laryngeal mask airway insertion. We also recorded sequential blood pressure and pulse rate, the incidence of adverse airway events and the acceptability of the induction technique. Propofol had a faster time to cessation of finger tapping (p < 0:05) and jaw relaxation (p < 0:01). These differences disappeared with the final induction stage and sevoflurane in nitrous oxide and oxygen had the faster time to regular settled breathing, though this did not reach statistical significance. Cardiovascular stability was good and comparable in all groups. There were few adverse airway events in any group and none caused oxygen saturation to fall below 96%. There was more excitation in the gaseous induction groups, though this did not interfere with induction. Patient satisfaction with induction was high.

Conditions for laryngeal mask insertionA comparison of propofol versus sevoflurane with or without alfentanil

“…Hall et al [6] in their study, found that sevoflurane was slightly slower for induction than propofol. In our study, we found that the induction time for sevoflurane was shorter than propofol.…”

“…The conditions for LMA insertion after inhalation induction with sevoflurane are as good as with propofol [6]. However, inhalation induction with sevoflurane, without any co-induction agents produces more excitation before insertion of LMA and takes more time to produce jaw relaxation [6].…”

Target‐controlled propofol vs. sevoflurane: a double‐blind, randomised comparison in day‐case anaesthesia

“…Patients were instructed to take deep breaths at a normal rate and to tap their finger repeatedly on the edge of the trolley. Cessation of finger tapping was taken to signify loss of consciousness [8], which was confirmed by loss of the eyelash reflex. After loss of consciousness, ventilation was gently assisted by hand.…”

“…To facilitate this comparison, it would be necessary to administer the volatile agent for induction and maintenance of anaesthesia. Sevoflurane therefore appeared to be the most logical choice of volatile agent, as it has already been shown to be comparable with propofol during induction of anaesthesia [7,8], and it is increasingly used in day-case anaesthesia.…”

“…In addition, the study was not blinded and anaesthesia was induced with propofol in the inhalation group. We chose to use sevoflurane as our comparator anaesthetic because it can be used satisfactorily to induce anaesthesia in adults [7,8], allowing a comparison between 'pure' inhalation and intravenous anaesthesia, as well as greatly facilitating a blinded comparison. Although halothane could potentially have been used in place of sevoflurane, it is associated with a high incidence of adverse cardiac events during induction of anaesthesia in adults [10] and also has an unsuitable recovery profile for day-case anaesthesia.…”