Somatosensory, visual and brainstem auditory evoked potentials were recorded in 10 unpremedicated patients anaesthetized with isoflurane in oxygen. Recordings were made at 0.5%, 1.1% and 1.65% (six patients) end-tidal isoflurane concentration. There were statistically significant increases in the latencies of the somatosensory (N20), visual and brainstem auditory potentials (waves III and V) with increasing concentrations of isoflurane. The central conduction time was prolonged. Amplitudes of the somatosensory and visual potentials were reduced with increasing concentrations of isoflurane. The effects of isoflurane on evoked potentials are similar to those of halothane and enflurane. It is possible that changes in evoked potential measurements may be useful as a neurophysiological indicator of anaesthetic depth.
In a prospective, randomized, double-blind clinical study, we have studied 100 children, aged 2-12 yr, to compare halothane and sevoflurane in outpatient dental anaesthesia. All patients were unpremedicated and received inhalation induction using nitrous oxide in oxygen supplemented with either halothane (maximum inspired concentration 5%) or sevoflurane (maximum inspired concentration 8%). Time to loss of the eyelash reflex was more rapid using sevoflurane although time to adequate anaesthesia (to allow insertion of a mouth prop) was slower in the sevoflurane group. The incidence of cardiac arrhythmia was higher during halothane (62%) than during sevoflurane anaesthesia (28%) (P < 0.005) and the arrhythmias were more often ventricular in origin. The two agents were comparable in terms of ease of use and quality of anaesthesia, and times to eye opening and satisfying discharge criteria were similar. We conclude that sevoflurane has qualities that have made halothane the most used inhalation agent for children, and that it is superior to halothane in dental outpatients where cardiac arrhythmias are a particular problem.
SummaryIn this study we compared the performance of the single use flexible laryngeal mask airway (LMA Flexible™) with the original reusable LMA Flexible™ in paediatric dento‐alveolar day‐case surgery. The aim of the study was to determine whether these two supraglottic airway devices were clinically equivalent when used for simple dental extractions in children under general anaesthesia. This randomised comparative trial in 100 healthy children used first attempt airway insertion success as its primary outcome measure. Secondary outcomes included the adequacy of ventilation, incidence of airway obstruction and the requirement for device manipulation and the incidence of adverse airway outcomes during recovery from anaesthesia. No difference was found between the devices in first attempt insertion success rate (94% with reusable LMA Flexible and 90% with single use LMA Flexible, p = 0.358), and ease of insertion was also similar (p = 0.5). Both devices performed equally well during surgery, with no significant differences in episodes of intra‐operative airway compromise (p = 0.387), and both the single use and reusable LMA Flexible displayed excellent recovery characteristics, with no occurrences of emergence airway obstruction. No blood was discovered within the inner LMA tube shaft in either device, implying that both protected against tracheobronchial soiling. We conclude therefore that the single use LMA Flexible is an acceptable alternative to the reusable LMA Flexible.
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