Evoked potentials during isoflurane anaesthesia

Abstract

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.