Dose-related effect of sevoflurane sedation on higher control of eye movements and decision making.

Abstract

Saccadic latency may provide an objective method to assess sedative doses of anaesthetic on cortical oculomotor mechanisms and decision making. We tested the effects of random doses of 0, 0.1, 0.2 and 0.3 MAC sevoflurane in six subjects, in a double-blind study using two measures of behavioural impairment: saccadic latency and stop signal reaction time (SSRT) in a countermanding task. Saccadic latency and SSRT both increased with increasing doses of sevoflurane. In both measures, reciprocal reaction time was linearly related to dose in each subject: all but two of the twelve regression coefficients were statistically significant (P<0.05). In one subject, SSRT was significantly more sensitive than simple latency (P<0.05); for the others there was no significant difference. Measurements of this kind could potentially provide estimates of cortical effects of sevoflurane sedation, and give a clinically useful measure of cognitive fitness.