EFFECT OF LOW CONCENTRATIONS OF NITROUS-OXIDE AND ISOFLURANE ON PEAK VELOCITY OF SACCADIC EYE-MOVEMENTS

Peak velocity of saccadic eye movements was studied in six healthy volunteers who were each given, on separate days, 5% and 10% MAC of nitrous oxide (5% and 10% end-tidal) or of isoflurane (0.06% and 0.12% end-tidal) or air, each gas for 25 min. Subjective assessment following each treatment was also undertaken. No significant difference was found between air and either 5% or 10% nitrous oxide. However, significant differences occurred at 15 and 25 min after 0.06% isoflurane compared with air (P < 0.05) and highly significant differences were present 5, 15 and 25 min after 0.12% isoflurane when compared with air and nitrous oxide (P < 0.01). In contrast, there was little difference between the three gases by subjective assessment.