BACKGROUND AND OBJECTIVE: Variability in blink duration was examined to see whether it was sensitive to sevoflurane sedation at 0.05 and 0.1 minimum alveolar concentration (MAC). METHODS: Blinks were measured with an infrared transducer in eight subjects. Sedation was scored using a visual analogue scale (VAS). RESULTS: At baseline, 0.05 and 0.1 MAC sevoflurane, respectively, the overall median value of blink duration and its interquartile range were 95 (80-110) ms, 198 (163-245) ms and 210 (130-980) ms. The median percentage of blinks exceeding 500 ms was 0% (0-0.7%), 33.3% (25.5-34.7%) and 25% (15.7-63.3%) respectively. Values during 0.05 and 0.1 MAC sevoflurane were significantly different from baseline (P < 0.035) but not from each other. Baseline visual analogue scales showed large intersubject variability. Compared with baseline, VAS scores were higher at 0.05 MAC (P < 0.035) but not at 0.1 MAC. After discontinuing sevoflurane, median blink duration returned to baseline with a recovery half-life of 2.6 min (R2 = 0.95). Conclusion Blink duration is a sensitive measure of sevoflurane sedation even at 0.05 MAC.
BACKGROUND AND OBJECTIVE: Variability in blink duration was examined to see whether it was sensitive to sevoflurane sedation at 0.05 and 0.1 minimum alveolar concentration (MAC). METHODS: Blinks were measured with an infrared transducer in eight subjects. Sedation was scored using a visual analogue scale (VAS). RESULTS: At baseline, 0.05 and 0.1 MAC sevoflurane, respectively, the overall median value of blink duration and its interquartile range were 95 (80-110) ms, 198 (163-245) ms and 210 (130-980) ms. The median percentage of blinks exceeding 500 ms was 0% (0-0.7%), 33.3% (25.5-34.7%) and 25% (15.7-63.3%) respectively. Values during 0.05 and 0.1 MAC sevoflurane were significantly different from baseline (P < 0.035) but not from each other. Baseline visual analogue scales showed large intersubject variability. Compared with baseline, VAS scores were higher at 0.05 MAC (P < 0.035) but not at 0.1 MAC. After discontinuing sevoflurane, median blink duration returned to baseline with a recovery half-life of 2.6 min (R2 = 0.95). Conclusion Blink duration is a sensitive measure of sevoflurane sedation even at 0.05 MAC.