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 To compare the effects on cardiovascular changes induced by tracheal intubation when small doses of either remifentanil or sufentanil are used in the presence of midazolam.

Methods Thirty normotensive, ASA physical status I–II patients, receiving general anaesthesia for major abdominal surgery, received an intravenous midazolam premedication (0.05 mg kg−1) 10 min before induction. They were randomly allocated to receive in a double-blind fashion an intravenous bolusofeither(a)remifentanil given as a bolus dose 1 μg kg−1 (n = 15), or else (b) sufentanil 0.1 μg kg−1 infused over 60s (n = 15). In each instance this loading dose was followed by a continuous intravenous infusion (0.1 μg kg−1 min−1 or 0.01 μg kg−1 min−1 of remifentanil or sufentanil, respectively). General anaesthesia was induced with propofol (2 mg kg−1), followed by atracurium besilate (0.5 mg kg−1) to facilitate tracheal intubation. Following intubation, the lungs were mechanically ventilated with a 60% nitrous oxide in oxygen mixture and a 1% inspired sevoflurane.

Results Arterial pressure and heart rate were recorded before induction of anaesthesia (baseline), immediately before intubation, immediately after tracheal intubation and every minute for the first five minutes thereafter. No differences in systolic and diastolic arterial pressures were observed between the two groups. At the end of the study period, systolic and diastolic pressures slightly decreased from preinduction values in both groups. Four patients in the remifentanil group (26%) and five patients in sufentanil group (33%) showed at least one systolic pressure value <90 mm Hg during the study period (P = not significant); however, the observed decreases in systolic pressure were transient and did not require treatment. Heart rate values were not affected by tracheal intubation in either group.

Conclusions In healthy normotensive patients without cardiovascular disease the use of a relatively small dose of either remifentanil or sufentanil after standard midazolam premedication results in a similar and clinically acceptable effectiveness in blunting the cardiovascular changes induced by tracheal intubation.