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 bolus of either (a) remifentanil given as a bolus dose 1 microgram kg-1 (n = 15), or else (b) sufentanil 0.1 microgram kg-1 infused over 60 s (n = 15). In each instance this loading dose was followed by a continuous intravenous infusion (0.1 microgram kg-1 min-1 or 0.01 microgram 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 mmHg 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.