[Comparison of rapid anesthetic induction with sevoflurane vs target-controlled infusion of propofol]

To determine whether inhalation induction is faster than target-controlled infusion (TCI).

Patients in ASA physical status 1 or 2 who were scheduled for elective surgery were randomized to a propofol TCI group or a sevoflurane group. Both groups received a TCI of 5 ng L(-1) of remifentanil. Rapid induction was performed using an effect-site TCI of 2.8 microg mL(-1) of propofol in the propofol group and 8% sevoflurane in the sevoflurane group. We recorded time until loss of the palpebral reflex, hemodynamic variables, respiratory variables, hypnotic depth of anesthesia using the auditory evoked potentials index (AAI), and the moment the anesthesiologist decided to intubate. Also recorded was the time taken to reach an AAI of less than 40, which was established as the threshold of hypnotic depth sufficient for tracheal intubation.

Forty-four patients were enrolled in the trial. The palpebral reflex loss time was 60 (44-90) seconds in the TCI-propofol group and 72 (38-265) seconds in the sevoflurane group (P<.05). An AAI of less than 40 was reached in 105 (90-195) seconds in the TCI-propofol group and in 230 (125-355) seconds in the sevoflurane group. The variation in the calculated effect-site concentration (Ce) was consistent with the direction of change in the AAI value, which decreased as Ce increased; the variation in the expired fraction of sevoflurane did not show the same relationship. The anesthesiologist was not authorized to intubate 2 patients in the sevoflurane group as the AAI threshold was not reached. The decrease in blood pressure was significantly greater in patients in the sevoflurane group than in those in the propofol group.

Anesthetic induction is faster with a TCI of propofol based on Ce than with sevoflurane. The propofol Ce was consistent with the direction of change in the AAI.