The combined induction using two or more agents has a potential benefit that anesthesia could be induced with smaller anesthetic agents with fewer side effects. We studied the effects of co-administration with midazolam and remifentanil on the dose of propofol, the time to loss of consciousness (LOC) and hemodynamics during tracheal intubation.

Sixty patients were randomly assigned to three groups. Group 1 was induced with target-controlled propofol alone. Group 2 received midazolam (0.05 mg/kg) and target-controlled propofol. Group 3 received midazolam (0.025 mg/kg), remifentanil (2 ng/ml) and target-controlled propofol. The time to LOC, the infused propofol dose and the effect site concentration at LOC were recorded. After LOC, rocuronium (0.6 mg/kg) was given and tracheal intubation was performed. The noninvasive blood pressure, heart rate (HR) and bispectral index were recorded.

The time and the dose of propofol to LOC were significantly reduced in group 2, 3 than in group 1 (P < 0.05). Compared with pre-induction values, mean blood pressure at immediately after intubation was increased in group 1, 2 with no change in group 3. The HR immediately after intubation was significantly increased in all groups compared to the pre-induction values, but the rate of increase of HR in group 3 were significantly lower than those group 1, 2 (P < 0.05).

The co-administration with midazolam and remifentanil reduces the time to LOC and the dose of propofol. That also attenuates hemodynamics during tracheal intubation under target-controlled infusion of propofol.