The effects of midazolam and remifentanil on induction of anesthesia and hemodynamics during tracheal intubation under target-controlled infusion of propofol

BACKGROUND: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.