Randomized placebo-controlled trial to assess the effect of remifentanil and propofol on bispectral index and sedation

The effect of the combination of opiates and hypnotics on bispectral index (BIS) is unclear. This double-blind placebo-controlled trial investigated the effect on BIS and sedation of different infusion doses of remifentanil combined with a steady infusion of propofol. Forty patients initially received a target-controlled infusion of propofol 2 mu g ml(-1) for 15 min. They were then randomized to receive either placebo, 0.01, 0.05 or 0.1 mu g kg(-1) min(-1) remifentanil for a further 15 min. We found a significant correlation between the dose of remifentanil and the change of BIS after 15 min of infusion. The correlation between all the sedation scores and their corresponding BIS was also significant. We concluded that remifentanil, in combination with propofol, reduces BIS when used for sedation.