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 t he effect on BIS and sedation of different infusion doses of remifentanil c ombined with a steady infusion of propofol. Forty patients initially receiv ed 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 correl ation between the dose of remifentanil and the change of BIS after 15 min o f infusion. The correlation between all the sedation scores and their corre sponding BIS was also significant. We concluded that remifentanil, in combi nation with propofol, reduces BIS when used for sedation.