Effect of sufentanil on bispectral index in the elderly

We examined the impact of adding sufentanil during anaesthesia induction with propofol on bispectral index values in elderly patients (≥ 65 years). Patients were randomly assigned to receive a target‐controlled sufentanil infusion (effect‐site concentration of 0.3 ng.ml^?1) or matching placebo, followed by a target‐controlled propofol induction (initial effect‐site concentration of 0.5 μg.ml^?1; step‐wise increase of 0.5 μg.ml^?1) until loss of consciousness defined as an Observer's Assessment of Alertness/Sedation score < 2. Seventy‐one patients (sufentanil 35, placebo 36) completed the study. Mean (SD) age was 72.3 (5.8) years; 41% were women. At loss of consciousness, mean (SD) bispectral index value was 75.0 (8.6) with sufentanil and 70.0 (8.0) with placebo; mean difference ?5.0 (95% confidence interval ?8.9 to ?1.1), p = 0.013. Post‐hoc analyses suggest that the difference was significant in men only (mean difference ?7.3 (?11.8 to ?2.6), p = 0.003). Sufentanil co‐induction with propofol results in higher bispectral index values at loss of consciousness in elderly patients.