Pre-administration of remifentanil in target-controlled propofol and remifentanil anesthesia prolongs anesthesia induction in neurosurgical patients: A double-blind randomized controlled trial

Background: Pre- and co-administration of remifentanil in target-controlled propofol and remifentanil anesthesia are the most common methods in clinical practice. However, anesthesia induction time by timing remifentanil administration was not identified. Therefore, we investigated the induction time of anesthesia based on type of remifentanil administration in target-controlled anesthesia. Methods: A total of 60 patients were randomly assigned to 1 of 2 groups: Pre-administered with remifentanil before propofol infusion (Group R, n=30) and co-administered with remifentanil with propofol (Group N, n=30). The primary outcome was total induction time based on the order of remifentanil administration. Secondary outcomes were from start of the propofol infusion time to loss of consciousness (LOC), rocuronium onset time, time to Bispectral index (BIS) 60, and hemodynamic variables. Results: The mean±SD of total induction time was 180.5±49.0 s in Group N and 246.3±64.7 s in Group R (mean difference: 65.8 seconds; 95% CI: 35.0-96.5 s, P<.01). Time to BIS 60 and rocuronium onset time were longer in the Group R (P<.01 and P<.01, respectively). The Dheart rate and Δcardiac output values were lower in the Group R (P=.02 and P=.04, respectively). Injection pain was reported by 11 of 28 (39%) in the Group N and in 2 of 28 (7%) in the Group R (difference in proportion: 32%, 95% CI: 10-51%, P=.01). Conclusion: Pre-administration of remifentanil in target-controlled propofol and remifentanil anesthesia prolongs total induction time about 35% compared to co-administration of remifentanil and propofol by decreased CO.