Narcotrend monitoring allows faster emergence and a reduction of drug consumption in propofol-remifentanil anesthesia

Abstract

Background: The Narcotrend is a new electroencephalographic monitor designed to measure depth of anesthesia, based on a six-letter classification from A (awake) to F (increasing burst suppression) including 14 substages. This study was designed to investigate the impact of Narcotrend monitoring on recovery times and propofol consumption in comparison to Bispectral Index® (BIS®) monitoring or standard anesthetic practice. Methods: With institutional review board approval and written informed consent, 120 adult patients scheduled to undergo minor orthopedic surgery were randomized to receive a propofol-remifentanil anesthetic controlled by Narcotrend, by BIS®, or solely by clinical parameters. Anesthesia was induced with 0.4 μg · kg-1 · min-1 remifentanil and a propofol target-controlled infusion at 3.5 μg/ml. After intubation, remifentanil was reduced to 0.2 μg · kg-1 · min-1, whereas the propofol infusion was adjusted according to clinical parameters or to the following target values: during maintenance to D0 (Narcotrend) or 50 (BIS®); 15 min before the end of surgery to C1 (Narcotrend) or 60 (BIS®). Recovery times were recorded by a blinded investigator, and average normalized propofol consumption was calculated from induction and maintenance doses. Results: The groups were comparable for demographic data, duration of anesthesia, and mean remifentanil dosages. Compared with standard practice, patients with Narcotrend or BIS® monitoring needed significantly less propofol (standard practice, 6.8 ± 1.2 mg · kg-1 · h-1 vs. Narcotrend, 4.5 ± 1.1 mg · kg-1 · h-1 or BIS®, 4.8 ± 1.0 mg · kg-1 · h-1; P < 0.001), opened their eyes earlier (9.3 ± 5.2 vs. 3.4 ± 2.2 or 3.5 ± 2.9 min), and were extubated sooner (9.7 ± 5.3 vs. 3.7 ± 2.2 or 4.1 ± 2.9 min). Conclusions: The results indicate that Narcotrend and BIS® monitoring are equally effective to facilitate a significant reduction of recovery times and propofol consumption when used for guidance of propofol titration during a propofol-remifentanil anesthetic.