Automated Propofol and Remifentanil Delivery Effective

Closed-loop coadministration of propofol and remifentanil maintains Bispectral Index values

FRIDAY, March 11 (HealthDay News) -- Automated delivery of propofol and remifentanil using a controller maintains the Bispectral Index (BIS) values better than manual administration during general anesthesia, according to a study published in the March issue of Anesthesia & Analgesia.

Ngai Liu, M.D., Ph.D., from the Hôpital Foch in Suresnes, France, and colleagues compared the closed-loop coadministration of propofol and remifentanil using a proportional-integral-derivative controller guided by BIS, with manual target-controlled infusion during induction and maintenance of general anesthesia in surgical patients. Participants were randomly assigned to dual closed-loop (83 patients) or manual administration (84 patients). The groups were compared by calculating a global score that included the percentage of adequate anesthesia (BIS between 40 and 60), median absolute performance error, and wobble.

The investigators found that the dual-loop group had a better global score and spent a higher percentage of time with a BIS between 40 and 60 compared to the manual group. In addition, in the dual-loop group there were less overshoot and undershoot periods (BIS less than 40 or more than 60), and a lower burst suppression ratio. The dual-loop group required more frequent and smaller adjustments to the propofol and remifentanil infusions. More remifentanil was consumed, and the tracheal extubation was quicker in the dual-loop group.

"Our results indicate that automated coadministration of propofol and remifentanil using BIS for the controller allows an improvement in global score," the authors write.

The hospital and several of the study authors hold a patent for the gain constants and control algorithm used to make this controller. Alaris Medical provided equipment for this study.

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