Evaluation of a novel closed-loop total intravenous anaesthesia drug delivery system: a randomized controlled trial

We have developed an automatic anaesthesia system for closed-loop administration of anaesthesia drugs. The control variables used were bispectral index (BIS) and Analgoscore for hypnosis and antinociception, respectively. One hundred and eighty-six patients were randomly enrolled in two groups. Propofol, remifentanil, and rocuronium were administered using closed-loop feedback control (closed-loop, n 93) or manually (control group, n 93). The clinical performance of hypnosis control was determined by calculating the offset from a BIS of 45: excellent, good, poor, and inadequate control was defined as BIS values within 10, from 11 to 20, from 21 to 30, or 30 offset from the target. The clinical performance of analgesia was defined as the offset from Analgoscore values. Data presented as mean (standard deviation) (95 confidence interval). Excellent or good control of hypnosis was achieved significantly longer in the closed-loop group [47.0 (9.8) (45.0/49.0), 34.4 (4.7) (33.5/35.4)] than in the control group [37.3 (14.3) (34.4/40.2) and 32.3 (7.6) (30.7/33.7)], respectively (P0.0001 and 0.0085). Poor and inadequate control of hypnosis was significantly shorter in the closed-loop group [10.8 (5.0) (9.8/11.8) and 7.7 (6.2) (6.4/9.0)] than in the control group [14.7 (6.8) (13.3/16.0) and 15.8 (14.7) (12.8/18.8)], respectively (P0.0001). Excellent control of analgesia was achieved significantly longer in the closed-loop group [78.7 (16.2) (75.4/82.0)] than in the control group [73.7 (17.8) (70.1/77.3)] (P0.0456). The closed-loop system was better at maintaining BIS and Analgoscore than manual administration.