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

Background 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. Methods 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). Results 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 ( P P P =0.0456). Conclusions The closed-loop system was better at maintaining BIS and Analgoscore than manual administration.