Comparison of closed loop vs. manual administration of propofol using the Bispectral index in cardiac surgery

Background: In recent years, electroencephalographic indices of anaesthetic depth have facilitated automated anaesthesia delivery systems. Such closed‐loop control of anaesthesia has been described in various surgical settings in ASA I–II patients (1–4), but not in open heart surgery characterized by haemodynamic instability and higher risk of intra‐operative awareness. Therefore, a newly developed closed‐loop anaesthesia delivery system (CLADS) to regulate propofol infusion by the Bispectral index (BIS) was compared with manual control during open heart surgery. Methods: Forty‐four adult ASA II–III patients undergoing elective cardiac surgery under cardiopulmonary bypass were enrolled. The study participants were randomized to two groups: the CLADS group received propofol delivered by the CLADS, while in the manual group, propofol delivery was adjusted manually. The depth of anaesthesia was titrated to a target BIS of 50 in both the groups. Results: During induction, the CLADS group required lower doses of propofol (P