Clinical evaluation of bispectral index-guided closed-loop infusion of propofol for preschool children: A multi-center randomized controlled study.

Importance: The closed-loop infusion system can automatically adjust and maintain the depth of anesthesia by using the propofol target-controlled infusion (TCI) model under the feedback guidance of the bispectral index (BIS).

Objective: To evaluate the safety and superiority of closed-loop TCI of propofol guided by BIS during maintenance of generalized intravenous anesthesia for preschool children.

Methods: A total of 120 children aged 1-6 years were enrolled and were divided into a closed-loop feedback group (Group C) and an open-loop manual control group (Group O), with 60 participants in each group. For anesthesia maintenance, the propofol infusion rate was adjusted by the injection system under the guidance of BIS in Group C and was manually adjusted by anesthesiologists according to the BIS and clinical experience in Group O, to maintain a BIS level of 50. The time ratio of adequate anesthesia (40 ≤ BIS ≤ 60), light anesthesia (BIS > 60), and deep anesthesia (BIS < 40) were recorded.

Results: A total of 119 patients (59 in Group C and 60 in Group O) were enrolled in the study. Group C demonstrated a higher time ratio of adequate anesthesia (P = 0.014) compared to Group O. The time ratio of light anesthesia and the global score was lower in Group C than in Group O (P = 0.010, P = 0.015, respectively). The frequency of adjustment per unit of time was higher in Group C for propofol (P < 0.001), while it was lower for remifentanil (P = 0.010).

Interpretation: BIS-guided closed-loop infusion of propofol is safe and effective for preschool children. The depth of anesthesia is controlled more accurately and smoothly.