BACKGROUND:
The aim of the study was to investigate whether closed-loop compared to manual bispectral index (BIS)–guided target-controlled infusion of propofol and remifentanil could decrease the incidence of postoperative neurocognitive disorders after elective major noncardiac surgery.
METHODS:
Patients aged >50 admitted for elective major noncardiac surgery were included in a single-blind randomized (ratio 2:1) trial. The anesthetic protocol was allocated by randomization into either closed-loop or manual BIS-guided propofol and remifentanil titration. The BIS target range was 40–60. All patients had cognitive assessment the day before surgery and within 72 hours after surgery using a battery of neuropsychological tests. The primary outcome was the rate of postoperative neurocognitive disorders. Postoperative neurocognitive disorders were defined as a decrease >20% from baseline on at least 3 scores. Intergroup comparison of the primary outcome was performed using the χ2 test.
RESULTS:
A total of 143 and 61 patients were included in the closed-loop and manual groups, respectively (age: 66 [8] vs 66 [9] years). The primary outcome was observed in 18 (13%) and 10 (16%) patients of the closed-loop and manual groups, respectively (relative risk [95% confidence interval {CI}], 0.77 [0.38-1.57], P = .47). Intraoperative propofol consumption was lower (4.7 [1.4] vs 5.7 [1.4] mg·kg−1·h−1, mean difference [MD] [95% CI], −0.73 [−0.98 to −0.48], P < .0001) and the proportion of time within the BIS target range higher (84 [77–89] vs 74 [54–81]%, MD [95% CI], 0.94 [0.67-1.21], P < .0001) in the closed-loop group.
CONCLUSIONS:
Closed-loop compared to manual BIS-guided total intravenous anesthesia provided a significant reduction in episodes of an excessive depth of anesthesia while decreasing intraoperative propofol requirement but no evidence for a reduction of the incidence of postoperative neurocognitive disorders after elective major noncardiac surgery was observed.
KEY POINTS
- Question: Could closed-loop compared to manual target-controlled infusion of propofol and remifentanil lower the rate of postoperative neurocognitive disorders after elective major noncardiac surgery?
- Findings: Closed-loop compared to manually-driven BIS-guided total intravenous anesthesia provided a significant reduction in episodes of an excessive depth of anesthesia while decreasing intraoperative propofol requirement but no evidence for a reduction of the incidence of postoperative neurocognitive disorders after elective major noncardiac surgery was observed.
- Meaning: This randomized controlled trial failed to demonstrate that the propofol sparing effect provided by closed-loop anesthesia is sufficient alone to decrease the risk of postoperative neurocognitive disorders after elective major noncardiac surgery.