A Randomized Trial: Bispectral-guided Anesthesia Decreases Incidence of Delayed Neurocognitive Recovery and Postoperative Neurocognitive Disorder but Not Postoperative Delirium

Background: Postoperative cognitive dysfunction (POCD), also known as delayed neurocognitive recovery (up to 30 days) and postoperative neurocognitive disorder (up to 12 months), is a frequent complication of the neurological system associated with poor outcome. This randomized controlled trial aimed to determine whether bispectral (BIS) monitoring is correlated with delayed neurocognitive recovery, postoperative neurocognitive disorder, or postoperative delirium (POD).

Methods: Among 197 patients included in the study, 100 were assigned to the BIS group and 97 to the control group. The BIS index was kept at 40-60 in the BIS group, and the depth of anesthesia in the control group was maintained according to anesthetists' clinical experience. Cognitive function was evaluated from the 1-7 day after the operation and the time of discharge, and at 1 month, 6 months, and 1 year after the operation.

Results: The incidence of delayed neurocognitive recovery (3% 21.6%, <0.001, at 7 day) (3% 21.1%, <0.001, at 1 month) and postoperative neurocognitive disorder (6.2% 21.3%, =0.002, at 6 month) (4.4% 16.3%, , at 1 year) were lower in the BIS group, while there was no significant difference in POD between the two groups (12% 19.6%, =0.144). The average value of intraoperative BIS was lower in the BIS group (43.75 50.69, <0.001). The postoperative hospitalization time (9.99 12.41, <0.001) and the mortality (5.4% 14.4%, =0.042) were significantly decreased, while satisfaction was higher in the BIS group (39% 24.7%, =0.009).

Conclusion: BIS decreases delayed neurocognitive recovery and postoperative neurocognitive disorder; however, it is not associated with POD. BIS monitoring could effectively lessen postoperative hospitalization and mortality and increase patient satisfaction.