Effects of Dexmedetomidine on Postoperative Quality of Recovery and Electroencephalogram in Elderly Patients Undergoing Total Knee Arthroplasty: A Randomized Clinical Trial

Anesthesia management strategies in elderly patients undergoing total knee arthroplasty (TKA) are critical to the postoperative quality of recovery (QoR), and changes in electroencephalogram (EEG) associated with anesthesia drugs may play an important role in this process. This study aimed to determine the effects of different doses of dexmedetomidine on postoperative QoR in elderly TKA patients, and whether there is a correlation with specific EEG changes. In this randomized controlled trial, elderly patients (aged ≥ 60 years) undergoing elective TKA were randomly allocated in a 1:1:1 ratio to 0.6 μg/kg/h dexmedetomidine (Group D2), 0.3 μg/kg/h dexmedetomidine (Group D1) and saline (Group N). On postoperative days 1 and 3, the15-item Quality of Recovery (QoR-15) scale was used to evaluate the postoperative recovery of patients among the three groups. Perioperative EEG data were also recorded. The difference of QoR-15 scores on postoperative day 1 was significant for Group D2 vs Group N (126 [123-129] points vs 120 [116-123] points; median difference, 6 points [95% CI, 4 to 8]; P < 0.001) and Group D2 vs Group D1 (126 [123-129] points vs 122 [118-126]; median difference, 4 points [95% CI, 2 to 5]; P = 0.001), but not for Group D1 vs Group N. However, no significant difference was observed in the global and dimensional QoR-15 scores on postoperative day 3 among the three groups. Intraoperative EEG power spectra analysis revealed a decrease in α oscillation peak power and an increase in slow oscillation peak power in Group D1 and Group D2, compared with Group N. In addition, the slow oscillation peak power exhibited weak positive correlations with QoR-15 scores on postoperative day 1 (r = 0.319, P < 0.001). A loading dose of dexmedetomidine (0.5 μg/kg) infused within 10 minutes before anesthesia induction, followed by a maintenance at 0.6 μg/kg/h, improved QoR-15 on postoperative day 1 in elderly TKA patients, which may be partly related to the fact that dexmedetomidine deepens anesthesia by increasing the slow oscillation peak power in the appropriate range.