Abstract
BACKGROUND: The perioperative administration of low-dose ketamine has shown potential in postoperative pain management, opioid sparing, and enhancing pain control. This study aimed to investigate the impact of low-dose ketamine on processed electroencephalography (EEG) signals during anesthesia. METHODS: Forty patients with American Society of Anesthesiologists physical status I-II undergoing elective gynecological surgery were enrolled. EEG monitoring was initiated upon induction of anesthesia. Anesthesia was maintained with desflurane and alfentanil immediately after induction. Fifteen minutes after induction, the ketamine group received a 0.3 mg/kg bolus followed by 0.05 mg/kg/h infusion until completion of surgery. The control group received equivalent saline. Postoperative assessments included pain score (visual analog scale), morphine usage, and quality of recovery. RESULTS: The ketamine group had significantly higher Patient State Index (PSi) values at 10, 20, and 30 minutes after ketamine administration compared to the controls. Ketamine administration led to significant alterations in EEG patterns, including reduced relative power in delta and theta frequency bands, and increased relative power in beta and gamma frequency bands at 10 minutes post-administration. Relative power in the alpha frequency band significantly decreased at 10, 20, and 30 minutes post-administration. However, there were no differences in intraoperative alfentanil consumption, postoperative morphine usage, and pain scores between the two groups. CONCLUSION: Low-dose ketamine administration during desflurane anesthesia led to notable changes in EEG patterns and PSi values. These findings provide valuable insights into the impact of ketamine on brain activity, and offer essential information for clinical anesthesiologists.