Effect of Continuous Infusion of Different Doses of Esketamine on the Bispectral Index During Sevoflurane Anesthesia: A Randomized Controlled Trial

Purpose: To investigate and quantify the effect of continuous esketamine infusion at different doses on the bispectral index (BIS) during sevoflurane anesthesia. Methods: A total of 120 patients scheduled for elective laparoscopic renal surgery were randomly divided into three groups. Under steady anesthesia and surgical situations, the patient was started on continuous infusion of the study drug: 0.125 mg/kg/h esketamine (group E1), 0.25 mg/kg/h esketamine (group E2), and the same volume of saline (group C). The primary outcome was changes in BIS value after 15 min (T 15 ), 30 min (T 30 ), 45 min (T 45 ), and 60 min (T 60 ) of drug infusion. The secondary outcomes were 95% spectral edge frequency (SEF95), electromyogram (EMG), heart rate (HR), and mean arterial pressure (MAP) from T 0 to T 60 . Furthermore, postoperative pain, postoperative recovery, and perioperative adverse events were evaluated. Results: Compared with group C, group E1 exhibited significant BIS elevation at T 30 –T 60 and group E2 at T 15 –T 60 ( P < 0.001). Compared with group E1, group E2 showed a more significant BIS elevation at T 15 –T 60 ( P < 0.001). The area under the curve (AUC) of BIS and SEF95 were significantly higher in group E2 than in groups C and E1 ( P < 0.05). BIS value for any of the three groups was significantly correlated with SEF95 ( P < 0.001). No significant differences were observed in the AUC of EMG, HR, and MAP among the three groups. Intraoperative remifentanil consumption and postoperative NRS of pain on movement were significantly reduced in group E2 compared with groups C and E1 ( P < 0.05). Conclusion: Continuous infusion of both 0.125 and 0.25 mg/kg/h of esketamine increased the BIS value during sevoflurane anesthesia, and the BIS value gradually stabilized with the prolongation of the infusion time. Keywords: esketamine, bispectral index, 95% spectral edge frequency, sevoflurane