Effects of S-ketamine added to patient-controlled analgesia on early postoperative pain and recovery in patients undergoing thoracoscopic lung surgery: A randomized double-blinded controlled trial

To investigate whether the addition of S-ketamine to patient-controlled hydromorphone analgesia decreases postoperative moderate-to-severe pain and improves the quality of recovery (QoR) in patients undergoing thoracoscopic lung surgery. Single-center prospective randomized double-blinded controlled trial. Tertiary university hospital. 242 patients undergoing thoracoscopic lung surgery. Patients were randomized to receive intravenous patient-controlled analgesia (IV-PCA) with hydromorphone alone or hydromorphone combined with S-ketamine (0.5 mg/kg/48 h, 1 mg/kg/48 h, or 2 mg/kg/48 h). Primary outcome was proportion of patients with moderate-to-severe pain. (numerical rating scale [NRS] pain scores ≥4 when coughing) within 2 days after surgery. Postoperative QoR scores and other prespecified outcomes were also recorded. Of 242 enrolled patients, 220 were included in the final analysis. The results demonstrated that the incidence of postoperative moderate-to-severe pain was significantly different between the hydromorphone group and combined S-ketamine group (absolute difference, 27.9%; 95% confidence interval [CI], 11.7% to 42.1%; P < 0.001). Patients who received S-ketamine had lower NRS pain scores at rest and when coughing on postoperative day 1 (POD1; median difference 1 and 1, P < 0.001) and postoperative day 2 (POD2; median difference 1 and 1, P < 0.001). The QoR-15 scores were higher in the combined S-ketamine group on POD1 (mean difference 6, P < 0.001) and POD2 (mean difference 6, P < 0.001) than in the hydromorphone group. A higher dose of S-ketamine was associated with deeper sedation. No differences were detected in the other safety outcomes. Addition of S-ketamine to IV-PCA hydromorphone significantly reduced the incidence of postoperative moderate-to-severe pain and improved the QoR in patients undergoing thoracoscopic lung surgery. Trial registration: Chinese Clinical Trail Register (identifier: ChiCTR2200058890).