Effect of S-Ketamine on Postoperative Delirium in Elderly Patients Undergoing Arthroplasty: A Randomized Controlled Trial.

Summary

Among 372 elderly arthroplasty patients under neuraxial anesthesia, S-ketamine reduced postoperative delirium within 3 days (8.06% vs 20.43%; adjusted OR 0.29, 95% CI 0.14–0.63; P=0.002). Early postoperative pain during activity and rescue analgesia use were lower with S-ketamine, whereas hallucinations, dizziness, and nightmares were more frequent. Other complications were uncommon and similar between groups.

Key Findings

• Postoperative delirium within 3 days: 8.06% (S-ketamine) vs 20.43% (placebo); adjusted OR 0.29 (95% CI 0.14–0.63; P=0.002).
• Lower pain during exercise/physical therapy and reduced need for rescue analgesia on postoperative day 1 with S-ketamine.
• Higher incidence of hallucinations, dizziness, and nightmares with S-ketamine; other complications were infrequent with no significant differences.

Clinical Implications

Perioperative teams may consider S-ketamine as part of multimodal analgesia under neuraxial anesthesia to prevent postoperative delirium in elderly arthroplasty patients, balancing benefits against increased psychotomimetic adverse effects and ensuring monitoring and counseling.

Limitations

• Single-center setting may limit generalizability; neuraxial anesthesia context may not extend to general anesthesia.
• Short follow-up (3 days) for delirium assessment; increased psychotomimetic adverse events require mitigation strategies.

Future Directions

Multicenter trials to validate efficacy across settings, dose-finding to minimize psychotomimetic effects, evaluation under general anesthesia, and longer-term cognitive/functional outcomes.