- Postoperative delirium (POD) is common among elderly patients undergoing total hip arthroplasty (THA) and total knee arthroplasty (TKA) under neuraxial anesthesia, with a reported incidence of 11–20.7%.
- POD is associated with prolonged hospital stay, increased healthcare costs, higher mortality, poor cognitive outcomes, and increased risk of dementia.
- Previous meta-analyses have suggested that S-ketamine (an enantiomer of ketamine) can reduce POD following elective surgery under general anesthesia, potentially by blunting a neuroinflammatory response to surgery.
- Despite this, other studies have suggested that general anesthetics (e.g., sevoflurane, midazolam, and propofol) may in fact partly counteract S-ketamine’s neuroprotective effects.
- The authors of this study therefore hypothesized that the neuroprotective effects of S-ketamine may be fully preserved by the avoidance of general anesthesia.
- In this single-center, prospective, randomized, double-blind, placebo-controlled trial, the authors randomized 372 elderly patients undergoing either THA or TKA under neuraxial anesthesia to receive either an infusion of S-ketamine (0.2mg/kg) or placebo over one hour.
- In addition, patients randomized to the S-ketamine group had S-ketamine included in their postoperative patient-controlled intravenous analgesia (PCIA) infusions along with sufentanil and ondansetron. Patients in the placebo group only received sufentanil and ondansetron in their PCIA infusions.
- All participants received a preoperative adductor canal or iliac fascia block, as well as a neuraxial anesthetic as selected by the anesthesia team.
- The primary outcome was the incidence of POD within the first 3 days postoperatively.
- POD occurred in 15 patients (8.06%) in the S-ketamine group, compared with 38 patients (20.43%) in the placebo group (adjusted odds ratio 0.29; 95% CI 0.14–0.63; P = 0.002).
- The authors concluded that S-ketamine significantly reduces POD risk in elderly patients undergoing THA/TKA under neuraxial anesthesia.
Summary of "Effect of S-Ketamine on Postoperative Delirium in Elderly Patients Undergoing Arthroplasty: A Randomized Controlled Trial"
Summary published May 11, 2026
