Analgesic effect of intraoperative intravenous S(+)-ketamine during total knee arthroplasty (TKA) surgery: Study protocol for a randomized controlled clinical trial Analgesic effect of intraoperative intravenous S(+)-ketamine during total knee arthroplasty (TKA) surgery

Abstract

Abstract Introduction: Poor management of acute pain after total knee arthroplasty (TKA) increases the risk of complications in elderly patients. S(+)-ketamine in subanaesthetic doses is available as an adjuvant to the standard regimen of opioids, presenting prominent analgesic effects and opioid-sparing effects. Appropriate multimodal medication projects are required to decrease postoperative opioid use and improve effects in elderly patients undergoing TKA. Methods This is a randomized, placebo-controlled trial. A total of 144 participants aged ≥ 65 years old undergoing TKA will be randomly allocated into the S(+)-ketamine and placebo groups in a 1:1 ratio. S(+)-ketamine or placebo will be intravenously administered at 0.3 mg/kg/h during the operation by anesthesiologists. Blinded evaluation by trained investigators will be completed at 2 hours, 24 hours and 48 hours after surgery. The primary outcome measure is the numeric rating scale (NRS) score at rest and movement at 24 hours after surgery. The secondary outcomes include the NRS scores at rest and movement at 2 hours and 48 hours after surgery, the number of patients who require additional analgesics during the first 48 hours after operation, the total consumption of opioids or nonsteroid anti-inflammatory drugs during the first 48 hours after operation and adverse events at 2,24, 48 hours after operation. Trial registration number: NCT05289050