Evaluation of efficacy of ketamine for prevention of chronic pain in patients with Lower Limb amputation.

This randomised, parallel-group, participant- and investigator-blinded active-controlled trial (n=88) in India is assessing strategies to prevent phantom limb pain after lower limb amputation. The study compares a conventional pain management protocol with a multimodal analgesic approach, both including intravenous ketamine infusion at 0.15 mg/kg/hour continued for 48 hours post-operatively. The trial is designed to evaluate whether this perioperative analgesic regimen can reduce the development and severity of chronic pain following amputation. Primary outcomes focus on pain control in the immediate post-operative period and longer-term phantom limb pain. Within 48 hours, the investigators will measure pain severity using the visual analogue scale, opioid consumption, including total dose, number of doses, and time to first rescue analgesia. Phantom limb pain incidence and severity will then be assessed at 1, 3, and 6 months after surgery using the Phantom Pain Questionnaire. The study also includes psychological outcomes measured with the Hospital Anxiety and Depression Scale and the Pain Catastrophizing Scale. Secondary outcomes include adverse drug effects and patient satisfaction with pain management. No phase is specified.