Perineural Methylene Blue Infusion in Lower Limb Amputation Surgery

This prospective randomized controlled study will be conducted to evaluate the analgesic effect of continuous perineural infusion of methylene blue with bupivacaine on acute postoperative pain and to evaluate its preventive role against chronic phantom pain in patients undergoing lower limb amputation surgery

Post amputation pain remains an extremely challenging pain condition to treat, so the prevention of phantom pain is our goal to decrease its incidence. Methylene blue, an inhibitor of nitric oxide synthase and guanylate cyclase, has been widely applied for a variety of pain-related diseases due to its characteristic abilities, such as the blocking of pain transmission, antioxidant, and anti-inflammatory effects. Methylene blue can maintain local anesthesia for approximately 20 days so it can be used as a nerve block to relieve pain, especially refractory neuropathic pain.