Effect of Epidural Magnesium on the Incidence of Chronic Postoperative Pain After Video-Assisted Thoracic Surgery

Abstract

The aim of this study was to determine whether the epidural administration of magnesium during the perioperative period decreased the incidence of chronic postoperative pain (CPOP) at 3 months after video-assisted thoracic surgery. Prospective, randomized, and blinded. A university hospital. Patients. Before the induction of anesthesia, the patients were assigned randomly to receive normal saline, 5 mL, (group C, n = 72) or magnesium sulfate, 100 mg (group M, n = 72), epidurally. At the end of surgery, group C received a continuous infusion of a mixture of 0.2% ropivacaine, 226 mL, and fentanyl, 1,200 μg, through a patient-controlled epidural analgesia pump for 48 hours. In group M, magnesium sulfate, 500 mg, was added to the infusion. The incidence and severity of CPOP were assessed by a telephone survey 3 months after surgery. Patients were asked whether they experienced pain and to rank the severity of the pain using a 3-point scale (1, mild; 2, moderate; 3, severe). The incidences of CPOP were 42.4% in group C and 49.1% in group M. The severities of pain in the patients with CPOP were 1.0 (1-2) in group C and 1.0 (1-2) in group M. The incidence and severity of CPOP did not differ between the 2 groups. The epidural administration of magnesium from before the induction of anesthesia to 48 hours postoperatively did not decrease significantly the incidence or severity of CPOP in patients undergoing video-assisted thoracic surgery.