The Effect of Adding Magnesium Sulfate to Epidural Bupivacaine and Morphine on Post-Thoracotomy Pain Management: A Randomized, Double-Blind, Clinical Trial.

Post-thoracotomy pain is very severe and may cause pulmonary complications. Thoracic epidural analgesia can greatly decrease the pain experience and its consequences. However, finding new methods to decrease the amount of administered opioids is an important issue of research. We aimed to evaluate the effect of adding epidural magnesium sulphate to bupivacaine and morphine on pain control and the amount of opioid consumption after thoracotomy. Eighty patients undergoing thoracotomy at a tertiary cardiothoracic referral centre were enrolled in a randomized, double-blind trial. Patients were randomly allocated to two groups. Bupivacaine (12.5 mg) and morphine (2 mg) were administered epidurally to all patients at the end of operation. Patients in the magnesium (Mg) group received epidural magnesium sulphate (50 mg), and patients in the control (C) group received normal saline as an adjuvant. Visual analogue scale (VAS) score and the amount of morphine consumption were measured during 24 hr post-operation. Thirty-nine patients in the Mg group and 41 patients in the C group completed the study. Patients in the Mg group had significantly less VAS score at recovery time (p < 0.05), 2 hr (p < 0.01) and 4 hr (p < 0.05) after surgery. The patient-controlled analgesia pump was started earlier in the C group than in the Mg group (p < 0.05). The amount of morphine needed in the Mg group was significantly lower than in the C group (5.64 +/- 1.69 mg/24 hr versus 8.44 +/- 3.98 mg/24 hr; p < 0.001). Pruritus was seen in the C group (9.7%) and absent in the Mg group (p < 0.05). Co-administration of magnesium sulphate with bupivacaine and morphine for thoracic epidural analgesia after thoracotomy leads to a reduction in post-operative pain score and the need for opioid administration.