Perioperative systemic magnesium sulphate to minimize acute and chronic post-thoracotomy pain: a prospective observational study.

Abstract

Thoracotomy leads to acute and chronic post-thoracotomy pain (CPTP). The purpose of this study was to investigate the effect of magnesium sulphate (MgSO4) administered perioperatively on acute postoperative and CPTP syndrome. One hundred patients were enrolled in this prospective, observational study. Analgesic medication was provided according to the World Health Organization pain relief ladder (control group). The study group received additionally MgSO4 (40 mg/kg over 10 minutes) during induction of anesthesia followed by an infusion over 24 hours (10 mg/kg/h). The presence and severity of pain were assessed before surgery, on postsurgical days 1-8, 30 and 90, respectively. The Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) was used pre- and postoperatively for documentation of neuropathic pain. The incidence and severity of CPTP were assessed by a telephone survey 30 and 90 days after surgery. Numerical rating scale (NRS) pain scores at rest were significantly lower in the study group receiving MgSO4 at days 1 to 8 (P<0.05). Thirty days after surgery, 2.1% of the MgSO4-patients had a LANSS score ≥12 compared to 14.3% in the control group (P=0.031). No patient had a LANSS score ≥12 in the study group compared to the control group (0% vs. 12.2%, P<0.05) 90 days following surgery. MgSO4 administration reduces postoperative pain at rest according to the NRS pain scores and is effective in preventing chronic neuropathic post-thoracotomy pain measured by LANSS score. Prospective-randomized trials are needed to confirm the results of the present study.