Effect of Continuous Paravertebral Dexmedetomidine Administration on Intraoperative Anesthetic Drug Requirement and Post-Thoracotomy Pain Syndrome After Thoracotomy: A Randomized Controlled Trial.

OBJECTIVES To assess the effect of paravertebral administration of dexmedetomidine as an adjuvant to local anesthetic on the intraoperative anesthetic drug requirement and incidence of post-thoracotomy pain syndrome. DESIGN Prospective, randomized, controlled, double-blind trial. SETTING Single university hospital. PARTICIPANTS The study comprised 30 patients who underwent elective thoracotomy and were assigned randomly to either the Ropin or Dexem group (n = 15 each). INTERVENTIONS All patients received the study medications through paravertebral catheter. Patients in the Ropin group received a bolus of 15 mL of 0.75% ropivacaine over 3-to-5 minutes followed by an infusion of 0.2% ropivacaine at 0.1 mL/kg/hour. Patients in the Dexem group received 15 mL of 0.75% ropivacaine plus dexmedetomidine, 1 µg/kg bolus over 3-to-5 minutes followed by an infusion of 0.2% ropivacaine plus 0.2 µg/kg/hour of dexmedetomidine at 0.1 mL/kg/hour. MEASUREMENTS AND MAIN RESULTS The primary outcome of the study was intraoperative anesthetic drug requirement. The secondary outcome was the incidence of post-thoracotomy pain syndrome 2 months after surgery. The amount of propofol required for induction of anesthesia was significantly less in the Dexem group (Dexem 49.33±20.51 v 74.33±18.40 in the Ropin group, p = 0.002). End-tidal isoflurane needed to maintain target entropy was significantly less in the Dexem group at all time points. Intraoperative fentanyl requirement was lower in the Dexem group (Dexem 115.33±33.77 v 178.67±32.48 in the Ropin group, p = 0.002). Postoperative pain scores and morphine consumption were significantly less in the Dexem group (p<0.001). The incidence of post-thoracotomy pain syndrome was comparable between the 2 groups (69.23% v 50%, p = 0.496). CONCLUSIONS Paravertebral dexmedetomidine administration resulted in decreased intraoperative anesthetic drug requirement, less pain, and lower requirements of supplemental opioid in the postoperative period. However, it had no effect on the incidence of post-thoracotomy pain syndrome.