Dexmedetomidine in Thoracoscopic Surgery: Opioid-Sparing Strategy

Study protocol All patients received target-controlled infusion (TCI) propofol (3-5 μg ml-1), 2% lidocaine 1.5 mg kg-1 and cisatracurium (0.15-0.2 mg kg-1) or rocuronium (0.6-1.0 mg kg-1). During induction, the dexmedetomidine group received a loading dose of 0.5 µg kg-1 of dexmedetomidine for 10 minutes. Meanwhile, propofol TCI was started with target of bispectral index set between 40 and 60. After the loading dose was complete, tracheal intubation was performed without opioid analgesic. The following maintenance dose was set as 0.5 µg kg-1 h-1 until the specimen was excised and two-lung ventilation was performed. Dexmedetomidine was then stopped. In contrast, the conventional control group was administered an intermittent bolus dose of fentanyl (0.3-0.5 µg kg-1) to reduce stimuli before tracheal intubation. In the maintenance phase, parecoxib (40 mg) or propacetamol (1 g) was given if indicated. Anaesthesia was maintained with TCI propofol, and the depth of anaesthesia was monitored using a bispectral index between 40 and 60. Fentanyl was used as a rescue analgesic during the operation. In both groups, when the patient's HR or mean arterial pressure (MAP) was \>25% of the baseline, an intermittent bolus dose of 15-25 µg fentanyl was administered. At the end of surgery, patients received intercostal nerve block under thoracoscopy by surgeon. Haemodynamic stabilisation was achieved in the following situations. If analgesic was administered but the MAP remained elevated at \>25% of baseline, nicardipine was considered. If hypotension with MAP dropped \>25% from baseline, ephedrine was considered. If bradycardia with HR dropped to \<50, atropine was considered. Pain intensity was assessed in the post-anaesthesia care unit (PACU) using a numerical rating scale (NRS) ranging from 0 to 10 every 15 minutes until 1 hour after surgery. The goal NRS score was \<3. If the severity was higher than 3, an intermittent bolus of fentanyl was used. Furthermore, we recorded postoperative complications including nausea, vomiting and respiratory compromise. On the following day, we visited the patient to record complications, severity of postoperative pain and analgesia use in the general ward.