Analgesic properties of a dexmedetomidine infusion after uvulopalatopharyngoplasty in patients with obstructive sleep apnea

BACKGROUND: Dexmedetomidine is an alpha(2) -adrenergic agonist with sedative and analgesic properties. This study aimed to investigate if the use of a continuous dexmedetomidine infusion with i.v. morphine patient-controlled analgesia (PCA) could improve postoperative analgesia while reducing opioid consumption and opioid-related side effects. METHODS: In this prospective randomized, double-blinded, controlled study, 39 patients with obstructive sleep apnea syndrome undergoing uvulopalatopharyngoplasty were assigned to two groups. Group D (dexmedetomidine group) received a loading dose of dexmedetomidine 1 μg.kg(-1) i.v., 30 minutes before the anticipated end of surgery, followed by infusion at 0.6 μg.kg(-1) h(-1) for 24 hours. Group P (placebo group) received a bolus and infusion of placebo. In both groups, postoperative pain was initially controlled by i.v. morphine titration and then PCA with morphine. Cumulative PCA morphine consumption, pain intensities, sedation scores, cardiovascular and respiratory variables and opioid-related adverse effects were recorded for 48 hours after operation. RESULTS: Compared with placebo group, patients in the dexmedetomidine group required 52.7% less PCA morphine during the first 24 hours postoperatively, with significantly better visual analogue scale scores, less incidence of respiratory obstruction (5 vs. 12 patients, respectively; P = .037) and longer time to first analgesic request (21 (11) vs. 9 (4) minutes; P = .002). Fewer patients in group D experienced nausea and vomiting than those in group P (7 vs. 24 patients, respectively; P < .05). CONCLUSION: Continuous dexmedetomidine infusion may be a useful analgesic adjuvant for patients susceptible to opioid-induced respiratory depression.