Clinical analgesic efficacy and side effects of dexmedetomidine in the early postoperative period after arthroscopic knee surgery

STUDY OBJECTIVES: To determine the analgesic efficacy of dexmedetomidine in the early postoperative period. DESIGN: Randomized, double-blind, double placebo-controlled clinical trial. SETTING: University medical center. PATIENTS: 30 ASA physical status I, II, and III patients with cruciate ligament lesion and joint fibrosis who were scheduled for knee arthroscopy. INTERVENTIONS: Patients were prospectively randomized to receive dexmedetomidine one mcg/kg(-1) intravenously (IV), for 10 minutes followed by dexmedetomidine 0.3 mcg/kg(-1) for 50 minutes or propacetamol two g, IV, for 10 minutes. MEASUREMENTS: Pain scores, time to onset analgesia, and morphine consumption were measured. Open-label rescue morphine 5 mg IV was available as needed during the postdosing evaluation period of 8 hours. Hemodynamic data, sedation scores, and renal and hepatic function were assessed for control of adverse events. MAIN RESULTS: Pain scores with dexmedetomidine and propacetamol were similar. There were no differences in the number of patients who required supplemental rescue analgesia (7/15 vs 4/15; P = 0.44), but total morphine requirements were higher with dexmedetomidine (45 mg) versus propacetamol (20 mg) in the 8-hour follow-up (P < 0.05). The most frequent adverse events with dexmedetomidine were bradycardia and hypertension. CONCLUSIONS: Dexmedetomidine provides a modest analgesic effect after knee arthroscopy, but the side effects of this drug, such as hypertension and bradycardia, may restrict the use of large bolus doses.