Safety and Efficacy of Dexmedetomidine for Postoperative Pain after Major Elective Surgery in In-Patients

Arain, Shahbaz R.; Ruehlow, Renee M.; Ebert, Thomas J., 2002: Safety and Efficacy of Dexmedetomidine for Postoperative Pain after Major Elective Surgery in In-Patients. Anesthesiology Abstracts Of Scientific Papers Annual Meeting. : Abstract A-55,.

INTRODUCTION: 

Dexmedetomidine (DEX), a potent alpha2-agonist, has been approved for sedation in the ICU. It is reported also to have analgesia-sparing properties. We evaluated the safety and efficacy of DEX compared with morphine sulfate (MSO4) when used for postoperative analgesia in major surgical cases (in-patients). 

 

METHODS: After IRB approval and informed consent, 28 patients were randomized to receive either conventional therapy with MSO4 (0.08 mg/kg loading dose) or DEX (1 mug/kg loading dose over 10 min, initial infusion rate at 0.4 mug/kg/hr). Therapy was initiated 30 min prior to completion of the elective major surgical procedure (primarily abdominal or orthopedic cases) and continued for 4 hr into recovery. Supplemental MSO4 was provided as needed for the conventional therapy group, whereas supplemental DEX (up to 0.7 mug/kg/hr) was initially employed for pain in the DEX group followed by supplemental MSO4 as needed. ECG, BP, O2 sat, respiratory rate (RespR), sedation (RAMSAY and Visual Analog Scale (VAS)), pain (VAS) and nausea (VAS) were evaluated. Anesthetic technique was standardized. RESULTS: 

There were no differences in patient demographics, type or duration of surgery, blood loss, fluid supplementation, or use of intraoperative opioids, anesthetics and adjuvants between groups. Initial loading of DEX or MSO4 did not cause significant hemodynamic changes. In the recovery period, there were no significant differences in BP, O2 sat, RespR or levels of sedation. Patients receiving DEX had significantly lower heart rates during recovery (DEX, 64+-2; MSO4, 84+-3 bpm)(mean+-sem). Pain scores were equivalent between groups. To control postoperative pain, the average use of MSO4 in the first hour of recovery was more than 3-fold higher in patients receiving conventional therapy with MSO4 compared to DEX (17.5+-2 vs. 5+-2 mg) and not significantly different thereafter. This resulted in equivalent pain scores between treatment groups. Eight of 14 patients randomized to DEX required no MSO4 in the PACU. The DEX group had significantly lower levels of nausea. VAS sedation was significantly less in the DEX vs. MSO4 group (45 vs. 57, scale 0-100) in the PACU. 

 

DISCUSSION: 

 The use of DEX in major surgical procedures for postoperative pain control was effective and without adverse events when compared to MSO4. In addition, DEX was associated with lower heart rates, less nausea and sedation and the use of substantially less MSO4 in the early postoperative period. These effects might offer advantages for patients who are at risk of myocardial ischemia, or for patients where higher doses of opioids might be disadvantageous.