BACKGROUND: Dexmedetomidine (Dex), an alpha(2) agonist, has well-known anesthetic and analgesic-sparing effects. We designed this prospective, randomized, double-blind, and placebo-controlled dose-ranging study to evaluate the effect of Dex on both early and late recovery after laparoscopic bariatric surgery.
METHODS: Eighty consenting ASA II-III morbidly obese patients were randomly assigned to 1 of 4 treatment groups: (1) control group received a saline infusion during surgery, (2) Dex 0.2 group received an infusion of 0.2 microg x kg(-1) x h(-1) IV, (3) Dex 0.4 group received an infusion of 0.4 microg x kg(-1) x h(-1) IV, and (4) Dex 0.8 group received an infusion of 0.8 microg x kg(-1) x h(-1) IV. Mean arterial blood pressure values were maintained within +/-25% of the preinduction baseline values by varying the inspired desflurane concentration. Perioperative hemodynamic variables, postoperative pain scores, and the need for "rescue" analgesics and antiemetics were recorded at specific intervals. Follow-up evaluations were performed on postoperative days (PODs) 1, 2, and 7 to assess severity of pain, analgesic requirements, patient satisfaction with pain management, quality of recovery, as well as resumption of dietary intake and recovery of bowel function.
RESULTS: Dex infusion, 0.2, 0.4, and 0.8 microg x kg(-1) x h(-1), reduced the average end-tidal desflurane concentration by 19, 20, and 22%, respectively. However, it failed to facilitate a significantly faster emergence from anesthesia. Although the intraoperative hemodynamic values were similar in the four groups, arterial blood pressure values were significantly reduced in the Dex 0.2, 0.4, and 0.8 groups compared with the control group on admission to the postanesthesia care unit (PACU) (P < 0.05). The length of the PACU stay was significantly reduced in the Dex groups (81 +/- 31 to 87 +/- 24 vs 104 +/- 33 min in the control group, P < 0.05). The amount of rescue fentanyl administered in the PACU was significantly less in the Dex 0.2, 0.4, and 0.8 groups versus control group (113 +/- 85, 108 +/- 67, and 120 +/- 78 vs 187 +/- 99 microg, respectively, P < 0.05). The percentage of patients requiring antiemetic therapy was also reduced in the Dex groups (30, 30, and 10% vs 70% in the control group). However, the patient-controlled analgesia morphine requirements on PODs 1 and 2 were not different among the four groups. Pain scores in the PACU, and on PODs 1, 2, and 7, in the three Dex groups were not different from the control group. Finally, quality of recovery scores and times to recovery of bowel function and hospital discharge did not differ among the four groups.
CONCLUSIONS: Adjunctive use of an intraoperative Dex infusion (0.2-0.8 microg x kg(-1) x h(-1)) decreased fentanyl use, antiemetic therapy, and the length of stay in the PACU. However, it failed to facilitate late recovery (e.g., bowel function) or improve the patients' overall quality of recovery. When used during bariatric surgery, a Dex infusion rate of 0.2 microg x kg(-1) x h(-1) is recommended to minimize the risk of adverse cardiovascular side effects.
