Comparison of the morphine-sparing effect of intraoperative dexmedetomidine with and without loading dose following general anesthesia in multiple-fracture patients: A prospective, randomized, controlled clinical trial

Intraoperative dexmedetomidine (DEX) with or without loading dose both promote morphine-sparing effect in patient-controlled analgesia on postoperative acute pain. However, the contribution of the loading dose to this effect is largely unknown, especially in long-lasting surgeries. The present study was designed to investigate the role of a loading dose of DEX in this morphine-sparing effect in multiple-fracture patients following general anesthesia. Eighty-six patients scheduled multiple-fracture surgeries under general anesthesia were allocated into 3 groups which were maintained with propofol/remifentanil/Ringer solution (PRR), propofol/remifentanil/DEX with (PRD(w)), or without (PRD(o)) DEX loading dose before induction, respectively. Time to first morphine request and 24-hour morphine consumption was monitored. Pain intensity was evaluated with visual analog scale. During the first 24 hours following surgery, patients in the PRD(w/o) group showed increased time to first request of postoperative morphine and decreased total morphine consumption as compared with PRR patients. There was no significant difference with respect to these parameters between patients from the PRD(w) and PRD(o) groups. More patients from the PRD(w) groups experienced intraoperative bradycardia when compared to those from the PRR or PRD(o) group. This randomized controlled trial indicates that the morphine-sparing effect of intraoperative DEX was not affected by a loading dose in long-time surgeries.