Background: Preemptive analgesia has been difficult to show in human experiments. If ketorolac has preemptive effects, then there may be an advantage to administering it at the beginning of surgery despite the potential for increased blood loss.
Methods: The authors performed a randomized, double-blind, controlled trial of 48 patients scheduled for ankle fracture surgery in a county trauma hospital. Anesthesia management was standardized and included adequate opioid analgesia (5 microg/kg fentanyl and 0.1 mg/kg morphine). Intravenous 30 mg ketorolac was administered to 23 patients before tourniquet inflation and to 25 patients after tourniquet inflation. Visual analog scale pain scores, morphine patient-controlled analgesia consumption, nausea-vomiting, and postoperative bleeding were measured.
Results: The 23 patients given ketorolac before tourniquet inflation had no increase in pain postoperatively compared with their preoperative baseline (P = 0.280). The 25 patients who received ketorolac minutes later after tourniquet inflation had significant increases in their postoperative pain compared with their preoperative baseline (P = 0.00116). This effect was short-lived, and by 6 h the pain score in this group was not significantly more than it was preoperatively. Intergroup comparison showed a lower visual analog scale score at 2 (P = 0.0203) and 4 h (P = 0.00549) in the preemptive group and lower nausea scores at hour 6 (P = 0.00704). There was no difference in patient-controlled analgesia consumption between groups.
Conclusions: Intravenous 30 mg ketorolac appears to have preemptive analgesic effects in patients undergoing ankle fracture repair. Ketorolac administered before tourniquet inflation prevents postoperative pain being perceived as more intense than preoperative pain.