Ketorolac for prevention of acute postoperative pain

BACKGROUND: Since NSAIDs are competitive antagonists of cyclooxygenase, they prevent the biosynthesis of prostaglandins, responsible for enhanced nociceptive sensitization and primary hyperalgesia. If NSAIDs administration is performed after eicosanoids cascade activation by surgical trauma, already released prostaglandins can exert their hyperalgesic effects for a finite time. Therefore prophylactic administration of NSAIDs (pre-emptive analgesia) should improve their effectiveness on acute postoperative pain. AIM OF STUDY: To assess the analgesic effect of preoperatively administered ketorolac, compared with its administration after surgical trauma. MATERIALS AND METHODS: Thirty adult patients, ASA physical status I-II, undergoing elective septoplasty, were allocated randomly in two groups, depending on timing of i.v. administration of ketorolac 0.4 mg/kg: 10 min before induction (group I); or 5 min after decollement of nasal septum cartilaginoid plan (group II). No other analgesic drugs were given. Postoperative pain was assessed with objective (SAP, DAP, HR) and subjective (VAS, BS 11) methods at 60, 90, 120, 150, and 180 min after the end of surgery. Rate and severity of any side-effect were recorded. RESULTS: Both VAS and BS 11 showed significant better pain relief after preoperative ketorolac at all time, without any adverse effect. Same result was shown by SAP at 60 and 90 min postoperatively. CONCLUSIONS: Due to prevention of nociceptive sensitization of prostaglandins released by tissue trauma, prophylactic NSAIDs administration to surgical patients with mild to moderate postoperative pain can improve their antinociceptive effects.