Effect of Intraoperative Continuous I.V. Fentanyl on Tourniquet Induced Cardiovascular Changes and Postoperative Preemptive Analgesia in Total Knee Replacements / 대한통증학회지

BACKGROUND: It is difficult to treat tourniquet-induced hypertension despite adequate anesthesia, and the mechanism of that is not known. And it may be possible that intraoperative continuous infusion of opioid induces preemptive analgesia postoperatively. We investigated the effect of intraoperative continuous i.v. fentanyl on tourniquet induced cardiovascular changes and postoperative preemptive analgesia in total knee replacements. METHODS: Sixty patients were randomly assigned to two groups; In study group (1.5microgram/kg loading and 0.5microgram/kg/hr continuous infusion of fentanyl before skin incision and tourniquet inflation) and control group (no treatment). Anesthesia was maintained with enflurane (1-2 MAC) and 50% nitrous oxide in oxygen. Arterial pressure and heart rate were compared between two groups. They received postoperative pain treatment with patient-controlled analgesia (PCA) with fentanyl during the postoperative 48 hours after total knee replacement. Visual analog scale (VAS) scores at either rest or movement were used to assess pain. Total fentanyl dose delivered, number of PCA requests, supplemental analgesics, overall satisfaction score and adverse events were evaluated. RESULTS: There were no significant differences between the two groups on cardiovascular changes by tourniquet induced pain effect. VAS, PCA delivered dose and PCA demands at movement in the 24-48 hour decreased in study group compared with control group (P < 0.05). But there were no significant differences between the two groups on the other time periods except 24-48 hour's patient satisfaction and adverse events. CONCLUSIONS: We suggest that intraoperative continuous i.v. fentanyl infusion dose not affect cardiovascular change by tourniquet induced pain. But it may induce preemptive analgesia postoperatively.

The Preemptive Analgesic Effect of Intravenous Ketamine after Lumbar Spine Instrumentation / 대한마취과학회지

BACKGROUND: Well-localized and noxious stimuli are found to produce long-lasting neuronal sensitization. Ketamine is a NMDA receptor antagonist and exerts antinociceptive effects in many pain tests. The aim of this study was to investigate the pre-emptive and analgesic sparing effect of intravenous ketamine in adults aged 30-53 after lumbar spinal instrumentation surgery. METHODS: We compared the effects of preoperative and postoperative intravenous ketamine 0.5 mg/kg on pain after lumbar spinal instrumentation in a double-blind, randomized study in 30 adult patients. After the induction of anesthesia, patients were allocated randomly to receive ketamine intravenously either before (n = 15) or immediately after (n = 15) surgery. Patients were instructed to ask for analgesics whenever they required pain relief and all demands were recorded. Intravenous patient-controlled analgesia (PCA) using butorphanol 16 mg and ketorolac 150 mg was introduced after recovery from general anesthesia. Visual analogue scale (VAS) pain scores were recorded at 1, 2, 3, 4, 5, 6, 9, 12, 24, 36 and 48 hours postoperatively and the total infusion dose of PCA drugs were assessed at 24 hours postoperatively. RESULTS: VAS scores in the preoperative group were significantly lower than in the postoperative group during the first 9 hours after cessation of the operation. The total infusion dose of PCA drugs was significantly lower in the preoperative group (butorphanol 9.1 +/- 0.3 mg, ketorolac 85.3 +/- 2.5 mg) than postoperative group (butorphanol 10.7 +/- 0.2 mg, ketorolac 100.3 +/- 2 mg) (P < 0.05). No serious adverse reactions occurred. CONCLUSIONS: Preoperative intravenous ketamine 0.5 mg/kg in lumbar spinal instrumentation is more effective in reducing postoperative analgesic requirements than it is when given after the operation.