Minimum Effective Combination Dose of Epidural Morphine and Fentanyl for Posthysterectomy Analgesia

Abstract

Recent studies have produced conflicting results regarding whether the addition of epidural fentanyl improves postoperative analgesia from epidural morphine. Therefore, we prospectively determined the dose-response relationship and the minimum effective combination dose of epidural morphine and fentanyl (fentanyl given after morphine) for posthysterectomy analgesia. We studied 120 patients undergoing radical abdominal hysterectomy. All patients had epidural lidocaine 1.5% with epinephrine (1:200,000) for surgical anesthesia followed by light general anesthesia with endotracheal intubation. They were assigned randomly into six groups according to the combination of each narcotic dose: morphine 2 mg, morphine 2 mg/fentanyl 50 micrograms, morphine 2 mg/fentanyl 100 micrograms, morphine 4 mg, morphine 4 mg/fentanyl 50 micrograms, and morphine 4 mg/fentanyl 100 micrograms. Morphine and fentanyl were given epidurally in a double-blind manner approximately 60 and 15 min, respectively, before the completion of surgery. For 2 mg of morphine, the addition of 50 or 100 micrograms of fentanyl improved pain relief during the first 6 h postoperatively (P < 0.05), provided longer duration of analgesia (P < 0.05), and required less analgesic supplement (P < 0.05), but did not alter the incidence of side effects. For 4 mg of morphine, the same conclusion was drawn, except that vomiting occurred more frequently with addition of 100 micrograms of fentanyl (P < 0.05). Among fentanyl groups, there was no significant difference in pain scores, duration of analgesia, and analgesic requirements. Therefore, we conclude that epidural fentanyl given after morphine improves early postoperative analgesia from epidural morphine, and the minimum effective combination dose is morphine 2 mg/fentanyl 50 micrograms for posthysterectomy surgery analgesia.

Enhanced pain management for post-gastrectomy patients with combined epidural morphine and fentanyl

“…Our previous study in post-hysterectomy analgesia using the same opioid combination demonstrated that 2 nag morphine + 50 tag fentanyl was the minimum effective combination dose. 4 The results of the present study agree with respect to the beneficial effect of adding fentanyl to epidural morphine after major abdominal surgery, but disagree in that a larger combination dose was required to obtain a similar analgesia profile after gastrectomy than after hysterectomy. However, direct comparison may be difficult since different surgical sites and patient populations were involved.…”

“…[1][2][3][4] Epidural administration of fentanyl during Caesarean section followed by morphine resulted in either inferior 1 or no improvement a in postoperative analgesia compared with epidural morphine alone. On the other hand, epidural fentanyl given after morphine improved post-hysterectomy analgesia without increasing adverse side effects.…”