Comparison of epidural butorphanol versus epidural morphine in postoperative pain relief

Epidural route is preferable for postoperative pain relief in thoraco-abdominal and lower limb surgeries. We aimed to compare epidural butorphanol versus morphine for postoperative analgesia up to 24 hours in open nephrectomy surgery.

80 ASA physical status I and II adult patients were selected for this randomized double blind prospective study. A standard balanced general anesthesia technique was applied for all patients. Epidural catheter was placed in lower thoracic inter-vertebral space before the start of surgery. Injection butorphanol 0.04 mg/kg in group B (n = 40) or morphine 0.06 mg/kg in group M (n = 40) was given in a double blind manner after completion of surgery and before extubation through the epidural catheter. Patients were observed for pain relief by Visual Analogue Scale (VAS) for the next 24 hours. Dose was repeated when VAS was > 4. The onset and peak effect of pain relief, duration of analgesia of 1st dose, frequency of drug administration and side effects if any were observed.

The average onset of analgesia was 26.5 +/- 7.61 minutes with butorphanol and 62.5 +/- 13.4 minutes with morphine group which was statistically significant (p < 0.05). The mean peak effect of pain relief following 1st dose was 173 +/- 51.25 minutes with butorphanol and 251 +/- 52.32 minutes with morphine group. The duration of pain relief after 1st dose was statistically significant and was 339.13 +/- 79.57 minutes in group B and 709.75 +/- 72.12 minutes in group M which was gradually increased on repeated dosing in group B while it was almost same in Group M. Number of doses required in 24 hours was significantly higher (p < 0.05) in butorphanol group than morphine group. Somnolence was the main side effect in group B while pruritus was the main side effect with group M.

Epidural butorphanol appears to provide safer and faster postoperative analgesia without much untoward effects but its analgesic action is short so more repeated doses are required than morphine via epidural catheter up to 24 hours.