Comparison of postoperative analgesia with 0.8 mg and 1.6 mg intrathecal nalbuphine; a randomized controlled trial

Abstract

Background & Objectives: Intrathecal opioids provide an easy and efficient method of prolonging postoperative analgesia due to its action on the spinal opioid receptors. Nalbuphine is a mixed opioid agonist – antagonist which has better side effect profile than morphine. It is easily available in India without a need for narcotics license. The optimal dose of nalbuphine as an adjuvant to intrathecal bupivacaine is not known, as the availability of other narcotics, e.g. fentanyl, sufentanyl etc., in the West has diminished the need to use, and thus to research partial opioids like nalbuphine.

The aim of our study was to compare the duration of postoperative analgesia with 0.8 mg and 1.6 mg of nalbuphine when used as an additive with 0.5% hyperbaric bupivacaine in patients undergoing lower abdominal and lower limb surgeries.

Methodology: 66 patients undergoing various lower abdominal and lower limb surgeries were randomized into 2 groups and received either 0.8 mg or 1.6 mg intrathecal nalbuphine with 3.2 ml of 0.5% hyperbaric bupivacaine. The duration of postoperative analgesia, hemodynamic stability and incidence of adverse effects were noted.

Results: The mean duration of postoperative analgesia in 0.8 mg and 1.6 mg group were 247 ± 12 and 239 ± 10 min respectively (p = 0.007). The incidence of bradycardia was more in 1.6 mg group but did not reach statistical significance. The inability of the higher dose to achieve longer analgesia might be due to a ceiling effect and anti-analgesic actions of nalbuphine.

Conclusion:  A dose of 0.8mg of nalbuphine as an intrathecal adjuvant seems to be optimal for providing prolonged postoperative analgesia with minimal side effects.