Effect of Different Doses of Buprenorphine in Combination with Bupivacaine in the Management of Postoperative Analgesia: A Comparative Study.

Background: Longer duration of analgesia, ceiling effect on respiratory depression, and the antihyperalgesia property make buprenorphine a good adjuvant for managing moderate-to-severe postoperative pain.

Aims: The aim of this study is to evaluate the onset and duration of postoperative analgesia of three different doses of buprenorphine of 60, 100, and 150 μg given intrathecally along with hyperbaric bupivacaine in patients undergoing lower limb surgeries.

Setting and design: This prospective observational study was carried out in the anesthesia department of a tertiary care hospital.

Materials and methods: The study included 90 patients of either sex, aged 18-60 years, scheduled for elective lower limb surgery under subarachnoid block. Patients were randomly allocated into three groups (30 each) receiving different doses of buprenorphine. In addition, all patients received 3 mL of 0.5% hyperbaric bupivacaine.

Statistical analysis used: The Chi-square test or Fisher's exact test was used to find out the association between the categorical variables. The association of quantitative variables between the groups was assessed by Kruskal-Wallis test while within the groups was assessed by repeated-measures analysis of variance test.

Results: Baseline characteristics such as age, gender, and American Society of Anesthesiologist physical status classification were comparable among the three groups. Sensory block, motor block, and total duration of analgesia were significantly higher with higher doses of buprenorphine. The mean difference in the duration of analgesia was comparable in patients receiving 100 μg (720 min) and 150 μg (825 min) of buprenorphine. Bradycardia as a side effect was only in patients receiving 150 μg of buprenorphine.

Conclusion: Risk-benefit of different doses of buprenorphine suggests that 100 μg may be the ideal dose for a better quality of spinal block and maintaining hemodynamic stability.