PROSPECTIVE OBSERVATIONAL STUDY TO ASSESS TWO DIFFERENT DOSES OF BUPRENORPHINE (30 µG AND 75 µG) GIVEN INTRATHECALLY ALONG WITH HYPERBARIC BUPIVACAINE AS ANALGESIC IN PATIENTS UNDERGOING LOWER LIMB ORTHOPEDIC SURGERIES

Abstract

Background: Effective postoperative pain management is essential following lower limb orthopedic surgeries, as inadequate analgesia may delay mobilization, prolong hospital stay, and adversely affect patient recovery. Intrathecal buprenorphine is a commonly used opioid adjuvant that enhances the duration and quality of spinal anesthesia. However, the optimal dose capable of providing prolonged analgesia while maintaining safety remains uncertain. Methods: This prospective observational study was conducted among 60 patients undergoing elective lower limb orthopedic surgeries under spinal anesthesia. Patients were allocated into two groups of 30 each. Group A received 30 μg intrathecal buprenorphine with 0.5% hyperbaric bupivacaine, while Group B received 75 μg intrathecal buprenorphine with 0.5% hyperbaric bupivacaine. Sensory and motor block characteristics, duration of postoperative analgesia, Visual Analogue Scale (VAS) scores, rescue analgesic requirements, hemodynamic parameters, and adverse effects were evaluated and compared between groups. Results: The onset of sensory block was significantly faster in Group B than Group A (3.2 ± 0.7 vs 3.8 ± 0.9 minutes; p=0.02). The duration of sensory block was significantly prolonged in Group B (280 ± 30 vs 220 ± 25 minutes; p<0.001). Similarly, motor block duration was significantly longer in Group B (250 ± 25 vs 200 ± 20 minutes; p<0.001). The duration of postoperative analgesia was significantly greater in patients receiving 75 μg buprenorphine (520 ± 50 minutes) compared with those receiving 30 μg buprenorphine (360 ± 40 minutes; p<0.001). Time to first rescue analgesia was prolonged (525 ± 48 vs 365 ± 42 minutes; p<0.001), and rescue analgesic requirements were significantly lower in Group B. Postoperative VAS scores remained significantly lower in Group B from the second postoperative hour onward. Hemodynamic parameters were comparable between groups, and no significant differences were observed in adverse effects. No patient developed respiratory depression. Conclusion: Intrathecal buprenorphine at a dose of 75 μg provided superior sensory and motor block characteristics, prolonged postoperative analgesia, lower postoperative pain scores, and reduced rescue analgesic requirements compared with 30 μg buprenorphine. Both doses demonstrated comparable hemodynamic stability and safety profiles. Therefore, 75 μg intrathecal buprenorphine appears to be a more effective adjuvant to hyperbaric bupivacaine for lower limb orthopedic surgeries.