A Prospective Observational Study of Unilateral Spinal Anaesthesia Using Low-Dose Hyperbaric Bupivacaine with Buprenorphine in Unilateral Lower Limb Surgeries

Introduction: Spinal anaesthesia is widely used for lower-limb surgeries, conventional bilateral spinal anaesthesia is often associated with adverse effects such as hypotension, bradycardia, postoperative nausea and vomiting, urinary retention, and delayed motor recovery, mainly due to extensive sympathetic blockade. Lowdose hyperbaric local anaesthetic solutions, slow injection techniques, prolonged lateral positioning, and the use of intrathecal opioid adjuvants have been shown to improve the success of unilateral spinal anaesthesia. Objective- To evaluate the success rate, block characteristics, hemodynamic changes, and adverse effects of unilateral spinal anaesthesia using low-dose hyperbaric bupivacaine combined with intrathecal buprenorphine in patients undergoing unilateral lower-limb surgery. Materials and Methods: This hospital-based prospective observational study was conducted over 18 months in a tertiary care centre in Rajasthan, India. Eighty-eight patients aged 18–65 years, belonging to ASA physical status I and II, undergoing elective unilateral lower-limb surgeries were included. Unilateral spinal anaesthesia was performed using 6 mg of 0.5% hyperbaric bupivacaine combined with 90 µg of buprenorphine, administered intrathecally at a rate of 0.5 ml/min with patients maintained in the lateral decubitus position for 20 minutes. Sensory, motor, and sympathetic blocks were assessed, along with hemodynamic parameters and postoperative adverse events. Data were analysed using appropriate statistical tests. Results: The mean age of patients was 46.9 ± 14.8 years. Hemodynamic parameters showed statistically significant reductions after spinal anaesthesia (p < 0.001), but these changes were clinically acceptable. Dense motor block was achieved predominantly on the dependent side, while most patients showed minimal or no motor and sensory block on the non-dependent side. Postoperative nausea was observed in 3.4% of patients, and no vomiting was reported. Conclusion: Unilateral spinal anaesthesia using low-dose hyperbaric bupivacaine with intrathecal buprenorphine provides effective surgical anaesthesia with good hemodynamic stability, limited contralateral spread, and a low incidence of adverse effects. It is a safe and effective alternative to conventional bilateral spinal anaesthesia for selected unilateral lower-limb surgeries.