Assessment of low-dose slow-injection unilateral spinal Anaesthesia with 6 mg 0.5% hyperbaric bupivacaine and 90 µg buprenorphine

Background: Spinal anaesthesia is a simple, reliable, and widely practiced technique offering excellent postoperative analgesia but may cause hypotension, urinary retention, and delayed recovery. Unilateral spinal anaesthesia minimizes these complications by restricting the block to the operative side, providing better haemodynamic stability, reduced motor block on the non-operative side, and faster ambulation. Its effectiveness depends on low-dose, slow-injection administration while maintaining the lateral position. Adding intrathecal opioids enhances analgesia without prolonging motor block. Aim and Objectives: To evaluate the success rate of unilateral spinal anaesthesia using 1.2 ml (6 mg) of 0.5% hyperbaric bupivacaine with 0.3 ml (90 μg) buprenorphine, injected slowly at 0.5 ml/min. Materials and Methods: This prospective study included 85 patients undergoing unilateral lower limb surgeries. Anaesthesia was administered in the lateral position and patients were turned supine after 20 minutes. Sensory and motor block levels, limb temperature difference, haemodynamic parameters, and use of atropine or vasopressors were recorded. Postoperative parameters included nausea, vomiting, motor block duration, and time to first micturition. Results: A successful unilateral block was achieved in 73.8% of patients. Unilateral sympathetic, motor, and sensory blocks occurred in 82.5%, 77.5%, and 76.3% of patients, respectively. Most achieved a T12–L1 sensory level. Mean systolic pressure fell by 13 mmHg, with vasopressor use in only 2.5%. No patient required atropine or developed urinary retention. Motor recovery occurred within 2.5–5.5 hours. Nausea occurred in 2.5%, with no vomiting. Conclusions: This technique provided effective unilateral spinal anaesthesia with minimal haemodynamic changes and side effects.