Effect of injection speed of hyperbaric bupivacaine 0.5% in spinal anesthesia on block quality and hemodynamic changes in elective cesarean sections

Background: Spinal anesthesia (SA) with hyperbaric bupivacaine 0.5% is a standard technique for lower segment cesarean sections (LSCS). However, the impact of injection speed on block quality, hemodynamic stability, and recovery remains unclear. This study compared the effects of slow versus fast injection speeds of hyperbaric bupivacaine on anesthetic outcomes. Methods: In this prospective, randomized study, 60 ASA PS-II patients, aged 25–35 years, were randomly allocated into two groups: Group A (n = 30) received injection over 25 sec, and Group B (n=30) received injection of hyperbaric bupivacaine over 50 sec. Key outcomes included sensory block onset, maximum block level, hemodynamic trends, recovery parameters, analgesia requirements, and adverse events. Results: Baseline characteristics were similar between two groups. Time to achieve T10 dermatome (Group A: 3.22 ± 0.85 min; Group B: 3.54 ± 0.92 min) and maximum sensory block level (Group A: T6 ± 1.2; Group B: T7 ± 1.4) showed no significant differences. Hemodynamic stability was comparable, with similar hypotension rates (Group A: 10; Group B: 12). Recovery metrics, including sensory block regression (Group A: 15.2 ± 2.1 min; Group B: 16.0 ± 2.3 min) and full recovery time (Group A: 45.7 ± 6.3 min; Group B: 47.1 ± 6.5 min), were slightly faster in Group A but not statistically significant. Rescue analgesia and adverse events were equivalent in the groups. Conclusion: Slow and fast injection speeds of hyperbaric bupivacaine 0.5% for LSCS demonstrated equivalent efficacy in block quality, hemodynamic stability, recovery, and safety. These findings support flexibility in injection speed based on clinical context and operator preference. Keywords: Spinal anesthesia; hyperbaric bupivacaine; cesarean section; injection speed; sensory blockade; motor blockade; hemodynamic stability; postoperative pain management; adverse events; maternal safety; neuraxial anesthesia; recovery metrics; obstetric anesthesia Citation: Naveena P, Naveenkumar P, Kumar B. A, Shanmugasundaram S. Choudhary AK, Panneerselvam Periasamy P. Effect of injection speed of hyperbaric bupivacaine 0.5% in spinal anesthesia on block quality and hemodynamic changes in elective cesarean sections. Anaesth. pain intensive care 2025;29(1):105-111. DOI: 10.35975/apic.v29i1.2670 Received: December 12, 2024; Reviewed: December 26, 2024; Accepted: January 01, 2025