Comparison of Fractionated Dose Versus Bolus Dose of Hyperbaric Bupivacaine Injection in Spinal Anesthesia: Hemodynamic Stability in Elderly Patients Undergoing Lower Limb Surgeries

Spinal anesthesia (SA) with a bolus dose provides a rapid onset but often leads to hemodynamic instability, particularly in elderly patients. Fractionated dosing of hyperbaric bupivacaine may offer a dense block with greater stability and prolonged analgesia. This study compares the effects of bolus and fractionated dosing on hemodynamic parameters in elderly patients undergoing lower limb surgeries. In this randomized controlled trial, 60 elderly patients (n=60 patients; 30 patients per group) of more than 60 years were randomly assigned to receive either a bolus dose (Group B) or fractionated doses (Group F) of hyperbaric bupivacaine for SA. Intraoperative monitoring included blood pressure, heart rate, oxygen saturation, and ECG. Hemodynamic parameters were analyzed at serial intervals up to 180 minutes. Demographic and baseline parameters were comparable between groups. A statistically significant difference in mean arterial pressure (MAP) and diastolic blood pressure (DBP) was observed only at 90 minutes post-anesthesia (MAP: Group F 90.71 mmHg vs. Group B 84.63 mmHg, p = 0.043; DBP: Group F 74.90 mmHg vs. Group B 69.04 mmHg, p = 0.025). The fractionated group required fewer vasopressor interventions (p = 0.001). Fractionated dosing of hyperbaric bupivacaine in SA demonstrated improved hemodynamic stability at specific time points and reduced vasopressor requirements in elderly patients. However, due to limited power and isolated significance, further large-scale, blinded studies are needed to confirm the clinical relevance of fractionated dosing in elderly patients.