Impact of Fractionated Versus Bolus Intrathecal Hyperbaric Bupivacaine Administration on Postoperative Nausea and Vomiting in Patients Undergoing Elective Lower Abdominal and Lower Limb Surgeries: A Prospective Randomized Comparative Study

Abstract

Background: Postoperative nausea and vomiting (PONV) remains one of the most common and distressing complications following spinal anaesthesia. Fractionated intrathecal administration of hyperbaric bupivacaine has been suggested to improve haemodynamic stability, which may indirectly reduce the incidence of PONV. This study compared the effect of fractionated and conventional bolus administration of intrathecal hyperbaric bupivacaine on PONV in patients undergoing elective lower abdominal and lower limb surgeries.

Methods: A prospective, randomized comparative study was conducted in 100 ASA physical status I–II patients aged 18–60 years undergoing elective lower abdominal and lower limb surgeries under spinal anaesthesia. Patients were randomly allocated into two groups. Group B received 3 mL of 0.5% hyperbaric bupivacaine as a single bolus, while Group F received the same dose in two fractions administered 90 seconds apart. The primary outcome was the incidence of PONV during the first 24 postoperative hours. Secondary outcomes included intraoperative hypotension, haemodynamic parameters, and rescue antiemetic requirement.

Results: Baseline characteristics were comparable between the groups. The incidence of hypotension was significantly lower in Group F than in Group B. PONV occurred less frequently in Group F (18%) than in Group B (28%); however, the difference was not statistically significant (p=0.23). Patients receiving fractionated spinal anaesthesia also required fewer rescue antiemetics and demonstrated better haemodynamic stability throughout the intraoperative period.

Conclusion: Fractionated intrathecal administration of 0.5% hyperbaric bupivacaine provided superior haemodynamic stability compared with conventional bolus administration and demonstrated a clinically favourable trend toward reducing postoperative nausea and vomiting. Although the reduction in PONV did not reach statistical significance, the lower incidence of hypotension and reduced rescue antiemetic requirement suggest that fractionated spinal anaesthesia may be a useful alternative to the conventional bolus technique, particularly in patients where haemodynamic stability is desirable. Larger multicentre studies are warranted to confirm its effect on PONV.