What question did this study set out to answer?

This study aims to compare the effectiveness and safety of fixed versus height-adjusted doses of bupivacaine in spinal anesthesia during elective cesarean sections.

March 18, 2026

Comparative Study of Fixed Dose versus Height-adjusted Dose of Heavy Bupivacaine in Spinal Anesthesia for Elective Cesarean Section

Key Points

This study aims to compare the effectiveness and safety of fixed versus height-adjusted doses of bupivacaine in spinal anesthesia during elective cesarean sections.
Single-center, prospective, double-blind, randomized controlled trial
Sixty parturients received either fixed or height-adjusted bupivacaine doses
Primary endpoint was maternal hypotension; secondary endpoints included block characteristics and neonatal Apgar scores
Maternal hypotension occurred in 63% of fixed dose group vs. 27% in height-adjusted group (P < 0.01)
Significantly lower reductions in blood pressure in height-adjusted group
Fewer vasopressor boluses needed in height-adjusted group (0.8 vs. 2.3, P < 0.001)
Reduced nausea and vomiting in height-adjusted group (7% vs. 23%, P = 0.03)

Abstract

Abstract Background: Maternal hypotension is the most common and significant complication of spinal anesthesia for cesarean delivery, increasing maternal nausea, vomiting, and risk of fetal acidosis. The traditional fixed intrathecal dose of 0.5% hyperbaric bupivacaine does not account for patient height, an important determinant of block spread and sympathetic blockade. Materials and Methods: In this single-center, prospective, double-blind, randomized controlled trial, 60 American Society of Anesthesiologists I–II parturients undergoing elective lower-segment cesarean section received either a fixed intrathecal dose of 0.5% hyperbaric bupivacaine 2.2 ml (Group F) or a height-adjusted dose of 0.06 mg cm −1 body height (Group H; ≈1.7–2.1 ml). No intrathecal opioids or adjuvants were given. Standard preloading, monitoring, and management of hypotension and bradycardia were applied. The primary endpoint was maternal hypotension; secondary endpoints were block characteristics, vasopressor requirement, maternal side effects, and neonatal Apgar scores. Results: Baseline demographics and hemodynamics were comparable. Hypotension occurred in 63% of Group F versus 27% of Group H ( P < 0.01). Group H experienced significantly smaller reductions in systolic and mean arterial pressure. Patients in this group also required fewer mephentermine boluses (0.8 ± 0.6 vs. 2.3 ± 1.1) and a lower total vasopressor dose (3.4 ± 2.1 mg vs. 9.2 ± 3.5 mg), with all differences being statistically significant ( P < 0.001). Anesthetic quality and motor block were equivalent. Nausea and vomiting were reduced (7% vs. 23%, P = 0.03). Neonatal Apgar scores exceeded 8 in both the groups, with no neonatal intensive care unit admissions. Conclusions: Height-adjusted intrathecal bupivacaine ensures reliable surgical anesthesia with improved maternal hemodynamic stability and fewer side effects, without compromising neonatal outcomes.

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