Dose-response relationship of prophylactic norepinephrine infusion for prevention of spinal anesthesia-induced hypotension during caesarean delivery: A comparative study of normal weight and obese parturients.

Within each group, patients received norepinephrine infusion at 0.02-0.06 µg·kg⁻¹·min⁻¹.

Standardized combined spinal-epidural anesthesia with 16 mg hyperbaric ropivacaine was used, and infusion was started immediately after spinal injection.

ED50 and ED95 were 0.022 (95% CI 0.015-0.029) and 0.051 (0.041-0.061) µg·kg⁻¹·min⁻¹ in normal weight, compared with 0.036 (0.029-0.043) and 0.080 (0.058-0.102) µg·kg⁻¹·min⁻¹ in obese parturients.

Neonatal outcomes and maternal adverse effects were comparable.