Comparative study on the manually-controlled variable-rate versus fixed-rate infusion of norepinephrine for preventing hypotension during spinal anesthesia for cesarean delivery

•It is still controversial whether manually-controlled variable-rate infusion is more effective than fixed-rate infusion of norepinephrine for prophylaxis against maternal hypotension during spinal anesthesia for cesarean delivery.•The incidence of maternal hypotension was significantly lower in variable-rate infusion than that in fixed-rate infusion (9% versus 30%) (P < 0.001). No significant difference was found in the serial changes in SBP and HR for the first 15 min. Variable-rate infusion showed higher frequency of physician interventions compared with the fixed-rate infusion (P < 0.001).•When norepinephrine was infused at an initial dose of 0.05 μg/kg/min for preventing hypotension during spinal anesthesia for cesarean delivery, neither variable-rate infusion nor fixed-rate infusion regimen was optimal.