The hemodynamic effects of bolus norepinephrine and phenylephrine in the treatment of hypotensive events in preeclamptic women with severe features following spinal anesthesia during cesarean section: a randomized controlled trial.

STUDY

OBJECTIVE

To investigate the hemodynamic effects of rescue bolus administration of norepinephrine (NE) and phenylephrine (PE) in the treatment of hypotensive events in preeclamptic women with severe features following spinal anesthesia during cesarean section.

METHODS

A total of 40 preeclamptic women with severe features (n = 20 per group) experienced hypotensive events (defined as SBP below 80% of baseline value) following spinal anesthesia were randomly receive 6 µg NE or 75 µg PE as a rescue measure. The primary outcomes were the maximal changes and the percentage of these changes in hemodynamic indicators, including systolic blood pressure (SBP), heart rate (HR), cardiac output (CO), and systemic vascular resistance (SVR) within a 3-min period following the administration of NE or PE. Additionally, the occurrence of maternal bradycardia, reactive hypertension, analysis of umbilical artery blood gas, and assessment of neonatal Apgar score were recorded.

RESULTS

In the NE group, there was a lower magnitude of maximal changes (85.40 ± 17.76 vs. 71.10 ± 11.88 beats/min, p = 0.005; 7.78 ± 1.98 vs. 6.11 ± 1.44 L/min, p = 0.004) after vasopressor administration, accompanied by lower respective percentages of change (-15.54% ± 11.49% vs. -23.41% ± 10.03%, p = 0.026; -1.75% ± 6.50% vs. -16.56% ± 10.21%, p < 0.001) for HR and CO, as well as a decreased incidence of bradycardia (5.0% vs. 30.0%, p = 0.030) compared to the PE group.

CONCLUSION

Either 6 µg NE or 75 µg PE can effectively rescue and exhibit comparable efficacy in managing hypotensive events following spinal anesthesia in preeclamptic women with severe features. However, NE demonstrates superior capability in maintaining CO and HR.