Vol. 6, Issue 1, Part A (2024)

Background: Hypotension and decreased cardiac output after subarachnoid block for caesarean delivery result in adverse effects on the parturient and foetus. Though phenylephrine is currently the preferred vasopressor for post-spinal hypotension, norepinephrine may be a more suitable choice because of less negative effects on heart rate and cardiac output. The present study compares the effectiveness of these agents, as prophylactic infusions and therapeutic bolus administration, in managing post-spinal hypotension.
Methods: Hundred parturients scheduled for elective caesarean section under SAB were randomised into the following 4 groups: NE-I and PE-I (norepinephrine and phenylephrine infusions at 2 mcg/min and 25 mcg/min respectively), NE-B and PE-B (norepinephrine and phenylephrine boluses of 8 mcg and 100 mcg respectively). Blood pressure and heart rate were noted every 2 minutes and APGAR noted at 1 and 5 min.
Result: The mean heart rate and systolic blood pressure at each time point did not show any significant differences between groups. Incidence of hypotension was significantly lower in the infusion groups. There was a highly significant difference in the proportion of patients who received vasopressor boluses. Nausea and/or vomiting was significantly more frequent in the bolus groups. There was no significant difference in the 1-minute and 5-minute APGAR scores.
Conclusion: The study shows that both drugs given as prophylactic infusions were more effective at maintaining the blood pressure. The incidence of nausea and vomiting was also significantly lower in the infusion groups. There was no significant difference in effectiveness between the two drugs.