Efficacy of Prophylactic Norepinephrine and Phenylephrine Infusions against Spinal Hypotension during Lower Segment Caesarean Section- A Randomised Clinical Study

Introduction: Hypotension after Subarachnoid Block (SAB) can affect mother and foetus and can be prevented by prophylactic use of vasopressors. Phenylephrine (PE) has been a popular and effective drug as prophylaxis against hypotension. Norepinephrine (NE) is recently tried for this purpose. Aim: To compare PE infusion with NE infusion prophylactically against SAB induced hypotension during Lower Segment Cesarean Section (LSCS). Materials and Methods: This randomised clinical study was conducted in the Department of Anaesthesiology at a Tertiary Care Hospital, Ballari, Karnataka, India. The duration of the study was 12 months, from December 2018 to November 2019. A total of 156 primigravida and multigravida with singleton term pregnancy, posted for caesarean section under SAB received prophylactic infusions of either NE 5 mu g/minute (group NE) or PE 50 mu g/minute (group PE) immediately after SAB till end of the surgery. The primary outcome of the study was to assess the incidence of hypotension. The secondary outcomes included incidence of nausea, vomiting, hypertension, tachycardia, bradycardia and the neonatal outcomes. Related categorical and numerical variables were subjected to suitable statistical tests and analysed using Statistical Package for Social Sciences (SPSS) version 20.0. Results: The mean age of the study participants of group NE was 24.47 +/- 2.52 years and group PE was 23.91 +/- 2.63 years, respectively. The age, parity and surgical duration was comparable between the groups. The incidence of hypotension was 17.9% in group NE and 26.8% in group PE (p-value=0.182). No significant differences in total doses of vasopressors used were noted. The incidence of bradycardia in group NE was 3.8% and 21.8% in the group PE (p=0.053). No adverse events or neonatal outcomes were observed. Conclusion: The incidence of hypotension and the total dose of vasopressors administered were similar in the two groups receiving prophylactic infusion doses (NE or PE). Incidence of bradycardia was greater in the parturients receiving PE infusion.