Effectiveness of norepinephrine versus phenylephrine intravenous boluses for the treatment of hypotension in elective lower-segment cesarean section under spinal anesthesia: A randomized controlled, double-blind study

Abstract

Background and Aim: Hypotension following spinal anesthesia is a common adverse effect during caesarean sections, with potentially harmful consequences for both the mother and the fetus. While phenylephrine is the current first-line treatment for maternal spinal hypotension during obstetric anesthesia, norepinephrine has been proposed as a possible alternative due to its weaker β-agonist-mediated positive chronotropic action. However, there is a lack of comparative data on the safety and efficacy of these two drugs in obstetric anesthesia. This study aimed to compare the number of bolus doses of phenylephrine and norepinephrine required to treat hypotension after spinal anesthesia in lower segment caesarean sections, as well as to evaluate maternal and fetal outcomes in both groups, including complications. Materials and Method: A prospective double-blinded randomized controlled trial was conducted, The study included 60 term parturients between the ages of 18 and 40, who had singleton pregnancy and were categorized as American Society of Anaesthesiologists (ASA) physical class II, and who were scheduled for elective caesarean section under spinal anesthesia. the parturients were randomized into two groups: Group N and Group P. Group P patients received an intravenous dose of phenylephrine 100 μg, while Group N patients received an intravenous dose of 8 μg whenever the systolic arterial pressure dropped below 20% of the baseline.primary objective was number of intravenous drugs required to treat spinal hypotension, secondary objective were incidence of maternal and foetal Complications. The data was collected on a form and entered into Excel. Statistical analysis was done using Epi Info 7.2.1.0 for Windows. The Kolmogorov-Smirnov test was used to check normality. Mean and standard deviation or median and range were used to present numerical data, while frequency and percentage were used for categorical data. T-tests compared quantitative variables, and Chi-square tests compared categorical data. Two-tailed tests were used, and a P-value of <0.05 was considered significant. Result: The patient's demographic profile was comparable in both groups.T he number of bolus doses of study drug required to treat spinal hypotension was significantly lower in Group N versus P (1.50 ± 0.57 vs. 2.13 ± 0.73, p =0.001)Incidence of bradycardia was more in group P, but not statistically significant. Other maternal complications like bradycardia, hypertension, nausea, vomiting, shivering were comparable in both groups. Conclusions: According to our study, Intermittent boluses of norepinephrine were effective in the management of spinal-induced hypotension during caesarean section. Norepinephrine boluses can thus be considered as an alternative to phenylephrine boluses.

Keywords

• cesarean section
• double-blind study
• hypotension
• norepinephrine
• phenylephrine
• randomized controlled trial