Study Comparing Phenylephrine Bolus and Infusion for Maternal Hypotension and Neonatal Outcome during Cesarean Section under Spinal Anesthesia

BACKGROUND: Phenylephrine(PE) bolus and infusion have been compared for post spinal hypotension and neonatal effects during cesarean section(CS) under spinal anesthesia(SA). AIM: The primary aim of this study was to compare bolus doses of 50μg of PE with a fixed infusion rate of 50 μg/min of the same drug given prophylactically. The secondary aim was to study the neonatal outcome and side effects with the two regimes. SETTINGS AND DESIGN: This prospective,randomized,comparative study was conducted in the department of Anesthesia in a tertiary care teaching hospital. MATERIALS AND METHODS: This study was conducted on 100 normotensive women undergoing CS under SA. The patients were randomized into two groups of 50 each. Group A received bolus of 50 μg PE after the systolic BP(SBP) fell by 20% from the baseline and Group B received a prophylactic infusion of 50 μg/min PE. The changes in heart rate (HR), BP and side effects were compared till delivery. The neonatal APGAR scores were compared at 1 and 5 minutes and an umbilical artery sample was sent for blood gas analysis. STATISTICAL ANALYSIS: Categorical variables were shown in number and percentage. Normally distributed continuous variables were presented as mean ± SD and compared using unpaired t-test. Non normally distributed continuous variables were displayed as median and were compared using Mann-Whitney test. A P value of <0.05 was considered significant. RESULTS: In group A, the HR was higher than in group B throughout the monitoring period. (P < 0.001). In group A, SBP trend showed a fall of more than 20% from the base line in 44 patients. The mean fall in SBP was -28.06 ± 5.3 mmHg% in Group A while in group B the mean fall in SBP was only -0.44 ± 4.3mmHg%. Nausea and vomiting was less in group B. There was no difference in APGAR or neonatal acidosis on ABG. CONCLUSION: There was a tighter control of BP in the infusion group vs. the bolus group while the neonatal outcome was similar in both the groups.