One year Randomized Clinical Trial to Compare the Efficacy of Intravenous bolus Phenylephrine and ephedrine in Maintaining Arterial Blood Pressure during spinal Anaesthesia in Caesarean Section

Abstract

Background: Maternal hypotension during spinal anaesthesia for Caesarean section is a persistent problem which can result in adverse maternal and fetal outcome. Various methods are used in prevention and treatment of post spinal hypotension. The most logical approach appears to be adequate preloading and use of vasopressors. We have studied intravenous bolus Phenylephrine and Ephedrine for maintainence of arterial blood pressure during spinal anaesthesia for Caesarean section. Objective: To compare the efficacy of intravenous bolus dose of Phenylephrine ( 40 mcg ) and Ephedrine ( 6mg ) for maintenance of arterial pressure following spinal anaesthesia for elective Caesarean section and to compare the number of boluses required in each group. Study design: Randomized clinical trial. Methods: After obtaining written informed consent, hundred patients with singleton full term pregnancy undergoing Caesarean section under subarachnoid block were randomly divided using computer generated randomization table, into two groups of fifty each, Group P received Phenylephrine 40 mcg and Group E received Ephedrine 6 mg IV bolus. Baseline blood pressure and pulse rate measured. Following intravenous preload with 10ml/kg of Ringer lactate solution, all patients received intrathecal 2 ml of 0.5% hyperbaric Bupivacaine through 23 G Quincke needle at L3-L4 space in lateral position. Pulse rate, systolic, diastolic and mean arterial pressures were recorded at every 2 min for 20 min and thereafter every 5 min till 60 minutes. Whenever hypotension ( fall in BP>20% of baseline or less than 90 mm of Hg) occurred, patients received the study vasopressor drug. The number of IX boluses given were noted. Pediatrician assessed APGAR score of every neonate at 1 min and 5 minutes after delivery. Results: In Phenylephrine group, the SBP is restored to more than 80% of its basal value almost immediately within 2 minutes after administration of the bolus dose and is maintained all throughout till the end of 60 minutes. In Ephedrine group, SBP is restored to its 80% of the basal value at 10 minutes, but is maintained consistently till the end of 60 min. Number of boluses required and APGAR score of the baby were comparable in both the groups. Conclusion: Both the vasopressors namely Phenylephrine 40 mcg and Ephedrine 6 mg IV bolus effectively maintained arterial blood pressure during spinal anaesthesia for Caesarean section, although Phenylephrine is more efficacious and had quicker peak effects and does not cause increase in heart rate as compared to Ephedrine.