Abstract :
Introduction: Currently phenylephrine is a preferred 1 line vasopressor for maintenance of blood pressure during spinal anaesthesia, may be associated with reflex bradycardia and decreased cardiac output, posing risk to mother or foetus. Norepinephrine may be an useful alternative as being potent alpha with weak beta adrenergic agonist activity.
Aims: This study compared the effectiveness of prophylactic and treatment boluses of norepinephrine and phenylephrine to maintain systolic blood pressure at or above 80% of baseline value during spinal anesthesia for cesarean delivery with the primary aim to compare cardiac output. Secondary aims were total doses of study drug required, neonatal outcome and perioperative complications.
Materials and Methods: Total 100, term pregnant women with ASA status II undergoing caesarean delivery under spinal anaesthesia were enrolled in this prospective, double blind controlled study. Patients were randomized to receive prophylactic bolus dose of norepinephrine (6 µg) or phenylephrine (100 µg) immediately after spinal anaesthesia. Systolic blood pressure, cardiac output and heart rate were monitored. Intermittent bolus doses were repeated whenever required. Student ‘t’ test and chi square test were used for analysing the data.
Results: Both the drugs were able to maintain the systolic blood pressure ? 80% of baseline (p=0.356). Significant difference observed in cardiac output while comparing both the groups from 3 to 15 minutes after spinal anesthesia (p=0.014). The incidence of bradycardia was lower in norepinephrine group as compared to phenylephrine group (P=0.018).
Conclusion: Norepinephrine is as effective as phenylephrine for maintenance of blood pressure after spinal anaesthesia for caesarean delivery with stable heart rate and cardiac output.
Keyword :
Caesarean delivery, Norepinephrine, Phenylephrine, Spinal anaesthesia, Vasopressor.