Background: Hypotension is a frequent complication during spinal anesthesia for caesarean section which decreases uterine blood flow causing fetal hypoxia, acidosis and neonatal depression. Methods: After institutional ethics committee approval and written informed consent taken, 60 parturients (ASA I/II) undergoing elective caesarian section were equally divided into two groups receiving bolus doses of either ephedrine (5 mg, gr.E) or phenylephrine (100 microgram, gr.P) after subarachnoid block (SAB) whenever systolic blood pressure decreased greater than 20% from baseline. Hemodynamic were monitored for 75 minutes following subarachnoid block. All patients received subarachnoid block with 25 G Quincke’s needle in left lateral position via midline approach using 0.5% hyperbaric Bupivacaine (2.4 ml) to achieve sensory level of T6 and preloaded with Ringer lactate (10 ml/kg). Umbilical artery blood gas analysis was done within 5 min of baby delivery. Neonatal outcome was assessed by Apgar score at 1, 5 and 10 min. Both groups were compared with respect to the number of vasopressor boluses required, differences in fetal blood gas and complications occurred. Results: Number of boluses required to treat hypotension was similar in both groups [2.43±1.13 (E) vs., 2.13±1.17 (P); p=0.23).  SBP was higher in gr.P at 12, 14, 16 and 18 min after SAB. But, diastolic blood pressure was higher in gr. E at 35, 40, 45, 50 and 55 min (P<0.05); although the difference remained clinically insignificant. There was no difference in mean blood pressure (MAP). No difference was found in Apgar score at 1, 5 & 10 min. with all neonates having mean Apgar score greater than 8. There was no difference in umbilical arterial blood pH [7.304±0.063 vs., 7.306±0.064 respectively in GROUP P & E; (P=0.66)]. Incidence of vomiting was more in GROUP E [6.67% vs., 0]. Headache for transient period was observed, more in group E [6.67% vs., 3.34%]. Conclusion: We conclude that both phenylephrine and ephedrine are safe and effective in maintaining maternal blood pressure within 20% of baseline without significant differences in fetal blood pH. However, use of ephedrine is associated adverse effects like tachycardia, vomiting and headache.

 

Keywords: Ephedrine; Phenylephrine; Caesarian; Spinal anesthesia; Fetal acidosis.