Phenylephrine administration : A comparative study between prophylactic infusion and bolus usage for the prevention and treatment of hypotension in cesarean section during spinal anaesthesia

  We compared two methods of administration of phenylephrine,infusion vs Bolus dose(control group) in the prevention and treatment of hypotension in cesarean section under spinal anesthesia.

METHODS:

100 parturients with ASA I who were scheduled for emergency caesarean section were chosen. Spinal anesthesia was performed using 10 mg hyperbaric bupivacaine . In the infusion group ,Phenylephrine 100μg /min was infused for the initial 3 minutes after the subarachnoid block and were supplemented with 100μg infusion,whenever the systolic blood pressure was below the baseline value. In the control group (Bolus dose) phenylephrine 100 μg bolus was given when the systolic blood pressure decreased to 20% of the baseline value. The following parameters were noted as per study protocol,  Pulse rate and blood pressure every  minute until delivery of the baby and every five minutes thereafter, various time intervals from Subarachnoid block to delivery of the baby, APGAR scores a to asses the neonatal outcome, Analysis of umbilical cord blood gas values (pH, paco2) Total dose of the Phenylephrine used ,episodes of the hypotension,usage of atropine and Incidence of nausea and vomiting. RESULTS:

In the infusion group there was less hypotension (p< 0.0001), Total dosage of phenylephrine was more in infusion group 300–600mcg vs 100–300 mcg with p value <.0001,Fetal outcome measured by APGAR was better in the infusion group(p <.0001), fetal acid base status showed no difference in both groups, the usage of atropine was more in the control group (p<0.0202),there was no incidence of nausea or vomiting in both groups.

CONCLUSION:We conclude that Phenylephrine infusion is an effective and simple method of reducing the incidence and magnitude of hypotension during spinal anesthesia for caesarean delivery with no adverse effect on neonatal outcome