A COMPARATIVE STUDY BETWEEN PROPHYLACTIC PHENYLEPHRINE INFUSION & COLLOID CO-HYDRATION FOR PREVENTION OF HYPOTENSION FOLLOWING SPINAL ANESTHESIA FOR CAESAREAN SECTION.

Abstract

Background: Spinal anesthesia for caesarean section may cause maternal hypotension that can have deleterious effects on uterine blood flow, fetal well-being and neonatal outcome as determined by umbilical vessel pH and Apgar score. An effective method to prevent hypotension following spinal anesthesia for caesarian section has not yet been described. Prophylactic phenylephrine infusion to prevent spinal hypotension was studied and compared with colloid co-hydration therapy.

Methods: 40 full term ASA grade I and II pregnant patients who were posted for caesarean section were randomly selected and distributed into two groups. In group I, immediately after intrathecal injection, phenylephrine was infused at 40 µg/min for 2 min unless systolic blood pressure was greater than 120% of baseline. Phenylephrine infusion was continued until delivery at the rate of 40 µg/min whenever systolic blood pressure, measured each minute, was less than or equal to baseline. In group II, rapid colloid infusion with 6% Hydroxy Ethyl Starch was done at the rate of 12 ml/kg simultaneously with spinal anesthetic administration.

Results: Blood pressure remained mostly stable in phenylephrine group (109.60 ± 4.00 mm Hg). Number of occasions of fall in B.P. below 80% of baseline were 12 times in phenylephrine group as against 28 times in colloid co-hydration group. Umbilical vessel pH in phenylephrine group was 7.28 ± 0.07 as compared to 7.27 ± 0.05 in colloid co-hydration group.

Conclusion: Prophylactic phenylephrine infusion is more effective than colloid co-hydration therapy in preventing spinal hypotension and its ill effects.

Key words: Phenylephrine, Spinal Hypotension, Caesarean Section, Spinal anaesthesia.