Efficacy of fixed-dose phenylephrine bolus for treating post-spinal hypotension: Comparison between pre-eclamptics and normotensives.

Background and Aims: Pre-eclamptic parturients may have an exaggerated response to vasopressors. This study compares the efficacy of a 50 µg fixed bolus of phenylephrine for treatment of post-spinal hypotension in pre-eclamptic versus normotensive parturients. Material and Methods: After written informed consent and ethics committee approval, 30 normotensive and 30 pre-eclamptic parturients between 18 and 40 years with singleton term pregnancy about to undergo cesarean section (CS) under spinal anesthesia were included. Post-spinal hypotension was treated with a 50 µg fixed bolus of phenylephrine. The cumulative dose of phenylephrine, the number of boluses, and the median dose required to treat the first hypotensive episode, total number of hypotensive episodes, maternal side effects, neonatal appearance, pulse, grimace, activity, and respiration (APGAR) scores, and umbilical arterial cord blood pH were noted. Statistical analysis was done using Student's t-test, Mann-Whitney U-test, Chi-square test/Fisher's exact test as appropriate. A P <0.05 was considered significant. Results: The cumulative dose and number of boluses of phenylephrine required to treat post-spinal hypotension were comparable. The median dose required to treat the first episode of post-spinal hypotension was also similar (p = 0.792). The time to develop the first hypotensive episode was significantly earlier for group N (p = 0.002). The efficacy of a single fixed bolus of 50 µg phenylephrine was similar in both groups (p = 1.000). Neonatal median APGAR scores at 1 min after birth were significantly higher for group N (p = 0.016). Conclusion: A fixed-dose bolus of 50 µg phenylephrine is safe and effective in treating post-spinal hypotension in pre-eclampsia. The efficacy of phenylephrine is comparable in pre-eclamptic and normotensive parturients.