The present study thus aims to compare two equivalent falls in systolic and mean arterial pressure for defining (and concomitantly treating) postspinal hypotension in patients of preeclampsia undergoing cesarean section, with regards to neonatal and maternal outcome. 

Primary objective is to compare postspinal hypotension defined as  20% or more fall in systolic blood pressure or in mean arterial pressure, in patients of preeclampsia undergoing cesarean section with regards to umbilical artery pH.

Methods

The anesthetic management for these patients will be standardized as per routine practice. This will include standardized aspiration prophylaxis, non-invasive monitoring and single-shot spinal block using hyperbaric bupivacaine.

Systolic, diastolic and mean arterial pressures as well as heart rate will be measured every minute from the spinal injection until delivery of the baby. Hypotension after spinal anesthesia will be defined as a decrease in systolic arterial pressure of 20% or more from baseline for group S20; and similar fall in mean arterial pressure for group M20. Whenever postspinal hypotension occurs it will be treated with 50 microgm of phenylephrine (i.v.), repeated every minute, till the blood pressure rises above the hypotensive threshold. 

Statistical analysis will be performed using SPSS (SPSS Inc., Chicago, IL, USA). Intergroup comparison will be done with Pearson’s Chi-square, Fisher’s exact test or Mann–Whitney U-test t-teat as appropriate, after testing for normal distribution using K-S test. Intergroup trends of arterial pressure and heart rate for the study period will be analyzed using mixed-model analysis, taking the best covariance structure based on Akaike’s information criterion (AIC).