Comparison of incidence of spinal anaesthesia induced hypotension between patients with severe preeclampsia and low risk pregnant women undergoing emergency caesarean delivery: a prospective cohort study

Problem statement: Historical belief regarding optimal anaesthetic technique for caesarean delivery in severe preeclamptic women was that spinal anaesthesia causes precipitous hypotension in severe pre-eclampsia patients due to rapid sympathetic blockade, contracted intravascular volume and limited fluid administration.. Later many clinical studies confirmed the safety of spinal anaesthesia in severe pre-eclampsia patients and recommended  lumbar neuraxial anaesthesia as the preferred mode of anaesthesia. The same authors observed the incidence of hypotension was less in severe pre eclamptic patients compared to that of normal pregnant women.. These authors speculated that higher sympathetic activity with high vascular tone, raised circulating factors with potent pressor activity and increased sensitivity to pressor drugs contributed to lesser degree of  hypotension. However, a multicentre study reported a higher incidence of hypotension is spinal anaesthesia compared to epidural anaesthesia3. Also fluid strategies used in the above studies are not consistent with the current practice of co-loading.

Rationale:  Although risk comparison trials in severe pre-eclampsia has reported less incidence of spinal anaesthesia induced hypotension, data supporting the same among the Indian population is lacking. Moreover, varied incidences of hypotension in severe pre-eclamptic patients have been reported (the incidence of hypotension documented in the study by Visalyaputra et al was 51% as opposed to 16.6% in the study conducted by Antoine G. M. Aya et al.) Also fluid management protocols used are not consistent with present practice. The studies have followed preloading of IV fluids preoperatively {1500-2000 ml of ringer lactate 500ml of 6% hydroxyethyl starch} as opposed to the current concept favouring co-loading of fluids.Due to these conflicting observations, we would like to observe and compare the incidence of post spinal hypotension between severe pre-eclamptic patients and low risk pregnant women undergoing emergency caesarean delivery.

 Novelty: Varied incidence of hypotension in severe pre-eclampsia after spinal anaesthesia has been reported. The fluid management protocol used in the studies was also not consistent with the current practice. Furthermore, major studies had a population consisting of elective caesarean section and no study provided data neither on emergency caesarean sections exclusively nor on an Indian population.

Expected outcome and application: The expected outcome would be, whether the observation of low incidence of post-spinal hypotension made by previous studies is prevalent in our population of severe pre-eclamptic women undergoing emergency LSCS.