Data on central hemodynamics of pregnant women during regional anesthesia is lacking. The purpose of this study is to determine the 1) influence of heart rate (HR), stroke volume (SV), systemic vascular resistance (SVR) and IV fluid administration on maternal hypotension after epidural anesthesia and 2) the pattern of these variables throughout C-section. Despite preventative measures, hypotension during regional anesthesia for cesarean section is common. Maternal hypotension poses a risk to fetal oxygenation, causes maternal nausea and vomiting, and poses maternal danger when extreme. Intravenous fluid is most often used to prevent hypotension, but an optimal volume of fluid has not been found and the incidence of hypotension varies widely. Fluid alone at best reduces the incidence of hypotension at 38%. An underlying practice assumption is that regional anesthesia, which results in a chemical sympathectomy, causes hypotension by reducing venous return and does not significantly reduce widely. Fluid alone at best reduces the incidence of hypotension at 38%. An underlying practice assumption is that regional anesthesia, which results in a chemical sympathectomy, causes hypotension by reducing venous return and does not significantly reduce SVR. This view is based on an average 15% (range up to 40%) reduction in SVR in non-pregnant persons. But there is evidence that SVR is reduced more in pregnant than non-pregnant women during regional anesthesia. If SVR is reduced sufficiently, fluid alone will not increase cardiac output enough to prevent hypotension. In this case, addressing SVR should result in superior prevention of hypotension. Determining which variables have a significant influence on the pattern of hypotension over time is necessary to direct future interventional studies. Elimination of maternal hypotension will reduce the risk of fetal hypoxemia, maternal discomfort, and maternal morbidity while improving maternal enjoyment of the birth experience.
