Comparative Study of the Effect of 6% Hydroxyethyl Starch 130/0.42 vs Lactated Ringer's Preload on the Hemodynamic Status of Parturients Undergoing Spinal Anesthesia for Elective Cesarean Delivery. Arterial Pulse Contour Analysis (FloTrac/VigileoTM) is Employed for Continuous Monitoring of Maternal Hemodynamic Parameters

Regional anesthesia (spinal, epidural) is considered the method of choice for anesthesia obstetric deliveries because of the ability to use fewer drugs, a more direct experience of childbirth and the capability to provide excellent postoperative analgesia. However, the incidence of hypotension after spinal anesthesia for cesarean delivery is high and can lead to maternal and fetal morbidities. Certain interventions may reduce the incidence and severity of spinal anesthesia induced hypotension, including the use of vasopressors and intravenous pre- or co-hydration using different types of volume expanders; crystalloid or colloid solutions. Such interventions aim to increase maternal cardiac output, which is the key in attenuating the hypotensive response to spinal anesthesia. The primary purpose of this study is to compare the efficacy of intravenous prehydration (preloading) of healthy parturients scheduled for caesarean section with either a crystalloid (Ringer's lactated) or colloid solution (HES 130/0.42) in the prevention of hypotension after spinal anesthesia. The FloTrac/VigileoTM device provides continuous monitoring of maternal cardiac output by employment of a minimally invasive technique based on arterial pulse contour analysis. Assessment of maternal hemodynamic status using the FloTrac/VigileoTM constitutes a secondary outcome. Other secondary outcomes are total amount of vasopressors used, neonatal outcome, intraoperative side effects and maternal satisfaction scores.