The parturient will be allocated into one of two equal groups (n=30), a severe preeclampsia group (A) and a normotensive group (B). All will receive colload (500 ml voluven) as a coload via wide bore (16 Gauge ) cannula within 5-10 minutes during induction of spinal anesthesia. Standard monitoring with electrocardiography, automated non-invasive arterial pressure (NIAP) measurement, and pulse oximetry will be performed. Systolic arterial pressure (SAP), mean arterial pressure (MAP) and diastolic arterial pressure (DAP) will be monitored. Baseline values will be recorded in the supine position. Central venous line will be inserted in severe preeclampsia group and central venous pressure will be measured every 10 minutes.
Spinal anesthesia will be induced with a total of 10 mg of 0.5% hyperbaric bupivacaine and 25 µg fentanyl (total volume 2.5 ml) at the L3-4 interspace in the sitting position then the patient will be returned immediately to the supine position with left lateral tilt.
