Informed written consent will be taken from all subjects included in the study after approval of the study by the local ethical committee.~All subjects will be subjected to thorough history taking with risk factors, medical histories, general clinical examination, local clinical examination, laboratory investigations as complete blood count and coagulation profile.~Standardized anesthetic care will be provided according to institutional standards, which include fasting, antacid premedication and noninvasive hemodynamic monitoring After arrival in the operating room, patients will be positioned supine with left lateral tilt, pulse oximeter, ECG leads, non-invasive blood pressure cuff and cardiometry leads (4 surface ECG electrodes is attached to the left side of the neck and the lower thorax (approximately at the level of the xiphoid process) will be attached to patient for monitoring of blood pressure (bp), heart rate, fluid responsiveness (thoracic volume variations and stroke volume variations), cardiac index and systemic vascular resistance and values will be recorded as a baseline and every 10 minutes after intrathecal injection.~10 ml/kg/hr lactated ringer solution will be infused to all patients through an 18 gauge intravenous cannula for 30 minutes as a preload before spinal anesthesia then reduced to maintenance infusion of 6 ml/kg/hr.~Patients will be then placed in sitting position. After skin disinfection and skin infiltration with lidocaine 1%, spinal anesthesia will be performed with 2ml 0.5% hyperbaric bupivacaine (10 mg) in addition to 0.5 ml fentanyl (25 μg) at L3-L4 or L4-L5.~The patient will be then returned to the left-tilted supine position. The study drug regimen will be started immediately after intrathecal injection.
This study will be conducted on 40 healthy women having spinal anesthesia for elective cesarean delivery in the operating rooms at Menoufia university hospital.