Ultrasound Guided Fluid Loading Before Spinal Anesthesia

isotonic saline solution infusion (fluid preloading) to achieve correction of hypovolemia before spinal anesthesia using cardiac ultrasoud guidance by measurment of VTI variation after a 250ml saline solution loading, with a maximum of 4 challenges, until hypovolemia complete correction

"isotonic saline solution coloading after spinal anesthesia associated with recsue boluses of Ephedrine would be the standard of care in this arm. No correction of hypovolemia is done before spinal anesthesia. parturients receive a cristalloid coloading with saline isotonic solution with rescue boluses of ephedrine if hypotesion happens after spinal anesthesia"