Preoperative Blood Volume Optimization Using Transthoracic Echocardiography

Stroke volume optimization using transthoracic echocardigraphy (sub aortic velocity time integral) before induction of total intravenous anesthesia. Fluids bolus of 250 ml of cristalloids will be successively administered until the sub aortic velocity time integral increase will be \< 10%

Optimization of stroke volume following induction of general anesthesia using oesophageal stroke volume measurement. 250 ml bolus of cristalloids succesively administered until the stroke volume increase \<10%