Inclusion Criteria:  Adult patient ASA status 1-3 who were orally informed and did refuse to participate. Patient in whom general anesthesia with tracheal intubation were planned. Patient in whom an arterial catheter and a monitoring of cardiac output by esophageal Doppler were indicated for hemodynamic optimization Patient with cardiac sinusal mode  Exclusion Criteria:  Patient < 18-year-old Cardiac arrythmia Patient with anomaly in oro-pharyngo-esophageal tractus Patients with hemostasis anomaly (PT < 30%, platelets < 50 000 elements/mm3) Patient in whom the cardiac output monitoring or measurement was not possible by Esophageal Doppler or echography Patients in whom cardiac arrythmia occurred during the procedure of hemodynamic optimization.