Respiratory changes in aortic blood velocity have been described as an indicator of fluid responsiveness when measured in the left ventricular outflow tract by trans esophageal echography. A threshold value of 12% allowed discrimination between responders and nonresponders with a sensitivity of 100% and a specificity of 89%. The suprasternal window is already used to measure cardiac output. The primary endpoint of this study is to determine the predictive value of the respiratory variability in aortic blood velocity measured by suprasternal view (∆VpicSS) as an indicator of fluid responsiveness. The secondary endpoint is to compare maximum velocity and velocity time integral measured by suprasternal and transthoracic view.

Inclusion Criteria:

• Age more than 18 years
• American Society of Anesthesiologists (ASA) score 1 or 2
• General Anesthesia with mechanical ventilation
• General Surgery

Exclusion Criteria:

• Arrhythmia
• Spontaneous breathing activity
• Significant valvular disease