Inclusion Criteria:  Elective surgery  General surgical procedures Estimated duration of anesthesia > 60 minutes ASA class 2 or 3  Exclusion Criteria:  Emergency procedure Reoperation, redo procedure Patient who is incapable of acting Uncontrolled hypotension (<90 mmHg) Uncontrolled hypertension (>180 mmHg) High risk valvular disease (Aortic Stenosis) Endocrine hypertension (Conn's syndrome, phaeochromocytoma) Sepsis (infection and SOFA≥2 pt) Conditions blocking lung ultrasound (pneumothorax without drainage, former pulmonary resection, pleural effusion affecting more than 2 interspaces) Pregnancy