Inclusion criteria were adult patients aged 18 year and above, American Society of Anesthesiologists physical status II to IV, scheduled for intermediate and high risk abdominal and vascular surgery (as defined by the european guidelines on non-cardiac surgery: cardiovascular assessment and management), and equipped with a radial arterial catheter and transoesophageal doppler monitor Patients less than 18 year-old, adults under protection, pregnant women, patients with atrial fibrillation, history of right ventricular dysfunction, known left ventricular ejection fraction < 30%, or preoperative pulmonary disease were excluded.