After intravenous line placement and monitoring (IntelliVue MP70 Philips HealthCare, Amsterdam, The Netherlands) with continuous 5-lead electrocardiography, pulse oximetry, and bispectral index, after local anaesthesia a radial intra-arterial catheter was inserted and connected to a pressure transducer zeroed at the intersection of the mid axillary line and the fifth intercostal space. Arterial pressure and pulse pressure variation (PPV) were continuously displayed on the IntelliVue MP70 monitor. After a 3 to 5 min preoxygenation, anaesthesia was induced and maintained using target-controlled total intravenous anaesthesia with propofol and remifentanil. If a neuromuscular blocking agent was administered its effect was monitored by accelerometry at the thumb following Train-of-Four stimulations of the ulnar nerve repeated every 30 seconds. Following orotracheal intubation; patients were ventilated with controlled ventilation mode (inspired Oxygen fraction 40%, tidal volume: 8ml.kg-1, PEEP at +5 to +8 cmH2O, inspiratory to expiratory ratio of ½, respiratory rate between 10 and 15 min-1 to maintain an end-tidal carbon dioxide partial pressure of 30 to 35 mmHg). An oesophageal Doppler probe connected to its monitor was inserted after tracheal intubation (CardioQ-ODM, Deltex Medical, UK). Then, a fluid challenge was performed with 250 ml of colloid or crystalloid at the discretion of anaesthesiologist and repeated if the SV increased by more than 10%.