For acute respiratory distress syndrome patients, protective ventilatory strategy suggested low tidal volume to 6 ml/Kg. On the contrary, high PEEP needed for acute respiratory distress syndrome to prevent VALI induces a leftward shift to the steep pat of the Frank-Starling curve and increase the fluid responsiveness. Whether the dynamic preload indicators (PPV and SVV) are still effective in acute respiratory distress syndrome patients for predicting fluid responsiveness remain controversial.