The optimal amount caloric intake were still controversy in critically ill patients in literature. There were no significant outcome difference with different caloric intake in acute lung injury patients. In order to identify the optimal amount caloric intake in acute lung injury patients, we conduct a prospectively observational study to see whether the caloric differences influence hospital mortality.

The is a prospectively observational study. The data including basic demographic data, daily PN/EN caloric intake, days of ICU stay, days of hospital stay, hospital mortality, days of ventilator use.. will be collected. Statistic analysis included chi-square, student t test, logistic regression and ROC curve will be applied to analyze the different characteristics between survived and died patients. Also we can figure out the optimal cut value of caloric intake with best outcome by ROC curve analysis. We plan enrolled 200 participants within study period.

Inclusion Criteria:

Age older than 20 year old Respiratory failure with ventilator Fit the diagnostic criteria of ARDS (2012 Berlin Criteria)

Exclusion Criteria:

Expected ICU stay less than 72 hours

Age older than 20 year old Respiratory failure with ventilator Fit the diagnostic criteria of ARDS