Acute respiratory distress syndrome (ARDS) is a life-threatening condition requiring respiratory support to maintain oxygenation. Very few biomarkers about ARDS have been identified but none of them has a sufficient specificity or sensitivity to characterize by itself the severity of lung condition. Investigators hypothesize that there is considerable change occurring in metabolic profiles in mild, moderate, and severe ARDS in comparison to healthy cohort, which can be detectable through serum analysis using NMR based metabolomics study. This research would help to understand metabolomics kinetics during the ARDS disease progression. Overall, NMR-based metabolomics study would provide an insight into the mediators involved in pathogenesis and progression of ARDS.