The acute respiratory distress syndrome(ARDS)has a high morbidity and mortality in patients admitted to intensive care units(ICUs). It represents a significant public health issue. No large nationwide, multicenters study of ARDS has been conducted in China. The purposes of this study are to analyse: 1)the incidence and outcomes of ARDS in ICU; 2) factors associated the mortality ; and 3) risk factors for development of ARDS .

All patients admitted to the participating ICUs during a 6-month period(from January 1, 2015 to July 1,2015 ) will be screened at ICU admission and daily for the occurrence of ARDS ( AECC criteria) for a maximum of 28 days after ICU admission.

Data collection:

1. For all patients, Demographic characteristics, admission category, the patient source intervention during ICU , APACHEII , SOFA score and discharge information will be collected
2. For patients with ARDS, data about ABG , parameters of MV, hemodynamic on day0 to day7 and last day of MV will be collected.
3. For patients without ARDS at ICU admission, data about risk factor for ARDS ,such as LIPS score, parameters of MV , and fluid balance on ICU day0 to day7 will be collected.

Inclusion Criteria:

all patients age >18 yrs admitted to 24 participating ICUs

Exclusion Criteria:

No patients should be excluded (regardless of age, underlying disease, life expectancy, etc).

All patients admitted to the participating ICUs during a 6-month period(from January 1, 2015 to July 1,2015 )