Stratification of the Acute Respiratory Distress Syndrome

Study Overview
=================
Brief Summary
-----------------
The American-European Consensus Conference (AECC) and the Berlin definitions of the Acute Respiratory Distress Syndrome (ARDS) could be adequate for epidemiologic studies, but it is not adequate for inclusion of patients into therapeutic clinical trials. Despite recent reports on the effects of standardized ventilator settings on PaO2/FIO2 and fulfillment of AECC and Berlin definitions of ARDS, it is still a matter of debate whether the assessment of hypoxemia at 24 hours is the most appropriate tool for stratifying lung severity in patients with ARDS. The investigators will perform an observational, multicenter, prospective audit in a network of intensive care units in Spain and China for validating and confirming that the assessment of hypoxemia at 24 hours after ARDS onset is the most valuable tool for stratifying and predicting outcome in patients with ARDS.

Detailed Description
-----------------
In 1994, the American-European Consensus Conference (AECC) defined ARDS as follows: 1) acute and sudden onset of severe respiratory distress, 2) bilateral infiltrates on frontal chest radiograph, 3) absence of left atrial hypertension or no clinical signs of left heart failure, and 4) severe hypoxemia, as PaO2/FiO2 ratio <200 mmHg, regardless of FIO2 or PEEP levels. Although this definition could be adequate for epidemiologic studies, it is not adequate for inclusion of patients into therapeutic clinical trials. In 2012, a proposal for updating the ARDS definition (the Berlin criteria) was published and an empirical classification was proposed according to three PaO2/FiO2 cut-off values at ARDS onset: severe (≤100 mmHg), moderate (>100-≤200), and mild (>200-≤300) on PEEP≥5 cmH2O. However, despite that there is sufficient evidence about the interactions between PEEP and FiO2, the Berlin criteria did not mandate the assessment of hypoxemia at 24 hours under standarized guidelines. The PaO2/FIO2 can be easily manipulated. Alterations in PEEP and FIO2 can dramatically change the PaO2/FIO2. Despite recent reports on the effects of standardized ventilator settings on PaO2/FIO2 and fulfillment of AECC definitions of ARDS, it is still a matter of debate whether the assessment of hypoxemia at 24 hours is the most appropriate tool for stratifying lung severity in patients with ARDS. The investigators will examine whether the assessment of hypoxemia at 24 h after ARDS diagnosis under standard guidelines for ventilatory management have an impact on the stratification of lung severity and on predicting mortality of ARDS patients in the intensive care unit.

Official Title
-----------------
STratification AND Outcome of Patients With the Acute Respiratory Distress Syndrome

Conditions
-----------------
Acute Respiratory Distress Syndrome (ARDS)

Intervention / Treatment
-----------------
* Other: stratification


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Patients meeting the AECC definition for ARDS on PEEP greater or equal than 5 cmH2O (or the Berlin criteria for moderate and severe ARDS). Exclusion Criteria: None

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Prospective cohort<br>Stratification of patients admitted into a network of Spanish ICUs. | Other: stratification<br>* Patients will be stratified based on the values of relevant demographics, pulmonary and systemic variables in relation to mortality in the intensive care unit.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| range of values of variables associated with the highest or lowest mortality |  | within the first 24 h of ARDS onset | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| stratification by risk of death based on variables associated with worst outcome |  | ICU stay | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
mechanical ventilation, stratificacion, lung severity