Quantitative Computed Tomography for Mortality Risk Stratification in ARDS

Study Overview
=================
Brief Summary
-----------------
Acute respiratory distress syndrome remains a deadly disease with hospital mortality remaining between 40 to 50%. ARDS mortality risk factors have been identified from patient history, common clinical and biological variables in the lung SAFE study. Part of ARDS mortality is attributable to ventilator-induced lung injury (VILI), in relation with inappropriate settings on the ventilator. Tidal hyperinflation and recruitment/derecruitment during lung inflation are 2 identified mechanisms leading to VILI, that may be identified on computed tomography while poorly identified with variables collected at the bedside. The aim of this study is to identify whether tidal hyperinflation identified on computed tomography is a risk factor for ARDS mortality, independently from know bio-clinical risk factors.

Official Title
-----------------
Quantitative Computed Tomography for Mortality Risk Stratification in ARDS

Conditions
-----------------
Acute Respiratory Distress Syndrome

Intervention / Treatment
-----------------
* Radiation: Low dose computed tomography to evaluate biomechanical parameters in the lung


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: 1. Patient aged 15 or older with ARDS according to the Berlin definition 2. invasive mechanical ventilation with PaO2/FiO2 ≤ 300 mm Hg 3. with computed tomography acquired at both end-expiration and end-inspiration, or at both PEEP 5 and 15 cm H2O at end-expiration 4. PEEP setting according to a PEEP/FiO2 table, with secondary adjustment according to hemodynamic tolerance 5. Tidal volume 6 ml/kg of predicted body weight or less Exclusion Criteria: 1. Use of contrast agent during computed tomography acquisition 2. ARDS criteria onset since more than 72 hours or ECMO onset since more than 72 hours 3. Proven COPD 4. Pneumothorax or bronchopleural fistula 5. Patient with spontaneous breathing preventing realization of end-expiratory and end-inspiratory pauses 6. Previous inclusion in current study 7. Patient under a legal protective measure

Ages Eligible for Study
-----------------
Minimum Age: 15 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 |
| --- | --- |
| tidal hyperinflation<br>As the study aim to identify whether tidal hyperinflation is an independent predictor for ARDS mortality, and as this variable will be entered as a quantitative predictor in the multivariate model, the study encompass a single group of patient (i.e. all included patients) | Radiation: Low dose computed tomography to evaluate biomechanical parameters in the lung<br>* In the participating to the study, response to PEEP increase and tidal inflation are evaluated with a software computing biomechanical parameters (tidal hyperinflation and lung recruitability). Tidal hyperinflation and recruitment are computed on CT images acquired within 72 hours after ARDS onset or with 72h after ECMO onset.<br>|

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

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Odd ratio of tidal hyperinflation assessed on CT at day-0 as an independent predictor of 90-day mortality | Tidal hyperinflation is computed as the volume difference of hyperinflated lung (i.e., with CT attenuation between -1000 and -900 Hounsfield units) between and-expiration and end-inspiration at the PEEP level chosen by clinician | Day-0 (time of realization of CT scan) | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
ARDS, computed tomography, alveolar recruitment, PEEP, tidal hyperinflation