Effect of PEEP on Ventilartion/Perfusion Ratios According to Different Phenotypes in Patients With ARDS (France)
Overview
- Phase
- Not Applicable
- Intervention
- Not specified
- Conditions
- ARDS
- Sponsor
- University Hospital, Angers
- Enrollment
- 50
- Locations
- 1
- Primary Endpoint
- Difference in ventilation/perfusion mismatch between PEEP 5 and 15 cmH2O according to the two studied phenotypes
- Status
- Recruiting
- Last Updated
- 4 months ago
Overview
Brief Summary
This study aim to compare the effect of Positive End Expiratory Pressure (PEEP) on ventilation/perfusion mismatch in two phenotypes of patients with moderate-to-severe Acute Respiratory Distress Syndrome (ARDS), characterized by their respiratory system elastance (Ers). Ventilation/perfusion mismatch will be assessed by Electrical Impedance Tomography (EIT).
Detailed Description
Acute Respiratory Distress Syndrome (ARDS) is characterized by hypoxemia caused by inflammatory lung injury. Recent studies showed an important variability in ARDS phenotypes . The recent COVID-19 crisis highlighted the presence of ARDS patients with severe hypoxemia and normal respiratory system compliance, and retrospective series confirmed the existence of this atypical ARDS pattern also in non-COVID etiologies. The dissociation between mechanics and hypoxemia may be related to a specific diversity in the pattern of ventilation-perfusion matching (V/Q matching) among patients with normal compliance and ARDS. In patients with low compliance, V/Q mismatch may be characterized by right-to-left shunt, secondary to collapse of the gravity-dependent regions; while, in patients with normal compliance, V/Q mismatch may show a redistribution of blood flow to hypo-ventilated lung areas by larger dead space and impaired hypoxic vasoconstriction. These differences may also influence the response to PEEP in terms of gas exchange and lung protection . It may also explain the failure for high PEEP levels to improve significantly mortality in the global ARDS population (i.e., with patients' selection only based on hypoxemia). Electrical Impedance Tomography (EIT) is a device allowing to assess ventilation and perfusion distribution. Thus, EIT can be used to evaluate global and regional V/Q matching, and could be used to understand mechanisms of hypoxemia, especially in patients with normal mechanics and ARDS. The aim of this study is to assess V/Q matching according to these different ARDS phenotypes, and to evaluate the effects of PEEP in each one.
Investigators
Eligibility Criteria
Inclusion Criteria
- Not provided
Exclusion Criteria
- Not provided
Outcomes
Primary Outcomes
Difference in ventilation/perfusion mismatch between PEEP 5 and 15 cmH2O according to the two studied phenotypes
Time Frame: immediately after each intervention
Ventilation/perfusion (V/Q) mismatch will be assessed by Electrical Impedance Tomography (EIT). Mismatch is expressed in %. Comparison between phenotype with higher and lower elastance will be performed.
Secondary Outcomes
- Difference in respiratory mechanics between PEEP 5 and 15 cmH2O according to the two studied phenotypes(immediately after each intervention)
- Difference in oxygenation between PEEP 5 and 15 cmH2O according to the two studied phenotypes(immediately after each intervention)
- Difference in carbon clearance between PEEP 5 and 15 cmH2O according to the two studied phenotypes(immediately after each intervention)
- Difference in dead space measured by capnometric volumetry between PEEP 5 and 15 cmH2O according to the two studied phenotypes(immediately after each intervention)
- Difference in dead space measured by calorimetry between PEEP 5 and 15 cmH2O according to the two studied phenotypes(immediately after each intervention)
- Correlations between V.Q mismacth and overdisension and lung collapsus(immediately after each intervention)
- Difference in venous oxygen saturation between PEEP 5 and 15 cmH2O according to the two studied phenotypes(immediately after each intervention)
- Correlation between V/Q mismatch markers and recruitability(immediately after each intervention)
- Correlations between V/Q mismatch assessed by EIT and dead space markers(immediately after each intervention)
- Difference in stress index between PEEP 5 and 15 cmH2O according to the two studied phenotypes(immediately after each intervention)