V/Q Matching Variations With PEEP in ARDS According to Compliance-based Phenotypes (France) (MISMATCHED FR)

Effect of PEEP on Ventilartion/Perfusion Ratios According to Different Phenotypes in Patients With ARDS (France)

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).

Study Overview

• Status: Recruiting
• Conditions: ARDS
• Intervention / Treatment: Procedure: PEEP decrease; Procedure: PEEP increase

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.

• Study Type: Interventional
• Enrollment (Estimated): 50
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: François Beloncle, MD; Phone Number: +33 241 35 58 65; Email: francois.Francois.Beloncle@chu-angers.fr
• Study Contact Backup: Name: UH Angers DRCI; Phone Number: +33 2 41 35 54 96; Email: DRCI-Promotion-Interne@chu-angers.fr

Study Locations

• France
  • Maine et Loire
    • Angers, Maine et Loire, France, 49933
      • Recruiting
      • Angers Hospital
      • Contact: François Beloncle, MD; Phone Number: +33 2 41 58 65; Email: Francois.Beloncle@chu-angers.fr
      • Contact: UH Angers DRCI UH Angers; Phone Number: +33 5 41 35 54 96; Email: DRCI-Promotion-Interne@chu-angers.fr
      • Principal Investigator: francois beloncle, MD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion criteria:

• intubated patients with moderate and severe ARDS (Berlin definition, PaO2/FiO2 ≤200 mmHg at PEEP 5 cmH2O)
• undergoing deep sedation
• on controlled mechanical ventilation
• between 24 hours and 5 days after intubation.

Exclusion criteria:

• age <18 years old; pregnancy
• patient undergoing legal protection
• contra-indications to EIT (e. g. severe chest trauma or wounds)
• pneumothorax; patient undergoing ECMO
• patient with BMI ≥35 kg/m2
• hemodynamic instability with MAP <60 mmHg despite vasopressors.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Strategy A: PEEP 15 cmH2O → PEEP 5 cmH2O	Procedure: PEEP decrease; Positive End Expiratory Pressure (PEEP) will be decreased from 15 to 5 cmH2O.
Active Comparator: Strategy B: PEEP 5 cmH2O → PEEP 15 cmH2O	Procedure: PEEP increase; Positive End Expiratory Pressure (PEEP) will be increased from 5 to 15 cmH2O.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Difference in ventilation/perfusion mismatch between PEEP 5 and 15 cmH2O according to the two studied phenotypes	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.	immediately after each intervention

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Difference in respiratory mechanics between PEEP 5 and 15 cmH2O according to the two studied phenotypes	Plateau pressure and total PEEP will be aggregated to compute driving pressure (Plateau pressure minus total PEEP, all in cmH2O). Respiratory system compliance will be computed by dividing tidal volume by driving pressure (in mL.cmH2O-1; respiratory system resistance will be computed as the inverse of compliance; all these values will be assessed and compared between the two PEEP levels. Comparison between phenotype with higher and lower elastance will be performed.	immediately after each intervention
Difference in oxygenation between PEEP 5 and 15 cmH2O according to the two studied phenotypes	PaO2 (in mmHg) will be assessed and compared between the two PEEP levels. Comparison between phenotype with higher and lower elastance will be performed.	immediately after each intervention
Difference in carbon clearance between PEEP 5 and 15 cmH2O according to the two studied phenotypes	PaCO2 (in mmHg) will be assessed and compared between the two PEEP levels. Ventilatory ratio (no unit) will be derived from the PaCO2 values. Comparison between phenotype with higher and lower elastance will be performed.	immediately after each intervention
Difference in dead space measured by capnometric volumetry between PEEP 5 and 15 cmH2O according to the two studied phenotypes	VCO2 (measured by Vcap, in mmHg) will be assessed and compared between the two PEEP levels. Comparison between phenotype with higher and lower elastance will be performed.	immediately after each intervention
Difference in dead space measured by calorimetry between PEEP 5 and 15 cmH2O according to the two studied phenotypes	VCO2 (measured by calorimetry, in mmHg) will be assessed and compared between the two PEEP levels. Comparison between phenotype with higher and lower elastance will be performed.	immediately after each intervention
Difference in venous oxygen saturation between PEEP 5 and 15 cmH2O according to the two studied phenotypes	SvO2 (in %) will be assessed and compared between the two PEEP levels. Comparison between phenotype with higher and lower elastance will be performed.	immediately after each intervention
Correlation between V/Q mismatch markers and recruitability	Recruitability will be assessed between 15 and 5 cmH2O by respiratory mechanics and EIT, as the recruited volumes value (in mL). R/I ratio will be derived from these data (no unit). V/Q mismatch will be computed by EIT, and expressed in %. Correlation will be performed by linear regression.	immediately after each intervention
Correlations between V/Q mismatch assessed by EIT and dead space markers	Dead space will be assessed by volumetric capnography (if available), venrtilatory ratio, and calorimetriy (if available). V/Q mismatch will be computed by EIT, and expressed in %. Correlation will be performed by linear regression.	immediately after each intervention
Correlations between V.Q mismacth and overdisension and lung collapsus	Overdistension (%) and lung collapsus (%) will be assessed during the Step 3, by EIT. These two values cannot be measured separately. V/Q mismatch will be computed by EIT, and expressed in %. Correlation will be performed by linear regression.	immediately after each intervention
Difference in stress index between PEEP 5 and 15 cmH2O according to the two studied phenotypes	stress index (no unit) will be assessed and compared between the two PEEP levels. Comparison between phenotype with higher and lower elastance will be performed.	immediately after each intervention

Collaborators and Investigators

• Sponsor: University Hospital, Angers

Study record dates

Study Major Dates

• Study Start (Actual): February 8, 2024
• Primary Completion (Estimated): August 1, 2026
• Study Completion (Estimated): September 1, 2026

Study Registration Dates

• First Submitted: September 27, 2022
• First Submitted That Met QC Criteria: October 10, 2022
• First Posted (Actual): October 13, 2022

Study Record Updates

• Last Update Posted (Actual): December 8, 2025
• Last Update Submitted That Met QC Criteria: December 2, 2025
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Keywords: compliance; pulmonary perfusion; recruitability; ventilation-perfusion mismatch
• Additional Relevant MeSH Terms: Behavior; Treatment Adherence and Compliance; Health Behavior; Patient Acceptance of Health Care; Patient Compliance
• Other Study ID Numbers: 2022-A00649-34

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No