Expiratory Flow Limitation Assessment (FLAIR)

Expiratory Fow Assessment in ARDS Patients

This study intended to assess the expiratory flow limitation (EFL) during tidal breath in patients intubated in intensive care unit (ICU) for moderate or severe acute respiratory distress syndrome (ARDS). EFL is defined as the lack of increase in expiratory flow in response to an increase in alveolar-to-atmospheric pressure gradient. It reflects airway closure. Early studies have been done using the Negative expiratory pressure (NEP) technique, which is no longer available. We proposed in present study a new method, which consists of diverting manually the expiratory flow to the atmosphere by-passing the expiratory valve. We aimed at assessing EFL at positive expiratory pressure (PEP) 5 cmH2O in semi-recumbent then in supine position together with measurement of trans-pulmonary pressure and regional lung ventilation. Higher PEP levels will be tested, namely 10, 15 and a trans-pulmonary PEP of 3 cmH2O, in semi-recumbent position.

Study Overview

• Status: Completed
• Conditions: Acute Respiratory Distress Syndrome
• Intervention / Treatment: Other: increase in positive end expiratory pressure

• Study Type: Interventional
• Enrollment (Actual): 25
• Phase: Not Applicable

Contacts and Locations

Study Locations

• France
  • Grenoble, France
    • Chu Grenoble Alpes
  • Lyon, France, 69004
    • Hôpital de la Croix Rousse

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• 18 years or more in age
• moderate to severe ARDS according to the Berlin definition : Intubated (or tracheotomized) and mechanically ventilated in the ICU
• no pregnancy
• informed consent from the next of kin

Exclusion Criteria:

• Contra-indication to PEP > 5 cmH2O
• extracorporeal membrane oxygenation (ECMO)
• chest tube
• mean arterial pressure < 65 mmHg
• Contra-indication to oesophageal device
• underlying disease fatal in less than one year
• active therapy limitation
• under guardian
• refusal to participate
• not affiliated to insurance regimen
• speaking barrier of the next of kin
• investigator not available

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Other: Patients with EFL at PEP 5; Patients with EFL at PEP 5 at the time of inclusion either in supine or semi-recumbent position	Other: increase in positive end expiratory pressure; increase in positive end expiratory pressure from 5 to 10 then 15 cmH2O then at the value for trans pulmonary end expiratory pressure amounting to 3 cmH2O
Other: Patients with no EFL at PEP 5; Patients with no EFL at PEP 5 at the time of inclusion in both supine and semi-recumbent positions	Other: increase in positive end expiratory pressure; increase in positive end expiratory pressure from 5 to 10 then 15 cmH2O then at the value for trans pulmonary end expiratory pressure amounting to 3 cmH2O

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
EFL at PEP 5 cmH2O	A Fleish 2 pneumotachograph and a port to measure airway pressure are attached at the Y piece of the ventilator circuit and connected to a Biopac 150. At the end of inspiration the air is expelled to the atmosphere upstream the expiratory valve. The flow volume loop at baseline and that during the manoeuver are plotted and patients classified as EFL or not EFL (NFL). Measurements are taken in semi-recumbent then after 5 minutes in supine position.	at inclusion

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Trans-pulmonary pressure at end expiratory at PEP 5	After insertion of esophageal balloon together with pneumotachograph and port for airway pressure trans-pulmonary pressure (airway-esophageal pressure) is measured after a 3-sec end-expiratory pause in semi-recumbent and then after 5 minutes in supine position	at inclusion
Trans-pulmonary pressure at end expiratory at PEP 10 in EFL and NFL patients	PEP is increased to 10 cmH2O and 15 minutes later trans-pulmonary pressure is measured after a 3-sec end-expiratory pause in semi-recumbent position	15 minutes after PEP set to 10 cm H2O
Lung compliance at PEP 10 in EFL and NFL patients	PEP is increased to 10 cmH2O and 15 minutes later lung compliance is measured after a 3-sec end-expiratory pause in semi-recumbent position	15 minutes after PEP set to 10 cm H2O
lung ventilation distribution at PEP 10 in EFL and NFL patients	PEP is increased to 10 cmH2O and 15 minutes later lung ventilation is measured by using electrical impedance tomography (EIT) in semi-recumbent position (an EIT belt having been inserted together with the previous measurement devices).	15 minutes after PEP set to 10 cm H2O
Transcutaneous oxygen saturation (SpO2) at PEP 10 in EFL and NFL patients	PEP is increased to 15cmH2O and 15 minutes later SpO2 is read from the vital functions monitoring device and SpO2/FIO2 computed	15 minutes after PEP set to 10 cm H2O
Trans-pulmonary pressure at end expiratory at PEP 15 in EFL and NFL patients	PEP is increased to 15 cmH2O and 15 minutes later trans-pulmonary pressure is measured after a 3-sec end-expiratory pause in semi-recumbent position	15 minutes after PEP set to 15 cm H2O
Lung compliance at PEP 15 in EFL and NFL patients	PEP is increased to 15 cmH2O and 15 minutes later lung compliance is measured after a 3-sec end-expiratory pause in semi-recumbent position	15 minutes after PEP set to 15 cm H2O
lung ventilation distribution at PEP 15 in EFL and NFL patients	PEP is increased to 15 cmH2O and 15 minutes later lung ventilation is measured by using electrical impedance tomography (EIT) in semi-recumbent position (an EIT belt having been inserted together with the previous measurement devices).	15 minutes after PEP set to 15 cm H2O
transcutaneous oxygen saturation (SpO2) at PEP 15 in EFL and NFL patients	PEP is increased to 15 cmH2O and 15 minutes later SpO2 is read from the vital functions monitoring device and SpO2/FIO2 computed.	15 minutes after PEP set to 15 cm H2O
Trans-pulmonary pressure at end expiratory at PEP to reach Trans-pulmonary pressure at end expiratory =+3 cmH2O in EFL and NFL patients	PEP is set to reach Trans-pulmonary pressure at end expiratory =+3 cmH2O and 15 minutes later trans-pulmonary pressure is measured after a 3-sec end-expiratory pause in semi-recumbent position	15 minutes after PEP set to reach Trans-pulmonary pressure at end expiratory =+3 cmH2O
Lung compliance at PEP to reach Trans-pulmonary pressure at end expiratory =+3 cmH2O in EFL and NFL patients	PEP is set to reach Trans-pulmonary pressure at end expiratory =+3 cmH2O and 15 minutes later lung compliance is measured after a 3-sec end-expiratory pause in semi-recumbent position	15 minutes after PEP set to reach Trans-pulmonary pressure at end expiratory =+3 cmH2O
lung ventilation distribution at PEP set to reach Trans-pulmonary pressure at end expiratory =+3 cmH2O in EFL and NFL patients	PEP is set to reach Trans-pulmonary pressure at end expiratory =+3 cmH2O and 15 minutes later lung ventilation is measured by using electrical impedance tomography (EIT) in semi-recumbent position (an EIT belt having been inserted together with the previous measurement devices).	15 minutes after PEP set to reach Trans-pulmonary pressure at end expiratory =+3 cmH2O
Transcutaneous oxygen saturation (SpO2) at PEEP set to reach Trans-pulmonary pressure at end expiratory =+3 cmH2O in EFL and NFL patients	PEEP is increased to 15 cmH2O and 15 minutes later SpO2 is read from the vital functions monitoring device and SpO2/FIO2 computed.	15 minutes after PEEP set to reach Trans-pulmonary pressure at end expiratory =+3 cmH2O
lung recruitment at PEEP 10 in EFL and NFL patients	PEEP is increased to 10 cmH2O and 15 minutes later lung recruitment is measured between PEEP 10 and PEEP 5 (in each body position) from volume-pressure curves recorded at PEEP 10 and PEEP 5. The lung recruitment is the change in lung volume for a given pressure (higher PEEP and 20 cmH2O)	15 minutes after PEEP set to 10 cm H2O
lung recruitment at PEEP 15 in EFL and NFL patients	PEEP is increased to 15 cmH2O and 15 minutes later lung recruitment is measured between PEEP 15 and PEEP 5 (in each body position) from volume-pressure curves recorded at PEEP 15 and PEEP 5. The lung recruitment is the change in lung volume for a given pressure (higher PEEP and 20 cmH2O)	15 minutes after PEEP set to 15 cm H2O
lung recruitment at PEEP set to reach Trans-pulmonary pressure at end expiratory =+3 cmH2O in EFL and NFL patients in EFL and NFL patients	PEEP is increased to PEEP set to reach Trans-pulmonary pressure at end expiratory =+3 cmH2O and 15 minutes later lung recruitment is measured between PEEP set to reach Trans-pulmonary pressure at end expiratory =+3 cmH2O and PEEP 5 (in each body position) from volume-pressure curves recorded at PEEP set to reach Trans-pulmonary pressure at end expiratory =+3 cmH2O and PEEP 5. The lung recruitment is the change in lung volume for a given pressure (higher PEEP and 20 cmH2O)	15 minutes after PEEP set to 15 cm H2O

Collaborators and Investigators

• Sponsor: Hospices Civils de Lyon
• Investigators: Principal Investigator: Claude Guerin, Pr, Hospices Civils de Lyon

Publications and helpful links

General Publications

• Guerin C, Terzi N, Galerneau LM, Mezidi M, Yonis H, Baboi L, Kreitmann L, Turbil E, Cour M, Argaud L, Louis B. Lung and chest wall mechanics in patients with acute respiratory distress syndrome, expiratory flow limitation, and airway closure. J Appl Physiol (1985). 2020 Jun 1;128(6):1594-1603. doi: 10.1152/japplphysiol.00059.2020. Epub 2020 Apr 30.

Study record dates

Study Major Dates

• Study Start (Actual): February 5, 2018
• Primary Completion (Actual): May 2, 2019
• Study Completion (Actual): May 2, 2019

Study Registration Dates

• First Submitted: March 6, 2018
• First Submitted That Met QC Criteria: March 6, 2018
• First Posted (Actual): March 13, 2018

Study Record Updates

• Last Update Posted (Estimated): December 5, 2025
• Last Update Submitted That Met QC Criteria: November 28, 2025
• Last Verified: November 1, 2025

More Information

Terms related to this study

• Keywords: ARDS; expiratory flow limitation; trans-pulmonary pressure; airway closure
• Additional Relevant MeSH Terms: Respiratory Tract Diseases; Lung Diseases; Respiration Disorders; Respiratory Distress Syndrome; Therapeutics; Airway Management; Respiratory Therapy; Respiration, Artificial; Positive-Pressure Respiration
• Other Study ID Numbers: 69HCL17_0595; 2017-A02557-46 (Other Identifier: ANSM)

Drug and device information, study documents

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