Prevalence of Airway ClosureAOP-VENTNCT07512713
Abbreviated Title: Airway Opening Pressure in Mechanically VENTilated Patients
An observational study of Prevalence of Airway Closure and in Adults in Intensive Care, run by University Hospital, Clermont-Ferrand at 1 site in France.
Trial summary
Context: Mechanical ventilation is an essential treatment for patients admitted to intensive care. It is estimated that approximately 50% of adult patients admitted to intensive care require invasive mechanical ventilation. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Prevalence of Airway Closure, in Adults in Intensive Care, Mechanical Ventilation in Controlled Mode
- How many people
- 500 participants
- Where
- 1 siteFrance
- Study dates
- May 2026to Feb 2028
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Eligible patients will be prospectively included over a period of two weeks (14 consecutive days) in 38 intensive care units in France.
Who may be able to join
- Age ≥ 18 years old
- Patients admitted to a participating ICU
- Patients receiving invasively ventilation for any cause We will only include patients under controlled mechanical ventilation because airway closure is difficult to assess in spontaneously breathing patients.
- Non-inclusion Criteria:
- A patient admitted to hospital or transferred to the intensive care unit without a documented time of intubation
- Have a tracheotomy/tracheostomy at the time of inclusion
Show all 10Show fewer
- Are receiving an assist ventilation mode
- Patient or relative's refusal to participate for data collection
- Pregnant or breast-feeding women
- Legal protection (i.e., patient under a tutelage, or curatorship, or placed under judicial incarceration)
Who cannot join
None listed.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
France1 site
CHU de Clermont-Ferrand
Clermont-Ferrand
Lise LACLAUTRE, promo_interne_drci@chu-clermontferrand.fr
pierre COUHAULT
About this study
Official title: Assessment of Airway Opening Pressure in Critically Ill Adults Receiving Mechanical Ventilation: a Multicenter Prospective Observational Cohort Study
Context:
Mechanical ventilation is an essential treatment for patients admitted to intensive care. It is estimated that approximately 50% of adult patients admitted to intensive care require invasive mechanical ventilation. However, inappropriate ventilator settings expose patients to the risk of ventilator-induced lung injury (VILI). In particular, the cyclical opening and closing of the alveolar units can damage lung tissue and trigger an inflammatory response.
Read more
Measuring and monitoring airway pressure (Paw), particularly plateau pressure (Pplat) and driving pressure (DP), is essential in order to adjust ventilator settings and is the subject of international recommendations.
However, these static pressures may not accurately reflect alveolar pressure. Partial or complete closure of the airways can influence the measurement of Pplat and DP. Airway closure corresponds to an interruption in communication between the proximal airways and the alveoli when airway pressure is below the airway opening pressure (AOP) threshold (airway opening pressure or AOP). In the event of such closure, insufflation only begins when the airway pressure reaches this critical threshold. Consequently, in the event of airway closure, the airway pressure may differ from the alveolar pressure and thus distort the assessment of respiratory mechanics. Furthermore, when positive end-expiratory pressure (PEEP) is set below the critical AOP threshold, cyclic opening and closure of the alveolar units may occur, potentially contributing to VILI.Detection of airway closure and measurement of the corresponding AOP can be performed at the patient's bedside by simply examining the ventilator curves during slow-flow insufflation or by measuring conductive pressure. Despite the potential implications of airway closure for the assessment of respiratory mechanics in mechanically ventilated patients, its prevalence is not defined. It has been reported that this phenomenon may affect 20 to 50% of patients with acute respiratory distress syndrome (ARDS). It has also been suggested that this phenomenon may affect obese patients, asthmatic patients, or patients receiving insufficient PEEP.
Objectives:
The main objective of this multicentre observational study is to assess the prevalence of airway closure in a large population of adults in intensive care receiving invasive mechanical ventilation.
Type of study:
Multicentre observational cohort study
Number of centres:
39 intensive care units
Study procedure:
Phase 1: Identification and registration of participating centres Phase 2: Implementation of the study and data collection All patients undergoing invasive mechanical ventilation in controlled mode will undergo AOP measurement (analysis of the Paw curve during slow-flow insufflation according to standard clinical practice) between 8am and 10am on the day of inclusion, by a doctor other than the one in charge of the patient.
No changes will be made to the initial ventilator settings. The data will be collected anonymously on an eCRF. A standardised protocol for measuring AOP will be provided. The measurement will be repeated at H+12 alongside the collection of the usual ventilatory mechanics and oxygenation data (compliance, driving pressure, Pplat, mechanical power, PaO2/FiO2).
Phase 3: management and analysis of pseudonymised data
Read the detailed description
Eligible patients will be included prospectively over a period of two weeks (14 consecutive days); the two-week period will be left to the discretion of each intensive care unit participating in the research (within a total 'window' of two months). Any patient admitted to intensive care requiring invasive mechanical ventilation in controlled mode for the condition for which they were admitted will undergo AOP measurement (analysis of the Paw curve during slow-flow insufflation according to standard practice) between 8am and 10am on the day of inclusion, by a doctor other than the one in charge of the patient.No changes will be made to the initial ventilator settings. The data will be collated pseudonymously on an eCRF. A standardised protocol for measuring AOP will be provided. The measurement will be repeated at H12 alongside the collection of the usual ventilatory mechanics and oxygenation data (compliance, driving pressure, Pplat, mechanical power, PaO2/FiO2).
For newly admitted patients (ventilation duration < 24 hours), in participating centres that accept it, data will be collected upon discharge from intensive care or on day 28, whichever comes first, in order to gather the following prognostic information: total duration of mechanical ventilation up to day 28, time to weaning from ventilation, number of days alive without invasive ventilation support on day 28, mortality on day 28.
- Conditions
- Prevalence of Airway Closure, in Adults in Intensive Care, Mechanical Ventilation in Controlled Mode
- Keywords
- airway closure AOP
What is being measured
The primary outcome is the main question the study is designed to answer.
The primary outcome is the proportion of critically ill receiving mechanically ventilated patients with complete airway closure (AOP higher than PEEP).
Complete airway closure and corresponding AOP will be identified on the pressure-time curve of the ventilator using a low-flow inflation (5 L/min, respiratory rate 5/min, tidal volume 6 mL/kg predicted body weight) after a prolonged exhalation to PEEP 5 cmH2O in volume-controlled mode.
Measured: Data collection will be done twice (12-hour intervals) on the day of enrollment in the study. For newly admitted patients to participating ICUs, data collection will be done at day 1 and day 2.
Secondary outcomes (9)
Mechanical power (MP)
MP will be calculated by the following equation15: MP (J/min) = 0.098 × VT × RR × [PEEP + (0.5 × DP) + (Ppeak - Pplat)], where VT is tidal volume, RR respiratory rate, DP Driving Pressure, Ppeak peak airway pressure and Pplat plateau airway pressure.
Measured: At day 1 and day 2 (if inclusion criteria are met)
Mechanical power, computed using AOP instead total PEEP
In patients with airway closure and AOP greater than PEEP
Measured: At day 1 and day 2
Conductive pressure (Pcond) and resistive pressure (Pres)
Pcond and Pres will be identified on the pressure-time curve in volume-controlled mode using the initially set flow rate and then using using constant-flow of 50, 60 and 70 L/min.
AOP will be calculated by the following equation: AOP = PEEP + (Pcond - Pres)
Measured: From the ventilator at day 1 and day 2
Driving pressure of the respiratory system (DPrs)
computed as Pplat - PEEP, Driving pressure computed using AOP instead of PEEP (in patients with airway closure and AOP greater than PEEP)
Measured: At day 1 and day 2
Total duration to first separation attempt
Number of days until the first attempt at separation (spontaneous breathing trial or direct extubation)
Measured: Upon discharge from intensive care or on day 28
Total duration to successful weaning from the ventilator,
Defined as extubation followed by 48 hours of spontaneous breathing without mechanical ventilation.
Measured: Upon discharge from intensive care or on day 28
Total duration of ventilation
Total duration of ventilation to ICU discharge or day 28, whichever comes first
Measured: Upon discharge from intensive care or on day 28
Days alive and off the ventilator
Days alive and off the ventilator at ICU discharge or day 28, whichever comes first
Measured: Upon discharge from intensive care or on day 28
Reintubation (y/n)
Reintubation (y/n) at ICU discharge or day 28, whichever comes first
Measured: Upon discharge from intensive care or on day 28
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Apr 2026
- Study startMay 2026 (estimated)
- Primary completionFeb 2028 (estimated)
- Study completionFeb 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Prevalence of Airway ClosureStudies of the same condition, open and under way.
- More trials run by University Hospital, Clermont-FerrandThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 500 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University Hospital, Clermont-Ferrand
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Pierre COUHAULT, PH, Principal investigator, University Hospital, Clermont-Ferrand
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07512713
- Sponsor's protocol ID
- RNI 2025 COUHAULT (AOP-VENT)
- Other IDs
- ANSM
- Acronym
- AOP-VENT
- Status last verified
- Dec 2025
- First submitted
- 27 Mar 2026
- Last updated
- 6 Apr 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 6 Apr 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Assessment of Airway Opening Pressure in Critically Ill Adults Receiving Mechanical Ventilation: a Multicenter Prospective Observational Cohort Study
- ClinicalTrials.gov ID
- NCT07512713
- Acronym / sponsor ID
- AOP-VENT / RNI 2025 COUHAULT (AOP-VENT)
- Conditions
- Prevalence of Airway Closure, in Adults in Intensive Care, Mechanical Ventilation in Controlled Mode
- Keywords
- airway closure AOP
- Study type
- Observational
- Recruitment status
- Not yet recruiting
- Enrolment
- 500 participants (estimated)
- Lead sponsor
- University Hospital, Clermont-FerrandUniversity, hospital or other
- Study start
- May 2026 (estimated)
- Primary completion
- Feb 2028 (estimated)
- Study completion
- Feb 2028 (estimated)
- First posted
- 6 Apr 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Context:
Mechanical ventilation is an essential treatment for patients admitted to intensive care. It is estimated that approximately 50% of adult patients admitted to intensive care require invasive mechanical ventilation. However, inappropriate ventilator settings expose patients to the risk of ventilator-induced lung injury (VILI). In particular, the cyclical opening and closing of the alveolar units can damage lung tissue and trigger an inflammatory response.
Measuring and monitoring airway pressure (Paw), particularly plateau pressure (Pplat) and driving pressure (DP), is essential in order to adjust ventilator settings and is the subject of international recommendations.
However, these static pressures may not accurately reflect alveolar pressure. Partial or complete closure of the airways can influence the measurement of Pplat and DP. Airway closure corresponds to an interruption in communication between the proximal airways and the alveoli when airway pressure is below the airway opening pressure (AOP) threshold (airway opening pressure or AOP). In the event of such closure, insufflation only begins when the airway pressure reaches this critical threshold. Consequently, in the event of airway closure, the airway pressure may differ from the alveolar pressure and thus distort the assessment of respiratory mechanics. Furthermore, when positive end-expiratory pressure (PEEP) is set below the critical AOP threshold, cyclic opening and closure of the alveolar units may occur, potentially contributing to VILI.Detection of airway closure and measurement of the corresponding AOP can be performed at the patient's bedside by simply examining the ventilator curves during slow-flow insufflation or by measuring conductive pressure. Despite the potential implications of airway closure for the assessment of respiratory mechanics in mechanically ventilated patients, its prevalence is not defined. It has been reported that this phenomenon may affect 20 to 50% of patients with acute respiratory distress syndrome (ARDS). It has also been suggested that this phenomenon may affect obese patients, asthmatic patients, or patients receiving insufficient PEEP.
Objectives:
The main objective of this multicentre observational study is to assess the prevalence of airway closure in a large population of adults in intensive care receiving invasive mechanical ventilation.
Type of study:
Multicentre observational cohort study
Number of centres:
39 intensive care units
Study procedure:
Phase 1: Identification and registration of participating centres Phase 2: Implementation of the study and data collection All patients undergoing invasive mechanical ventilation in controlled mode will undergo AOP measurement (analysis of the Paw curve during slow-flow insufflation according to standard clinical practice) between 8am and 10am on the day of inclusion, by a doctor other than the one in charge of the patient.
No changes will be made to the initial ventilator settings. The data will be collected anonymously on an eCRF. A standardised protocol for measuring AOP will be provided. The measurement will be repeated at H+12 alongside the collection of the usual ventilatory mechanics and oxygenation data (compliance, driving pressure, Pplat, mechanical power, PaO2/FiO2).
Phase 3: management and analysis of pseudonymised data
Detailed description
Eligible patients will be included prospectively over a period of two weeks (14 consecutive days); the two-week period will be left to the discretion of each intensive care unit participating in the research (within a total 'window' of two months). Any patient admitted to intensive care requiring invasive mechanical ventilation in controlled mode for the condition for which they were admitted will undergo AOP measurement (analysis of the Paw curve during slow-flow insufflation according to standard practice) between 8am and 10am on the day of inclusion, by a doctor other than the one in charge of the patient.No changes will be made to the initial ventilator settings. The data will be collated pseudonymously on an eCRF. A standardised protocol for measuring AOP will be provided. The measurement will be repeated at H12 alongside the collection of the usual ventilatory mechanics and oxygenation data (compliance, driving pressure, Pplat, mechanical power, PaO2/FiO2).
For newly admitted patients (ventilation duration < 24 hours), in participating centres that accept it, data will be collected upon discharge from intensive care or on day 28, whichever comes first, in order to gather the following prognostic information: total duration of mechanical ventilation up to day 28, time to weaning from ventilation, number of days alive without invasive ventilation support on day 28, mortality on day 28.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Eligible patients will be prospectively included over a period of two weeks (14 consecutive days) in 38 intensive care units in France.
Key inclusion criteria (10 listed)
- Age ≥ 18 years old
- Patients admitted to a participating ICU
- Patients receiving invasively ventilation for any cause We will only include patients under controlled mechanical ventilation because airway closure is difficult to assess in spontaneously breathing patients.
- A patient admitted to hospital or transferred to the intensive care unit without a documented time of intubation
- Have a tracheotomy/tracheostomy at the time of inclusion
Key exclusion criteria (0 listed)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
The primary outcome is the proportion of critically ill receiving mechanically ventilated patients with complete airway closure (AOP higher than PEEP).
Time frame: Data collection will be done twice (12-hour intervals) on the day of enrollment in the study. For newly admitted patients to participating ICUs, data collection will be done at day 1 and day 2.
Complete airway closure and corresponding AOP will be identified on the pressure-time curve of the ventilator using a low-flow inflation (5 L/min, respiratory rate 5/min, tidal volume 6 mL/kg predicted body weight) after a prolonged exhalation to PEEP 5 cmH2O in volume-controlled mode.
9 secondary outcomes
Mechanical power (MP)
Time frame: At day 1 and day 2 (if inclusion criteria are met)
Mechanical power, computed using AOP instead total PEEP
Time frame: At day 1 and day 2
Conductive pressure (Pcond) and resistive pressure (Pres)
Time frame: From the ventilator at day 1 and day 2
Driving pressure of the respiratory system (DPrs)
Time frame: At day 1 and day 2
Total duration to first separation attempt
Time frame: Upon discharge from intensive care or on day 28
Total duration to successful weaning from the ventilator,
Time frame: Upon discharge from intensive care or on day 28
Total duration of ventilation
Time frame: Upon discharge from intensive care or on day 28
Days alive and off the ventilator
Time frame: Upon discharge from intensive care or on day 28
Reintubation (y/n)
Time frame: Upon discharge from intensive care or on day 28
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 6 Apr 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Pierre COUHAULT, PH principal investigator
University Hospital, Clermont-Ferrand
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Prevalence of Airway Closure and in Adults in Intensive Care, run by University Hospital, Clermont-Ferrand at 1 site in France.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 10 inclusion and 0 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 6 Apr 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in France. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Lise LACLAUTRE (+33 473 754 963, promo_interne_drci@chu-clermontferrand.fr), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
The primary outcome is the proportion of critically ill receiving mechanically ventilated patients with complete airway closure (AOP higher than PEEP). (time frame: Data collection will be done twice (12-hour intervals) on the day of enrollment in the study. For newly admitted patients to participating ICUs, data collection will be done at day 1 and day 2.). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 6 Apr 2026.