Assessment of the Reproducibility of the Recruitment-to-inflation Ratio (R/I Ratio) Measurement in Patients With Acute Respiratory Distress Syndrome

NCT07666503 | Not Yet Recruiting

• 2 other identifiers: APHP2518772025-A02834-45
• Study Type: observational
• Target: 80
• Locations: 1 country
• Sites: 4

Brief Summary

Acute respiratory distress syndrome (ARDS) is a severe lung condition that often requires invasive mechanical ventilation in the intensive care unit. In these patients, setting the ventilator appropriately is essential to improve oxygenation while limiting ventilator-induced lung injury. One important ventilator setting is positive end-expiratory pressure (PEEP), which helps keep the lungs open. However, the optimal PEEP level may vary from one patient to another. The recruitment-to-inflation ratio (R/I ratio) is a bedside measurement used to estimate the potential for lung recruitment during a decrease in PEEP. It compares the compliance of the lung volume recruited by PEEP with the compliance of the already aerated lung. A higher R/I ratio suggests that increasing PEEP is more likely to reopen collapsed lung units, whereas a lower R/I ratio suggests limited recruitability and a higher likelihood that additional pressure would mainly distend lung areas that are already open. In clinical practice, the R/I ratio is increasingly used to guide PEEP adjustment, with the aim of improving recruitment and oxygenation while avoiding unnecessary increases in airway pressure. However, although the R/I ratio is used in routine care, there are currently no data demonstrating that this measurement is reproducible when repeated in the same patient under similar conditions. The hypothesis of this study is that the R/I ratio is reproducible when measured twice in the same patient under stable conditions, including no significant changes in ventilator settings, hemodynamic status, or ongoing treatments. This prospective, multicenter, non-interventional study will include adult ICU patients with ARDS who are receiving invasive mechanical ventilation, deep sedation, and assist-control ventilation. For each patient, airway opening pressure will be assessed, and the R/I ratio will be measured twice on the same day by a trained clinician, between 20 and 120 minutes apart, without changes in ventilator settings or treatments likely to influence the measurement. The main objective is to evaluate the within-patient reproducibility of the R/I ratio. Secondary objectives include describing changes in airway opening pressure and R/I ratio over time, assessing the reproducibility of expired tidal volume during the maneuvers, and evaluating the clinical tolerance of these ventilatory measurements. The study will include 80 patients across 4 French intensive care units. No additional intervention outside routine care will be performed. Clinical, ventilatory, and biological data already collected as part of usual care will be recorded.

Conditions

Acute Respiratory Distress Syndrome (ARDS)

Keywords

Mechanical Ventilation; Positive End-Expiratory Pressure; Lung Recruitment; Lung Recruitability; Respiratory Mechanics; Airway Opening Pressure; Reproducibility of Results; Intraclass Correlation Coefficient

Outcome Measures

Primary Outcomes (1)

• Intraclass Correlation Coefficient of the Recruitment-to-Inflation Ratio (R/I)

  Intra-patient reproducibility of the recruitment-to-inflation ratio (R/I) assessed using an intraclass correlation coefficient (ICC, two-way mixed-effects model, absolute agreement) between two measurements (T1 and T2) performed under stable clinical conditions.

  Same day as inclusion, between 20 and 120 minutes between the two measurements

Secondary Outcomes (5)

• Absolute and relative difference in recruitment-to-inflation ratio (R/I) between two measurements (T1 and T2)

  Same day as inclusion, between 20 and 120 minutes between the two measurements

• Intra-patient reproducibility and variability of expired tidal volume (Vte)

  Same day as inclusion, between 20 and 120 minutes between the two measurements

• Longitudinal evolution of recruitment-to-inflation ratio (R/I)

  From inclusion up to ICU discharge (maximum 28 days)

• Longitudinal evolution of airway opening pressure (AOP)

  From inclusion until ICU discharge (up to 28 days)

• Incidence of adverse events during ventilatory measurement procedures

  Periprocedural (from initiation to immediate completion of each R/I or AOP measurement procedure), assessed during the ICU stay (up to 28 days)

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

Adult patients admitted to intensive care units in participating centers for acute respiratory distress syndrome and requiring invasive mechanical ventilation will be screened for inclusion. The study population will be drawn from routine clinical practice in four French academic intensive care units where airway opening pressure and recruitment-to-inflation ratio measurements are performed as part of standard care in selected patients with moderate to severe disease.

You may qualify if:

• Adult patient (age ≥ 18 years)
• Patient hospitalized in the Intensive Care Unit (ICU) for acute respiratory distress syndrome (according to the Berlin definition), requiring invasive mechanical ventilation with deep sedation and controlled mechanical ventilation mode
• Patient or next of kin informed about the study and not objecting to participation

You may not qualify if:

• Undrained pneumothorax or any contraindication to a transient increase in airway pressure
• Known or suspected intracranial hypertension
• Patient under legal protection (e.g., guardianship)
• Not affiliated with a social security system
• Presence of spontaneous respiratory effort
• Presence of a leak in the ventilatory circuit
• Hemodynamic instability (e.g., uncontrolled shock, increasing vasopressor requirement)
• Uncontrolled severe hypoxemia
• Undrained pneumothorax or any contraindication to a transient increase in airway pressure
• Known or suspected intracranial hypertension

Sponsors & Collaborators

• Assistance Publique - Hôpitaux de Paris: lead

Study Sites (4)

Hôpital Henri Mondor

Créteil, France

Location

Hôpital Bicêtre

Le Kremlin-Bicêtre, France

Location

Hôpital La Pitié-Salpetrière

Paris, France

Location

Hôpital Saint-Antoine

Paris, France

Location

MeSH Terms

Conditions

Respiratory Distress Syndrome

Condition Hierarchy (Ancestors)

Lung Diseases; Respiratory Tract Diseases; Respiration Disorders

Central Study Contacts

Tai PHAM

CONTACT

145217245; tai.pham@aphp.fr

Nicolas BIARD

CONTACT

nicolasbiard.bl@gmail.com

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: June 1, 2026
• First Posted: June 24, 2026
• Study Start: June 30, 2026
• Primary Completion (Estimated): June 30, 2027
• Study Completion (Estimated): June 30, 2027
• Last Updated: June 24, 2026

Record last verified: 2026-05

Locations

FR (4)