Avalanche Phenomenon During Airways Opening in Acute Respiratory Distress Syndrome

NCT05224323 | Recruiting

• 1 other identifier: AVALANCHE
• Study Type: observational
• Target: 50
• Locations: 1 country
• Sites: 1

Brief Summary

Acute respiratory distress syndrome accounts for 23% of mechanically ventilated patients and is associated with high mortality rate. Although life-saving, mechanical ventilation may worsen lung injury through two main mechanisms: lung overdistension and atelectrauma. Indeed, the cyclic opening and closure of airways during tidal ventilation may cause lung and bronchial injuries as suggested by animal models and autopsy findings. Complete airways closure has recently been described in 40% of patients with acute respiratory distress syndrome, and setting positive end-expiratory pressure above the airway opening pressure may limit atelectrauma. However, animal and mathematical models suggest that above the airway opening pressure, more distal airways open unevenly according to their own opening pressure, resulting in an "avalanche"-like phenomenon during lung inflation. This phenomenon has never been described in humans. A better understanding of the opening of airways in acute respiratory distress syndrome may help to limit ventilation-induced lung injury and to improve outcomes.

Conditions

Acute Respiratory Distress Syndrome

Outcome Measures

Primary Outcomes (1)

• To assess the prevalence of "avalanche" phenomenon during low-flow lung inflation.

  The distribution of pressure drops on low-flow inflation pressure-volume curves will be described and plotted on a log-log scale graph. "Avalanche" phenomenon will be defined if this distribution follows power law (i.e. is linear on a log-log scale) with a R2 ≥ 0.80. The prevalence of "avalanche" phenomenon will be described as frequency and 95% confidence interval.

  At inclusion

Secondary Outcomes (3)

• To compare characteristics of patients and their outcomes according to the existence of "avalanche" phenomenon during low-flow lung inflation.

  Day 28

• To assess the existence of an inflection point on the low-flow deflation pressure-volume curve.

  At inclusion

• To assess the airway pressure value of the inflection point on the low-flow deflation pressure-volume curve in patients with an inflexion point on the low-flow deflation pressure-volume curve

  At inclusion

Interventions

Airway pressure, flow, esophageal pressure, ventilation distribution OTHER

After informed consent, baseline characteristics of patients will be collected. Airway pressure, flow and esophageal pressure will be recorded using high sampling rate and ventilation distribution using electrical impedance tomography will be recorded during the study. The ventilator will be set at a positive end-expiratory pressure of 15 cmH2O during 10 minutes. Then, respiratory rate will be decreased to 8 breaths/min, and positive end-expiratory pressure will be decreased to 5 cmH2O over one breath to measure the recruited volume. Then, three low-flow inflation and deflation pressure-volume curves will be performed before resuming clinical ventilator settings. Patients will be followed until Day 28 after inclusion or ICU discharge. Maneuvers performed are part of the usual care of patients with acute respiratory distress syndrome in our unit.

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

Patients with moderate-to-severe acute respiratory distress syndrome will be included within the first 72 hours after meeting the Berlin definition criteria. After ruling out exclusion criteria and obtaining informed consent from their relatives, patients will be included in the study.

You may qualify if:

• Age ≥ 18
• Moderate-to-severe acute respiratory distress syndrome within the first 72 hours after meeting the Berlin definition criteria:
• Within 1 week of a known clinical insult or new or worsening respiratory symptoms;
• Bilateral opacities (not fully explained by effusions, lobar/lung collapse, or nodules);
• Respiratory failure not fully explained by cardiac failure or fluid overload;
• PaO2/FiO2 ≤ 200 mmHg with positive end-expiratory pressure ≥ 5 cmH2O.
• Absence of spontaneous breathing efforts
• Consent to participate to the study from the patient and/or its surrogate

You may not qualify if:

• Pneumothorax
• Broncho-pleural fistula
• Tracheostomy
• Hemodynamic instability
• Severe hypoxemia
• Suspected of proven intracranial hypertension
• Chronic obstructive lung disease
• Pacemaker or defibrillator
• Decision to withhold of withdraw life-sustaining measures
• Under protection

Sponsors & Collaborators

• Poitiers University Hospital: lead

Study Sites (1)

CHU Poitiers

Poitiers, 86000, France

RECRUITING

Related Publications (2)

• Suki B, Barabasi AL, Hantos Z, Petak F, Stanley HE. Avalanches and power-law behaviour in lung inflation. Nature. 1994 Apr 14;368(6472):615-8. doi: 10.1038/368615a0.

  PMID: 8145846 BACKGROUND

• Chen L, Del Sorbo L, Grieco DL, Shklar O, Junhasavasdikul D, Telias I, Fan E, Brochard L. Airway Closure in Acute Respiratory Distress Syndrome: An Underestimated and Misinterpreted Phenomenon. Am J Respir Crit Care Med. 2018 Jan 1;197(1):132-136. doi: 10.1164/rccm.201702-0388LE. No abstract available.

  PMID: 28557528 BACKGROUND

MeSH Terms

Conditions

Respiratory Distress Syndrome

Condition Hierarchy (Ancestors)

Lung Diseases; Respiratory Tract Diseases; Respiration Disorders

Central Study Contacts

Rémi Coudroy, MD, PhD

CONTACT

+ 33 5 49 44 40 07; remi.coudroy@chu-poitiers.fr

Céline DELETAGE

CONTACT

+33 5 49 44 38 54; celine.deletage@chu-poitiers.fr

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Target Duration: 28 Days
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: January 25, 2022
• First Posted: February 4, 2022
• Study Start: March 1, 2022
• Primary Completion (Estimated): September 1, 2026
• Study Completion (Estimated): October 1, 2026
• Last Updated: December 24, 2025

Record last verified: 2025-12

Locations

FR (1)