Avalanche Phenomenon During Airways Opening in Acute Respiratory Distress Syndrome
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- The protocol lists: Airway pressure, flow, esophageal pressure, ventilation distribution.
- Who it may be relevant to
- Registry conditions: Acute Respiratory Distress Syndrome. Basic parameters: from 18 years · All.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- France
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
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Overview
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.
Interventions
- Other Airway pressure, flow, esophageal pressure, ventilation distribution
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
Primary outcome measures
- To assess the prevalence of "avalanche" phenomenon during low-flow lung inflation. [Time frame: At inclusion]
Secondary outcome measures (3)
- To compare characteristics of patients and their outcomes according to the existence of "avalanche" phenomenon during low-flow lung inflation. [Time frame: Day 28]
- To assess the existence of an inflection point on the low-flow deflation pressure-volume curve. [Time frame: 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 [Time frame: At inclusion]
Eligibility criteria
Inclusion criteria
- 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
Exclusion criteria
- 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
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: No
Study design
- Observational model
- Cohort
Study locations
France · 1 center
- CHU Poitiers — Poitiers
Publications
- 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
- 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
Identifiers
NCT: NCT05224323 · AVALANCHE