Clinical trial NCT05224323: Avalanche Phenomenon During Airways Opening in Acute Respiratory Distress Syndrome
Official title: Avalanche Phenomenon During Airways Opening in Acute Respiratory Distress Syndrome
Study type: OBSERVATIONAL
Overall status: UNKNOWN
Conditions: Acute Respiratory Distress Syndrome
Lead sponsor: Poitiers University Hospital
Sponsor class: OTHER
First posted: 2022-02-04
Enrollment: 50
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Observational model: COHORT
Time perspective: PROSPECTIVE
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.

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.


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

Primary outcomes:
measure: To assess the prevalence of "avalanche" phenomenon during low-flow lung inflation.
timeFrame: At inclusion
Secondary outcomes:
measure: To compare characteristics of patients and their outcomes according to the existence of "avalanche" phenomenon during low-flow lung inflation.
timeFrame: Day 28
measure: To assess the existence of an inflection point on the low-flow deflation pressure-volume curve.
timeFrame: At inclusion
measure: 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
timeFrame: At inclusion
Other outcomes:
Locations:
city: Poitiers
country: France
facility: CHU Poitiers
Study officials:
References:
citation: 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.
citation: 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.