Avalanche Phenomenon During Airways Opening in Acute Respiratory Distress Syndrome

• Conditions: Acute Respiratory Distress Syndrome

• Registration Number: NCT05224323
• Lead Sponsor: Poitiers University Hospital

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.

Detailed Description

Not available

Study Timeline

• Study First Submitted: 2022-01-25
• Study First Submitted QC: 2022-01-25
• Study First Posted: 2022-02-04
• Status Verified: 2022-03
• Study Start: 2022-03-01
• Last Update Submitted: 2022-03-01
• Last Update Posted: 2022-03-02
• Primary Completion: 2023-03
• Study Completion: 2023-09

Recruitment & Eligibility

• Status: UNKNOWN
• Sex: All
• Target Recruitment: 50

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

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
To assess the prevalence of "avalanche" phenomenon during low-flow lung inflation.	At inclusion	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.

Secondary Outcome Measures

Name	Time	Method
To compare characteristics of patients and their outcomes according to the existence of "avalanche" phenomenon during low-flow lung inflation.	Day 28	Continuous variables will be summarized as mean ± standard deviation or median \[25th-75th percentile\] according to their distribution and compared by means of the Mann-Whitney or the Student's t test. Categorical variables will be summarized as frequency (percentage) and 95% confidence interval, and compared by means of Fisher or Chi2 test.
To assess the existence of an inflection point on the low-flow deflation pressure-volume curve.	At inclusion	The slope of the low-flow deflation pressure-volume curve will be computed by means of linear regression and summarized as mean ± standard deviation or median \[25th-75th percentile\] according to its distribution. The existence of an inflexion point will be summarized as number (percentage) and 95% confidence interval. The airway pressure corresponding to this inflexion point will be summarized as mean ± standard deviation or median \[25th-75th percentile\] according to its distribution.
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	The airway pressure corresponding to the inflexion point on the low-flow deflation pressure-volume curve will be summarized as mean ± standard deviation or median \[25th-75th percentile\] according to its distribution.

Trial Locations

Locations (1)

CHU Poitiers; 🇫🇷 Poitiers, France