Individualization Flow in Patients Treated With High Flow Nasal Therapy (iFLOW)

Study Overview
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Brief Summary
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In patients with acute hypoxemic respiratory failure (AHRF), High Flow Nasal Therapy (HFNT) improves oxygenation, tolerance, and decreases work of breathing as compared to standard oxygen therapy by facemask. The hypothesis is that this flow challenge (ROX index variation from 30 to 60L/min) could be used as a test for assessing changes in lung aeration, analyzed by the variation in end expiratory lung volume (ΔEELV), in patients treated with HFNC. It may allow to personalize the flow settings during HFNC. In this sense, an increase in EELV will be observed with higher flows in responders and, therefore, these participants may benefit from increasing the flow. In contrast, to increase the flow in non-responders (no significant increase in EELV with higher flows) increase the risk of patient self-inflicted lung injury (P-SILI).

Official Title
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Assessing Recruitability for Flow Individualization in Patients Treated With Nasal High Flow: a Physiological Study (The iFLOW Study)

Conditions
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High-Flow Nasal Cannula, Oxygen Therapy, Acute Respiratory Failure, Respiratory Failure, Lung Injury

Intervention / Treatment
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* Device: High Flow Nasal Cannula at 30L/min
* Device: High Flow Nasal Cannula at 45L/min
* Device: High Flow Nasal Cannula at 60L/min


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adult patient admitted to the ICU requiring NHF due to AHRF that will be defined as an SpO2/FIO2 ratio <315 Exclusion Criteria: Patient with indication for immediate CPAP, NIV, or invasive mechanical ventilation Hemodynamic instability defined as a need of continuous infusion of epinephrine or norepinephrine > 1 mg/h Severe acidosis (pH ≤ 7.25) Pregnant woman Tracheotomised patient Formalized ethical decision to withhold or withdraw life support Patient under guardianship Patient deprived of liberties Patient already enrolled in the present study in a previous episode of acute respiratory failure Patient who does not consent.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Supportive Care
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: 30 L/min<br>HFNC at 30L/min. FiO2 adjusted to reach SpO2 95% | Device: High Flow Nasal Cannula at 30L/min<br>* Flow will be set at 30L/min, FiO2 will be adjusted manually to maintain SpO2within the target range<br>|
| Experimental: 45 L/min<br>HFNC at 45L/min. FiO2 adjusted to reach SpO2 95% | Device: High Flow Nasal Cannula at 45L/min<br>* Flow will be set at 45L/min, FiO2 will be adjusted manually to maintain SpO2within the target range<br>|
| Experimental: 60 L/min<br>HFNC at 60L/min. FiO2 adjusted to reach SpO2 95% | Device: High Flow Nasal Cannula at 60L/min<br>* Flow will be set at 60L/min, FiO2 will be adjusted manually to maintain SpO2within the target range<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| To validate the correlation between the change in ROX index and the change in EELV | Change in ROX is defined as the difference in ROX index (SpO2/FiO2/respiratory rate) between 2 flows. Change in EELV is the difference in End-Expiratory Lung Volume as determined by EIT. | 20 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| To assess the changes in aeration distribution (by the variable center of ventilation (CoV)) measured by EIT at different flows (30L/min, 45 L/min and 60L/min). | Lung aeration as defined by the variable center of ventilation (CoV) in EIT. | 20 minutes | 
| To assess the changes in lung homogeneity (by the variable global inhomogeneity index (GI)) measured by EIT at differents flows (30L/min, 45 L/min and 60L/min). | Lung homogeneity as defined by global inhomogeneity index (GI) by EIT | 20 minutes | 
| To analyze the differences in SpO2 at different flows | SpO2 by pulseoxymetry | 20 minutes | 
| To analyze the differences in respiratory rate at different flows | Breaths/minute | 20 minutes | 
| To analyze the differences in the FiO2 used at different flows | FiO2 will be titrated manually to achieve a predefined SpO2 range (92 - 96%; 88-92% for patients with chronic respiratory disease) | 20 minutes | 
| To analyze the differences in patient comfort at different flows, using the visual analogic scale (from 0 to 10) | Comfort score by visual analogic scale. From 0 (worst outcome) to 10 (best outocome). | 20 minutes. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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High-Flow Nasal Cannula, Oxygen therapy, Electrical Impedance Tomography, Lung injury, Acute Respiratory Failure