High Flow During Weaning From Mechanical Ventilation

Study Overview
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Brief Summary
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Detection and relief of dyspnea in mechanically ventilated patients is a priority. Optimization of mechanical ventilation settings is unfortunately often insufficient to relieve dyspnea in patients entering the weaning process. Pharmacological treatments are effective but their use is likely to delay separation with the ventilator. Promoting the development of non-pharmacological interventions is therefore an interesting avenue. The hypothesis is that the application of high-flow humidified nasal air in orotracheally intubated patients can decrease the work of breathing and relieve dyspnea at the time of weaning from mechanical ventilation. Patients will be exposed to stepwise increase in high flow nasal air (0 L/min, 30 L/min, 50 L/min and 70 L/min) before to undergo a 60 minutes spontaneous breathing trial. During the protocol, dyspnea, inspiratory effort, respiratory drive, respiratory muscles electromyogram (EMG) and patient's comfort will be assessed.

Detailed Description
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Patients equipped with an esophageal probe and deemed ready to undergo a spontaneous breathing trial will be included. During, the inclusion visit, main characteristics of the patients and ICU stay will be collected in the patient's chart: age, sex, comorbidities, date of admission to intensive care, date of intubation, severity score (SOFA), reason for admission to intensive care , weight, height, ventilation settings, P0.1, respiratory rate, SpO2, dyspnea and comfort score. Secondarily, the quality of the esophageal pressure signal will be checked. Esophageal pressure will be collected using a nasogastric tube (NutriventTM, SIDAM, Italy). Esophageal pressure will be measured continuously by the Labchart system installed on the department's dedicated computer. Third, the EMG collection device will be implemented. EMG signals will be collected by surface electrodes on the scalene and intercostal muscles and on the sides of the nose. The electrodes are connected to collection modules operating with the LabChart system. Finally, the high-flow humidified air device will be installed (AIRVO 2; Fisher and Paykel Healthcare, Auckland, New Zealand) and nasal cannulas adapted to the patient's anatomy will be positioned. The FiO2 will be fixed at 21% for the duration of the study. The flow will be set at 0 L/min at the inclusion visit. The humidified air temperature will be set to 37°C. The protocol will consist of installing the high-flow humidified nasal oxygen therapy device and varying the nasal flow (4 different conditions: 0 L/min, 30 L/min, 50 L/min and 70 L/min) then performing the spontaneous breathing trial (duration 60 minutes). During each of the steps of the protocol, a collection of the intensity of the dyspnea, a measurement of the esophageal pressure, a measurement of the respiratory drive, an EMG measurement of the respiratory muscles and a comfort assessment will be carried out.

Official Title
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Effect of High Flow Nasal Air on Dyspnea During Weaning From Mechanical Ventilation

Conditions
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Acute Respiratory Failure

Intervention / Treatment
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* Device: High Flow Nasal Air


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age > 18 years old orotracheal intubation Decision to initiate a spontaneous breathing trial by the clinical team Visual analogic scale of dyspnea > 3/10 Informed consent to participate Patient covered by the national health Exclusion Criteria: No esophageal probe in place Extubation planned without a spontaneous breathing trial Glasgow coma scale< 12 Patient's refusal No coverage by the national health insurance Patient under legal protection of justice

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 90 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: Other
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Experimental group<br>installation of the high-flow humidified nasal oxygen therapy device and variation of the inspiratory flow rate (0 L/min, 30 L/min, 50 L/min and 70 L/min) then performance of the weaning test. of the weaning test. During each step of the protocol (= each variation of the inspiratory flow), the intensity of the dyspnea will be collected, the esophageal pressure will be measured, the respiratory control will be measured, the EMG of the respiratory muscles will be measured and the comfort will be measured. Each step lasts about 15 minutes with 5 minutes of wash-out before the next step. Once the 4 conditions are tested, the weaning test is performed (without wash-out), for a duration of one hour. The whole test lasts 2h15. | Device: High Flow Nasal Air<br>* Administration of air at high flow by using a high flow nasal oxygenation (FiO2 21%) device<br>* Other names: High Flow Nasal Cannula;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| intensity of dyspnea by Mechanical ventilation Respiratory Distress Observational Scale (IC-RDOS). | Scale of 1 to 10 with 10 corresponding to significant dyspnea | at inclusion, compare to 15, 35, 55, 75, 105 and 135 min | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| inspiratory effort | Amplitude of the esophagus pressure | at inclusion, compare to 15, 35, 55, 75, 105 and 135 min | 
| respiratory drive | inspiratory occlusion pressure (P0.1) | at inclusion, compare to 15, 35, 55, 75, 105 and 135 min | 
| respiratory muscles activity | electromyogram of the respiratory muscles | at 15 min to inclusion, compare to, 35, 55, 75, 105 and 135 min | 
| patient comfort | Visual analogic scale. Scale of 1 to 10 with 10 corresponding to minimal comfort | at inclusion, compare to 15, 35, 55, 75, 105 and 135 min | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Dyspnea, Weaning, Mechanical ventilation, High flow nasal air