Effects of Treatment With High Flow Nasal Cannulas on Respiratory Pattern and Work of Breathing Among Patients.

Study Overview
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Brief Summary
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This study evaluates the work of breathing among patients under various conditions of treatment with high flow nasal cannulas. Sixteen spontaneously breathing patients with respiratory failure (hypercapnic or hypoxemic) will be included. The design of this study is a cross over of four treatment periods with different flow settings.

Detailed Description
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High flow oxygen therapy (HFOT) is a promising technique increasingly used in the management of acute respiratory failure. In hospitalised hypoxemic patients, recent clinical evidence showed that HFOT can reduce endotracheal intubation and reduce mortality. Physiologically, the HFOT causes a decrease in respiratory rate and minute-ventilation and may be associated with a decrease in PaCO2. It is possible that these effects are associated with decreased work of breathing, which could explain some of the benefits in terms of comfort and efficiency. The objective of this research is to evaluate the impact of a wash-out of anatomical dead space by high flow nasal cannulas on respiratory parameters and on the work of breathing. The investigators will evaluate the baseline status with conventional oxygen therapy methods (low flows), and then compare it with three different levels of high flow oxygen therapy in a randomised order. The primary endpoint will be the work of breathing.

Official Title
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Effects of Treatment With High Flow Nasal Cannulas on Respiratory Pattern and Work of Breathing Among Patients.

Conditions
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Respiratory Failure

Intervention / Treatment
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* Device: Airvo 2; Ficher and Paykel HealthCare
* Device: Oxygen delivery via conventional nasal mask


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Spontaneously breathing patients exhibiting a respiratory distress defined by a respiratory rate ≥ 20 breaths/min associated with either hypoxemia (SpO2<90% with O2≥3L/min) ; or hypercapnia (PaCO2>45 mmHg with a respiratory acidosis (pH<7,38). Exclusion Criteria: Patients below 18yo, pregnant or breastfeeding women; Patients enrolled in another study excluding co-enrolment; History of ear nose and throat disease (i.e. surgery, epistaxis, trauma), eso-gastric disease (i.e. esophageal varices, digestive haemorrhage), rheumatologic or neurologic disease possibly interfering with the design of the study; Acute respiratory or cardiovascular disease contra-indicating the enrolment in the study protocol (i.e. acute coronary syndrome, pulmonary embolism, pneumothorax); Need for immediate intubation or for continuous noninvasive ventilation and/or recent (<6h) arterial blood gases showing a respiratory acidosis with a pH<7.30; Patient feeling nauseous or under recent fed condition (<1h).

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: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Conventional flow via nasal prongs<br>Oxygen delivery via conventional nasal interface with flow adjusted to reach a target SpO2 according to the patient's condition. | Device: Oxygen delivery via conventional nasal mask<br>* Low flow of oxygen delivered through conventional nasal prongs<br>|
| Experimental: High flow nasal cannulas 20L/min<br>Oxygen delivery via high flow nasal cannulas (20L/min) with fraction of inspired oxygen (FiO2) adjusted to reach a target SpO2 according to the patient's condition. | Device: Airvo 2; Ficher and Paykel HealthCare<br>* High flow nasal cannulas<br>|
| Experimental: High flow nasal cannulas 40L/min<br>Oxygen delivery via high flow nasal cannulas (40L/min) with FiO2 adjusted to reach a target SpO2 according to the patient's condition. | Device: Airvo 2; Ficher and Paykel HealthCare<br>* High flow nasal cannulas<br>|
| Experimental: High flow nasal cannulas 60L/min<br>Oxygen delivery via high flow nasal cannulas (60L/min) with FiO2 adjusted to reach a target SpO2 according to the patient's condition. | Device: Airvo 2; Ficher and Paykel HealthCare<br>* High flow nasal cannulas<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Work of breathing | Work of breathing at the end of each period is calculated from the measurement of esophageal pressure and tidal volume (composite outcome) | 15 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Esophageal pressure-time product | Measured at the end of each period | 15 minutes | 
| Tidal volume | Measured at the end of each period | 15 minutes | 
| Comfort of breathing | Subjective evaluation at the end of each period | 15 minutes | 
| Blood gases | Arterial or capillary blood gases at the end of each period | 15 minutes | 
| Dyspnea | Evaluation on a borg scale at the end of each period | 15 minutes | 
| Respiratory rate | Measured at the end of each period | 15 minutes | 
| Heart rate | Measured at the end of each period | 15 minutes | 
| End-tidal carbon dioxide | Measured at the end of each period | 15 minutes | 
| Oxygen saturation | Measured at the end of each period | 15 minutes |