Correlation of Peak Tidal Inspiratory Flow Measured Before and After Extubation in Adult Patients With Hypoxemia

Study Overview
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Brief Summary
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In this study, patients who are ready for extubation and indicated for high-flow nasal cannula therapy after extubation will be enrolled, the investigators would measure the patient peak tidal inspiratory flow (PTIF) pre and post extubation to explore the correlation between the two PTIFs. Moreover, different HFNC flows would be applied, to explore the patient response in terms of oxygenation and lung aeration to different flow ratios that matched and are above post-extubation PTIF.

Detailed Description
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High-flow nasal cannula (HFNC) oxygen therapy has been shown to improve oxygenation, reduce the need for intubation for patients with acute hypoxemic respiratory failure (AHRF) and avoid reintubation for post-extubation patients who had high-risk factors. HFNC refers to the delivery of gas at flows that exceed the patient peak inspiratory flow during tidal breathing, However, patient peak tidal inspiratory flow (PTIF) is found to vary greatly among different patients, from 20 to 50 L/min, making it difficult to properly set HFNC in a way to achieve the desired effects. In two recently published studies in intubated patients, PTIF varied from 25-65 L/min or 40-80 L/min, thus this study aims to investigate the correlation between pre-extubation PTIF in different modalities of SBT and post-extubation PTIF for adult patients, who are indicated to use HFNC immediately after extubation. In addition, the investigators aim to explore the patient response in terms of oxygenation and lung aeration to different flow ratios that matched and are above post-extubation PTIF.

Official Title
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Correlation of Peak Tidal Inspiratory Flow Measured Before and After Extubation in Adult Patients With Hypoxemia, and Patients' Responses to Different Flows Above Their Peak Tidal Inspiratory Flow During High Flow Nasal Cannula Therapy

Conditions
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Hypoxemic Respiratory Failure

Intervention / Treatment
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* Other: HFNC flow set at patient peak tidal inspiratory flow
* Other: HFNC flow set at 1.33 times of patient peak tidal inspiratory flow
* Other: HFNC flow set at 1.67 times of patient peak tidal inspiratory flow
* Other: HFNC flow set at 2 times of patient peak tidal inspiratory flow


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adult intubated patients aged between 18 to 90 years Pass spontaneous breathing trial and receive the order to be extubated Have at least one of the indications to use HFNC after extubation Exclusion Criteria: Need to use inhaled epoprostenol via HFNC Pregnant Unable to use resuscitation mask, such as facial trauma, claustrophobia Non-English speaker Inability to verbally communicate Using extracorporeal membrane oxygenation (ECMO) Hemodynamically unstable Difficult airway

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: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Patients will be randomized to receive different HFNC flow settings (matching their peak tidal inspiratory flow [PTIF], 1.33 times of PTIF, 1.67 times of PTIF and 2 times of PTIF)
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: HFNC flow set at patient peak tidal inspiratory flow<br>HFNC flow will be set at the level that matches patient peak tidal inspiratory flow | Other: HFNC flow set at patient peak tidal inspiratory flow<br>* HFNC flow will be set at the level equal to patient peak tidal inspiratory flow<br>|
| Experimental: HFNC flow set at 1.33 times of patient peak tidal inspiratory flow<br>HFNC flow will be set at the level that is 1.33 times of patient peak tidal inspiratory flow | Other: HFNC flow set at 1.33 times of patient peak tidal inspiratory flow<br>* HFNC flow will be set at 1.33 times of patient peak tidal inspiratory flow<br>|
| Experimental: HFNC flow set at 1.67 times of patient peak tidal inspiratory flow<br>HFNC flow will be set at the level that is 1.67 times of patient peak tidal inspiratory flow | Other: HFNC flow set at 1.67 times of patient peak tidal inspiratory flow<br>* HFNC flow will be set at 1.67 times of patient peak tidal inspiratory flow<br>|
| Experimental: HFNC flow set at 2 times of patient peak tidal inspiratory flow<br>HFNC flow will be set at the level that is 2 times of patient peak tidal inspiratory flow | Other: HFNC flow set at 2 times of patient peak tidal inspiratory flow<br>* HFNC flow will be set 2 times of patient peak tidal inspiratory flow<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| SpO2/FIO2 | Twenty mins after each flow setting, pulse oximetry divided by fraction of inspired oxygen will be used to assess patient's oxygenation response to different flow | 20 minutes after each flow setting | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| End-expiratory lung volume assessed by EIT | Twenty mins after each flow setting, electrical impedance tomography (EIT) will be used to assess patient's end -expiratory lung volume 20 mins after each flow setting | 20 minutes after each flow setting | 
| self-evaluated comfort | Twenty mins after each flow setting, patient comfort will be assessed using a visual numerical scale with a score of 0 as the worst and 10 as the best comfort | 20 minutes after each flow setting | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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high-flow nasal cannula, flow setting, peak tidal inspiratory flow, hypoxemia