Around 20% of the obese patients with higher body mass index (BMI) who are taken off the breathing tube and breathing machine (ventilator) end up needing it back to support breathing. The re-application of breathing tube is associated with poor outcomes, including high risk of pneumonia, longer hospital stays, and death. The purpose of this study is to assess if prophylactic use of noninvasive breathing support after removing the breathing tube lowers the chance of needing the breathing tube again.

Patients with obesity are at risk of developing respiratory failure due to reduced lung volumes and chest wall compliance. Obesity is one of the easily identifiable, contributing factors of extubation failure that often leads to prolonged mechanical ventilation use and ICU stay. The early application of noninvasive respiratory support, especially NIV, has been shown to reduce reintubation rates in obese patients in a small, non-randomized study. However, prolonged use of NIV is often associated with decreased patient compliance and increased incidence of skin breakdown. HFNC is a noninvasive strategy that is comfortable, uses a nasal cannula and provides a high flow rate to meet the patient's inspiratory flow demand and thereby reduce work of breathing.

The purpose of this RCT will be to determine the effects of using NIV alternating with HFNC for reducing the treatment failure rate compared with HFNC alone in extubated patients with severe obesity. We hypothesize that early, prophylactic use of NIV alternating with HFNC will decrease the risk of respiratory failure (treatment failure) in severely obese patients.

Inclusion Criteria:

1. Adult, age ≥ 18 years old
2. Receiving invasive mechanical ventilation for ≥24 hours
3. BMI ≥40 kg/m2
4. Undergoing planned extubation per treating team
5. Arterial pH ≥7.35 or venous pH ≥ 7.31 within 30 mins of spontaneous breathing trial (SBT)

Exclusion Criteria:

1. Pregnant
2. Use of extra-corporeal membrane oxygenation
3. Chronic tracheostomy in place
4. Unplanned or accidental extubation
5. Terminal/compassionate extubation
6. Contraindication to NIV use
7. Intubated because of an acute exacerbation of COPD
8. Underlying neuromuscular disease
9. No reintubation requested by patient/family
10. Documented/known history of chronic hypercapnic respiratory failure on home NIV (including bilevel PAP).
11. Enrolled in any other outcome study
12. Treating clinician feels that HFNC or NIV are either mandatory or contraindicated for a given patient