Weaning Trial
- Cut in half and watch response
- Turn off and watch response
- Wean FiO2 before flow (~10% / hour)
How does HFNC decrease work of breathing?
- Primarily via dead space washout
- Secondarily via minor PEEP
The magnitude of positive airway pressure generated by HFNC is modest and highly dependent on flow rate and mouth closure, with end-expiratory nasopharyngeal pressures ranging from approximately 1 to 7 cm H₂O at flows of 40–60 L/min, but much lower when the mouth is open.[1-2]
While PEEP contributes to alveolar recruitment and reduced inspiratory effort in some patients, recent pediatric data indicate that dead space washout and reduction in respiratory rate are more consistent mechanisms than PEEP generation, especially in bronchiolitis.[3]
- High Flow Nasal Cannula Compared to Continuous Positive Airway Pressure: A Bench and Physiological Study.
- Effect of Respiratory Rate and Size of Cannula on Pressure and Dead-Space Clearance During Nasal High Flow in Patients With COPD and Acute Respiratory Failure.
- High-Flow Nasal Cannula Reduces Effort of Breathing but Not Consistently via Positive End-Expiratory Pressure.