Clinical Question – Why use High Flow Nasal Cannula? When should you use it over BIPAP?

HFNC offers several advantages compared to conventional oxygen therapy, including:

  1. Ability to deliver O2 at up to 60 LPMs at nearly 100% FiO2. This is huge compared to regular Nasal Cannula (1-6 LPMs, maxing out at 45% FiO2) and NRB (10-15 LPMs, ~ 95% FiO2).
  2. The oxygen is humidified. It’s comfortable to use. Unlike having a big honking mask blowing into your face, you get a smooth flow of Os up the nose.
  3. Provides a small amount of CPAP (2-6 cm H2O). This mechanically splints open the nasopharynx, preventing supraglottic collapse and decreasing nasopharyngeal resistance.
  4. Reduces work of breathing by assisting in dead-space washout.

When should you call RT to set-up HFNC?

  1. Type 1 (Hypoxemic) Respiratory Failure – This is the type of respiratory failure where oxygenation is the primary issue. Has great application in: Pneumonia, PE, Carbon Monoxide Poisonings.
  2. Respiratory Failure Patients where BIPAP is contraindicated – e.g. aspiration risk, actively vomiting, facial trauma, hyperactive delirium. If the patient fails HFNC, it can be used as a bridge to preoxygenate.
  3. Patients with copious respiratory secretions – Positive Pressure/BIPAP will impair expectoration.
  4. When the Diagnosis is Unclear – it’s much easier to speak to a patient on HFNC compared to BIPAP.
  5. Apneic Oxygenation – Preoxygenate with a NRB or BIPAP as normal. Push your meds and watch the SpO2 remain steady.
  6. Palliative Care Patients

Here’s a video of how to set-up HFNC. Picture credit goes to Reuben Strayer and SinaiEM alum Nelson Wong.


  1. PulmCrit – Mastering the Dark Arts of BiPAP and HFNC
  3. Deranged Physiology – High Flow Nasal Prongs
  4. EMUpdates – High Flow Nasal Cannula in the ED