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Is nasal high flow (NHF) suitable for treating patients with hypercapnic respiratory failure?

The facts about the impact of NHF on C02:

  • NHF reduces rebreathing of gas high in CO2 and oxygen-depleted - see the effect in action in the video below - on the left) 
  • The degree of dead space reduction appears to be flow-dependent (Moller et al. 2015) - see the graph below - on the right. 
Optiflow High Flow deadspace mechanism overview
NHF has been proven to reduce PaCO2 in COPD patients. Pantazopoulos et al. 2020. provides a review of the literature and proposes a treatment algorithm for COPD patients.

So, if the patient is:
  1. spontaneously breathing
  2. may benefit from a reduced PaCO2 or any of the other benefits of NHF
  3. is not otherwise indicated for mechanical ventilation (see guidance docs below)

NHF may be a suitable treatment.

Several studies are currently underway (registered on investigating the effects of NHF on clinical outcomes in patients with hypercapnia, to assess if NHF can improve physiological parameters and clinical outcomes when used as primary respiratory support.