clarify when or not high flow nasal cannulae may be proposed as a valid alternative choise for hypercapnic acute respiratory failure COPD patients and when could be better to swich to non-invasive mechanical ventilation ?
Well. There are a lot of studies coming out however, it is still unclear whether it is safe to use HFNC in severely hypercapnic patients and whether it is effective in patients with long term O2 therapy or domiciliary O2. Personally I have used in very limited number of cases and cannot give a definitive opinion
In our ED, initially we go for short-term NIV with lower concentration of O2 after receiving a case of acute severe COPD exacerbation. It potentially relieves the acute exertions and prevents early fatigue. Then we proceed to other modules according to the development of the patient's conditions.
Dear N. Belloumi ,
In patients with acute severe exacerbations of COPD and hypercapnic RF, O2 therapy should be used with caution, especially in preclinical settings, as it increases the risk of death [1] and the risk of potentially fatal rebound hypoxemia upon abrupt removal [2].
A study by Girardis M. et al. showed that the unnecessary use of higher FiO2 could lower the probability of 60 days’ survival [3].
The (only) RCT by Lee M. et al. comparing the use of HFNC and NIV in AECOPD with MODERATE hypercapnic failure concluded that both strategies are equally effective [4].
According to current ERS/ATS guidelines by Rochwerg B. et al., the use of NIV in AECOPD patients with acute or acute on chronic RF with acidosis (pH
If you go to Google Scholar (https://scholar.google.com/) and search for "role of HFNC in acute exacerbation of COPD," you will find many published papers. Some of the studies compare HFNC and NIV.
Also suggest looking at the COPD Foundation's "Pocket Consultant Guide for the Diagnosis and Management of COPD" (https://www.copdfoundation.org/Praxis/Community/Blog/Article/747/Resource-of-the-Month-Just-updated-The-COPD-Foundation-s-Pocket-Consultant-Guide.aspx).
Regarding Aung Kyaw Soe's comment ... High Flow Nasal Cannula (HFNC) does not necessarily imply high FIO2. Done correctly you can have high gas flowrate, and a controlled low FIO2.
with high flow nasal cannulae you should not give high FiO2 to avoid exacerbation of hypercarpnia by haldane effect and elevation of dead space. For both technics (HFNC and NIV) their limiting factor is the effect of hypercapnia and acidosis on the level of consciouseness.
Thanks for your comment, Michael McPeck
Yes, you have pointed out an important advantage/possibility of HFNC.
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