P8. Humidification therapy

Several trials have shown that nasal high flow (NHF) humidified air in stable COPD patients reduces transcutaneous CO2 (PtCO2) and respiratory rate. Fraser et al also found that 20 minutes of NHF reduced PtCO2 and respiratory rate and increased tidal volume in 30 male oxygen dependent COPD patients (Fraser 2016).  Of note, the patients reported that the standard nasal oxygen interface provided more dyspnea relief and was more comfortable.  In 6 non-hypoxic COPD patients, Biselli et al found that nocturnal NHF significantly decreased the work of breathing and improved PtCO2 levels, whereas oxygen produced only a minimal reduction in the work of breathing and increased carbon dioxide levels (Biselli 2017). McKinstry et al demonstrated a modest flow-rate dependent reduction in transcutaneous CO2 and respiratory rate with NHF compared to room air (McKinstry 2018).  A NHF flow rate of 45L/ min provided a 2.4 mm Hg (−2.9 to −1.8), P < 0.001 reduction in PtCO2 and a 4.3 (−5.5 to −3.1), P < 0.001 reduction in breaths per minute compared with room air.

A randomised trial by Rea et al (Rea 2010) found that NHF for up to 2 hours daily reduced annual exacerbation days and days to first exacerbation but not hospital admission compared with usual care in a group of 108 patients, with COPD/ bronchiectasis. Quality of life and lung function also improved. No sham treatment was given. No cost evaluation data were provided in this study.

In a 12 month study by Storgaard et al (Storgaard 2018), 200 Danish patients with stable hypoxaemic COPD who had commenced long term oxygen therapy (LTOT) within the preceding 3 months were randomised to LTOT alone or LTOT plus high flow nasal cannula (HFNC)  at 20 litres/minute with oxygen flow unchanged (mean 1.75 (0.8) L) for at least 6 hours per day. 67 patients in the HFNC group completed the trial and 71 in LTOT group. Analysis was by intention to treat. Exacerbation rate was decreased in the HFNC group but not hospitalisations. In a small study crossover by Nagata et al (Nagata 2018), use of nocturnal HFNC in addition to LTOT also demonstrated  significant  benefit in quality of life (SGRQ-C score improved by 7.8 points; (95% CI, 3.7-11.9; p<0.01) and measured PCO2 (-4.1 95% CI  -6.5, -1.7) .

The role of long term domiciliary HFNC is as yet still unclear.  Prospective randomised controlled trials in the appropriate COPD patient population with meaningful clinical endpoints are required before long term domiciliary NHF can be recommended.

In the acute setting, high flow nasal oxygen has a role in hypoxic respiratory failure where hypercapnia has been excluded (Stephan 2015, Frat 2015).