High flow nasal cannula during walking in severe COPD patients: a randomized controlled trial.

Exercise tolerance may be significantly impaired in severe COPD. NIV increases the walking distance; however a 35% of patients do not tolerate it (Walker DJ et al. COPD 2015;1:546-51). Recently, it has been demonstrated that high flow nasal cannula (HFNC) improves the endurance time in severe COPD patients (Cirio S et al. Respir Med. 2016 Sep;118:128-132). However, the lack of an internal battery has limited its use for moving. Our study aimed to investigate if HFNC powered by an external battery increases the walking distance in COPD patients with exercise limitation. Thirteen stable COPD patients with a walking distance lower than 70% of predicted value associated to a modified Borg dyspnea SB ≥5 at 6-minute walk test (6MWT), were included. They performed two consecutive 6MWTs, in a randomised cross-over design: with and without HFNC at the same oxygen inhaled fraction. Twelve patients (one dropped-out) (mean ±SD age 69.5 ±10.3 yrs, forced expiratory volume in 1 second 25±5.6% predicted) were analysed. Walking distance was significantly higher using HFNC (median 306m (IQR 246-342) compare to no-HFNC (267m (IQR 228-294) (p In conclusion, HFNC may be safely used also during walking. In severe COPD with exercise limitation it improves the walking distance without worsening of dynamic hyperinflation.