Effects of high flow nasal cannula during exercise in COPD patients with exercise induced desaturation

Introduction: Chronic obstructive pulmonary disease(COPD) with exercise induced desaturation(EID) have poor prognosis. Pathophysiology of EID is increased dead space ventilation. High flow nasal cannula(HFNC) was shown to reduce dead space and delivered constant FiO2. Added HFNC during exercise could improve exercise training in COPD with EID. Aims: To compare the effects of supplemental HFNC, oxygen cannula(OC) and without oxygen(control) during exercise in COPD patients with EID. Methods: We performed a randomized crossover study in stable COPD patients with EID. Subjects were assigned to wear HFNC, OC or no oxygen supplement during constant work rate(WR) exercise testing on cycle ergometer. Work rate was set at 70% of maximum WR derived from a maximum incremental exercise test. Each test was randomly sequenced of device selection and performed on separate day. HFNC was set to deliver flow rate 60 Lpm, FiO2 0.4 and OC was set at 6 Lpm during exercise. We recorded exercise endurance time(Tex), time to desaturation(Tdsat) and rate perceived dyspnea(RPE). We used mixed effect linear regression model to compare between 3 groups. Results: Thirteen subjects were enrolled. Mean±SD age was 71.3±9.1 years and FEV1 66.4±19.5% predicted. Tex of HFNC and OC tests were 793.4±270.2vs768.3±265.4 sec compare to control 698.6±299.9 sec (p=0.12 and p= 0.25). Both HFNC and OC tests had longer Tdsat than control, 793.4±270.2vs675.7±288.5 and 364.7±339.8sec respectively, (p=0.008 and p=0.03). At iso-time, differences of RPE were not significantly reduced. Conclusions: HFNC and oxygen cannula slightly improved exercise endurance time in COPD patients with EID and lengthen time to desaturation during exercise.