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BackgroundThe effectiveness of the domiciliary use of high-flow nasal cannula oxygen therapy (HFNC) in patients with chronic hypercapnic respiratory failure due to chronic obstructive pulmonary disease (COPD) remains controversial.ObjectivesTo investigate the efficacy and safety of domiciliary HFNC use in stable hypercapnic COPD patients.MethodsThis multicenter, open-label, randomized controlled trial enrolled patients with stable hypercapnic COPD. Over 52 weeks, we compared long-term oxygen therapy (LTOT) alone versus domiciliary HFNC plus LTOT (HFNC/LTOT). The primary endpoint was the frequency of moderate/severe COPD exacerbations. We also compared changes from baseline levels in arterial blood gas, SpO2, pulmonary function, health-related quality of life (HRQOL), and a six-minute walk test.ResultsWe enrolled 104 patients in total; from these, we removed mismatching patients and then assigned 49 and 50 patients to HFNC/LTOT and LTOT groups, respectively, for safety analysis; 47 and 46 patients for HFNC/LTOT and LTOT groups, respectively, for efficacy analysis. Thirty-seven (79%) and 41 patients (89%) in HFNC/LTOT and LTOT, respectively, completed the final evaluation. HFNC significantly reduced the frequency of COPD exacerbations and prolonged the duration without moderate or severe COPD exacerbations over the 52-week study period (p = 0.002, p = 0.032, respectively). The adjusted odds ratios (95% confidence intervals [CIs]) of the frequency of COPD exacerbations in LTOT against HFNC/LTOT was 2.85 (1.48, 5.47). The median survival time (95% CI) to the first COPD exacerbation with moderate or severe for the LTOT group was 25 weeks (14.1, 47.4); however, the HFNC/LTOT group did not reach the median survival time. HFNC also caused statistically significant differences (p < 0.05) in the SpO2, FVC (%FVC), and FEV1 (%FEV1); however, these improvements were transient. There were no other improvements in arterial blood gas, pulmonary function, HRQOL, or six-minute walk test parameters. In addition, no safety concerns were identified for HFNC.ConclusionsHFNC may be a reasonable therapeutic choice in stable hypercapnic COPD patients with a history of exacerbations.Trial registration number: UMIN000028581, NCT03282019 (http://www.umin/ac.jp, https://clinicaltrials.gov/)

Background: Long-term oxygen therapy, including ambulatory oxygen, has been widely used for patients with COPD having chronic respiratory failure. However, factors important for selecting suitable carriers of ambulatory oxygen, such as a cylinder cart or backpack, remain unclear for patients with moderate-to-severe COPD. Methods: Twelve patients with moderate-to-severe COPD (mean age, 69.6 ± 7.3 years) performed a six-minute walk test (6MWT) with a cylinder cart and backpack in random order. The parameters of 6MWT with each carrier, pulmonary function test results, and a questionnaire about the preference of each carrier after 6MWTs were analyzed. Results: The Δ distance (distance walked with a backpack - that waked with a cylinder cart) positively correlated with FEV1 (r=0.678, P=0.02) and lung diffusing capacity for carbon monoxide (DLCO) (r=0.606, P=0.048). Patients who could walk longer with a backpack were significantly higher in FEV1 (1.3 ± 0.8 vs. 0.8 ± 0.1 L, P=0.040) and DLCO (13.6 ± 2.1 vs. 8.2 ± 3.3 ml/min/mmHg, P=0.02) than those who walked longer with a cylinder cart. Additionally, patients who could walk longer with a backpack showed a lower maximum pulse rate and pulse rate after 6MWT than those who walked longer with a cylinder cart. Further, patients who preferred a backpack were significantly higher in percentage of predicted FVC (%FVC; 94.4 ± 17.2 vs. 65.5 ± 11.6% P=0.02) and lower in residual volume (2.7 ± 0.8 vs. 4.0 ± 0.6 L, P=0.042) than those who preferred a cylinder cart. Conclusions: FEV1, DLCO, and pulse rate during and/or after 6MWT can be important factors in the selection of proper ambulatory oxygen transport carriers for greater exercise capacity in patients with COPD having chronic respiratory failure.