The use of high-flow nasal oxygen (HFNO) delivered with a battery-supplied portable device was more effective than usual oxygen supplementation for improving walking distance in patients with chronic obstructive pulmonary disease (COPD) and severe exercise limitation, according to study findings published in Respiration.

Patients in the study were recruited from a single center in Italy. All patients had COPD, were between the ages of 45 and 85 years, and had severe exercise limitation defined by a 6-minute walking test (6MWT) distance less than 300 meters with perceived dyspnea at the end of the test. In total, the study enrolled 20 stable patients with COPD after baseline 6MWT who required an oxygen inspiratory fraction (FiO2) less than 0.60 during exercise.

In the crossover trial, patients randomly performed a 6MWT on 2 consecutive days with either HFNO with a portable device (HFNO test) or oxygen supplementation by a Venturi mask (control) at isoFiO2. At the end of the tests, the investigators assessed walked distance, perceived dyspnea, pulse oximetry, and inspiratory capacity. Patient-reported comfort was also assessed at the end of the tests.

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A total of 9 patients (mean age, 70.3±10.2 years) were on home long-term oxygen therapy (LTOT), while 11 patients (mean age, 68.1±7.5 years) did not require oxygen during exercise. Patients with LTOT had a significantly lower mean body mass index (23.9±7.4 kg/m2 vs 25.2±3.8 kg/m2, respectively; P =.018).

At baseline, the mean 6MWT distance was 227.2±61.1 m. At the end of the study, the walking distance improved more with HFNO than with the control (+61.1±37.8 vs +39.7±43.8 m, respectively; P =.01). Specifically, the corresponding mean 6MWT distances for control and HFNO tests were 267.0±53.7 m and 288.4±58.7 m, respectively. Patients who were on LTOT had a significantly lower improvement in the 6MWT between control and HFNO test compared with patients not on LTOT (7.01±21.9 vs 33.1±33.3, respectively).

The investigators found no differences between the 2 tests in regard to dyspnea, peripheral oxygen saturation, or inspiratory capacity. The HFNO test was considered more comfortable by patients than the control test.

Limitations of the study included its small sample size, the lack of blinding across patients and assessors, as well as the assessment of only changes in inspiratory capacity vs other parameters of respiratory mechanics and hemodynamics.

The researchers wrote that while it may prove difficult “to propose the use” of the HFNO device in patients’ everyday life, the “tool might be useful in rehabilitation settings.” The investigators added that further studies were needed to identify clinical characteristics of patients most likely to respond to this treatment, as well as to assess the effectiveness of the portable device during the activities of the daily life.


Carlucci A, Rossi V, Cirio S, et al. Portable high-flow nasal oxygen during walking in patients with severe chronic obstructive pulmonary disease: a randomized controlled trial. Respiration. 2021;100(12):1158-1164. doi:10.1159/000517033