In the study, “Physical Inactivity, Functional Status and Exercise Capacity in COPD Patients Receiving Home-Based Oxygen Therapy,” published in the journal COPD: Journal of Chronic Obstructive Pulmonary Disease, researchers aimed to identify the factors strongly associated with, or even determinants of, low levels of physical activity in daily life (PADL) in individuals with chronic obstructive pulmonary disease (COPD).[1] The study claims that these factors could be assessed in clinical practice and used to bring about interventions to improve them.
In this cross-sectional, observational study, the population sample consisted of patients registered on a long-term home oxygen therapy program. Eligible patients were set up with two separate home visits:

  • Visit One: The study aims were explained, patients signed a voluntary informed-consent form and pulmonary function was assessed.
  • Visit Two: All of the functional and exercise-capacity tests were conducted, and the questionnaires were applied. All assessments were performed by a previously trained, qualified physical therapist.

According to the study, all equipment and interfaces used were supplied under the municipal long-term home oxygen therapy program. The oxygen supply came from an EverFlo 5 LPM electric oxygen concentrator from Philips, and the interface used by the study participants was a nasal cannula. Pulmonary function was assessed with a spirometer, the Spirobank G from MIR, using the ATS/ERS guidelines and reference values for the Brazilian population. The severity of airway obstruction was classified according to the GOLD criteria. Fatigue was measured using the Brazilian Portuguese version of the Fatigue Severity Scale. Exercise capacity was assessed using the 6-Minute Step Test (6MST) and 1-minute Sit-to-Stand Test (STST).

The results of the study showed that COPD patients with longer daily duration of long-term oxygen therapy (LTOT) had reduced PADL.1 However, the researchers note that this could be because all the patients used an electric oxygen concentrator rather than a portable oxygen concentrator or refillable cylinders, which they say are expensive to refill and not necessarily affordable. Since the average use of LTOT was 18 hours, the researchers say their patients were “limited during most of the day by the length of the nasal cannula tubing to the concentrator, preventing them from going outside or even moving around the house.”[1]

The study also presented a correlation between fatigue and physical activity, with 90% of the study population reporting fatigue during daily activities.[1] However, the researchers urged further study to determine whether there is a clear causal relationship between these variables. Furthermore, both the result of the STST and daily time on LTOT were able to significantly explain severe physical inactivity in these individuals.