High-flow Nasal Cannula Oxygen Increased Exercise Tolerance
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High-flow nasal cannula oxygen therapy (HFNC) increases exercise tolerance — improving endurance times and reducing leg fatigue — in adults with stable idiopathic pulmonary fibrosis (IPF) having exercise-induced low blood oxygen levels, according to a small trial in Japan.
Notably, HFNC’s benefits were superior to those of standard oxygen therapy, supporting its use in IPF treatment, particularly during pulmonary rehabilitation. However, larger studies are needed to confirm its efficacy, the researchers noted.
Findings were detailed in the study, “Effect of high-flow nasal cannula oxygen therapy on exercise tolerance in patients with idiopathic pulmonary fibrosis: A randomized crossover trial,” published in the journal Respirology.
IPF is a chronic lung disease of unknown origin characterized by the formation of scar tissue in the lungs, making it hard for patients to breathe. Reduced physical activity is associated with a poorer prognosis in IPF patients, who have limited exercise capacity due to exercise-induced hypoxemia, or low blood oxygen levels.
“Nevertheless, it is important to perform [pulmonary rehabilitation] in IPF to enhance exercise tolerance and strengthen muscles,” which are associated with better outcomes, the researchers wrote.
Given that this form of rehabilitation therapy also includes aerobic exercise, “methods that minimize exercise-induced hypoxemia and dyspnea [shortness of breath] are warranted,” the team added.
Supplemental oxygen may help improve exercise tolerance and lessen shortness of breath during exercise therapy. Previous studies showed that HFNC was superior to conventional oxygen therapy at improving endurance times and reducing dyspnea and leg fatigue in people with chronic obstructive pulmonary disease (COPD), another serious chronic lung condition.
HFNC is a technique in which patients breathe in a heated, humidified gas mixture containing oxygen. It is widely used in IPF patients to overcome the lack of blood oxygenation associated with acute respiratory failure. However, the effects of HFNC on exercise tolerance in people with IPF remain largely unknown.
To address this, researchers in Japan conducted an open-label trial at the Kobe City Medical Center General Hospital, between December 2019 and November 2020.
The study enrolled 24 adults (18 men and six women) with stable, mild IPF who experienced exercise-induced hypoxemia. Participants, with a median age of 77.5 years, underwent two random-order, constant-load, bicycle-based exercise tests with HFNC or conventional oxygen therapy, separated by a week.
In one group, the exercise test was conducted first with HFNC and then with standard therapy, while an inverse order was applied in the other group. No patient had ever used these oxygen delivery devices.
All participants underwent initial incremental exercise testing without any oxygen supplementation to determine their maximal work rate and assess initial (baseline) values of each pre-selected indicator.
The study’s main goal was to assess changes in endurance time, defined as the time until exercise testing cessation due to shortness of breath, leg fatigue, or other symptoms. Secondary goals included changes in heart rate, oxygen saturation (oxygen being carried in the blood), shortness of breath, leg fatigue, and level of comfort while using the devices.
Results showed that 21 participants (87.5%) responded to HFNC, 11 of whom (52.4%) also showed improvements with standard oxygen therapy. Two other patients responded to conventional therapy only.
Both HFNC and conventional oxygen therapy significantly improved patients’ endurance time, oxygen saturation, and reduced shortness of breath, relative to baseline. Only HFNC resulted in a significant reduction in leg fatigue.
Notably, when comparing the two oxygen therapies, researchers found that HFNC was superior to conventional oxygen therapy at increasing endurance time (647.5 seconds, or about 10.5 minutes, vs. 577.5 seconds), oxygen saturation (96% vs. 94%), and reducing leg fatigue.
There were no significant differences between the two forms of oxygen therapy regarding maximum heart rate, shortness of breath, and comfort. No adverse events were reported.
These findings support the use of supplemental oxygen therapy, particularly HFNC, in exercise therapy in people with IPF.
Given that three patients did not respond to HFNC, further optimization of oxygen flow rate and fraction of inhaled oxygen may be needed, the team noted.
Future multicenter, larger studies are needed to confirm the safety and effectiveness of HFNC in improving exercise tolerance in IPF patients. Further research also should work on identifying the physiological mechanisms behind such potential benefits, the researchers noted.
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