Effects of Oxygen Supplementation During the 6-Minute Walk Test in Chronic Respiratory Failure or Exertional Hypoxemia

The aim of this multicenter crossover trial is to describe the effect of adding a therapeutic dose of exertional oxygen therapy, in terms of exercise performance, gas exchange, heart rate, symptoms perception and subjective easiness of performance, in a cohort of subjects hospitalized in specialized pulmonary rehabilitation centers with a diagnosis of chronic respiratory failure and/or exertional hypoxemia due to chronic obstructive pulmonary disease or interstitial lung disease. Researchers will compare the walking performance during 6-minute walk test performed with the liters of oxygen administered as prescribed at rest (for patients with chronic respiratory failure) or in room air (for patients with exertional hypoxemia only), to the performance during a 6-minute walk test performed with the double the flow rate prescribed at rest, or with 2 L/min for patients with exertional hypoxemia only. The two tests will be performed in random order, at least 3 hours apart and no later than 24 hours apart from each other. The main outcome will be the difference between the distance walked in the two 6-minute walk test in the two conditions. Furthermore, will be also collected and compared: the oxygen saturation and heart rate every minute, the initial and final dyspnea and fatigue, as assessed by Borg scale, and the easiness of performance through a dedicated questionnaire. The estimated sample size will be 114 patients. This study will provide some basis for a more accurate prescription of exercise-related oxygen therapy, offering insights into the phenotype of patients who may derive the greatest benefit from this intervention. It will also stimulate discussion regarding the optimal timing and dosing of oxygen administration during exertion in patients with respiratory failure.