Long-term oxygen therapy (LTOT) is the reference treatment for chronic respiratory failure. This treatment is based on the principle of oxygen supplementation via a source to correct hypoxemia in patients. At present, adherence to this treatment is difficult to evaluate (reporting by patients), but the results of the literature show poor LTOT compliance. It is therefore important to accurately measure the oxygen consumption by patients and to understand the factors explaining LTOT compliance. The ultimate aim is to improve our patient management to make them more observant in order to improve the therapeutic efficacy of the treatment.