[Long-term oxygen therapy for chronic respiratory failure. Rationale, indications, modalities]

Long-term oxygen therapy (LOT) has become quite popular over the last 20 years due to better knowledge of the beneficial effect (improved life expectancy, improved quality of life, stabilization of the pulmonary hypertension) and to technological progress (concentrators, liquid oxygen). Ambulatory techniques have greatly contributed to the widespread use of oxygen therapy as has the decision of the French National Health Insurance System to reimburse this costly treatment. Almost all the studies devoted to the clinical and functional aspects of LOT have concerned patients with chronic obstructive pulmonary disease (COPD). By extension, it is generally accepted that LOT is warranted in other forms of respiratory failure (diffuse fibrosis, cyphoscoliosis, cystic fibrosis, etc.) when blood gas criteria similar to those retained for COPD are present: PaO(2)<=55 mmHg during stable periods with control measurements at lest 3 weeks apart; PaO(2) between 56 and 60 mmHg if there is also an elevated red cell count or pulmonary hypertension, signs of cor pulmonale ou frank hypoxemia during sleep. These consensus indications are widely accepted but other indications remain controversial: should LOT be prescribed for moderate hypoexmia (PaO(2) >=60 mmHg), exercise-induced hyoxemia alone, sleep hypoxemia alone? Appropriate studies are lacking so systematic prescription of LOT cannot be recommended in these three situations. The duration of LOT should be >=16 h/d, and if possible >=18 h/d. It has been established that objective results (life expectancy, improvement in pulmonary hypertension) are better for longer daily treatment. Patient compliance is however often insufficient. In addition to education, the best way to improve patient participation is to strive for improved quality of life with oxygen therapy (portable device, liquid oxygen) in these patients.