COPD and respiratory distress

Oxygen and its mixing with air are used in hospitals and at home for oxygen therapy. The treated pathologies are hypoxia (mismatch between tissue needs and contributions in oxygen to the lungs) and hypoxemia (decreased oxygen concentration in the blood).
The consequences for the patient can be acute respiratory distress and even chronic respiratory distress COPD (Chronic Obstructive Pulmonary Diseases).
The WHO estimated prevalence of 3% of the world population, a tenth is treated in hospital or at home. Symptoms can be a shock, even hemorrhagic shock , disorders of consciousness. There is a direct link with pollution and cigarette