Use in chronic conditions[edit]
A common use of supplementary oxygen is in patients with chronic obstructive pulmonary disease (COPD), the occurrence of chronic bronchitis or emphysema, a common long term effect of smoking, who may require additional oxygen to breathe either during a temporary worsening of their condition, or throughout the day and night. It is indicated in COPD patients with PaO
2 ≤ 55mmHg or SaO
2 ≤ 88% and has been shown to increase lifespan.[2][3][4]
Oxygen is often prescribed for people with breathlessness, in the setting of end-stage cardiac or respiratory failure, advanced cancer or neurodegenerative disease, despite having relatively normal blood oxygen levels. A 2010 trial of 239 subjects found no significant difference in reducing breathlessness between oxygen and air delivered in the same way