· There is strong evidence of survival benefit of long-term oxygen therapy (LTOT) in patients with COPD and severe chronic hypoxaemia when used for at least 15 hours daily.
· Therefore, oxygen therapy in COPD must be used with care in the acute setting but it can have distinct benefits in the long term. Chronic hypoxaemia causes slowly progressive pulmonary hypertension with the development of right ventricular hypertrophy and possible cor pulmonale with secondary polycythaemia. Secondary polycythaemia increases blood viscosity and hence resistance to flow. There is also sludging and a tendency to thrombosis.
· A Cochrane review of randomised controlled trials (RCTs) of domiciliary oxygen therapy for COPD found:
· Long-term home oxygen therapy improved survival in a selected group of COPD patients with severe hypoxaemia (arterial PaO2 less than 55 mm Hg (8.0 kPa)).
· Home oxygen therapy did not appear to improve survival in patients with mild-to-moderate hypoxaemia or in those with only arterial desaturation at night.
· National Institute for Health and Care Excellence Clinical Knowledge Summaries recommend that, if the patient will not stop smoking, oxygen therapy should be withheld.There is a real risk of fire and burns to the face and any benefit relating to polycythaemia is counteracted by smoking.