Long Term Oxygen therapy

The assessment of hypoxic patients with COPD for oxygen therapy is important because this is the only treatment that has been shown to reduce mortality in this disease. The evidence for this comes from a seminal paper published in the 1980s known as the NOTT study (1) but evidence also comes from the MRC LTOT trial (2). These studies revealed that in patients with COPD and chronic hypoxia survival could be improved by the administration of oxygen for between 16 and 19 hrs. per day. A good summary of the oxygen trials is seen in the review by Alpers3.

Who should receive it?

Firstly the diagnosis of COPD has to be secure, the patient should ideally be a non-smoker and have severe disease. Patients with an FEV1 of <30% predicted and oxygen saturations of 92% or less should have an oxygen assessment, this is likely to become a QOF criteria for COPD. It is also one of the NICE Quality Standards criteria published in 2011. Other patient groups who should be assessed are those with cor pulmonale and/or polycythaemia.

Oxygen assessments are usually performed in secondary care, in Southampton City they are performed in The Respiratory Centre (TRC). Assessments should be at least 6 weeks after an exacerbation and performed on 2 separate occasions. Patients with a PaO2<7.3 or those with a PaO2 of <8.0 with cor pulmonale or polycythaemia are suitable for treatment. HOOFS (home oxygen ordering forms) are processed in the TRC.

Ambulatory Oxygen

Ambulatory oxygen therapy is usually prescribed to patients who require long term oxygen therapy and who leave the home on a regular basis receive oxygen for sufficient hours to gain the benefits of LTOT. For those patients who do not meet the criteria for LTOT, ambulatory oxygen therapy has been proposed as a means of improving exercise capacity and or health status. There is some evidence that AO improves the quality of life in those patients who desaturate during exercise. Ambulatory oxygen therapy therefore should only be prescribed after a specialist has performed an appropriate assessment.

Short Term Burst Oxygen Therapy

The use of short-term burst oxygen therapy has no evidence in the literature and is very expensive to prescribe. Its use is not recommended.

(1) Nocturnal Oxygen Therapy Trial Group. Continuous or nocturnal oxygen therapy in hypoxemic chronic obstructive lung disease a clinical trial. Ann Intern Med 1980; 93: 391±398.

(2) Report of the Medical Research Council Working Party. Long-term domiciliary oxygen therapy in chronic hypoxic cor pulmonale complicating chronic bronchitis and emphysema. Lancet 1981; 1: 681±686

(3) A review of long-term oxygen therapy for chronic obstructive pulmonary disease A. J. Crockett, J. M. Cranston, J. R. Moss And J. H. Alpers. Respiratory Medicine (2001) 95 437-443