Chronic hypoxaemia in chronic bronchitis and emphysema may lead to the development of pulmonary hypertension, and the occurrence of cor pulmonale remains a bad prognostic sign. This stage of the disease may be associated with a reduced respiratory drive, leading to hypercapnia and hypoxaemia. Long term oxygen treatment improves tissue oxyg?nation, reduces pulmonary hypertension, and prolongs survival in hypoxic cor pulmonale. Thus a controlled clinical trial of the Medical Research Council showed that 15 hours of continuous oxygen treatment a day was necessary and that an improvement was observed only after 500 days of treatment.l The use of chronic supplementary oxygen in this condition has been discussed previously.2 The introduction of oxygen concentrators has made home treatment with oxygen cheaper and more convenient,3 but it is essential that patients are adequately evaluated before this treatment is started and that they are supervised during treatment.4 Treatment of hypoxaemia solely with drugs, or in combination with oxygen treatment, remains a possibility. Interest has been shown in drugs that stimulate respiration and improve oxyg?nation in these patients, one particular drug being the peripheral chemo receptor stimulant almitrine. The use of pulmonary vasodilators to reduce the pulmonary hypertension of chronic obstructive airways disease is also being investigated.
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