[Acute and long-term effects of chronic obstructive lung diseases]

In patients with chronic obstructive pulmonary diseases and cor pulmonale, long-term treatment with oxygen leads to a reduction in pulmonary arterial pressure. The aim of this study was investigate the question as to the extent to which pulmonary arterial pressure reduction in response to acute administration of oxygen differed from the long-term effect of oxygen treatment, and whether it was possible to determine prognostic factors that would identify the patients who would obtain particular benefit from long-term oxygen therapy. Twenty patients suffering from severe obstruction, global respiratory failure and precapillary hypertension, were treated with oxygen for a period of 20 +/- 6 months. At the beginning of the treatment, the acute oxygen-induced reversibility of pulmonary hypertension with an FIO2 of 80% was established. After an average of 20 months, catheter examination was repeated. A comparison was made between reversibility with acute oxygen and the long-term effects of oxygen. Long-term treatment with oxygen led to a reduction in pulmonary arterial pressure (18%), which was comparable to the reversibility established for acute oxygen inspiration (20%). While, over the long-term, a reduction in pulmonary arterial pressure was caused solely by a drop in pulmonary vessel resistance, acute application of oxygen resulted in an approximately equal decrease in pulmonary vessel resistance and cardiac output. The more pronounced the pulmonary hypertension prior to treatment the greater the pressure reduction achieved with long-term oxygen treatment. Patients with a particularly marked acute oxygen reversibility also had greater long-term benefit, in the sense that, in these cases, the decrease in pulmonary arterial pressure was more substantial than in patients with smaller acute reversibility.