[Functional and clinical differentiation of chronic respiratory failure]

Respiratory insufficiency is defined as hypoxemia due to bronchopulmonary disorders. The site of the underlying disease can be exclusively in the parenchyma and vessels of the lung, but also in the pumping mechanisms with resulting CO2-retention. A combination of these phenomena is usually seen in patients of the predominant bronchitic Type B of chronic obstructive lung disease. Vascular and parenchymatous lesions cause hypoxemia by decrease of diffusion capacity, distribution inequality of blood flow and ventilation, and also shunting mechanisms. CO2-retention is not to be expected in these cases. The therapeutic approach is based on the individual predominance of functional findings in a given patient, and include medication to relieve bronchial obstruction, substitution of oxygen and measures for mechanical support of breathing. Especially bronchial obstruction should be identified as early as possible in the course of the disease in order to prevent inevitable and irreversible morphological changes.