Diffusing capacities and ventilation: perfusion ratios in patients with the clinical syndrome of alveolar capillary block.

Studies were performed on 10 patients with the clinical syndrome of alveolar capillary block while each patient was breathing four different inspired oxygen mixtures. The data were interpreted using the principle of the Bohr integral isopleth with which alveolar oxygen tension in the differently ventilated parts of the lung can initially be treated as unknown. It is then possible to determine the distribution of ventilation, of perfusion, of diffusing capacity, of lung volume, and of alveolar and end capillary blood oxygen tension in the variously functioning parts of the lung. In two patients shunts were the major factor interfering with oxygen transfer. In four others inequalities in ventilation: perfusion ratios and in diffusing capacity in different parts of the lung were the factors interfering with oxygen transfer. In four more patients ventilation: perfusion ratios were the same throughout the lung, the only disturbance of oxygen transfer being in the total diffusing capacity or in its distribution between the different parts of the lung.