Site and type of impaired lung function in extrinsic allergic alveolitis.

We investigated 109 persons exposed and sensitized against organic antigens. 46 of them (group I) are affected with the typical clinical and roentgenological signs of allergic alveolitis. The other 59 subjects (group II) were sensitized only. Included in all examinations were immunological diagnosis by means of counterimmunoelectrophoresis, systematic interviewing for case histories, and registration of respiratory symptoms. Pulmonary function was recorded by means of the following techniques: analysis of ventilation (flow-volume indices), respiratory mechanics of the larger airways and lung (body plethysmography, esophageal balloon technique), respiratory mechanics of the small airways (closing volume, amplitude of cardiogenic oscillations), distributional analysis, diffusion analysis, blood gas analysis, and right heart catheterization. Extrinsic allergic alveolitis caused changes in lung mechanics, in airways as well as in lung tissue. The most impressive findings in allergic alveolitis are mechanical inequalities of ventilation. These inequalities may be caused by changed mechanics of overall airways indicated by obstruction parameters and by changed structure of lung tissue reflected in decreased compliance, transfer factors and increased pulmonary arterial pressure. Not only a restrictive but also an obstructive disturbance of ventilation is found. Impairments are less in sensitized persons. We find slight mechanical and ventilatory inhomogeneities. An overall airway obstruction is obvious but not to such a large extent as in allergic alveolitis. On the contrary, here the lung tissue is not affected. Compliance and diffusion are within the normal range. There is no typical functional pattern specific for the diagnosis of allergic alveolitis.