Functional correlates of lung involvement in Wegener's granulomatosis. Use of pulmonary function tests in staging and follow-up.

To examine the usefulness of pulmonary function testing in the clinical management of patients with Wegener's granulomatosis, 22 subjects with biopsy proved disease were evaluated using routine functional parameters. Although reduced lung volumes and diffusing capacity occurred frequently, the most common abnormality was in obstruction to airflow. Comparison of these functional parameters with roentgenographic and clinical findings revealed that reduced lung volumes were useful in detecting focal infiltrates, mass or cavitary lesions and diffuse interstitial involvement whereas airflow measurements were useful in detecting focal large airway lesions. In people with evidence of limitation of airflow, respiratory complications frequently developed in the form of acute tracheal obstruction of lobar collapse. In addition, serial evaluation of lung function during treatment revealed that although in most patients lung volumes and airflow obstruction improved or stabilized, a reduction of diffusing capacity was common. These studies suggest that routine pulmonary function testing may be a useful tool in the staging of patients with Wegener's granulomatosis and in following responses to therapy.