Materials and Methods
Twenty patients with ILD and ten healthy control subjects recruited from employees of the medical center participated in the study. The diagnosis of ILD was based on a chest radiograph showing bilateral interstitial markings and normal heart size, pulmonary function tests, and histologic confirmation of an infiltrative process. The following different types of ILD were represented: idiopathic pulmonary fibrosis (n=ll); connective tissue disease (n = 2); sarcoidosis (n = 2); hypersensitivity pneumonitis (n = l); metastatic carcinoma (n = 2); radiation fibrosis (n= 1); and silicosis (n = 1). Biopsy of the lung was not performed in the two patients with connective tissue disease, in the patient with radiation fibrosis, or in the patient with silicosis. All of the patients complained of breathlessness during physical exertion at the time of investigation, and none was receiving cardiorespiratory or corticosteroid medications. At the time of testing, all patients were clinically stable. more
All control subjects were in good health and had normal lung (unction and 12-lead electrocardiogram. None was familiar with the purpose or techniques of the study. The protocol was approved by the Committee for Protection of Human Subjects at our institution, and written informed consent was obtained from all participants. For each subject, testing was conducted on a single day in the following order.
Pulmonary Function Tests
Flow-volume curves were measured with subjects in the seated position using the M100B testing system (Gould Inc, Dayton, OH). Values were selected from the best of three efforts having the greatest sum of FVC and FEV,. Predicted normal values were taken from Morris et al.w Lung volumes were measured by body plethysmography using the 2800 Autobox system (Gould Inc, Dayton, OH); predicted normal values were based on data from Bates et al.M Single-breath diffusing capacity for carbon monoxide was measured with the M100B system; the average of two values was used. Predicted normal values for Dsb were taken from Crapo and Morris.