Ten patients had been taking low-dose steroids and/or d-penicillamine for one to three years. Six of ten patients had been taking prednisolone 10-mg/ day, two patients had been taking d-penicillamine 250 mg/day, and two patients had been taking prednisolone and d-penicillamine. An appropriate informed consent was obtained from all the subjects studied.
Pulmonary function tests (Transferscreen II/o Jaeger, Germany) included the following: (1) spirometry; (2) recording of maximum expiratory flow-volume curves and maximum flow at 75, 50, and 25 percent of vital capacity; (3) lung volume determination, using the helium dilution technique; and (4) measurement of carbon monoxide diffusing capacity using the single breath method. The following indices were analyzed: forced vital capacity (FVC), forced expiratory volume in 1 s (FEVJ, FEV/FVC ratio, maximum expiratory flow at 25 percent of vital capacity (MEF25), total lung capacity (TLC), residual volume (RV£ RV/TLC ratio, diffusing capacity for CO (Deo), and the Dco/alveolar volume ratio, otherwise named the Kco index. For both FVC and FEVlt the largest value between three acceptable efforts of each patient is presented, while the mean value of at least two efforts is presented for lung volume and diffusing capacity measurements.