Role of Single-Breath Carbon Monoxide-diffusing Capacity in Monitoring the Pulmonary Effects of Bleomycin in Germ Cell Tumor Patients¹

Serial pulmonary function tests including single-breath carbon monoxide-diffusing capacity (DLco), forced vital capacity (FVC), and forced expiratory volume in 1 sec were performed in a relatively homogeneous group of male patients with germ cell tumors treated with vinblastine, bleomycin, and cis-diamminedichloroplatinum. Of the pulmonary function tests used, the DLco was shown to be the most sensitive indicator of subclinical bleomycin pulmonary effects. Decreases in DLco were both total dose and schedule dependent. Patients receiving their total dose of bleomycin at a rate of 25 ± 2 (S.D.) units/week developed a linear decrease in DLco with increasing total doses of bleomycin. Changes in FVC did not correlate with bleomycin total dose. Although both the mean DLco and FVC decreased after completion of bleomycin therapy, the mean FVC returned to base-line levels rapidly, whereas the decrease in mean DLco was persistent for several months. When routine volumetric tests (FVC and forced expiratory volume in 1 sec) and DLco are used in a systematic manner, DLco is the most sensitive indicator of the subclinical pulmonary effects of bleomycin in germ cell tumor patients treated with vinblastine, bleomycin, and cis-diamminedichloroplatinum.