Studies on radiogenic pneumopathy. 3

From 1980 to 1984 lung function was investigated for a total of 105 patients with healthy lungs (76 mammary carcinomas, 29 testicular tumors) with healthy lung regions being inevitably exposed during radiotherapy at the linear accellerator 'Neptun 10p'. At nine intervals within a year after irradiation we determined the blood gases p/sub a/O2 with and without physical load of ergooxytensiometry (EOT). p/sub a/O2 and the base-acid status with measurement of pH, buffer bases (PB), base excess (BE) and standard bicarbonate (SBC). p/sub a/O2 without strain showed even for high degree of pneumonitis no significant drop. EOT after 6 minutes of exercise on a bicycle ergometer with an equivalent of 80 Watts facilitates a detection of even minor changes in the lung. p/sub a/O2 drops to 80% of its initial value for a high degree of pneumonitis with the minimum in the average at 88 d. The minimum p/sub a/O2 coincides with the maximum degree of pneumonitis. From the drop of p/sub a/O2 significant hints for a developing pneumonitis are obtained, a real early diagnosis, however, is hardly possible. p/sub a/CO2 and the acid-base metabolism showed no influence of radiogenic pneumopathy. (author)