Radiographic determination of total lung capacity in patients with pneumonectomy

To determine whether total lung capacity (TLC) can be measured from plain chest radiographs in patients with pneumonectomy, we examined 20 such patients (17 male, 3 female) who had pneumonectomy for lung carcinoma. In 16 patients the right lung was preserved, and in 4 the left. The TLC was measured with the helium dilution method and by planimetry of the anterior and lateral projections of the lung on chest radiographs, summing the anterior and lateral projected areas of the lung to a single value, S. The correlation between S and TLC by helium gas dilution was r = 0.95. Linear fit of TLC to S explained 99.5% of the variance in TLC, with the equation. The side resected did not influence the predictive value (p < 0.001). The interquartile range of the residual error was +/-130 ml, and standard error was 64 ml. Therefore in patients with pneumonectomy, TLC of the preserved lung may be estimated within +/-130 ml by planimetry of the anterior and lateral chest radiographs.