Steady state regional gas exchange in health and disease studied with 133Xe.

By inducing a steady state of 133Xe exchange across the lung and measuring the 133Xe concentration in individual lung regions, we were able to measure steady state regional ventilation/perfusion ratios (VA/Q). This technique was combined with independent assessments of regional ventilation and blood flow, and a variety of subjects studied. Erect normal subjects showed an apex-to-base gradient in VA/Q which, though sizable, did not explain all VA/Q variation reported in such lungs. Seated post-pneumonectomy patients wew examined; the increased flow through the remaining lung decreased, apex-to-base differences in perfusion and VA/Q, but ventilation distribution was unchanged. [...