STUDIES OF THE VENTILATION-PERFUSION RELATIONSHIPS IN THE LUNGS OF SUBJECTS WITH CHRONIC PULMONARY EMPHYSEMA, FOLLOWING A SINGLE INTRAVENOUS INJECTION OF RADIOACTIVE KRYPTON (Kr85). I. PRESENTATION AND VALIDATION OF A THEORETICAL MODEL *

Abstract

For purposes of analysis of relationships between alveolar ventilation and blood perfusion, the body of patients with chronic pulmonary emphysema is considered to consist of 3 compartments linked by the circulation: well and poorly ventilated alveoli and tissues. The differential equations describing this model are solved for Kr85 concentration in arterial and mixed venous blood and expired gas, as well as in the various alveolar gases. Expired gas, arterial and mixed venous blood samples were analyzed for up to 30 minutes after intravenous injection of respectively 600 and 1000 [mu]c of Kr85 in 2 patients. The slow elimination of the injectate is determined by the large volume of very poorly ventilated alveoli. Three methods for determining the distribution of blood flow among the differently ventilated alveoli are presented. They depend on the analysis of rates of change of Kr85 concentration in some or all of the three vehicles (expired gas, arterial and mixed venous blood) available for sampling.