STUDIES ON GAS RESORPTION FROM OCCLUDED LUNGS.

These studies showed that adsorption atelectasis results from the oabstruction of an airway with the resultant adsorption of gases distal to the obstruction by blood flowing through the pulmonary capillary bed. The gas exchange resulting in lung volume change is a function of gas partial pressure difference between the lung and the blood and the solubility coefficients for the gases present. However, no indication of studies determining the rate of lung collapse or the volume of lung collapsing for various gas mixtures could be found. Therefore, experiments were designed to study the volume and rate of lung collapse in rats with different inspired gas mixtures utilizing a new plethysmographic method. Arterial blood gases and pulmonary gas tensions were analysed to evaluate the factors determining final collapse volumes, the rate of lung volume change, and the time course of gas exchange resulting in final collapse volumes. Lung collapse was complete in denitrogenated animals. When the inspired gas was 100 oxygen the rate of lung collapse is constant at any given barometric pressure and can be accurately predicted if carbon dioxide and water vapor are considered. Theoretical treatment of the factors determining the rate of collapse is presented. Author