Studies of free collapse in the intact human lung.

Abstract

Abstract 1.1. Free collapse of the lungs was studied in healthy young men by the rapid voluntary adjustment of intrathoracic pressure to an atmospheric level. A pressure constant spirometer was used to measure volume and volume flow rate. 2.2. A mathematical analysis of the mechanics of free collapse was presented. 3.3. An analysis of 45 free collapse curves revealed, within limits, that the behavior of the lungs could be predicted from static measurements of pulmonary compliance and interrupter measurements of the resistance to air flow. 4.4. The mean ratio of pressure to expiratory air flow during free collapse was 2.1 cm. of water per liter per second when measured at flow rates between 2 and 6 L. per second. 5.5. There was no increase in this ratio per unit of flow at rapid volume flow rates. This finding was attributed to the elastic properties of the bronchi and conducting airways.