The forces applied to the lung in health and disease

Abstract

The interaction between the lung and the chest wall and between adjacent lung units is such that when a part of the lung lags behind its neighbors, the pressure applied to it is amplified because of the distortions induced. This amplification acts as a homeostatic mechanism maintaining synchronous and homogeneous behavior of the lungs. Even in normal lungs, detectable phase lags are present between lower and upper lung zones at physiologic inspiratory flow rates, so that these mechanisms may be operating continuously, resulting in larger pleural pressure swings over lower lung zones. In disease, the mechanisms are even more important and must significantly influence the pathophysiology of a variety of diffuse lung diseases.