The Influence of Changes of Abdominal Tension upon Pulmonary Function.

Salkin (1) has recently studied normal physiological changes which occur in the abdominal cavity. He has described a process of adaptability in the abdominal muscles which tends to prevent changes in intra-abdominal pressure, and which he terms " abdominal accommodation." He considers this process to be a reflex mechanism dependent upon an intact neuromuscular system, and points out the clinical bearing on intraperitoneal conditions, and functional interrelationship between the pleural and peritoneal cavities. Previous attempts to obtain measurements of abdominal pressure have been accompanied by difficulties (2, 3, 4). When fluid is injected at a certain rate into the abdominal cavity hyperbolic curves are obtained in which the pressure rise is slow at first and then becomes more rapid. Although the physiology of the intra-abdominal pressure and tension of the abdominal wall has been studied in considerable detail, its relation to pressure within the pleural cavity has been insufficiently considered. Recent clinical observations by Gordon (5) have indicated the importance of change in abdominal pressure upon function of the thorax. He found that elevation of intra-abdominal pressure during pregnancy apparently influenced the course of chronic pulmonary diseases. In cases of chronic tuberculosis and bronchiectasis, cough, shortness of breath, and excessive sputum were diminished. He attributed the improvement to an increase of the intra-abdominal pressure, which in turn caused elevation of the leaves of the diaphragm. It has also been shown by Alexander and Kountz (6) that the vital capacity of an individual with chronic pulmonary emphysema may be improved by the application of an abdominal belt, which is believed to increase the intra-abdominal pressure and the tension of the abdominal wall. EXPERIMENTAL