Effect of body position on esophageal pressure and measurement of pulmonary compliance

Abstract

In order to assess the effect of body position on esophageal pressure and pulmonary compliance, esophageal pressures were measured by means of a ‘long’ thin-walled balloon at the same lung volumes in different body positions in human subjects. Pulmonary compliance was measured by relating esophageal pressure change to associated lung-volume change. The data indicate that in the supine position false values of esophageal pressure and pulmonary compliance may be obtained. These false values appeared to be caused by an altered esophageal pressure as a result of gravity pressing other mediastinal structures against the esophagus. In the upright, lateral and prone positions esophageal pressures were similar to each other but different from those obtained in the supine position. These results suggest that measurements of esophageal pressure and pulmonary compliance in recumbent subjects are most reliable when made in the prone or lateral positions. Submitted on December 1, 1958