Comparison of Published Pressure Gradient Symbols and Equations in Mechanics of Breathing

In the literature of pulmonary medicine we found dismaying diversity of and inconsistency in terms used to describe physiologic pressure gradients. Standardized terms, definitions, symbols, and equations published by the American Physiological Society, the American College of Chest Physicians, the American Thoracic Society, and the American Association for Respiratory Care have not been consistently used. Rather, researchers have often used their own definitions for transpulmonary pressure, transairway pressure, transthoracic pressure, transrespiratory pressure, and transdiaphragmatic pressure. We describe the variety of definitions and equations we found for those terms. We contend that it would benefit researchers, students, clinicians, and educators to define these terms precisely and use them consistently.