Transpulmonary pressure. The vertical pleural pressure gradient along with the methods suggested for computation of transpulmonary pressure are represented. In supine patients, pleural pressure varies according to a vertical gradient, lower in nondependent lung and higher in dependent lung. As a consequence, the pressure developed across the lung, namely transpulmonary pressure, is higher in nondependent lung compared to dependent lung. The directly measured transpulmonary pressure reflects the pressure acting on the dependent and midlung adjacent to the esophageal balloon (red solid circle) during both inspiration and expiration. The end-inspiratory transpulmonary pressure computed by the elastance-derived method represents the end-inspiratory pressure acting on the nondependent lung regions.