Measuring Lung Pressures in Critically Ill Children Who Are on Mechanical Ventilation

Transpulmonary pressure measurements are done by placing a catheter (often combined with a feeding tube) into the esophagus of a patient. Intermittently, the esophageal pressure is measured by inflating a small balloon on this catheter. The resulting esophageal pressure is accepted as representing the pleural pressure. The difference between this pressure and the airway pressure is the transpulmonary pressure and PEEP is raised or lowered to make this value zero so that the forces distending the alveoli are just balanced with the natural elasticity of the lung which wants to collapse the alveoli.