Regional esophageal pressures with lobar obstruction in dogs

The right lower lobes (RLL) of intact horizontal dogs were obstructed at FRC during spontaneous breathing and artificial ventilation (IPPB). At end inspiration, pressure within the RLL became less than tracheal pressure, and pressure in the lower esophagus declined to a greater extent than in the upper esophagus. Tidal pressure swings in the obstructed RLL were larger than in the esophagus during spontaneous breathing but smaller during IPPB implying that the elastic recoil of the RLL decreased during inspiration at the mediastinal side. All these changes were intensified during RLL atelectasis and counteracted by strapping of the lower chest wall. These results indicate that: (a) around a lobe moving out of phase with the rest of the lung, a force is created tending to minimize the lobar volume differences; (b) the obstructed lobe is deformed during inflation of the rest of the lung; (c) esophageal (and hence pleural) pressure gradient is modified by this localized intrapulmonary pathology apparently due to shape interactions between chest wall and lung.