The effect of overdistention of the lung on pulmonary function in beagle puppies

The removal of one lung from a beagle puppy results in minimal interference with lung function or the arterial gases. The removal of air from the empty pleural cavity results in a shift of the mediastinum and overdistention of the contralateral lung. An immediate decrease in the PO2 and increase in the PCO2 is seen. Significant increase in the alveolar-arterial CO2 gradient reflected marked increase in dead space ventilation. Biopsies of the overdistended lung demonstrated emphysema and disruption of alveoli. These changes may explain some of the deterioration of lung function and the complication of contralateral pneumothorax following repair of a Bochdalek diaphragmatic hernia. Our study suggests that the mediastinum should be stabilized in the midline after repair of a diaphragmatic hernia or after a pneumonectomy in an infant or small child.