TEMPORAL COURSE OF GAS-EXCHANGE AND MECHANICAL COMPENSATION AFTER RIGHT PNEUMONECTOMY IN IMMATURE DOGS

To determine the temporal progression and magnitude of functional comp ensation in immature dogs raised to maturity after extensive lung rese ction, we performed right pneumonectomy (R-Pnx) or right thoracotomy w ithout pneumonectomy (Sham) in matched foxhounds at 2 mo of age. At 4, 8, 20, 40, and 60 wk after surgery, static transpulmonary pressure-lu ng volume relationships were determined. Lung diffusing capacity, memb rane diffusing capacity, pulmonary capillary blood volume, pulmonary b lood flow septal lung tissue volume, and lung volumes were measured si multaneously by a rebreathing technique. During maturation, total lung capacity, lung volume at a given distending pressure, and compliance were lower in the R-Pnx group than in the Sham group (P < 0.05). Pulmo nary viscous resistance at maturity was elevated after R-Pnx. There we re no significant differences in total lung diffusing capacity, membra ne diffusing capacity, pulmonary capillary blood volume, pulmonary blo od flow, and septal lung tissue volume between groups. Compensation of alveolar-capillary gas exchange was complete by 4-8 wk after R-Pnx, b ut compensation of mechanical properties remained incomplete throughou t maturation. Relative magnitude of compensation after R-Pnx was great er in dogs than in adult dogs studied previously by similar techniques .