Static lung function in puppies after pneumonectomy.

We performed left pneumonectomy on eight puppies at 9 wk of age; seven littermates underwent a sham operation and functioned as controls. All were studied at 20 wk of age, at which time the remaining lung in the animals with pneumonectomy had the same volume, weight, and surface areas as both lungs of the controls. Total lung capacity (TLC) was the same in controls and postpneumonectomy dogs, but in the latter, the ratio of functional residual capacity to TLC (FRC/TLC) and that of residual volume to TLC (RV/TLC) were larger. Lung pressure-volume curves also differed, postpneumonectomy dogs demonstrating slightly greater recoil at lung volumes below TLC. Therefore, the increased FRC and RV of postpneumonectomy animals could not be ascribed to changes in lung recoil and must have been caused by increased chest wall recoil perhaps related to differences in shape between lung and chest wall. Studies of regional lung function revealed reduced aerated lung in the left hemithorax of the postpneumonectomy dogs and increased FRC/TLC and RV/TLC at the left base. The abnormal distribution of regional volumes did not account entirely for the increase in overall FRC and RV. Comparison of excised lung pressure-volume curves in those measured in intact animals revealed better agreement in postpneumonectomy dogs than in controls.