Gas exchange and lung mechanics during exercise in immature canines raised to maturity after right pneumonectomy

Immature male foxhounds underwent either right pneumonectotny (R-PNX, a=5) or right thoracotomy without pneumonectomy (SHAM, n=6) at 2 months of age. At 1 year after surgery, diffusing capacity of the lung for carbon monoxide (DL) and cardiac output (Qc) during exercise were measured by a rebreathing technique at increasing treadmill loads up to maximal Q2 uptake. Simultaneously total power on the lung (TLW) and dynamic compliance (Cdyn) were measured. Slope and intercept for the relationship of DL to Qc in (L/min)/kg body weights was compared between groups. R-PNX SHAM DL (mi-nun'l torr] kg- ' ) 2.59 0.419 2.46 0-478 NS Qc(nu-min-Lkrl) 688.1±79.1 711.9±12.8 NS Cdyn (ml'CmH2O-1) 57.3±7.5 119.7±12.5 p<0.001 TLW (kgm-min-1) 26.6±2.2 14,7±1.4 p<0.002 These data suggest that postpneumonectomy lung growth returns gas exchange and cardiac output at exercise to normal, but ventilatory power requirement was increased compared with the SHAM group, suggesting persistent abnormalities in the mechanical properties of the lung and/or airways in immature canines after pneumonectomv.