Alveolar-arterial equilibration in the lung of sheep.
In order to compare the efficiency of sheep lung with that of dog, gaseous exchange in hypoxia (FIO2 0.12-0.13) with and without CO in the inspired air ( FICO 0.001) was measured in 12 sheep (mean body weight = 30.4 kg) under pentothal anesthesia and artificial ventilation. Alveolar-arterial pressure difference of O2, % venous admixture and amount of VA/Q inhomogeneity were found to be substantially larger than in dog. Steady-state pulmonary diffusing capacity estimates, computed by three different procedures were, both for O2 and for CO, about 40% smaller than in dog. The DLO2/DLCO ratios were not significantly different from those determined on dog data: thus, the presumed beneficial effect of sheep small erythrocytes on O2 transfer could not be demonstrated. Because its DLO2/MO2 ratio is lower than that of dog, sheep appears to be more adequate than dog as a model for human alveolar-arterial gas exchange.
D000818:Animals; D002245:Carbon Dioxide / Q000502:physiology; D002248:Carbon Monoxide / Q000097:blood / Q000378:metabolism; D004285:Dogs / Q000378:metabolism; D007700:Kinetics; D010100:Oxygen / Q000378:metabolism* / Q000502:physiology; D010313:Partial Pressure; D011650:Pulmonary Alveoli / Q000378:metabolism*; D011653:Pulmonary Diffusing Capacity; D011659:Pulmonary Gas Exchange; D012119:Respiration; D012756:Sheep / Q000378:metabolism*; D014692:Ventilation-Perfusion Ratio
D002245:Carbon Dioxide; D002248:Carbon Monoxide; D010100:Oxygen