Burger R E, Meyer M, Graf W, Scheid P
Respir Physiol. 1979 Jan;36(1):19-37. doi: 10.1016/0034-5687(79)90012-4.
Pulmonary exchange of O2 and CO2 was measured in unidirectionally ventilated ducks in an attempt to determine lung O2 diffusing capacity, DO2. Perfusion shunt (= venous admixture) was estimated from O2 exchange in hyperoxia, and the ventilation shunt (ventilation of non-perfused parallel lung units) was estimated from exchange of the highly soluble inert gas, chloroform. Differences in the ventilation/perfusion ratio of parallel lung units were assessed from measurement of CO2 exchange using a parallel two-compartment model. DO2 values were calculated accounting for ventilation shunt, perfusion shunt, and inhomogeneity. Perfusion shunt averaged 2.7% and ventilation shunt, 9.4%. The ventilation/perfusion ratio in the two compartments differed on the average by a factor of 2.6. The uncorrected values of DO2, not accounting for lung inhomogeneities, progressively declined with increasing inspired PO2, but this dependence was less pronounced after correcting for lung inhomogeneities. The corrected value of DO2 averaged 100 mumol . min-1 . torr-1 for ducks of 1.8 kg mean body weight. DO2 did not differ when nitrogen was replaced by helium in the ventilatory gas indicating that diffusion within the air capillaries did not contribute a significant resistance to O2 uptake. The results suggest that neither functional inhomogeneities nor diffusion between lung gas and blood limit O2 uptake of the resting duck. Under conditions of elevated metabolism, however, these parameters may become rate-limiting for O2 supply.
在单向通气的鸭中测量了氧气（O₂）和二氧化碳（CO₂）的肺交换，以试图确定肺O₂扩散容量（DO₂）。通过高氧条件下的O₂交换估算灌注分流（即静脉血掺杂），并通过高溶解性惰性气体氯仿的交换估算通气分流（未灌注的平行肺单位的通气）。使用平行双室模型通过测量CO₂交换评估平行肺单位通气/灌注比的差异。计算DO₂值时考虑了通气分流、灌注分流和不均匀性。灌注分流平均为2.7%，通气分流为9.4%。两个室的通气/灌注比平均相差2.6倍。未校正的DO₂值（未考虑肺不均匀性）随着吸入PO₂的增加而逐渐下降，但在校正肺不均匀性后这种依赖性不太明显。对于平均体重为1.8 kg的鸭，校正后的DO₂值平均为100 μmol·min⁻¹·torr⁻¹。当通气气体中的氮气被氦气取代时，DO₂没有差异，这表明气毛细血管内的扩散对O₂摄取没有显著阻力。结果表明，无论是功能不均匀性还是肺气体与血液之间的扩散都不会限制静息鸭的O₂摄取。然而，在代谢升高的情况下，这些参数可能会成为O₂供应的限速因素。
