Piiper J, Meyer M, Marconi C, Scheid P
Respir Physiol. 1980 Oct;42(1):29-41. doi: 10.1016/0034-5687(80)90102-4.
Blood/gas equilibration of CO2 in lungs was studied in man by a rebreathing technique, in which the rate of uptake of the stable isotope 13CO2 in low concentration (inspired concentration about 0.07%) was measured at blood/gas equilibrium of the abundant CO2 isotope. The results were expressed in terms of overall conductance for alveolar gas-pulmonary blood equilibration (DCO2, pulmonary diffusing capacity for CO2). The following mean values of DCO2 were found in 3 healthy young men (in mmol . min-1 . Torr-1): rest, 8.0; during exercise (75 Watts), 13.7. Comparison with DO2 measured by rebreathing in the same conditions suggests equilibration of the CO2/HCO3(-)/H+ system in blood, rather than diffusion of CO2, as the limiting process in capillary/alveolar CO2 transfer. The term 'equilibration capacity' is thus suggested for DCO2. Calculations based on the experimental results show that the overall limitation of pulmonary CO2 exchange function resulting from this finite DCO2 is slight at rest, but of considerable extent in heavy exercise.
采用重复呼吸技术对人体肺部二氧化碳的血液/气体平衡进行了研究，该技术是在丰富的二氧化碳同位素的血液/气体平衡状态下，测量低浓度（吸入浓度约为0.07%）的稳定同位素13CO2的摄取速率。结果以肺泡气体-肺血液平衡的总传导率（DCO2，二氧化碳的肺扩散容量）表示。在3名健康年轻男性中发现了以下DCO2的平均值（单位为mmol·min-1·Torr-1）：静息时为8.0；运动时（75瓦）为13.7。在相同条件下通过重复呼吸测量的DO2与之比较表明，血液中CO2/HCO3(-)/H+系统的平衡，而非CO2的扩散，是毛细血管/肺泡间CO2转移的限制过程。因此，建议将DCO2称为“平衡容量”。基于实验结果的计算表明，这种有限的DCO2导致的肺二氧化碳交换功能的总体限制在静息时较小，但在剧烈运动时相当显著。
