Schrikker A C, de Vries W R, Zwart A, Luijendijk S C
Department of Medical Physiology, University of Utrecht, The Netherlands.
Pflugers Arch. 1989 Mar;413(5):523-7. doi: 10.1007/BF00594184.
The ratio of alveolar ventilations of He and SF6 (VA,He/VA,SF6) was determined in 7 healthy male subjects at rest and at three different levels of exercise on a bicycle ergometer (75, 150 and 225 W). This ratio was calculated from the ratio of the specific ventilations for these gases which were obtained from the decay of the end-tidal partial pressures of He and SF6 during a simultaneous, multiple-breath washout. In all experiments, VA for He was larger than VA for SF6. On the average, VA,He/VA,SF6 was equal to 1.09, and the mean values of this ratio at rest and at the three levels of exercise were not significantly different. Therefore, the difference in VA for He and SF6 (VA,He-VA,SF6) increased with increasing work load. Further, we used the mean value obtained for VA,He/VA,SF6 to calculate the ratio of excretion values (E1/E2) for pairs of hypothetical tracer gases with equal blood-gas partition coefficients and with different diffusivities in the gas phase. E1/E2 ranged from unity for lambda = 0 to about 1.08 for lambda = 10. At a given lambda, E1/E2 decreased with increasing ventilation-perfusion ratio of the lung. Thus, the difference between the excretion values of light and heavy tracer gases will be most pronounced under rest conditions and for gases that are well soluble in blood.
在7名健康男性受试者休息时以及在自行车测力计上进行三种不同运动强度（75瓦、150瓦和225瓦）的情况下，测定了氦气和六氟化硫的肺泡通气量之比（VA,He/VA,SF6）。该比值由这些气体的比通气量之比计算得出，比通气量通过同步多呼吸冲洗过程中氦气和六氟化硫潮气末分压的衰减获得。在所有实验中，氦气的VA大于六氟化硫的VA。平均而言，VA,He/VA,SF6等于1.09，该比值在休息时以及三种运动强度下的平均值无显著差异。因此，氦气和六氟化硫的VA差值（VA,He - VA,SF6）随工作负荷增加而增大。此外，我们用VA,He/VA,SF6的平均值计算了具有相等血气分配系数且在气相中扩散率不同的一对假设示踪气体的排泄值之比（E1/E2）。对于λ = 0，E1/E2为1，对于λ = 10，E1/E2约为1.08。在给定的λ下，E1/E2随肺通气灌注比增加而降低。因此，轻、重示踪气体排泄值的差异在休息条件下以及血液中溶解度良好的气体中最为明显。
