Johnson T S, Swanson G D, Sodal I E, Reeves J T, Virtue R W
J Appl Physiol Respir Environ Exerc Physiol. 1979 Jul;47(1):240-4. doi: 10.1152/jappl.1979.47.1.240.
The demonstration that the rate of rise of the alveolar fraction of nitrous oxide is enhanced when the inspired N2O concentration is high is termed the "concentration effect." A similar effect on a second gas has been termed the "second gas effect". These effects have been observed in open systems and attributed to differential changes between inspired and expired ventilation. The purpose of this investigation is to study these effects in a closed system. A breath-holding maneuver was utilized with a high and a low N2O concentration in argon and oxygen. The results indicate that breath holding with a high N2O concentration "concentrates" both the alveolar fraction of N2O and argon. These results are attributable to alveolar volume shrinkage as a consequence of the large absorption of N2O by the pulmonary blood. A mathematical model verifies this interpretation and suggests that volume shrinkage can be important in breath-holding maneuvers designed for noninvasive measurement of cardiac output and lung tissue volume.
当吸入的氧化亚氮浓度较高时，肺泡中氧化亚氮分数的上升速率会加快，这一现象被称为“浓度效应”。对第二种气体产生的类似效应则被称为“第二气体效应”。这些效应在开放系统中已被观察到，并归因于吸入和呼出通气之间的差异变化。本研究的目的是在封闭系统中研究这些效应。在氩气和氧气中，采用高浓度和低浓度的氧化亚氮进行屏气操作。结果表明，高浓度氧化亚氮屏气会使氧化亚氮和氩气的肺泡分数都“浓缩”。这些结果归因于肺血对氧化亚氮的大量吸收导致的肺泡体积缩小。一个数学模型验证了这一解释，并表明在为无创测量心输出量和肺组织体积而设计的屏气操作中，体积缩小可能很重要。
