Snyder B, Jaeger M J
J Appl Physiol Respir Environ Exerc Physiol. 1983 Mar;54(3):749-56. doi: 10.1152/jappl.1983.54.3.749.
To demonstrate that the regional partitioning of flow in central airways is direction dependent, we compared inspiratory and expiratory lobar flows in a hollow rigid cast of canine lungs. Lobar flows were measured by a hot-wire anemometer, simultaneous tracheal flows by a pneumotachograph, and data displayed as (lobar) flow-(tracheal) flow curves. For tracheal airflows between 50 and 370 ml/s, we found that inspiratory apical flows were smaller, and basal flows larger, than corresponding expiratory distributions. This effect was largely extinguished by substituting a gas mixture of 85% He-15% N2; resulting regional flows were comparable to expiratory distributions obtained on room air. Thus canine central airways structure induces a kinematically irreversible flow pattern, consistent with a model of "cascade flow" in which branching structure modifies the distribution only of inspiratory flow. These results support Fowler's concept that lung regions fill and empty sequentially and may be pertinent to analyses of regional washout.
为了证明中央气道中气流的区域划分与方向有关，我们在犬肺的空心刚性铸型中比较了吸气和呼气时的叶间气流。叶间气流通过热线风速仪测量，气管气流同时通过呼吸流速计测量，数据显示为（叶间）气流-（气管）气流曲线。对于50至370毫升/秒之间的气管气流，我们发现吸气时的尖部气流比相应的呼气分布小，而基部气流比呼气分布大。用85%氦-15%氮的混合气体替代后，这种效应基本消失；由此产生的区域气流与在室内空气中获得的呼气分布相当。因此，犬中央气道结构诱导了一种运动学上不可逆的气流模式，这与“级联气流”模型一致，在该模型中，分支结构仅改变吸气气流的分布。这些结果支持了福勒的概念，即肺区域依次充盈和排空，并且可能与区域冲洗分析相关。
