Bates J H, Baconnier P, Milic-Emili J
Meakins-Christie Laboratories, McGill University, Montreal, Quebec, Canada.
J Appl Physiol (1985). 1988 May;64(5):2204-14. doi: 10.1152/jappl.1988.64.5.2204.
The application of the flow interrupter technique to series and parallel models of the respiratory system is examined theoretically, assuming instantaneous transmission of pressures and incompressible gases in the lung air spaces. The initial pressure change observed immediately after occlusion divided by the preocclusion flow gives an initial resistance (Rinit) equal to that of the airway tree when the model consists of compartments connected in parallel. When the compartments are connected in series, Rinit is the resistance of the most proximal airway only. In general, the initial pressure change is followed by a second slower change, reflecting equilibration of pressures between the compartments. The total postocclusion pressure change divided by the flow gives a steady-state resistance (Rss) whose value depends on the ventilation history before occlusion. When this history consists of a relaxed expiration Rss asymptotes from Rinit to a value higher than the zero-frequency resistance of the model as the expiratory time increases. However, the relative contributions of serial and parallel pendelluft and viscoelasticity to Rss cannot be determined from pressure and flow measurements made at the airway opening. Therefore in disease, the interrupter method does not permit one to say whether ventilation inhomogeneity or alteration in lung tissue properties is the predominant abnormality.
在假设肺内气腔压力瞬间传导且气体不可压缩的情况下，从理论上研究了气流阻断技术在呼吸系统串联和并联模型中的应用。当模型由并联连接的腔室组成时，阻塞后立即观察到的初始压力变化除以阻塞前的流量，得到的初始阻力（Rinit）等于气道树的阻力。当腔室串联连接时，Rinit仅为最近端气道的阻力。一般来说，初始压力变化之后会有第二个较慢的变化，这反映了腔室之间压力的平衡。阻塞后总的压力变化除以流量得到稳态阻力（Rss），其值取决于阻塞前的通气历史。当该历史包括一次松弛呼气时，随着呼气时间增加，Rss从Rinit渐近到一个高于模型零频率阻力的值。然而，串联和并联摆动通气以及粘弹性对Rss的相对贡献无法从气道开口处的压力和流量测量中确定。因此，在疾病状态下，阻断法无法让人判断通气不均匀性或肺组织特性改变哪个是主要异常。
