Magnussen H, Holle J P, Hartmann V, Schoenen J D
Respiration. 1979;37(4):177-84. doi: 10.1159/000194024.
Measurement of Dco is known to be dependent upon functional inhomogeneities. Because different types of inhomogeneities are operative in patients with bronchial asthma and patients with emphysema, different changes of Dco with increasing breath-holding time, tA, are to be expected. We studied the change of Dco with increasing breath-holding time in healthy subjects, patients with asthma bronchiale and patients with emphysema. In the patients the severity of airway obstruction was about the same. The following results were obtained: (a) in healthy subjects and in the asthmatics Dco decreased with tA, in a similar manner, approaching a value (ml . min-1 . Terror-1) of 34.7 and 31.6 at 10 sec, respectively, and (b) in patients with emphysema Dco increased with tA, yielding negative values at small tA: 1.5 sec-23.4; 10 sec: 11.7. From these results we suggest that in healthy subjects and in patients with bronchial asthma parallel inhomogeneities influence the course of Dco. In emphysema the time couse of Dco is best explained with a faster intrapulmonary mixing of He compared to CO. This behavior indicates that in emphysema low Dco values can be mainly attributed to large diffusional resistances (stratification) within the lungs.
已知一氧化碳弥散量（Dco）的测量取决于功能不均匀性。由于不同类型的不均匀性在支气管哮喘患者和肺气肿患者中起作用，因此随着屏气时间（tA）增加，预计Dco会有不同变化。我们研究了健康受试者、支气管哮喘患者和肺气肿患者中Dco随屏气时间增加的变化。患者的气道阻塞严重程度大致相同。得到以下结果：（a）在健康受试者和哮喘患者中，Dco随tA以类似方式下降，在10秒时分别接近34.7和31.6（毫升·分钟⁻¹·千帕⁻¹）的值；（b）在肺气肿患者中，Dco随tA增加，在小tA时产生负值：1.5秒时为-23.4；10秒时为11.7。从这些结果我们认为，在健康受试者和支气管哮喘患者中，平行的不均匀性影响Dco的变化过程。在肺气肿中，Dco的时间变化过程最好用氦气在肺内的混合速度比一氧化碳快来解释。这种行为表明，在肺气肿中，低Dco值主要可归因于肺内较大的扩散阻力（分层）。
