Objectives

(1) To establish the general equation that describes relationship of DM_CO/Vc versus DL_NO/DL_CO under conditions with no functional heterogeneities. (2) To examine the effects of functional heterogeneities, including parallel and series (stratified) heterogeneities, on DL_NO/DL_CO.

Results and discussions: (1) Given that “true” θ_NO in pulmonary capillaries is represented by surface absorption-related θ_NO, relationship between DM_CO/Vc and DL_NO/DL_CO does not differ significantly from that obtained on premise of infinite θ_NO. DL_NO/DL_CO decided physiologically may mirror morphometric DM_CO/Vc actually working for gas exchange but not “total” morphometric ratio of DM_CO/Vc. (2) There are three parallel heterogeneities that affect diffusing capacity (D)-related parameters. Of them, only the heterogeneity of D/V_A, where V_A is alveolar volume, underestimates DL_CO and DL_NO. DL_NO/DL_CO does not alleviate negative impact of D/V_A heterogeneity, indicating that DM_CO/Vc estimated from DL_NO/DL_CO does not mirror “true” morphometric DM_CO/Vc in diseased lungs with D/V_A maldistribution. (3) Stratified heterogeneity underrates morphometric DM_CO, DM_NO, and DM_NO/DM_CO maximally by 1.4 %, 2.8 %, and 1.4 %, respectively, under conditions similar to single-breath D measurements, suggesting that effect of stratified heterogeneity on D measures is no longer needed to be considered in normal subjects but may be in patients having lung diseases with destructive lesions of acinar structures.

中文翻译：

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DLNO/DLCO 比率能否抵消腺泡区功能异质性的不利影响？

目标

(1) 建立描述无功能异质性条件下DM _CO /Vc与DL _NO /DL _CO关系的一般方程。(2) 检查功能异质性，包括平行和系列（分层）异质性，对 DL _NO / DL _{CO 的影响}。

结果与讨论： (1) 考虑到肺毛细血管中“真实”θ _NO由表面吸收相关的θ _{NO 表示}，DM _CO /Vc 与DL _NO /DL _CO之间的关系与在无限大的前提下获得的关系没有显着差异θ_否。生理学上决定的DL _NO / DL _CO可能反映实际用于气体交换的形态计量 DM _CO /Vc，但不是 DM _CO /Vc 的“总”形态计量比。(2) 存在影响扩散能力 (D) 相关参数的三个平行异质性。其中，只有 D/V _A的异质性，其中 V _A是肺泡体积，低估了 DL _CO和 DL _NO。DL _NO /DL _CO不会减轻 D/V _A异质性的负面影响，表明从 DL _NO /DL _CO估计的DM _CO /Vc不能反映D/V _{A 分布}不均的患病肺中的“真实”形态计量 DM _CO /Vc . (3) 分层异质性低估了形态计量 DM _CO、DM _NO和 DM _NO /DM _CO 在类似于单次呼吸 D 测量的条件下，最大分别为 1.4 %、2.8 % 和 1.4 %，这表明在正常受试者中不再需要考虑分层异质性对 D 测量的影响，但可能在患有肺的患者中具有腺泡结构破坏性病变的疾病。