Coffman Kirsten E, Chase Steven C, Taylor Bryan J, Johnson Bruce D
Mayo Graduate School, Mayo Clinic, 200 1(st) St. SW, Rochester, MN, USA.
Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, UK.
Respir Physiol Neurobiol. 2017 Jul;241:45-52. doi: 10.1016/j.resp.2016.12.007. Epub 2016 Dec 21.
Whether the specific blood transfer conductance for nitric oxide (NO) with hemoglobin (θ) is finite or infinite is controversial but important in the calculation of alveolar capillary membrane conductance (Dm) and pulmonary capillary blood volume (V) from values of lung diffusing capacity for carbon monoxide (DLCO) and nitric oxide (DLNO). In this review, we discuss the background associated with θ, explore the resulting values of Dm and V when applying either assumption, and investigate the mathematical underpinnings of Dm and V calculations. In general, both assumptions yield reasonable rest and exercise Dm and V values. However, the finite θ assumption demonstrates increasing V, but not Dm, with submaximal exercise. At relatively high, but physiologic, DLNO/DLCO ratios both assumptions can result in asymptotic behavior for V values, and under the finite θ assumption, Dm values. In conclusion, we feel that the assumptions associated with a finite θ require further in vivo validation against an established method before widespread research and clinical use.
一氧化氮（NO）与血红蛋白的特定血液转运传导率（θ）是有限还是无限存在争议，但在根据一氧化碳肺弥散量（DLCO）和一氧化氮（DLNO）的值计算肺泡毛细血管膜传导率（Dm）和肺毛细血管血容量（V）时很重要。在本综述中，我们讨论与θ相关的背景，探讨应用任一假设时Dm和V的结果值，并研究Dm和V计算的数学基础。一般来说，两种假设都能得出合理的静息和运动时的Dm和V值。然而，有限θ假设表明，次最大运动时V增加，而Dm不增加。在相对较高但仍属生理范围的DLNO/DLCO比值下，两种假设都可能导致V值出现渐近行为，在有限θ假设下，Dm值也会如此。总之，我们认为，在广泛的研究和临床应用之前，与有限θ相关的假设需要通过既定方法进行进一步的体内验证。
