Imperial College School of Medicine, Hammersmith Hospital, London, UK.
Eur Respir J. 2013 Feb;41(2):453-61. doi: 10.1183/09031936.00082112. Epub 2012 Aug 30.
The transfer factor of the lung for nitric oxide (T(L,NO)) is a new test for pulmonary gas exchange. The procedure is similar to the already well-established transfer factor of the lung for carbon monoxide (T(L,CO)). Physiologically, T(L,NO) predominantly measures the diffusion pathway from the alveoli to capillary plasma. In the Roughton-Forster equation, T(L,NO) acts as a surrogate for the membrane diffusing capacity (D(M)). The red blood cell resistance to carbon monoxide uptake accounts for ~50% of the total resistance from gas to blood, but it is much less for nitric oxide. T(L,NO) and T(L,CO) can be measured simultaneously with the single breath technique, and D(M) and pulmonary capillary blood volume (V(c)) can be estimated. T(L,NO), unlike T(L,CO), is independent of oxygen tension and haematocrit. The T(L,NO)/T(L,CO) ratio is weighted towards the D(M)/V(c) ratio and to α; where α is the ratio of physical diffusivities of NO to CO (α=1.97). The T(L,NO)/T(L,CO) ratio is increased in heavy smokers, with and without computed tomography evidence of emphysema, and reduced in the voluntary restriction of lung expansion; it is expected to be reduced in chronic heart failure. The T(L,NO)/T(L,CO) ratio is a new index of gas exchange that may, more than derivations from them of D(M) and V(c) with their in-built assumptions, give additional insights into pulmonary pathology.
肺一氧化氮转移因子（T(L,NO)) 是一种新的肺气体交换测试。该程序类似于已经建立的肺一氧化碳转移因子（T(L,CO))。从生理学上讲，T(L,NO) 主要测量从肺泡到毛细血管血浆的扩散途径。在 Roughton-Forster 方程中，T(L,NO) 作为膜弥散能力（D(M)) 的替代物。红细胞对一氧化碳摄取的阻力占从气体到血液总阻力的~50%，但对于一氧化氮则要小得多。T(L,NO) 和 T(L,CO) 可以通过单次呼吸技术同时测量，并且可以估计 D(M) 和肺毛细血管血容量（V(c))。与 T(L,CO) 不同，T(L,NO) 不依赖于氧分压和血细胞比容。T(L,NO)/T(L,CO) 比值偏向于 D(M)/V(c) 比值和 α；其中 α 是 NO 与 CO 的物理扩散率之比（α=1.97)。T(L,NO)/T(L,CO) 比值在重度吸烟者中增加，无论是否有肺气肿的计算机断层扫描证据，并且在自愿限制肺扩张时降低；预计在慢性心力衰竭中降低。T(L,NO)/T(L,CO) 比值是一种新的气体交换指数，它可能比从它们衍生而来的 D(M) 和 V(c) 及其内置假设更能深入了解肺部病理学。
