Xie C, Rong Z, Li Z, Yan Y, Light R W
Department of Pulmonary Medicine, First Affiliated Hospital of Sun Yat-sen University of Medical Sciences, Guangzhou.
Chin Med J (Engl). 1996 Nov;109(11):840-7.
To establish predicted values of membrane diffusing capacity (Dm) and pulmonary capacity blood volume (Vc), to compare the predicted values from our equations with those for Caucasians, to determine whether there are changes initially in Dm or Vc in patients with mild emphysema.
Diffusing capacity for carbon monoxide (DLco), Dm and Vc were determined in 86 normal subjects and 16 patients using the single-breath diffusing capacity for carbon monoxide (DLcosB) with two different alveolar concentrations of oxygen.
The predicted equations are as follows. For males, DLco (ml/min/mm Hg) = 0.37H-0.19A-27.8; Dm (ml/min/mm Hg) = 0.65H-0.24A-53.7; Vc(ml) = 0.88H-78.9. For females, DLco = 0.28H-22.7; Dm = 0.59H-53.6; Vc = 66.6-0.36A. DLco and Vc are lower in Chinese than Caucasians while Dm is similar in Chinese and Caucasians. Eleven of 16 patients had a low DLco (< 80% predicted value), 12 had a low Dm and 5 had a low Vc. Eight of 12 patients with a low Dm also had a low DLco, but in 4 the DLco was normal. Nine of 12 with low Dm had a normal Vc.
This study provides prediction equations of Dm and Vc. Chinese have a low DLco because their Vc is lower than Caucasians. The DLco and Dm are abnormal in a comparable percentage of patients. In patients with mild emphysema, the Dm becomes abnormal before the Vc.
建立膜弥散容量（Dm）和肺容量血容量（Vc）的预测值，将我们方程得出的预测值与高加索人的预测值进行比较，以确定轻度肺气肿患者的Dm或Vc最初是否有变化。
使用两种不同肺泡氧浓度的单次呼吸一氧化碳弥散容量（DLcosB），对86名正常受试者和16名患者测定一氧化碳弥散容量（DLco）、Dm和Vc。
预测方程如下。男性：DLco（ml/min/mm Hg）=0.37H - 0.19A - 27.8；Dm（ml/min/mm Hg）=0.65H - 0.24A - 53.7；Vc（ml）=0.88H - 78.9。女性：DLco = 0.28H - 22.7；Dm = 0.59H - 53.6；Vc = 66.6 - 0.36A。中国人的DLco和Vc低于高加索人，而中国人和高加索人的Dm相似。16名患者中有11名DLco较低（<预测值的80%），12名Dm较低，5名Vc较低。12名Dm较低的患者中有8名DLco也较低，但4名患者的DLco正常。12名Dm较低的患者中有9名Vc正常。
本研究提供了Dm和Vc的预测方程。中国人的DLco较低是因为其Vc低于高加索人。相当比例的患者DLco和Dm异常。在轻度肺气肿患者中，Dm在Vc之前出现异常。
