一氧化碳弥漫量

一氧化碳弥漫量（英语：Diffusing capacity of the lung for carbon monoxide，简称DLco或TLco^[1]）为一项测量肺泡与血液之间的气体交换能力的检查。本方法最早于1909年发展出来^[2]。

机制

本方法会先让受试者吸入微量的一氧化碳（CO），闭气数秒后呼出气体，再测量呼出气体的一氧化碳分压^[3]。一氧化碳与红血球具有高度亲和性，因此该指标与肺泡及血液的交换能力较为相关，较不会受心输出量（英语：cardiac output）影响^[4]。

DLco的测量会受到大气压力和海拔高度影响，这些误差可以用美国胸腔学会提供的方法进行校正^[5]。DLco的预期值也会受到血红蛋白、碳氧血红蛋白、性别，以及年龄影响。美国胸腔协会建议可以使用Cotes法对血红蛋白值进行校正^[6]^[7]。

DLCO 和 TLCO

一般来说，DLco的单位是“ml/min/mmHg”，而TLco的单位是“ml/min/kPa”。

影响因子

有许多呼吸性疾病会影响DLco的数值

减少

任何会影响肺泡交换面积的因素都会造成DLco下降：

肺泡壁交换障碍，如纤维化、肺泡炎（英语：Extrinsic allergic alveolitis）、血管炎
肺容积减低，如限制型肺病（英语：Restrictive lung disease）
肺气肿：肺泡遭到损伤，减少交换表面积^[8]
肺栓塞
心脏衰竭
肺高压
博来霉素（用量超过200单位时）
慢性心衰竭^[9]
低血容性贫血
胺碘酮累积用量过高；每日用量逾 400 mg。

但现在的技术能够校正因贫血导致的DLco下降。

增加

可能导致DLco增加的因子包含红血球增多症（英语：polycythaemia）、气喘（也可能正常），以及因为运动导致的肺脏血流量上升。其他因素还包含左至右心内分流（left to right intracardiac shunting）或肺泡出血（alveolar hemorrhage）^[10]。

临床意义

DLco 低于 60% 者代表若施行肺脏切除术，预后会不佳。FEV₁（英语：FEV1）有同样效果，但预测效果不若DLco好^[11]。

参考文献

^ Macintyre N, Crapo RO, Viegi G, et al. Standardisation of the single-breath determination of carbon monoxide uptake in the lung. Eur. Respir. J. October 2005, 26 (4): 720–35 [2018-04-28]. PMID 16204605. doi:10.1183/09031936.05.00034905. （原始内容存档于2019-10-18）.
^ Hughes J, Bates D. Historical review: the carbon monoxide diffusing capacity (DLCO) and its membrane (DM) and red cell (Theta.Vc) components. Respir Physiol Neurobiol. 2003, 138 (2-3): 115–42. PMID 14609505. doi:10.1016/j.resp.2003.08.004.
^ 高雄榮民醫院：衛教資料-肺動脈高壓診斷→肺動脈高壓診斷. [2018-04-28]. （原始内容存档于2018-04-29）.
^ Sue, DY; Oren, A; Hansen, JE; Wasserman, K. Diffusing capacity for carbon monoxide as a predictor of gas exchange during exercise. N. Engl. J. Med. 1987, 316 (21): 1301–1306. doi:10.1056/nejm198705213162103.
^ American Thoracic society, Single Breath Carbon Monoxide Diffusing Capacity (transfer factor) Recommendations for a Standard Technique- 1995 Update, Am J Respir Crit Care Med. 152 pp 2185-2198 (1995).
^ J.E. Cotes 1993, Lung Function, 5th Edition., Blackwell Scientific Publications, London
^ J.E. Cotes, J.M. Dabbs, P.C. Elwood, A.M. Hall, A. McDonald, and M.J. Saunders. Iron-deficiency anaemia: its effects on transfer factor for the lung (diffusing capacity) and ventilation and cardiac frequency during submaximal exercise. Clin. Sci. 42:325-33 (1972).
^ Bailey, Kristina L. The Importance of the Assessment of Pulmonary Function in COPD. The Medical clinics of North America. 1 July 2012, 96 (4): 745–752. ISSN 0025-7125. PMC 3998207  . PMID 22793942. doi:10.1016/j.mcna.2012.04.011.
^ Puri, Sundeep; Baker, B. Leigh; Dutka, David P.; Oakley, Celia M.; Hughes, J. Michael B.; Cleland, John G. F. Reduced Alveolar–Capillary Membrane Diffusing Capacity in Chronic Heart Failure: Its Pathophysiological Relevance and Relationship to Exercise Performance. Circulation. 1995-06-01, 91 (11): 2769–2774 [2018-04-28]. ISSN 0009-7322. PMID 7758183. doi:10.1161/01.CIR.91.11.2769. （原始内容存档于2018-06-24）（英语）.
^ Ruppel, G. L. (2009). Manual of Pulmonary Function Testing. ISBN 978-0-323-05212-2
^ Diffusion lung capacity for carbon monoxide (DLCO) is an independent prognostic factor for long-term survival after curative lung resection for cancer (p n/a) Michael J. Liptay, Sanjib Basu, Michael C. Hoaglin, Neil Freedman, L. Penfield Faber, William H. Warren, Zane T. Hammoud, Anthony W. Kim. Journal of Surgical Oncology. Published Online: Oct 1 2009 8:20AM doi:10.1002/jso.21407

参见

弥散量

外部链接

[pmid16204605-1] Macintyre N, Crapo RO, Viegi G, et al. Standardisation of the single-breath determination of carbon monoxide uptake in the lung. Eur. Respir. J. October 2005, 26 (4): 720–35 [2018-04-28]. PMID 16204605. doi:10.1183/09031936.05.00034905. （原始内容存档于2019-10-18）.

[2] Hughes J, Bates D. Historical review: the carbon monoxide diffusing capacity (DLCO) and its membrane (DM) and red cell (Theta.Vc) components. Respir Physiol Neurobiol. 2003, 138 (2-3): 115–42. PMID 14609505. doi:10.1016/j.resp.2003.08.004.

[3] 高雄榮民醫院：衛教資料-肺動脈高壓診斷→肺動脈高壓診斷. [2018-04-28]. （原始内容存档于2018-04-29）.

[4] Sue, DY; Oren, A; Hansen, JE; Wasserman, K. Diffusing capacity for carbon monoxide as a predictor of gas exchange during exercise. N. Engl. J. Med. 1987, 316 (21): 1301–1306. doi:10.1056/nejm198705213162103.

[5] American Thoracic society, Single Breath Carbon Monoxide Diffusing Capacity (transfer factor) Recommendations for a Standard Technique- 1995 Update, Am J Respir Crit Care Med. 152 pp 2185-2198 (1995).

[6] J.E. Cotes 1993, Lung Function, 5th Edition., Blackwell Scientific Publications, London

[7] J.E. Cotes, J.M. Dabbs, P.C. Elwood, A.M. Hall, A. McDonald, and M.J. Saunders. Iron-deficiency anaemia: its effects on transfer factor for the lung (diffusing capacity) and ventilation and cardiac frequency during submaximal exercise. Clin. Sci. 42:325-33 (1972).

[8] Bailey, Kristina L. The Importance of the Assessment of Pulmonary Function in COPD. The Medical clinics of North America. 1 July 2012, 96 (4): 745–752. ISSN 0025-7125. PMC 3998207  . PMID 22793942. doi:10.1016/j.mcna.2012.04.011.

[9] Puri, Sundeep; Baker, B. Leigh; Dutka, David P.; Oakley, Celia M.; Hughes, J. Michael B.; Cleland, John G. F. Reduced Alveolar–Capillary Membrane Diffusing Capacity in Chronic Heart Failure: Its Pathophysiological Relevance and Relationship to Exercise Performance. Circulation. 1995-06-01, 91 (11): 2769–2774 [2018-04-28]. ISSN 0009-7322. PMID 7758183. doi:10.1161/01.CIR.91.11.2769. （原始内容存档于2018-06-24）（英语）.

[10] Ruppel, G. L. (2009). Manual of Pulmonary Function Testing. ISBN 978-0-323-05212-2

[11] Diffusion lung capacity for carbon monoxide (DLCO) is an independent prognostic factor for long-term survival after curative lung resection for cancer (p n/a) Michael J. Liptay, Sanjib Basu, Michael C. Hoaglin, Neil Freedman, L. Penfield Faber, William H. Warren, Zane T. Hammoud, Anthony W. Kim. Journal of Surgical Oncology. Published Online: Oct 1 2009 8:20AM doi:10.1002/jso.21407

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