Diffusing capacity: Difference between revisions

Revision as of 18:45, 21 May 2020

Revision as of 18:02, 31 August 2020

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| OtherCodes = CPT: 94720

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'''Diffusing capacity''' of the lung (D_L) (also known as Transfer factor is another expression for the formerly used diffusing capacity.) measures the transfer of gas from air in the lung, to the [[red blood cell]]s in lung blood vessels. It is part of a comprehensive series of [[pulmonary function testing|pulmonary function tests]] to determine the overall ability of the [[lung]] to transport gas into and out of the blood. D_L, especially [[DLCO|D_LCO]], is reduced in certain diseases of the lung and heart. D_LCO measurement has been standardized according to a position paper<ref name="multiple">{{cite journal |vauthors=Macintyre N, Crapo RO, Viegi G, etal | year = 2005 | title = Standardisation of the single-breath determination of carbon monoxide uptake in the lung | url = | journal = Eur Respir J | volume = 26 | issue = 4| pages = 720–35 | doi = 10.1183/09031936.05.00034905 | pmid = 16204605 | s2cid = 18177228 }}</ref> by a task force of the [[European Respiratory Society|European Respiratory]] and [[American Thoracic Society|American Thoracic]] Societies.

In [[respiratory physiology]], the diffusing capacity has a long history of great utility, representing [[Electrical resistance and conductance|conductance]] of gas across the alveolar-capillary membrane and also takes into account factors affecting the behaviour of a given gas with hemoglobin.{{Citation needed|reason=uncited definition|date=March 2014}}

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== Interpretation ==

In general, a healthy individual has a value of <math>D_{L_{CO}}</math> between 75% and 125% of the average.<ref name=uppsala>LUNGFUNKTION - Practice compendium for semester 6. Department of Medical Sciences, Clinical Physiology, Academic Hospital, Uppsala, Sweden. Retrieved 2010.</ref> However, individuals vary according to age, sex, height and a variety of other parameters. For this reason, reference values have been published, based on populations of healthy subjects<ref>{{cite journal |vauthors=Miller A, Thornton JC, Warshaw R, Anderson H, Teirstein AS, Selikoff IJ | year = 1983 | title = Single breath diffusing capacity in a representative sample of the population of Michigan, a large industrial state. Predicted values, lower limits of normal, and frequencies of abnormality by smoking history | url = | journal = Am Rev Respir Dis | volume = 127 | issue = 3| pages = 270–7 | pmid = 6830050 | doi = 10.1164/arrd.1983.127.3.270 | doi-broken-date = 2020-0508-2131 }}</ref><ref>{{cite journal |vauthors=Knudson RJ, Kaltenborn WT, Knudson DE, Burrows B | year = 1987 | title = The single-breath carbon monoxide diffusing capacity. Reference equations derived from a healthy nonsmoking population and effects of hematocrit | url = | journal = Am Rev Respir Dis | volume = 135 | issue = 4| pages = 805–11 | pmid = 3565929 | doi=10.1164/arrd.1987.135.4.805}}</ref><ref>{{cite journal |vauthors=Cotes JE, Chinn DJ, Quanjer PH, Roca J, Yernault JC | year = 1993 | title = Standardization of the measurement of transfer factor (Diffusing capacity) | url = | journal = Eur Respir J Suppl | volume = 16 | issue = | pages = 41–52 | pmid = 8499053 | doi = 10.1183/09041950.041s1693 | s2cid = 54555111 }}</ref> as well as measurements made at altitude,<ref>{{cite journal |vauthors=Crapo RO, Morris AH, Gardner RM | year = 1982 | title = Reference values for pulmonary tissue volume, membrane diffusing capacity, and pulmonary capillary blood volume | url = | journal = Bull Eur Physiopathol Respir | volume = 18 | issue = 6| pages = 893–9 | pmid = 6927541 }}</ref> for children<ref>{{cite journal |vauthors=Koopman M, Zanen P, Kruitwagen CL, van der Ent CK, Arets HG | year = 2011 | title = Reference values for paediatric pulmonary function testing: The Utrecht dataset | url = | journal = Respir. Med. | volume = 105 | issue = 1| pages = 15–23 |pmid=20889322 | doi=10.1016/j.rmed.2010.07.020}} Erratum in ''Respir. Med.'' 2011 Dec;105(12):1970-1.</ref> and some specific population groups.<ref>{{cite journal |vauthors=Chin NK, Ng TP, Hui KP, Tan WC | date = Jun 1997 | title = Population based standards for pulmonary function in non-smoking adults in Singapore | url = | journal = Respirology | volume = 2 | issue = 2| pages = 143–9 | pmid = 9441128 | doi=10.1111/j.1440-1843.1997.tb00070.x}}</ref><ref>{{cite journal |vauthors=Piirilä P, Seikkula T, Välimäki P | year = 2007 | title = Differences between Finnish and European reference values for pulmonary diffusing capacity | url = | journal = Int J Circumpolar Health | volume = 66 | issue = 5| pages = 449–57 | pmid = 18274210 | doi = 10.3402/ijch.v66i5.18316 | s2cid = 22302973 }}</ref><ref>{{cite journal |vauthors=Ip MS, Lam WK, Lai AY, etal | title = Hong Kong Thoracic Society. Reference values of diffusing capacity of non-smoking Chinese in Hong Kong | url = | journal = Respirology | volume = 12 | issue = 4| pages = 599–606 | doi = 10.1111/j.1440-1843.2007.01084.x | pmid = 17587430 | date=July 2007}}</ref>

===Blood CO levels may not be negligible===

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====Lung conditions that increase <math>D_{L_{CO}}</math>.====

# Alveolar hemorrhage [[Goodpasture's syndrome]],<ref>{{cite journal|last=Greening|first=AP|author2=Hughes, JM|title=Serial estimations of carbon monoxide diffusing capacity in intrapulmonary haemorrhage.|journal=Clinical Science|date=May 1981|volume=60|issue=5|pages=507–12|pmid=7249536|doi=10.1042/cs0600507}}</ref> [[polycythemia]],<ref>{{cite journal|last=Burgess|first=J. H.|author2=Bishop, J. M.|journal=Journal of Clinical Investigation|volume=42|issue=7|pages=997–1006|doi=10.1172/JCI104804|pmc=289367|pmid=14016987|title=Pulmonary Diffusing Capacity and ITS Subdivisions in Polycythemia Vera|year=1963}}</ref> left to right [[Cardiac shunt|intracardiac shunts]],<ref>{{cite journal|last=AUCHINCLOSS JH|first=Jr|author2=GILBERT, R |author3=EICH, RH |title=The pulmonary diffusing capacity in congenital and rheumatic heart disease.|journal=Circulation|date=February 1959|volume=19|issue=2|pages=232–41|pmid=13629784|doi=10.1161/01.cir.19.2.232|s2cid=27264342}}</ref> due increase in volume of blood exposed to inspired gas.

# [[Asthma]] due to better perfusion of apices of lung. This is caused by increase in pulmonary arterial pressure and/or due to more negative pleural pressure generated during inspiration due to bronchial narrowing.<ref>{{cite journal|last=Collard|first=P|author2=Njinou, B |author3=Nejadnik, B |author4=Keyeux, A |author5= Frans, A |title=Single breath diffusing capacity for carbon monoxide in stable asthma.|journal=Chest|date=May 1994|volume=105|issue=5|pages=1426–9|pmid=8181330|doi=10.1378/chest.105.5.1426}}</ref>