Diffusing capacity: Difference between revisions

Revision as of 06:11, 12 December 2019

Revision as of 18:45, 21 May 2020

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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 = 20192020-1205-1221 }}</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 }}</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 }}</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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==History==

In one sense, it is remarkable that DL_CO has retained such clinical utility. The technique was invented to settle one of the great controversies of pulmonary physiology a century ago, namely the question of whether oxygen and the other gases were actively transported into and out of the blood by the lung, or whether gas molecules diffused passively.<ref>{{cite journal | author = Gjedde A | year = 2010 | title = Diffusive insights: on the disagreement of Christian Bohr and August Krogh | journal = Adv Physiol Educ | volume = 34 | issue = 4| pages = 174–185 | doi = 10.1152/advan.00092.2010 | pmid = 21098384 }}</ref> Remarkable too is the fact that both sides used the technique to gain evidence for their respective hypotheses. To begin with, [[Christian Bohr]] invented the technique, using a protocol analogous to the steady state diffusion capacity for carbon monoxide, and concluded that oxygen was actively transported into the lung. His student, [[August Krogh]] developed the single breath diffusion capacity technique along with his wife [[August Krogh|Marie]], and convincingly demonstrated that gasses diffuse passively,<ref>Krogh A. 1910 On the oxygen metabolism of the blood. Skand Arch Physiol 23: 193–199</ref><ref>Krogh A. 1910 On the mechanism of the gas-exchange in the lungs of the tortoise. Skand Arch Physiol 23: 200–216.</ref><ref>Krogh A. 1910 On the combination of hæmoglobin with mixtures of oxygen and carbonic acid. Skand Arch Physiol 23: 217–223.</ref><ref>Krogh A. 1910 Some experiments on the invasion of oxygen and carbonic oxide into water. Skand Arch Physiol 23: 224–235</ref><ref>Krogh A. 1910 On the mechanism of gas exchange in the lungs. Skand Arch Physiol 23: 248–278</ref><ref>Krogh A, Krogh M. 1910 On the tensions of gases in arterial blood. Skand Arch Physiol 23: 179–192.</ref><ref>Krogh A, Krogh M. 1910 Rate of diffusion into lungs of man. Skand Arch Physiol 23: 236–247</ref> a finding that led to the demonstration that capillaries in the blood were recruited into use as needed – a Nobel Prize–winning idea.<ref>{{Cite web | url=https://www.nobelprize.org/nobel_prizes/medicine/laureates/1920/krogh-bio.html | title=The Nobel Prize in Physiology or Medicine 1920}}</ref>

==See also==