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<title>Diffusing capacity</title>

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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Diffusing capacity</span></span>

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</style><table class="infobox"><tbody><tr><th colspan="2" class="infobox-above" style="background-color: lightblue">Diffusing capacity</th></tr><tr><th scope="row" class="infobox-label"><a href="Medical_Subject_Headings" title="Medical Subject Headings">MeSH</a></th><td class="infobox-data"><span class="reflink nourlexpansion"><a rel="nofollow" class="external text" href="https://meshb.nlm.nih.gov/record/ui?ui=D011653">D011653</a></span></td></tr><tr><th scope="row" class="infobox-label">Other <a href="Procedure_codes" class="mw-redirect" title="Procedure codes">codes</a></th><td class="infobox-data">CPT: 94720</td></tr></tbody></table>

<p><b>Diffusing capacity</b> of the lung (D<sub>L</sub>) (also known as <i>transfer factor</i>) measures the transfer of gas from air in the lung, to the <a href="Red_blood_cell" title="Red blood cell">red blood cells</a> in lung blood vessels. It is part of a comprehensive series of <a href="Pulmonary_function_testing" title="Pulmonary function testing">pulmonary function tests</a> to determine the overall ability of the <a href="Lung" title="Lung">lung</a> to transport gas into and out of the blood. D<sub>L</sub>, especially <a href="DLCO" class="mw-redirect" title="DLCO">D<sub>LCO</sub></a>, is reduced in certain diseases of the lung and heart. D<sub>LCO</sub> measurement has been standardized according to a position paper<sup id="cite_ref-multiple_1-0" class="reference"><a href="#cite_note-multiple-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> by a task force of the <a href="European_Respiratory_Society" title="European Respiratory Society">European Respiratory</a> and <a href="American_Thoracic_Society" title="American Thoracic Society">American Thoracic</a> Societies.

</p><p>In <a href="Respiratory_physiology" class="mw-redirect" title="Respiratory physiology">respiratory physiology</a>, the diffusing capacity has a long history of great utility, representing <a href="Electrical_resistance_and_conductance" title="Electrical resistance and conductance">conductance</a> of gas across the alveolar-capillary membrane and also takes into account factors affecting the behaviour of a given gas with hemoglobin.

</p><p>The term may be considered a misnomer as it represents neither <a href="Diffusion" title="Diffusion">diffusion</a> nor a <a href="Battery_(electricity)" class="mw-redirect" title="Battery (electricity)">capacity</a> (as it is typically measured under submaximal conditions) nor <a href="Capacitance" title="Capacitance">capacitance</a>. In addition, gas transport is only diffusion limited in extreme cases, such as for oxygen uptake at very low ambient oxygen or very high pulmonary blood flow.

</p><p>The diffusing capacity does not directly measure the primary cause of <a href="Hypoxemia" title="Hypoxemia">hypoxemia</a>, or low blood oxygen, namely mismatch of <a href="Ventilation/perfusion_ratio" title="Ventilation/perfusion ratio">ventilation to perfusion</a>:<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>

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<ul><li>Not all pulmonary arterial blood goes to areas of the lung where gas exchange can occur (the anatomic or physiologic shunts), and this poorly oxygenated blood rejoins the well oxygenated blood from healthy lung in the pulmonary vein. Together, the mixture has less oxygen than that blood from the healthy lung alone, and so is hypoxemic.</li>

<li>Similarly, not all inspired air goes to areas of the lung where gas exchange can occur (the <a href="Dead_space_(physiology)" title="Dead space (physiology)">anatomic and the physiological dead spaces</a>), and so is wasted.</li></ul>

<div class="mw-heading mw-heading2"><h2 id="Testing">Testing</h2></div>

<p>The <b>single-breath diffusing capacity test</b> is the most common way to determine <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle D_{L}}">

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</math></span><img src="./e44b39c353d4634b76f550679dcc7aed38a0cd47.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:3.276ex; height:2.509ex;" alt="{\displaystyle D_{L}}" loading="lazy"></span>.<sup id="cite_ref-multiple_1-1" class="reference"><a href="#cite_note-multiple-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> The test is performed by having the subject blow out all of the air that they can, leaving only the <a href="Lung_volumes" class="mw-redirect" title="Lung volumes">residual lung volume</a> of gas. The person then inhales a test gas mixture rapidly and completely, reaching the <a href="Lung_volumes" class="mw-redirect" title="Lung volumes">total lung capacity</a> as nearly as possible. This test gas mixture contains a small amount of carbon monoxide (usually 0.3%) and a <i><a href="Tracer_gas" class="mw-redirect" title="Tracer gas">tracer gas</a></i> that is freely distributed throughout the alveolar space but which doesn't cross the alveolar-capillary membrane. <a href="Helium" title="Helium">Helium</a> and <a href="Methane" title="Methane">methane</a> are two such gasses. The test gas is held in the lung for about 10 seconds during which time the CO (but <i>not</i> the tracer gas) continuously moves from the alveoli into the blood. Then the subject exhales.

</p><p>The anatomy of the airways means inspired air must pass through the mouth, trachea, bronchi and bronchioles (<a href="Anatomical_dead_space" class="mw-redirect" title="Anatomical dead space">anatomical dead space</a>) before it gets to the alveoli where gas exchange will occur; on exhalation, alveolar gas must return along the same path, and so the exhaled sample will be purely alveolar only after a 500 to 1,000 ml of gas has been breathed out. While it is algebraically possible to approximate the effects of anatomy (the <i>three-equation method</i><sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup>), disease states introduce considerable uncertainty to this approach. Instead, the first 500 to 1,000 ml of the expired gas is disregarded and the next portion which contain gas that has been in the alveoli is analyzed.<sup id="cite_ref-multiple_1-2" class="reference"><a href="#cite_note-multiple-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> By analyzing the concentrations of carbon monoxide and inert gas in the inspired gas and in the exhaled gas, it is possible to calculate <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle (D_{L_{CO}})}">

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<annotation encoding="application/x-tex">{\displaystyle (D_{L_{CO}})}</annotation>

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</math></span><img src="./94ec6db61fa29a28899e495bd8bbca0ec842461d.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:7.281ex; height:3.009ex;" alt="{\displaystyle (D_{L_{CO}})}" loading="lazy"></span> according to Equation <span id="math_2" class="reference nourlexpansion" style="font-weight:bold;">2</span>. First, the <i>rate</i> at which CO is taken up by the lung is calculated according to:

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</style><table role="presentation" class="numblk" style="margin-left: 3.2em;"><tbody><tr><td class="nowrap"><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\dot {V}}_{CO}={\frac {\Delta {[CO]}*V_{A}}{\Delta {t}}}}">

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<annotation encoding="application/x-tex">{\displaystyle {\dot {V}}_{CO}={\frac {\Delta {[CO]}*V_{A}}{\Delta {t}}}}</annotation>

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</math></span><img src="./89865e5e4c0f9e480915836763766754b0eec41d.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.005ex; width:20.241ex; height:5.843ex;" alt="{\displaystyle {\dot {V}}_{CO}={\frac {\Delta {[CO]}*V_{A}}{\Delta {t}}}}" loading="lazy"></span> . </td> <td></td> <td class="nowrap"><span id="math_4" class="reference nourlexpansion" style="font-weight:bold;">4</span></td></tr></tbody></table>

<dl><dd><dl><dd><dl><dd><dl><dd>The pulmonary function equipment monitors the change in the concentration of CO that occurred during the breath hold, <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \Delta {[CO]}}">

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<annotation encoding="application/x-tex">{\displaystyle \Delta {[CO]}}</annotation>

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</math></span><img src="./638cc583c947c0894cb46e2c75e4a45fa0579100.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:6.769ex; height:2.843ex;" alt="{\displaystyle \Delta {[CO]}}" loading="lazy"></span>, and also records the time <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \Delta {t}}">

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</math></span><img src="./ebe07d873eb6eb7ef68c4a43455a941af2338b0f.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:2.775ex; height:2.176ex;" alt="{\displaystyle \Delta {t}}" loading="lazy"></span>.</dd>

<dd>The volume of the alveoli, <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle V_{A}}">

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</math></span><img src="./6f799f117ef739f7d3645a44d17e2c9f4245ab52.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.82ex; height:2.509ex;" alt="{\displaystyle V_{A}}" loading="lazy"></span>, is determined by the degree to which the tracer gas has been diluted by inhaling it into the lung.</dd></dl></dd></dl></dd></dl></dd></dl>

<p>Similarly,

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<annotation encoding="application/x-tex">{\displaystyle P_{A_{CO}}=V_{B}*F_{A_{CO_{O}}}}</annotation>

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</math></span><img src="./3b045e759df147b6b82d25ab3ae35baacdb640b7.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.505ex; width:19.588ex; height:3.343ex;" alt="{\displaystyle P_{A_{CO}}=V_{B}*F_{A_{CO_{O}}}}" loading="lazy"></span> . </td> <td></td> <td class="nowrap"><span id="math_5" class="reference nourlexpansion" style="font-weight:bold;">5</span></td></tr></tbody></table>

<p>where

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<annotation encoding="application/x-tex">{\displaystyle F_{A_{CO_{O}}}}</annotation>

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</math></span><img src="./2b8239f07158be8caef3fa192aa538363e0c8a96.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.505ex; width:6.307ex; height:3.343ex;" alt="{\displaystyle F_{A_{CO_{O}}}}" loading="lazy"></span> is the initial alveolar fractional CO concentration, as calculated by the dilution of the tracer gas.</dd>

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</math></span><img src="./9165b1d4d7f450d87d2fc83af295636f5f2ee224.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.835ex; height:2.509ex;" alt="{\displaystyle V_{B}}" loading="lazy"></span> is the barometric pressure</dd></dl></dd></dl></dd></dl></dd></dl>

<p>Other methods that are not so widely used at present can measure the diffusing capacity. These include the steady state diffusing capacity that is performed during regular tidal breathing, or the rebreathing method that requires rebreathing from a reservoir of gas mixtures.

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<div class="mw-heading mw-heading2"><h2 id="Calculation">Calculation</h2></div>

<p>The diffusion capacity for oxygen <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle (D_{L_{O_{2}}})}">

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<annotation encoding="application/x-tex">{\displaystyle (D_{L_{O_{2}}})}</annotation>

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</math></span><img src="./7cfb8c7c65bf061b4e6757fd640a144374208e19.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.338ex; width:7.068ex; height:3.343ex;" alt="{\displaystyle (D_{L_{O_{2}}})}" loading="lazy"></span> is the proportionality factor relating the rate of oxygen uptake into the lung to the oxygen gradient between the capillary blood and the alveoli (per <a href="Fick's_laws_of_diffusion" title="Fick's laws of diffusion">Fick's laws of diffusion</a>). In <a href="Respiratory_physiology" class="mw-redirect" title="Respiratory physiology">respiratory physiology</a>, it is convenient to express the transport of gas molecules as changes in volume, since <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {V_{O_{2}}}\propto {n_{O_{2}}}}">

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<annotation encoding="application/x-tex">{\displaystyle {V_{O_{2}}}\propto {n_{O_{2}}}}</annotation>

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</math></span><img src="./99b48c1d42356ada96fe2ffc41acd27f90c2b7a3.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:10.484ex; height:2.843ex;" alt="{\displaystyle {V_{O_{2}}}\propto {n_{O_{2}}}}" loading="lazy"></span> (i.e., in a gas, a volume is proportional to the number of molecules in it). Further, the oxygen concentration (<a href="Partial_pressure" title="Partial pressure">partial pressure</a>) in the pulmonary artery is taken to be representative of capillary blood. Thus, <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle (D_{L_{O_{2}}})}">

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<annotation encoding="application/x-tex">{\displaystyle (D_{L_{O_{2}}})}</annotation>

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<annotation encoding="application/x-tex">{\displaystyle ({\dot {V}}_{O_{2}})}</annotation>

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<annotation encoding="application/x-tex">{\displaystyle D_{L_{O_{2}}}={\frac {{\dot {V}}_{O_{2}}}{P_{A_{O_{2}}}-P_{a_{O_{2}}}}}\simeq {\frac {{\dot {V}}_{O_{2}}}{P_{A_{O_{2}}}-P_{v_{O_{2}}}}}}</annotation>

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</math></span><img src="./2b752a223d6f0a635280261e2e3d29309f7e829f.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -3.005ex; width:37.77ex; height:7.343ex;" alt="{\displaystyle D_{L_{O_{2}}}={\frac {{\dot {V}}_{O_{2}}}{P_{A_{O_{2}}}-P_{a_{O_{2}}}}}\simeq {\frac {{\dot {V}}_{O_{2}}}{P_{A_{O_{2}}}-P_{v_{O_{2}}}}}}" loading="lazy"></span> </td> <td></td> <td class="nowrap"><span id="math_1" class="reference nourlexpansion" style="font-weight:bold;">1</span></td></tr></tbody></table>

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<annotation encoding="application/x-tex">{\displaystyle {\dot {V}}}</annotation>

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</math></span><img src="./49ef9fa9f410331b94e4578bab90e9edda5c919b.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.787ex; height:2.676ex;" alt="{\displaystyle {\dot {V}}}" loading="lazy"></span>, say "V dot". This is the notation of <a href="Isaac_Newton" title="Isaac Newton">Isaac Newton</a> for a first derivative (or rate) and is commonly used in respiratory physiology for this purpose.)</dd></dl></dd></dl>

<msub>

<mover>

</mover>

</mrow>

<msub>

</mrow>

</msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle {\dot {V}}_{O_{2}}}</annotation>

</semantics>

</math></span><img src="./9c00c4a53555298071b7c3135d9218cd9437bcd9.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:4.105ex; height:3.343ex;" alt="{\displaystyle {\dot {V}}_{O_{2}}}" loading="lazy"></span> is the rate that oxygen is taken up by the lung (ml/min).</dd>

<msub>

<msub>

<msub>

</mrow>

</msub>

</mrow>

</msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle P_{A_{O_{2}}}}</annotation>

</semantics>

</math></span><img src="./ce7783af7b9b6c1bc0de48ba4d3f058ec8565696.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.505ex; width:4.94ex; height:3.343ex;" alt="{\displaystyle P_{A_{O_{2}}}}" loading="lazy"></span> is the partial pressure of oxygen in the alveoli.</dd>

<msub>

<msub>

<msub>

</mrow>

</msub>

</mrow>

</msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle P_{a_{O_{2}}}}</annotation>

</semantics>

</math></span><img src="./509a9947546ef1addba8cce8771196bb2351d820.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.338ex; width:4.577ex; height:3.176ex;" alt="{\displaystyle P_{a_{O_{2}}}}" loading="lazy"></span> is the partial pressure of oxygen in the pulmonary artery.</dd>

<msub>

<msub>

<msub>

</mrow>

</msub>

</mrow>

</msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle P_{v_{O_{2}}}}</annotation>

</semantics>

</math></span><img src="./d9ad19da484d2996eb7091c15cf08f190ae94c04.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.338ex; width:4.505ex; height:3.176ex;" alt="{\displaystyle P_{v_{O_{2}}}}" loading="lazy"></span> is the partial pressure of oxygen in the systemic veins (where it can actually be measured).</dd></dl></dd></dl></dd></dl></dd></dl>

<p>Thus, the higher the diffusing capacity <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle D_{L}}">

<msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle D_{L}}</annotation>

</semantics>

</math></span><img src="./e44b39c353d4634b76f550679dcc7aed38a0cd47.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:3.276ex; height:2.509ex;" alt="{\displaystyle D_{L}}" loading="lazy"></span>, the more gas will be transferred into the lung per unit time for a given gradient in partial pressure (or concentration) of the gas. Since it can be possible to know the alveolar oxygen concentration and the rate of oxygen uptake - but not the oxygen concentration in the pulmonary artery - it is the venous oxygen concentration that is generally employed as a useful approximation in a clinical setting.

</p><p>Sampling the oxygen concentration in the pulmonary artery is a highly invasive procedure, but fortunately another similar gas can be used instead that obviates this need (<a href="DLCO" class="mw-redirect" title="DLCO">DLCO</a>). <a href="Carbon_monoxide" title="Carbon monoxide">Carbon monoxide</a> (CO) is tightly and rapidly bound to hemoglobin in the blood, so the partial pressure of CO in the capillaries is negligible and the second term in the denominator can be ignored. For this reason, CO is generally the test gas used to measure the diffusing capacity and the <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle D_{L}}">

<msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle D_{L}}</annotation>

</semantics>

</math></span><img src="./e44b39c353d4634b76f550679dcc7aed38a0cd47.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:3.276ex; height:2.509ex;" alt="{\displaystyle D_{L}}" loading="lazy"></span> equation simplifies to:

</p>

<msub>

<msub>

</mrow>

</msub>

</mrow>

</msub>

<mfrac>

<msub>

<mover>

</mover>

</mrow>

</mrow>

</msub>

<msub>

<msub>

</mrow>

</msub>

</mrow>

</msub>

</mfrac>

</mrow>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle D_{L_{CO}}={\frac {{\dot {V}}_{CO}}{P_{A_{CO}}}}}</annotation>

</semantics>

</math></span><img src="./0e0edb25d8a12c289541554d8407e6468cedd065.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.671ex; width:14.56ex; height:6.676ex;" alt="{\displaystyle D_{L_{CO}}={\frac {{\dot {V}}_{CO}}{P_{A_{CO}}}}}" loading="lazy"></span>. </td> <td></td> <td class="nowrap"><span id="math_2" class="reference nourlexpansion" style="font-weight:bold;">2</span></td></tr></tbody></table>

<div class="mw-heading mw-heading2"><h2 id="Interpretation">Interpretation</h2></div>

<p>In general, a healthy individual has a value of <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle D_{L_{CO}}}">

<msub>

<msub>

</mrow>

</msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle D_{L_{CO}}}</annotation>

</semantics>

</math></span><img src="./73ca4106596b9f7a533ca254bc2e5db26a39bb9a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:5.472ex; height:2.843ex;" alt="{\displaystyle D_{L_{CO}}}" loading="lazy"></span> between 75% and 125% of the average.<sup id="cite_ref-uppsala_4-0" class="reference"><a href="#cite_note-uppsala-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> 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<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> as well as measurements made at altitude,<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> for children<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> and some specific population groups.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup>

</p>

<div class="mw-heading mw-heading3"><h3 id="Blood_CO_levels_may_not_be_negligible">Blood CO levels may not be negligible</h3></div>

<p>In heavy smokers, blood CO is great enough to influence the measurement of <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle D_{L_{CO}}}">

<msub>

<msub>

</mrow>

</msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle D_{L_{CO}}}</annotation>

</semantics>

</math></span><img src="./73ca4106596b9f7a533ca254bc2e5db26a39bb9a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:5.472ex; height:2.843ex;" alt="{\displaystyle D_{L_{CO}}}" loading="lazy"></span>, and requires an adjustment of the calculation when COHb is greater than 2% of the whole.

</p>

<div style="font-weight: bold;line-height:normal;">The two components of <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle D_{L_{CO}}}">

<msub>

<msub>

</mrow>

</msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle D_{L_{CO}}}</annotation>

</semantics>

</math></span><img src="./73ca4106596b9f7a533ca254bc2e5db26a39bb9a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:5.472ex; height:2.843ex;" alt="{\displaystyle D_{L_{CO}}}" loading="lazy"></span></div>

<p>While <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle (D_{L})}">

<msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle (D_{L})}</annotation>

</semantics>

</math></span><img src="./630d3ce6230e95b69aaefe5eb5e7976068a0f779.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:5.085ex; height:2.843ex;" alt="{\displaystyle (D_{L})}" loading="lazy"></span> is of great practical importance, being the overall measure of gas transport, the interpretation of this measurement is complicated by the fact that it does not measure any one part of a multi-step process. So as a conceptual aid in interpreting the results of this test, the time needed to transfer CO from the air to the blood can be divided into two parts. First CO crosses the alveolar capillary membrane (represented by <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle D_{M}}">

<msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle D_{M}}</annotation>

</semantics>

</math></span><img src="./d3aa10d09d531274af84e897ad396944fd8f2660.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:3.883ex; height:2.509ex;" alt="{\displaystyle D_{M}}" loading="lazy"></span> ) and then CO combines with the hemoglobin in capillary red blood cells at a rate <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \theta }">

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle \theta }</annotation>

</semantics>

</math></span><img src="./6e5ab2664b422d53eb0c7df3b87e1360d75ad9af.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.09ex; height:2.176ex;" alt="{\displaystyle \theta }" loading="lazy"></span> times the volume of capillary blood present (<span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle V_{c}}">

<msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle V_{c}}</annotation>

</semantics>

</math></span><img src="./338b595db7a169754c5e088d9881010c2225f597.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.299ex; height:2.509ex;" alt="{\displaystyle V_{c}}" loading="lazy"></span>).<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> Since the steps are in series, the conductances add as the sum of the reciprocals:

</p>

<mfrac>

<msub>

<msub>

</mrow>

</msub>

</mrow>

</msub>

</mfrac>

</mrow>

<mfrac>

<msub>

</mrow>

</msub>

</mfrac>

</mrow>

<mfrac>

<mrow>

<msub>

</mrow>

</msub>

</mrow>

</mfrac>

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</mrow>

<annotation encoding="application/x-tex">{\displaystyle {\frac {1}{D_{L_{CO}}}}={\frac {1}{D_{M}}}+{\frac {1}{\theta *V_{c}}}}</annotation>

</semantics>

</math></span><img src="./23a69ece700b6c877f6d79222c978a1cad463349.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.671ex; width:23.387ex; height:6.009ex;" alt="{\displaystyle {\frac {1}{D_{L_{CO}}}}={\frac {1}{D_{M}}}+{\frac {1}{\theta *V_{c}}}}" loading="lazy"></span> . </td> <td></td> <td class="nowrap"><span id="math_3" class="reference nourlexpansion" style="font-weight:bold;">3</span></td></tr></tbody></table>

<div style="font-weight: bold;line-height:normal;">Any change in <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle V_{c}}">

<msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle V_{c}}</annotation>

</semantics>

</math></span><img src="./338b595db7a169754c5e088d9881010c2225f597.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.299ex; height:2.509ex;" alt="{\displaystyle V_{c}}" loading="lazy"></span> alters <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle D_{L_{CO}}}">

<msub>

<msub>

</mrow>

</msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle D_{L_{CO}}}</annotation>

</semantics>

</math></span><img src="./73ca4106596b9f7a533ca254bc2e5db26a39bb9a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:5.472ex; height:2.843ex;" alt="{\displaystyle D_{L_{CO}}}" loading="lazy"></span></div>

<p>The volume of blood in the lung capillaries, <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle V_{c}}">

<msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle V_{c}}</annotation>

</semantics>

</math></span><img src="./338b595db7a169754c5e088d9881010c2225f597.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.299ex; height:2.509ex;" alt="{\displaystyle V_{c}}" loading="lazy"></span>, changes appreciably during ordinary activities such as <a href="Physical_exercise" class="mw-redirect" title="Physical exercise">exercise</a>. Simply breathing in brings some additional blood <i>into</i> the lung because of the negative intrathoracic pressure required for inspiration. At the extreme, inspiring against a closed glottis, the <a href="M%C3%BCller's_maneuver" title="Müller's maneuver">Müller's maneuver</a>, pulls blood <i>into</i> the chest. The opposite is also true, as exhaling increases the pressure within the thorax and so tends to push blood out; the <a href="Valsalva_maneuver" title="Valsalva maneuver">Valsalva maneuver</a> is an exhalation against a closed airway which can move blood <i>out</i> of the lung. So breathing hard during exercise will bring extra blood into the lung during inspiration and push blood out during expiration. But during exercise (or more rarely when there is a <a href="Atrioventricular_septal_defect" title="Atrioventricular septal defect">structural defect</a> in the heart that allows blood to be shunted from the high pressure, systemic circulation to the low pressure, pulmonary circulation) there is also increased blood flow throughout the body, and the lung adapts by recruiting extra capillaries to carry the increased output of the heart, further increasing the quantity of blood in the lung. Thus <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle D_{L_{CO}}}">

<msub>

<msub>

</mrow>

</msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle D_{L_{CO}}}</annotation>

</semantics>

</math></span><img src="./73ca4106596b9f7a533ca254bc2e5db26a39bb9a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:5.472ex; height:2.843ex;" alt="{\displaystyle D_{L_{CO}}}" loading="lazy"></span> will appear to increase when the subject is not at rest, particularly during inspiration.

</p><p>In disease, <a href="Pulmonary_hemorrhage" title="Pulmonary hemorrhage">hemorrhage</a> into the lung will increase the number of haemoglobin molecules in contact with air, and so measured <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle D_{L_{CO}}}">

<msub>

<msub>

</mrow>

</msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle D_{L_{CO}}}</annotation>

</semantics>

</math></span><img src="./73ca4106596b9f7a533ca254bc2e5db26a39bb9a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:5.472ex; height:2.843ex;" alt="{\displaystyle D_{L_{CO}}}" loading="lazy"></span> will increase. In this case, the carbon monoxide used in the test will bind to haemoglobin that has bled into the lung. This does not reflect an increase in diffusing capacity of the lung to transfer oxygen to the systemic circulation.

</p><p>Finally, <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle V_{c}}">

<msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle V_{c}}</annotation>

</semantics>

</math></span><img src="./338b595db7a169754c5e088d9881010c2225f597.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.299ex; height:2.509ex;" alt="{\displaystyle V_{c}}" loading="lazy"></span> is increased in <b><a href="Obesity" title="Obesity">obesity</a></b> and when the subject lies down, both of which increase the blood in the lung by compression and by gravity and thus both increase <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle D_{L_{CO}}}">

<msub>

<msub>

</mrow>

</msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle D_{L_{CO}}}</annotation>

</semantics>

</math></span><img src="./73ca4106596b9f7a533ca254bc2e5db26a39bb9a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:5.472ex; height:2.843ex;" alt="{\displaystyle D_{L_{CO}}}" loading="lazy"></span>.

</p>

<div style="font-weight: bold;line-height:normal;">Reasons why <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \theta }">

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle \theta }</annotation>

</semantics>

</math></span><img src="./6e5ab2664b422d53eb0c7df3b87e1360d75ad9af.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.09ex; height:2.176ex;" alt="{\displaystyle \theta }" loading="lazy"></span> varies</div>

<p>The rate of CO uptake into the blood, <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \theta }">

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle \theta }</annotation>

</semantics>

</math></span><img src="./6e5ab2664b422d53eb0c7df3b87e1360d75ad9af.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.09ex; height:2.176ex;" alt="{\displaystyle \theta }" loading="lazy"></span>, depends on the concentration of hemoglobin in that blood, abbreviated <a href="Hemoglobin" title="Hemoglobin">Hb</a> in the CBC (<a href="Complete_Blood_Count" class="mw-redirect" title="Complete Blood Count">Complete Blood Count</a>). More hemoglobin is present in <a href="Polycythemia" title="Polycythemia">polycythemia</a>, and so <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle D_{L_{CO}}}">

<msub>

<msub>

</mrow>

</msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle D_{L_{CO}}}</annotation>

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</math></span><img src="./73ca4106596b9f7a533ca254bc2e5db26a39bb9a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:5.472ex; height:2.843ex;" alt="{\displaystyle D_{L_{CO}}}" loading="lazy"></span> is elevated. In <a href="Anemia" title="Anemia">anemia</a>, the opposite is true. In environments with high levels of CO in the inhaled air (such as <a href="Smoking" title="Smoking">smoking</a>), a fraction of the blood's hemoglobin is rendered ineffective by its tight binding to CO, and so is analogous to anemia. It is recommended that <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle D_{L_{CO}}}">

<msub>

<msub>

</mrow>

</msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle D_{L_{CO}}}</annotation>

</semantics>

</math></span><img src="./73ca4106596b9f7a533ca254bc2e5db26a39bb9a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:5.472ex; height:2.843ex;" alt="{\displaystyle D_{L_{CO}}}" loading="lazy"></span> be adjusted when blood CO is high.<sup id="cite_ref-multiple_1-3" class="reference"><a href="#cite_note-multiple-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup>

</p><p>The lung blood volume is also reduced when blood flow is interrupted by blood clots (<a href="Pulmonary_emboli" class="mw-redirect" title="Pulmonary emboli">pulmonary emboli</a>) or reduced by bone deformities of the thorax, for instance <a href="Scoliosis" title="Scoliosis">scoliosis</a> and <a href="Kyphosis" title="Kyphosis">kyphosis</a>.

</p><p>Varying the ambient concentration of oxygen also alters <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \theta }">

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle \theta }</annotation>

</semantics>

</math></span><img src="./6e5ab2664b422d53eb0c7df3b87e1360d75ad9af.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.09ex; height:2.176ex;" alt="{\displaystyle \theta }" loading="lazy"></span>. At high altitude, inspired oxygen is low and more of the blood's hemoglobin is free to bind CO; thus <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \theta }">

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle \theta }</annotation>

</semantics>

</math></span><img src="./6e5ab2664b422d53eb0c7df3b87e1360d75ad9af.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.09ex; height:2.176ex;" alt="{\displaystyle \theta }" loading="lazy"></span> is increased and <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle D_{L_{CO}}}">

<msub>

<msub>

</mrow>

</msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle D_{L_{CO}}}</annotation>

</semantics>

</math></span><img src="./73ca4106596b9f7a533ca254bc2e5db26a39bb9a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:5.472ex; height:2.843ex;" alt="{\displaystyle D_{L_{CO}}}" loading="lazy"></span> appears to be increased. Conversely, supplemental oxygen increases Hb saturation, decreasing <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \theta }">

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle \theta }</annotation>

</semantics>

</math></span><img src="./6e5ab2664b422d53eb0c7df3b87e1360d75ad9af.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.09ex; height:2.176ex;" alt="{\displaystyle \theta }" loading="lazy"></span> and <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle D_{L_{CO}}}">

<msub>

<msub>

</mrow>

</msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle D_{L_{CO}}}</annotation>

</semantics>

</math></span><img src="./73ca4106596b9f7a533ca254bc2e5db26a39bb9a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:5.472ex; height:2.843ex;" alt="{\displaystyle D_{L_{CO}}}" loading="lazy"></span>.

</p>

<div style="font-weight: bold;line-height:normal;">Lung diseases that reduce <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle D_{M}}">

<msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle D_{M}}</annotation>

</semantics>

</math></span><img src="./d3aa10d09d531274af84e897ad396944fd8f2660.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:3.883ex; height:2.509ex;" alt="{\displaystyle D_{M}}" loading="lazy"></span> and <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \theta *V_{c}}">

<msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle \theta *V_{c}}</annotation>

</semantics>

</math></span><img src="./bf60d1df53befb3876385aa6fa9d972328fad5da.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:5.585ex; height:2.509ex;" alt="{\displaystyle \theta *V_{c}}" loading="lazy"></span></div>

<p>Diseases that alter lung tissue reduce both <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle D_{M}}">

<msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle D_{M}}</annotation>

</semantics>

</math></span><img src="./d3aa10d09d531274af84e897ad396944fd8f2660.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:3.883ex; height:2.509ex;" alt="{\displaystyle D_{M}}" loading="lazy"></span> and <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \theta *V_{c}}">

<msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle \theta *V_{c}}</annotation>

</semantics>

</math></span><img src="./bf60d1df53befb3876385aa6fa9d972328fad5da.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:5.585ex; height:2.509ex;" alt="{\displaystyle \theta *V_{c}}" loading="lazy"></span> to a variable extent, and so decrease <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle D_{L_{CO}}}">

<msub>

<msub>

</mrow>

</msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle D_{L_{CO}}}</annotation>

</semantics>

</math></span><img src="./73ca4106596b9f7a533ca254bc2e5db26a39bb9a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:5.472ex; height:2.843ex;" alt="{\displaystyle D_{L_{CO}}}" loading="lazy"></span>.

</p>

<ol><li>Loss of lung parenchyma in diseases like <a href="Emphysema" title="Emphysema">emphysema</a>.</li>

<li>Diseases that scar the lung (the <a href="Interstitial_lung_disease" title="Interstitial lung disease">interstitial lung disease</a>), such as <a href="Idiopathic_pulmonary_fibrosis" title="Idiopathic pulmonary fibrosis">idiopathic pulmonary fibrosis</a>, or <a href="Sarcoidosis" title="Sarcoidosis">sarcoidosis</a></li>

<li>Swelling of lung tissue (<a href="Pulmonary_edema" title="Pulmonary edema">pulmonary edema</a>) due to <a href="Heart_failure" title="Heart failure">heart failure</a>, or due to an acute inflammatory response to allergens (<a href="Acute_interstitial_pneumonitis" title="Acute interstitial pneumonitis">acute interstitial pneumonitis</a>).</li>

<li>Diseases of the blood vessels in the lung, either inflammatory (<a href="Vasculitis" title="Vasculitis">pulmonary vasculitis</a>) or hypertrophic (<a href="Pulmonary_hypertension" title="Pulmonary hypertension">pulmonary hypertension</a>).</li></ol>

<div style="font-weight: bold;line-height:normal;">Lung conditions that increase <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle D_{L_{CO}}}">

<msub>

<msub>

</mrow>

</msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle D_{L_{CO}}}</annotation>

</semantics>

</math></span><img src="./73ca4106596b9f7a533ca254bc2e5db26a39bb9a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:5.472ex; height:2.843ex;" alt="{\displaystyle D_{L_{CO}}}" loading="lazy"></span>.</div>

<ol><li>Alveolar hemorrhage <a href="Goodpasture's_syndrome" class="mw-redirect" title="Goodpasture's syndrome">Goodpasture's syndrome</a>,<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> <a href="Polycythemia" title="Polycythemia">polycythemia</a>,<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> left to right <a href="Cardiac_shunt" title="Cardiac shunt">intracardiac shunts</a>,<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> due increase in volume of blood exposed to inspired gas.</li>

<li><a href="Asthma" title="Asthma">Asthma</a> 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.<sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup></li></ol>

<div class="mw-heading mw-heading2"><h2 id="History">History</h2></div>

<p>In one sense, it is remarkable that DL<sub>CO</sub> 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.<sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> Remarkable too is the fact that both sides used the technique to gain evidence for their respective hypotheses. To begin with, <a href="Christian_Bohr" title="Christian Bohr">Christian Bohr</a> 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, <a href="August_Krogh" title="August Krogh">August Krogh</a> developed the single breath diffusion capacity technique along with his wife <a href="August_Krogh" title="August Krogh">Marie</a>, and convincingly demonstrated that gasses diffuse passively,<sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-20" class="reference"><a href="#cite_note-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> a finding that led to the demonstration that capillaries in the blood were recruited into use as needed – a Nobel Prize–winning idea.<sup id="cite_ref-26" class="reference"><a href="#cite_note-26"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup>

</p>

<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

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</style><cite id="CITEREFMacintyreCrapoViegi2005" class="citation journal cs1">Macintyre N, Crapo RO, Viegi G, et al. (2005). <a rel="nofollow" class="external text" href="https://doi.org/10.1183%2F09031936.05.00034905">"Standardisation of the single-breath determination of carbon monoxide uptake in the lung"</a>. <i>Eur Respir J</i>. <b>26</b> (4): <span class="nowrap">720–</span>35. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1183%2F09031936.05.00034905">10.1183/09031936.05.00034905</a></span>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/16204605">16204605</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:18177228">18177228</a>.</cite></span>

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<li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text">West, J. 2011. Respiratory Physiology: The Essentials. 9e. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-1-60913-640-6</bdi></span>

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<li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><cite id="CITEREFGrahamMinkCotton1981" class="citation journal cs1">Graham BL, Mink JT, Cotton DJ (1981). "Improved accuracy and precision of single-breath CO diffusing capacity measurements". <i>J Appl Physiol</i>. <b>51</b> (5): <span class="nowrap">1306–</span>13. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1152%2Fjappl.1981.51.5.1306">10.1152/jappl.1981.51.5.1306</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/7298468">7298468</a>.</cite></span>

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<li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text"><cite id="CITEREFMillerThorntonWarshawAnderson1983" class="citation journal cs1">Miller A, Thornton JC, Warshaw R, Anderson H, Teirstein AS, Selikoff IJ (1983). "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". <i>Am Rev Respir Dis</i>. <b>127</b> (3): <span class="nowrap">270–</span>7. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1164%2Farrd.1983.127.3.270">10.1164/arrd.1983.127.3.270</a> (inactive 12 July 2025). <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/6830050">6830050</a>.</cite><span class="cs1-maint citation-comment"><code class="cs1-code">{{cite journal}}</code>: CS1 maint: DOI inactive as of July 2025 (link)</span></span>

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<li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text"><cite id="CITEREFCotesChinnQuanjerRoca1993" class="citation journal cs1">Cotes JE, Chinn DJ, Quanjer PH, Roca J, Yernault JC (1993). <a rel="nofollow" class="external text" href="https://doi.org/10.1183%2F09041950.041s1693">"Standardization of the measurement of transfer factor (Diffusing capacity)"</a>. <i>Eur Respir J Suppl</i>. <b>16</b>: <span class="nowrap">41–</span>52. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1183%2F09041950.041s1693">10.1183/09041950.041s1693</a></span>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/8499053">8499053</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:54555111">54555111</a>.</cite></span>

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<li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text"><cite id="CITEREFCrapoMorrisGardner1982" class="citation journal cs1">Crapo RO, Morris AH, Gardner RM (1982). "Reference values for pulmonary tissue volume, membrane diffusing capacity, and pulmonary capillary blood volume". <i>Bull Eur Physiopathol Respir</i>. <b>18</b> (6): <span class="nowrap">893–</span>9. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/6927541">6927541</a>.</cite></span>

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<li id="cite_note-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-9">^</a></b></span> <span class="reference-text"><cite id="CITEREFKoopmanZanenKruitwagenvan_der_Ent2011" class="citation journal cs1">Koopman M, Zanen P, Kruitwagen CL, van der Ent CK, Arets HG (2011). <a rel="nofollow" class="external text" href="https://doi.org/10.1016%2Fj.rmed.2010.07.020">"Reference values for paediatric pulmonary function testing: The Utrecht dataset"</a>. <i>Respir. Med</i>. <b>105</b> (1): <span class="nowrap">15–</span>23. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1016%2Fj.rmed.2010.07.020">10.1016/j.rmed.2010.07.020</a></span>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/20889322">20889322</a>.</cite> Erratum in <i>Respir. Med.</i> 2011 Dec;105(12):1970-1.</span>

</li>

<li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text"><cite id="CITEREFChinNgHuiTan1997" class="citation journal cs1">Chin NK, Ng TP, Hui KP, Tan WC (Jun 1997). "Population based standards for pulmonary function in non-smoking adults in Singapore". <i>Respirology</i>. <b>2</b> (2): <span class="nowrap">143–</span>9. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1111%2Fj.1440-1843.1997.tb00070.x">10.1111/j.1440-1843.1997.tb00070.x</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/9441128">9441128</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:31037816">31037816</a>.</cite></span>

</li>

<li id="cite_note-11"><span class="mw-cite-backlink"><b><a href="#cite_ref-11">^</a></b></span> <span class="reference-text"><cite id="CITEREFPiiriläSeikkulaVälimäki2007" class="citation journal cs1">Piirilä P, Seikkula T, Välimäki P (2007). <a rel="nofollow" class="external text" href="https://doi.org/10.3402%2Fijch.v66i5.18316">"Differences between Finnish and European reference values for pulmonary diffusing capacity"</a>. <i>Int J Circumpolar Health</i>. <b>66</b> (5): <span class="nowrap">449–</span>57. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.3402%2Fijch.v66i5.18316">10.3402/ijch.v66i5.18316</a></span>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/18274210">18274210</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:22302973">22302973</a>.</cite></span>

</li>

<li id="cite_note-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-12">^</a></b></span> <span class="reference-text"><cite id="CITEREFIpLamLai2007" class="citation journal cs1">Ip MS, Lam WK, Lai AY, et al. (July 2007). "Hong Kong Thoracic Society. Reference values of diffusing capacity of non-smoking Chinese in Hong Kong". <i>Respirology</i>. <b>12</b> (4): <span class="nowrap">599–</span>606. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1111%2Fj.1440-1843.2007.01084.x">10.1111/j.1440-1843.2007.01084.x</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/17587430">17587430</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:5897844">5897844</a>.</cite></span>

</li>

<li id="cite_note-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-13">^</a></b></span> <span class="reference-text"><cite id="CITEREFRoughtonForster1957" class="citation journal cs1">Roughton FJ, Forster RE (1957). "Relative importance of diffusion and chemical reaction rates in determining rate of exchange of gases in the human lung, with special reference to true diffusing capacity of pulmonary membrane and volume of blood in the lung capillaries". <i>J Appl Physiol</i>. <b>11</b> (2): <span class="nowrap">290–</span>302. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1152%2Fjappl.1957.11.2.290">10.1152/jappl.1957.11.2.290</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/13475180">13475180</a>.</cite></span>

</li>

<li id="cite_note-14"><span class="mw-cite-backlink"><b><a href="#cite_ref-14">^</a></b></span> <span class="reference-text"><cite id="CITEREFGreeningHughes,_JM1981" class="citation journal cs1">Greening, AP; Hughes, JM (May 1981). "Serial estimations of carbon monoxide diffusing capacity in intrapulmonary haemorrhage". <i>Clinical Science</i>. <b>60</b> (5): <span class="nowrap">507–</span>12. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1042%2Fcs0600507">10.1042/cs0600507</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/7249536">7249536</a>.</cite></span>

</li>

<li id="cite_note-15"><span class="mw-cite-backlink"><b><a href="#cite_ref-15">^</a></b></span> <span class="reference-text"><cite id="CITEREFBurgessBishop,_J._M.1963" class="citation journal cs1">Burgess, J. H.; Bishop, J. M. (1963). <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC289367">"Pulmonary Diffusing Capacity and ITS Subdivisions in Polycythemia Vera"</a>. <i>Journal of Clinical Investigation</i>. <b>42</b> (7): <span class="nowrap">997–</span>1006. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1172%2FJCI104804">10.1172/JCI104804</a>. <a href="PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> <span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC289367">289367</a></span>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/14016987">14016987</a>.</cite></span>

</li>

<li id="cite_note-16"><span class="mw-cite-backlink"><b><a href="#cite_ref-16">^</a></b></span> <span class="reference-text"><cite id="CITEREFAUCHINCLOSS_JHGILBERT,_REICH,_RH1959" class="citation journal cs1">AUCHINCLOSS JH, Jr; GILBERT, R; EICH, RH (February 1959). <a rel="nofollow" class="external text" href="https://doi.org/10.1161%2F01.cir.19.2.232">"The pulmonary diffusing capacity in congenital and rheumatic heart disease"</a>. <i>Circulation</i>. <b>19</b> (2): <span class="nowrap">232–</span>41. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1161%2F01.cir.19.2.232">10.1161/01.cir.19.2.232</a></span>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/13629784">13629784</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:27264342">27264342</a>.</cite></span>

</li>

<li id="cite_note-17"><span class="mw-cite-backlink"><b><a href="#cite_ref-17">^</a></b></span> <span class="reference-text"><cite id="CITEREFCollardNjinou,_BNejadnik,_BKeyeux,_A1994" class="citation journal cs1">Collard, P; Njinou, B; Nejadnik, B; Keyeux, A; Frans, A (May 1994). "Single breath diffusing capacity for carbon monoxide in stable asthma". <i>Chest</i>. <b>105</b> (5): <span class="nowrap">1426–</span>9. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1378%2Fchest.105.5.1426">10.1378/chest.105.5.1426</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/8181330">8181330</a>.</cite></span>

</li>

<li id="cite_note-18"><span class="mw-cite-backlink"><b><a href="#cite_ref-18">^</a></b></span> <span class="reference-text"><cite id="CITEREFGjedde_A2010" class="citation journal cs1">Gjedde A (2010). "Diffusive insights: on the disagreement of Christian Bohr and August Krogh". <i>Adv Physiol Educ</i>. <b>34</b> (4): <span class="nowrap">174–</span>185. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1152%2Fadvan.00092.2010">10.1152/advan.00092.2010</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/21098384">21098384</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:31010852">31010852</a>.</cite></span>

</li>

<li id="cite_note-19"><span class="mw-cite-backlink"><b><a href="#cite_ref-19">^</a></b></span> <span class="reference-text">Krogh A. 1910 On the oxygen metabolism of the blood. Skand Arch Physiol 23: 193–199</span>

</li>

<li id="cite_note-20"><span class="mw-cite-backlink"><b><a href="#cite_ref-20">^</a></b></span> <span class="reference-text">Krogh A. 1910 On the mechanism of the gas-exchange in the lungs of the tortoise. Skand Arch Physiol 23: 200–216.</span>

</li>

<li id="cite_note-21"><span class="mw-cite-backlink"><b><a href="#cite_ref-21">^</a></b></span> <span class="reference-text">Krogh A. 1910 On the combination of hæmoglobin with mixtures of oxygen and carbonic acid. Skand Arch Physiol 23: 217–223.</span>

</li>

<li id="cite_note-22"><span class="mw-cite-backlink"><b><a href="#cite_ref-22">^</a></b></span> <span class="reference-text">Krogh A. 1910 Some experiments on the invasion of oxygen and carbonic oxide into water. Skand Arch Physiol 23: 224–235</span>

</li>

<li id="cite_note-23"><span class="mw-cite-backlink"><b><a href="#cite_ref-23">^</a></b></span> <span class="reference-text">Krogh A. 1910 On the mechanism of gas exchange in the lungs. Skand Arch Physiol 23: 248–278</span>

</li>

<li id="cite_note-24"><span class="mw-cite-backlink"><b><a href="#cite_ref-24">^</a></b></span> <span class="reference-text">Krogh A, Krogh M. 1910 On the tensions of gases in arterial blood. Skand Arch Physiol 23: 179–192.</span>

</li>

<li id="cite_note-25"><span class="mw-cite-backlink"><b><a href="#cite_ref-25">^</a></b></span> <span class="reference-text">Krogh A, Krogh M. 1910 Rate of diffusion into lungs of man. Skand Arch Physiol 23: 236–247</span>

</li>

<li id="cite_note-26"><span class="mw-cite-backlink"><b><a href="#cite_ref-26">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.nobelprize.org/nobel_prizes/medicine/laureates/1920/krogh-bio.html">"The Nobel Prize in Physiology or Medicine 1920"</a>.</cite></span>

</li>

</ol></div></div>

<div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2></div>

<ul><li>Mason RJ, Broaddus VC, Martin T, King T Jr., Schraufnagel D, Murray JF, Nadel JA. (2010) Textbook of Respiratory Medicine. 5e. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-1-4160-4710-0</bdi>.</li>

<li>Ruppel, G. L. (2008) Manual of Pulmonary Function Testing. 9e. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-0-323-05212-2</bdi>.</li>

<li>West, J. (2011) Respiratory Physiology: The Essentials. 9e. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-1-60913-640-6</bdi>.</li>

<li>West, J. (2012) Pulmonary Pathophysiology: The Essentials. 8e. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-1-4511-0713-5</bdi>.</li>

</ul>

<div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2></div>

<ul><li><a rel="nofollow" class="external text" href="https://meshb.nlm.nih.gov/record/ui?name=Pulmonary+diffusing+capacity">Pulmonary+diffusing+capacity</a> at the U.S. National Library of Medicine <a href="Medical_Subject_Headings" title="Medical Subject Headings">Medical Subject Headings</a> (MeSH)</li>

<li><i><a href="MedlinePlus" title="MedlinePlus">MedlinePlus Encyclopedia</a></i>: <a rel="nofollow" class="external text" href="https://medlineplus.gov/ency/article/003854.htm">003854</a></li>

<li><a rel="nofollow" class="external text" href="http://www.rcjournal.com/cpgs/">American Association for Respiratory Care <i>Clinical Practice Guidelines</i></a></li>

<li><a rel="nofollow" class="external text" href="http://the-aps.org">The American Physiological Society home page</a></li>

<li><a rel="nofollow" class="external text" href="http://thoracic.org">The American Thoracic Society home page</a></li>

<li><a rel="nofollow" class="external text" href="http://ersnet.org">The European Respiratory Society home page</a></li></ul>

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</style><div id="Tests_and_procedures_involving_the_respiratory_system89" style="font-size:114%;margin:0 4em">Tests and procedures involving the <a href="Respiratory_system" title="Respiratory system">respiratory system</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Surgery" title="Surgery">Surgery</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Upper_respiratory_tract" class="mw-redirect" title="Upper respiratory tract">Upper RT</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<dd><a href="Rhinoplasty" title="Rhinoplasty">Rhinoplasty</a></dd>

<dd><a href="Septoplasty" title="Septoplasty">Septoplasty</a></dd>

<dd><a href="Somnoplasty" title="Somnoplasty">Somnoplasty</a></dd>

<dd><a href="Alarplasty" title="Alarplasty">Alarplasty</a></dd>

<dd><a href="Rhinectomy" title="Rhinectomy">Rhinectomy</a></dd>

<dd><a href="Rhinomanometry" title="Rhinomanometry">Rhinomanometry</a></dd>

<dd><a href="Acoustic_rhinometry" title="Acoustic rhinometry">Acoustic rhinometry</a></dd></dl>

<dl><dt><i><a href="Paranasal_sinuses" title="Paranasal sinuses">sinus</a></i></dt>

<dd><a href="Sinusotomy" title="Sinusotomy">Sinusotomy</a></dd></dl>

<dl><dt><i><a href="Larynx" title="Larynx">larynx</a></i></dt>

<dd><a href="Laryngoscopy" title="Laryngoscopy">Laryngoscopy</a></dd>

<dd><a href="Laryngectomy" title="Laryngectomy">Laryngectomy</a></dd>

<dd><a href="Laryngotomy" class="mw-redirect" title="Laryngotomy">Laryngotomy</a>

<dl><dd><a href="Thyrotomy" title="Thyrotomy">Thyrotomy</a></dd></dl></dd>

<dd><a href="Laryngotracheal_reconstruction" title="Laryngotracheal reconstruction">Laryngotracheal reconstruction</a></dd></dl>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Lower_respiratory_tract" class="mw-redirect" title="Lower respiratory tract">Lower RT</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<dl><dt><i><a href="Vertebrate_trachea" class="mw-redirect" title="Vertebrate trachea">trachea</a></i></dt>

<dd><a href="Cricothyrotomy" title="Cricothyrotomy">Cricothyrotomy</a></dd>

<dd><a href="Tracheo-oesophageal_puncture" class="mw-redirect" title="Tracheo-oesophageal puncture">Tracheoesophageal puncture</a></dd>

<dd><a href="Tracheotomy" title="Tracheotomy">Tracheotomy</a></dd></dl>

<dl><dt><i><a href="Bronchus" title="Bronchus">bronchus</a></i></dt>

<dd><a href="Bronchoscopy" title="Bronchoscopy">Bronchoscopy</a></dd></dl>

<dd><a href="Pneumonectomy" title="Pneumonectomy">Pneumonectomy</a></dd>

<dd><a href="Lobectomy" title="Lobectomy">Lobectomy</a></dd>

<dd><a href="Wedge_resection" title="Wedge resection">Wedge resection</a></dd>

<dd><a href="Lung_transplantation" title="Lung transplantation">Transplantation</a></dd>

<dd><a href="Decortication_of_lung" class="mw-redirect" title="Decortication of lung">Decortication</a></dd>

<dd><a href="Heart%E2%80%93lung_transplant" title="Heart–lung transplant">Heart–lung transplant</a></dd></dl>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Thoracic_wall" title="Thoracic wall">Chest wall</a>, <a href="Pleura" title="Pleura">pleura</a>,<br><a href="Mediastinum" title="Mediastinum">mediastinum</a>,<br>and <a href="Thoracic_diaphragm" title="Thoracic diaphragm">diaphragm</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<dl><dt><i><a href="Pleura" title="Pleura">pleura</a>/<a href="Pleural_cavity" title="Pleural cavity">pleural cavity</a></i></dt>

<dd><a href="Thoracentesis" title="Thoracentesis">Thoracentesis</a></dd>

<dd><a href="Pleurodesis" title="Pleurodesis">Pleurodesis</a></dd>

<dd><a href="Thoracoscopy" title="Thoracoscopy">Thoracoscopy</a></dd>

<dd><a href="Thoracotomy" title="Thoracotomy">Thoracotomy</a></dd>

<dd><a href="Chest_tube" title="Chest tube">Chest tube</a></dd></dl>

<dl><dt><i><a href="Mediastinum" title="Mediastinum">mediastinum</a></i></dt>

<dd><a href="Mediastinoscopy" title="Mediastinoscopy">Mediastinoscopy</a></dd></dl>

<dl><dd><a href="Nuss_procedure" title="Nuss procedure">Nuss procedure</a></dd></dl>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Tests</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Medical_imaging" title="Medical imaging">Medical imaging</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Bronchography" title="Bronchography">Bronchography</a></li>

<li><a href="CT_pulmonary_angiogram" title="CT pulmonary angiogram">CT pulmonary angiogram</a></li>

<li><a href="High-resolution_computed_tomography" title="High-resolution computed tomography">High-resolution computed tomography</a></li>

<li><a href="Spiral_computed_tomography" class="mw-redirect" title="Spiral computed tomography">Spiral CT</a></li>

<li><a href="Ventilation/perfusion_scan" title="Ventilation/perfusion scan">Ventilation/perfusion scan</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Clinical_prediction_rule" title="Clinical prediction rule">Clinical prediction rule</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Pneumonia_severity_index" title="Pneumonia severity index">Pneumonia severity index</a></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Lung_function_test" class="mw-redirect" title="Lung function test">Lung function test</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Body_plethysmography" class="mw-redirect" title="Body plethysmography">Body plethysmography</a></li>

<li><a href="Spirometry" title="Spirometry">Spirometry</a></li>

<li><a href="Bronchial_challenge_test" title="Bronchial challenge test">Bronchial challenge test</a></li>

<li><a href="Capnography" title="Capnography">Capnography</a></li>

<li><a href="Diffusion_capacity" class="mw-redirect" title="Diffusion capacity">Diffusion capacity</a></li>

<li><a href="Impulse_oscillometry" title="Impulse oscillometry">Impulse oscillometry</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Cell_biology" title="Cell biology">Cytology</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Bronchoalveolar_lavage" title="Bronchoalveolar lavage">Bronchoalveolar lavage</a></li>

<li><a href="Nasopharyngeal_swab" title="Nasopharyngeal swab">Nasopharyngeal swab</a></li>

<li><a href="Sputum_culture" title="Sputum culture">Sputum culture</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Blood_gas_test" title="Blood gas test">Blood gas test</a></li>

<li><a href="Pneumograph" title="Pneumograph">Pneumography</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other procedures</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th id="Oxygen_therapy41" scope="row" class="navbox-group" style="width:1%"><a href="Oxygen_therapy" title="Oxygen therapy">Oxygen therapy</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Tracheal_intubation" title="Tracheal intubation">Intubation</a></li>

<li><a href="Surgical_airway_management" title="Surgical airway management">Surgical airway management</a></li>

<li><a href="Mechanical_ventilation" title="Mechanical ventilation">Mechanical ventilation</a>

<ul><li><a href="Negative_pressure_ventilator" title="Negative pressure ventilator">Negative pressure ventilator</a></li>

<li><a href="Positive_pressure_ventilation" class="mw-redirect" title="Positive pressure ventilation">Positive pressure ventilation</a></li></ul></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Respiratory_therapy" class="mw-redirect" title="Respiratory therapy">Respiratory therapy</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Artificial_respiration" class="mw-redirect" title="Artificial respiration">Artificial respiration</a></li>

<li><a href="Hyperbaric_medicine" title="Hyperbaric medicine">Hyperbaric medicine</a></li>

<li><a href="Decompression_chamber" class="mw-redirect" title="Decompression chamber">Decompression chamber</a></li>

<li><a href="Heliox" title="Heliox">Heliox</a></li>

<li><a href="Nebulizer" title="Nebulizer">Nebulizer</a></li>

<li><a href="Postural_drainage" title="Postural drainage">Postural drainage</a></li>

<li><a href="Hyperinflation_therapy" title="Hyperinflation therapy">Hyperinflation therapy</a></li>

<li><a href="Pulmonary_hygiene" title="Pulmonary hygiene">Pulmonary hygiene</a></li>

<li><a href="Pulmonary_rehabilitation" title="Pulmonary rehabilitation">Pulmonary rehabilitation</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr></tbody></table></div></div><div><div class="zim-footer">

This article is issued from <a class="external text" title="Last edited on 2025-07-12" href="https://en.wikipedia.org/wiki/?title=Diffusing_capacity&oldid=1300044155">Wikipedia</a>. The text is available under <a class="external text" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en">Creative Commons Attribution-Share Alike 4.0</a> unless otherwise noted. Additional terms may apply for the media files.

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