diffusing capacity

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diffusing capacity

the rate at which a gas diffuses across the alveolocapillary membrane per unit difference in the partial pressure of the gas across the membrane, expressed in ml/min/mm Hg. Because of their high affinity for hemoglobin, both oxygen and carbon monoxide are limited in their rate of diffusion by their diffusing capacity. The diffusing capacity of the lung for these gases is symbolized by DlO2 and DlCO. The parameter usually measured is DlCO. The normal value for the diffusing capacity of oxygen is 20 ml/min/mm Hg. If, during quiet breathing, the pressure difference of oxygen averages 11 mm Hg, a total of approximately 220 ml of oxygen diffuses through the respiratory membrane each minute. During strenuous exercise or other conditions that increase pulmonary activity, the diffusing capacity may increase to three times as much as that during rest. Pulmonary diseases that damage the respiratory membrane greatly interfere with the capacity of the oxygen to pass through the membrane and oxygenate the blood.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

dif·fus·ing ca·pac·i·ty

(symbol, D, followed by subscripts indicating location and chemical species),
the amount of oxygen taken up by pulmonary capillary blood per minute per unit average oxygen pressure gradient between alveolar gas and pulmonary capillary blood; units are: ml/min/mm Hg; also applied to other gases such as carbon monoxide, which is used in the standard clinical measure of diffusing capacity.
Farlex Partner Medical Dictionary © Farlex 2012

diffusing capacity

Pulmonary medicine A measure of a substance's efficiency in transversing a particular barrier, which in the lungs corresponds to the ability of gases in the alveolar space to enter the blood, and of the gases in the blood to enter the alveoli for removal from the body by exhalation. See Pulmonary function test.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

dif·fus·ing ca·pa·ci·ty

(di-fyūz'ing kă-pas'i-tē)
The amount of oxygen taken up by pulmonary capillary blood per minute per unit average oxygen pressure gradient between alveolar gas and pulmonary capillary blood; units are: mL/min/mmHg; also applied to other gases such as carbon monoxide.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
References in periodicals archive ?
The non-smoker COPD group showed a higher prevalence of dyspnea, lower PaO2 and lower arterial oxygen saturation (SaO2%) with similar spirometry results, lung volumes, and diffusion capacity (Table 2).
(For providers: FEV1/FVC<0.7 hazard ratio [HR] 3.1; FEV1/ FVC<lower limit of normal HR 4.3; FEV1 %-predicted HR 1.3 per 10-unit lower; DLCO %-predicted HR 1.8 per 10-unit lower; emphysema >10% HR 2.4.) Higher death risk with signals of COPD, emphysema FEV1/FVC<0.7 3.1 FEV1/FVC<LLN 4.3 FEV1 %-predicted 1.3 DLCO %-predicted 1.8 Emphysema >10% 2.4 * FEV1 = forced expiratory volume in 1 second; FVC = forced vital capacity; DLCO = diffusion capacity of the lung for carbon monoxide (which measures the amount of oxygen transferred from air sacs in the lung to the blood).
28, 2018 (HealthDay News) -- Nintedanib plus sildenafil does not provide benefit over nintedanib alone for patients with idiopathic pulmonary fibrosis (IPF) and diffusion capacity of the lungs for carbon monoxide (DLCO) of 35 percent or less of the predicted value, according to a study published online Sept.
In the subgroup (Group 1, n = 12; Group 2, n = 16) consisting of patients who were eligible for testing and compatible with the measurement of carbon monoxide diffusing capacity (DLCO), no statistically significant difference was found between the groups in terms of diffusion capacity [Table 2].
Consequently, swimmers are known to have above-normal spirometry and higher pulmonary diffusion capacity (Mickleborough et al., 2008).
Diffusion capacity for Carbon-mono-oxide ([D.sub.LCO]) CO provides an excellent alternative in measuring diffusing capacity because CO normally is present in minimal amount in blood and binds to haemoglobin in the same manner as oxygen.
Two studies [1, 2] have reported that percent vital capacity (%VC), percent forced expiratory volume in 1 s ([%FEV.sub.1.0]), and percent carbon monoxide lung diffusion capacity ([%D.sub.LCO]) decrease by approximately 20%-30% at 1 month after surgery.
For determining the bearing capacity and stress diffusion capacity, most studies have used small-scale models test, which would have size effect and limitations to reflect the actual behaviors of the deformation and bearing capacity of foundation [15-17].
Pulmonary function tests showed the following: forced vital capacity (FVC): 2.09 L (68.22%), forced expiratory volume in 1 s (FEV1): 1.33 L (48.91%), total lung capacity: 2.73 L (61.5%), FEV1/FVC%: 65, and the diffusion capacity of lung for carbon monoxide was 49.59% of the predicted value.
According to [15] the simplified equivalent circuit of p-in junction at direct applied bias consists of diffusion capacity (which is parallel to barrier capacitance) and series resistance (Figure 7(a)).
In the restrictive type, respiratory function is impaired and a reduction in lung volume and diffusion capacity is seen.

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