Intrapulmonary mixing of gases studied with aerosols

Altshuler, Bernard; Palmes, E. D.; Yarmus, L.; Nelson, Norton

doi:10.1152/jappl.1959.14.3.321

Cited by 74 publications

(27 citation statements)

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“…Since monodisperse aerosol particles 0.5-1 µm in diameter behave like a "nondiffusive gas", they can be used as tracers for studying convective gas transport [9]. In the present experiments, a small volume (bolus) of the inspired air was labelled with these particles.…”

Section: Methodsmentioning

confidence: 99%

“…Figure 3a shows the half-width H50,c (mean±SD) of expired aerosol boluses as a function of the volumetric lung depth obtained for the 79 healthy subjects. It increased with increasing lung depth and can be approximated by a power function: H50,c = 12 Vp 0.57 (9) The relative population standard deviation (σp) was 13% for lung depth 800 cm 3 , 17% for lung depths 800 cm 3 > Vp ≥ 50 cm 3 , and 30% for Vp = 20 cm 3 . The intrasubject variability (σs) of H50,c for all lung depths was below 10% (table 3).…”

Section: Reference Valuesmentioning

confidence: 99%

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Aerosol bolus dispersion in healthy subjects

Brand

Rieger²,

Schulz³

et al. 1997

Eur Respir J

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Aerosol bolus dispersion is a physiological test of lungs, which uses monodisperse submicron particles to measure intrapulmonary convective gas mixing. In this study, aerosol bolus dispersion was measured in healthy subjects in order to assess reference values for possible clinical applications, to assess the reproducibility of these values, and to identify physical and physiological factors influencing aerosol bolus dispersion.Aerosol bolus dispersion was measured in 79 healthy subjects using 20 cm 3 aerosol boluses consisting of monodisperse di-2-ethylhexyl sebacate (DEHS) particles.The reproducibility of parameters characterizing the width of the exhaled bolus was of the same order as that of parameters of the flow-volume curve (10%). Aerosol bolus dispersion was independent of the level of lung inflation, and the slope of the relationship between flow rate and dispersion was on average not significantly different from zero (range 100-700 cm 3 ·s -1 ). Multiple linear regression showed that aerosol bolus dispersion increased with increasing total lung capacity of the subject.We conclude that differences in total lung capacity between individuals should be taken into account when using measures of aerosol bolus dispersion for possible clinical applications. Eur Respir J 1997; 10: 460-467 Changes in lung ventilation distribution are presumed to be an early indication of lung disease. Such changes have been observed in patients with various lung diseases [1, 2], and in smokers [3]. A simple and noninvasive diagnostic test, which is sensitive to such ventilatory disturbances, could efficiently supplement conventional methods used in lung diagnosis, occupational and environmental medicine, and epidemiology. The aerosol bolus dispersion test is a technique with the potential to meet these requirements. This technique employs monodisperse submicron aerosol particles as tracers of the convective gas transport in the lungs. Its diagnostic capabilities have been shown in several studies: ventilatory disturbances in patients with cystic fibrosis [4]; papaininduced peripheral lung injury in excised animal lungs [5]; and changes in lung ventilation distribution due to ozone exposure [6]. Recently, it has been shown that this technique has higher sensitivity and specificity than conventional lung function tests in detecting early lung impairment due to cigarette smoking [7].This study addresses one requirement for the possible clinical application of this technique, namely the reliable assessment of individual specific reference values for the healthy state. Respiratory experiments were conducted on a sample of 79 nonsmokers with normal, healthy lungs. The variability of the measurements over time was tested in two of these subjects over a period of 6 months. To characterize physical and physiological factors influencing aerosol bolus dispersion, the effect of lung inflation and flow rate was investigated in subgroups of these subjects. SubjectsSeventy nine healthy nonsmokers (38 males and 41 females) were includ...

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Section: Methodsmentioning

confidence: 99%

Section: Reference Valuesmentioning

confidence: 99%

Aerosol bolus dispersion in healthy subjects

Brand

Rieger²,

Schulz³

et al. 1997

Eur Respir J

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show abstract

“…Monodisperse aerosol particles can be considered as a nondiffusing gas [8], and can therefore be used as a tracer…”

Section: Aerosol Bolus Dispersionmentioning

confidence: 99%

“…Monodisperse aerosol particles can be considered as a nondiffusing gas [8], and can therefore be used as a tracer for convective gas transport. When a small volume (bolus) of such an aerosol is injected into a single breath of clean air, convective gas mixing during respiration will cause particle transport in initially particle free air volumes within the lungs.…”

Section: Aerosol Bolus Dispersionmentioning

confidence: 99%

Detection of early lung impairment with aerosol bolus dispersion

Brand¹,

Tuch²,

Manuwald³

et al. 1994

Eur Respir J

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The broadening of inhaled aerosol boluses (aerosol bolus dispersion) during respiration provides a noninvasive measure of convective gas mixing in the lungs. In this study, the sensitivity and specificity of this technique for the diagnosis of early lung impairment due to cigarette smoking was evaluated.Two hundred and sixteen randomly selected subjects (126 smokers and 90 nonsmokers) were investigated with aerosol dispersion in comparison to conventional lung function tests. The cumulative cigarette consumption of the subjects was quantified by "pack-years" (PY). Smokers were classified into the following groups: 0< PY ≤10; 10< PY ≤20; 20< PY ≤30; and PY >30.Forced expiratory volume in one second (FEV 1 ), maximal expiratory flow at 25, 50 and 75% vital capacity (MEF 25 , MEF 50 and MEF 75 ) decreased significantly with increasing cigarette consumption. In comparison to nonsmokers, FEV 1 was significantly reduced in smokers of 10< PY ≤30, and MEF 75 was significantly reduced in smokers of PY >20. Aerosol bolus dispersion increased with increasing PY. For all groups of smokers, even those with PY <10, bolus dispersion was significantly increased in comparison to lifelong nonsmokers, indicating alterations in convective gas mixing in the lungs. Calculation of receiver operating characteristics for the lung function parameters under consideration showed that bolus dispersion has a higher sensitivity and specificity than conventional lung function parameters.Hence, the aerosol bolus dispersion test could be a promising epidemiological tool to study early abnormalities in intrapulmonary gas mixing due to environmental factors. Eur Respir J., 1994Respir J., , 7, 1830Respir J., -1838 Various severe and epidemiologically important lung diseases originate in the lung periphery [1]. Chronic obstructive pulmonary disease (COPD) and asthma are diseases which are associated with a destruction, obstruction, or inflammation of peripheral airspaces. Unfortunately, conventional tests of lung function, such as spirometry or body-plethysmography, suffer from a lack of sensitivity in detecting such early peripheral lung impairment. Forced expiratory flow rates and total airway resistance reflect properties of the central airways and are almost unaffected by changes in the smaller airways [2]. On the other hand, it has been shown that the regional distribution of inhaled air is altered in smokers with normal spirometry [3]. Therefore, lung function tests which are sensitive for changes in lung ventilation pattern are supposed to be more suitable for the early detection of changes in the lung periphery caused by smoking and, presumably, other exogeneous factors.The aerosol bolus dispersion technique, applying boluses of submicron aerosol particles as a lung probe, delivers a quantitative measure of convective mixing in the lungs. This technique has been used for diagnostic purposes in several studies [4,5], and has shown interesting capabilities which promise to provide a powerful supplement to conventional lung function...

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“…Furthermore, it is likely that the percentage retention of particles in the human lung as a whole is minimal, or nearly so, for particles whose radius is about 0.1 a." 10 There appears to have been no systematic study of the relative rates of deposition of the vapours and the tarry particles of tobacco smoke in the human lung. The results of recent studies of physical pioperties of wood smoke might therefore be relevant.…”

Section: Smoke Vapours and Carcinogenesismentioning

confidence: 99%

Vulval Varicosities in Pregnancy

Koby¹

1959

BMJ

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Intrapulmonary mixing of gases studied with aerosols

Cited by 74 publications

References 0 publications

Aerosol bolus dispersion in healthy subjects

Aerosol bolus dispersion in healthy subjects

Detection of early lung impairment with aerosol bolus dispersion

Vulval Varicosities in Pregnancy

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