Effect of heart rate and stroke volume on gas mixing in dog lung

Horsfield, Keith; Gabe, I. T.; Mills, C.; Buckman, M. P.; Cumming, Gordon R.

doi:10.1152/jappl.1982.53.6.1603

Cited by 17 publications

(4 citation statements)

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“…Cardiogenic mixing is likely one contributor to this increase in dispersion. This is supported by observations from a study in dog lungs on the effect of heart rate and stroke volume on gas mixing where it was shown that cardiogenic mixing increases the effective diffusion coefficient in the airways [16]. …”

Section: Discussionsupporting

confidence: 57%

Cardiogenic mixing increases aerosol deposition in the human lung in the absence of gravity

2013

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Rationale Exposure to extraterrestrial dusts is an almost inevitable consequence of any proposed planetary exploration. Previous studies in humans showed reduced deposition in low-gravity compared with normal gravity (1G). However, the reduced sedimentation means that fewer particles deposit in the airways, increasing the number of particles transported to the lung periphery where they eventually deposit albeit at a smaller rate than in 1G. In this study, we determined the role that gravity and other mechanisms such as cardiogenic mixing play in peripheral lung deposition during breath holds. Methods Eight healthy subjects inhaled boluses of 0.5 μm-diameter particles to penetration volumes (Vp) of 300 and 1200ml that were followed by breath holds of up to 10 sec. Tests were performed in 1G and during short periods of microgravity (μG) aboard the NASA Microgravity Research Aircraft. Aerosol deposition and dispersion were calculated from these data. Results Results show that, for both Vp, deposition in 1G was significantly higher than in μG. In contrast, while dispersion was significantly higher in 1G compared to μG at Vp=1200ml, there was no significant gravitational effect on dispersion at Vp=300ml. Finally, for each G level and Vp, deposition and dispersion significantly increased with increasing breath-hold time. Conclusion The most important finding of this study is that, even in the absence of gravity, aerosol deposition in the lung periphery increased with increasing residence time. Because the particles used in this study were too large to be significantly affected by Brownian diffusion, the increase in deposition is likely due to cardiogenic motion effects.

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Section: Discussionsupporting

confidence: 57%

Cardiogenic mixing increases aerosol deposition in the human lung in the absence of gravity

2013

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“…Engel et al [18] found that the observed flow oscillations were due to the movement of the heart itself rather than pulsation of intrapulmonary vessels. Engel et al [18] and Horsfield et al [19] showed that the anatomic dead space (V,) measured by nitrogen washout curves increased postmortem and decreased with increasing end-inspiratory breathholding periods. They deduced that this enhanced V, was a result of gas mixing, caused by cardiogenic oscillations.…”

Section: Discussionmentioning

confidence: 99%

Effect of Heart Rate on Aerosol Recovery and Dispersion in Human Conducting Airways After Periods of Breathholding

Scheuch¹,

Stahlhofen²

1991

Experimental Lung Research

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With a newly developed aerosol inhalation device, small volumes of aerosols ("boluses") can be inspired predominantly into the conducting airways of the human lungs. The aerosol is injected by a fast-operating valve system using preselected volumes near the end of a clean air inhalation of 1000 cm3. Particle behavior in upper human airways was investigated by measuring particle recovery and bolus dispersion in exhaled air with a laser photometer positioned directly in front of the mouth after various periods of breathholding. The effect of physical motion of the heart on these measurements has been investigated by increasing the heart rate of a subject by more than a factor of 2. Monodisperse sebacate aerosols were used with droplets in the aerodynamic size (dac) range between 0.8 and 1.1 micron to minimize particle losses by diffusion and by inertial forces. It was shown that motion of the heart considerably influences both particle recovery and dispersion of such boluses during postinhalation periods of breathholding. For a twofold enhancement in heart frequency the standard deviation of the expired aerosol bolus was increased by up to 60% after certain breathholding periods. Particle recovery from shallow volumetric lung depths was significantly decreased.

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“…2) is, therefore, likely due to cardiogenic mixing. In a study of cardiac action on gas mixing in dog lungs, Horsfield et al (14) suggested that the flow pulsations resulting from the heart motions increased the effective diffusion coefficient in the conducting airways, whereas mixing in the distal part of the lung was only slightly affected. They explained the increase in mixing in the central airways as simply the result of the mechanical action of the heart.…”

Section: Dementioning

confidence: 99%

Effect of gravity on aerosol dispersion and deposition in the human lung after periods of breath holding

Darquenne

Paiva

Prisk

2000

Journal of Applied Physiology

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Darquenne, Chantal, Manuel Paiva, and G. Kim Prisk. Effect of gravity on aerosol dispersion and deposition in the human lung after periods of breath holding. J Appl Physiol 89: 1787-1792, 2000.-To determine the extent of the role that gravity plays in dispersion and deposition during breath holds, we performed aerosol bolus inhalations of 1-m-diameter particles followed by breath holds of various lengths on four subjects on the ground (1G) and during short periods of microgravity (G). Boluses of ϳ70 ml were inhaled to penetration volumes (V p ) of 150 and 500 ml, at a constant flow rate of ϳ0.45 l/s. Aerosol concentration and flow rate were continuously measured at the mouth. Aerosol deposition and dispersion were calculated from these data. Deposition was independent of breath-hold time at both V p in G, whereas, in 1G, deposition increased with increasing breath hold time. At V p ϭ 150 ml, dispersion was similar at both gravity levels and increased with breath hold time. At V p ϭ 500 ml, dispersion in 1G was always significantly higher than in G. The data provide direct evidence that gravitational sedimentation is the main mechanism of deposition and dispersion during breath holds. The data also suggest that cardiogenic mixing and turbulent mixing contribute to deposition and dispersion at shallow V p . aerosol bolus; cardiogenic mixing AEROSOL BOLUS INHALATIONS have largely been used to study deposition and mixing processes in specific volumetric regions of the lung (3,4,13,19). Particles are transported in the respiratory tract by the carrier gas, and they deviate from the streamlines mainly by diffusion, sedimentation, and inertia. Of these mechanisms, sedimentation is the only mechanism that is directly affected by a change in the gravity (G) level. The deposition and dispersion of aerosol boluses inhaled in microgravity (G) therefore differ from those inhaled in normal gravity (1G) because sedimentation plays a role in these processes. This has been shown by our group in previous studies (7,8), in which aerosol bolus inhalations with no breath hold before the subsequent exhalation were performed in G, 1G, and 1.6G. In these studies, both aerosol deposition (DE) and dispersion (H) increased with increasing G level, and this effect was more pronounced in the alveolar region of the lung than in the large airways.In the present study, we performed bolus inhalations of 1-m-diameter particles, followed by breath holds of various lengths, up to 5 s. The tests were performed on the ground (1G) and during short periods of G aboard the NASA Microgravity Research Aircraft, to determine the extent of the role that gravity plays in DE and H during breath holds. We show that gravitational sedimentation is the principal mechanism of DE during breath holding. The data also suggest that cardiogenic mixing contributes to DE and H and that the effect is larger in the central airways than in the alveolar region. METHODS Equipment.Aerosol bolus data were collected with the same equipment used in previous studies (7,8). The eq...

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Effect of heart rate and stroke volume on gas mixing in dog lung

Cited by 17 publications

References 0 publications

Cardiogenic mixing increases aerosol deposition in the human lung in the absence of gravity

Cardiogenic mixing increases aerosol deposition in the human lung in the absence of gravity

Effect of Heart Rate on Aerosol Recovery and Dispersion in Human Conducting Airways After Periods of Breathholding

Effect of gravity on aerosol dispersion and deposition in the human lung after periods of breath holding

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