Pulsatile gas flow in bronchi caused by the heart beat

West, John B.; Hugh‐Jones, P.

doi:10.1152/jappl.1961.16.4.697

Cited by 78 publications

(30 citation statements)

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“…Breath holds at end-inspiration flatten SIII and should be minimised [30,63]. The beating heart generates flow pulses within airways [79] causing cardiogenic gas mixing. Cardiogenic oscillations superimposed onto SIII add to signal noise.…”

Section: Ers/ats Consensus Statement Pd Robinson Et Almentioning

confidence: 99%

Consensus statement for inert gas washout measurement using multiple- and single- breath tests

Robinson¹,

Latzin²,

Verbanck³

et al. 2013

Eur Respir J

680

1,007

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Inert gas washout tests, performed using the single-or multiple-breath washout technique, were first described over 60 years ago. As measures of ventilation distribution inhomogeneity, they offer complementary information to standard lung function tests, such as spirometry, as well as improved feasibility across wider age ranges and improved sensitivity in the detection of early lung damage. These benefits have led to a resurgence of interest in these techniques from manufacturers, clinicians and researchers, yet detailed guidelines for washout equipment specifications, test performance and analysis are lacking. This manuscript provides recommendations about these aspects, applicable to both the paediatric and adult testing environment, whilst outlining the important principles that are essential for the reader to understand. These recommendations are evidence based, where possible, but in many places represent expert opinion from a working group with a large collective experience in the techniques discussed.Finally, the important issues that remain unanswered are highlighted. By addressing these important issues and directing future research, the hope is to facilitate the incorporation of these promising tests into routine clinical practice.

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Section: Ers/ats Consensus Statement Pd Robinson Et Almentioning

confidence: 99%

Consensus statement for inert gas washout measurement using multiple- and single- breath tests

Robinson¹,

Latzin²,

Verbanck³

et al. 2013

Eur Respir J

680

1,007

View full text Add to dashboard Cite

show abstract

“…It has been shown (54,55) that in humans, flow pulses corresponding to a volume displacement up to 5 ml, are present in any zone of the bronchial tree where they could be measured. More recently, Colebatch et al (56) calculated a mean volume displacement of 6.6 ml with a peak flow of 120 ml/s.…”

Section: Dispersionmentioning

confidence: 99%

Gas Mixing in the Airways and Airspaces

Verbanck¹,

Paiva

2011

Comprehensive Physiology

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Basic physical concepts of diffusion, convection, and dispersion pertaining to gas transport in the human airways are reviewed. Their incorporation into quantitative models of gas mixing is presented, also illustrating the crucial interaction of gas transport equations with the model geometry. Model simulations are confronted with the available experimental gas mixing indices such as the phase III slope obtained in normal human lungs, with some pertinent examples in laboratory animals and in human lung disease. The use of inert gases with differing diffusion coefficients and their associated phase III slope provides invaluable experimental information on gas mixing in the lungs, with the concept of the diffusion front playing a central role. Sources of inter- and intraregional ventilation heterogeneity can be related to the location of the diffusion front, which offers the possibility to distinguish between ventilation heterogeneity proximal to the diffusion front (driven by convection between lung units larger than acini) and more peripheral ventilation heterogeneity (driven by diffusion-convection interaction mainly within the acinus). While specific ventilation distribution and flow asynchrony co-act to generate convection-dependent ventilation heterogeneity, local structural asymmetry of the acinar air spaces is sufficient to generate diffusion-convection-dependent ventilation heterogeneity. The remaining hiatus in our understanding of ventilation heterogeneity in the human lung is described, together with some potential perspectives for its investigation.

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“…The physical motion of the heart generates an oscillating motion of air in the lungs, which results in an enhanced gas mixing in the airways (11,24). This mixing is usually referred to as cardiogenic mixing.…”

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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Pulsatile gas flow in bronchi caused by the heart beat

Cited by 78 publications

References 0 publications

Consensus statement for inert gas washout measurement using multiple- and single- breath tests

Consensus statement for inert gas washout measurement using multiple- and single- breath tests

Gas Mixing in the Airways and Airspaces

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

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