Distributions of lung ventilation and perfusion in prone and supine humans exposed to hypergravity.

@article{Rohdin2004DistributionsOL,
  title={Distributions of lung ventilation and perfusion in prone and supine humans exposed to hypergravity.},
  author={Malin Rohdin and J. Petersson and Margareta Mure and Robb W. Glenny and Sten G. E. Lindahl and Dag Linnarsson},
  journal={Journal of applied physiology},
  year={2004},
  volume={97 2},
  pages={
          675-82
        }
}
When normal subjects are exposed to hypergravity [5 times normal gravity (5 G)] there is an impaired arterial oxygenation that is less severe in the prone compared with supine posture. We hypothesized that under these conditions the heterogeneities of ventilation and/or perfusion distributions would be less prominent when subjects were prone compared with supine. Expirograms from a combined rebreathing-single breath washout maneuver (Rohdin M, Sundblad P, and Linnarsson D. J Appl Physiol 96… 
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16 Citations
Background Citations
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Methods Citations
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16 Citations

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Citation Type

Paradoxical redistribution of pulmonary blood flow in prone and supine humans exposed to hypergravity.
TLDR
Exposure to hypergravity in the supine and prone postures causes a redistribution of pulmonary blood flow from dependent to nondependent lung regions in all subjects in both postures, which is likely to attenuate rather than contribute to the arterial desaturation caused by hypergravity.
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It is concluded that pulmonary function is more effectively preserved in the prone than in the supine posture upon exposure to hypergravity, which is in agreement with previous findings of more extensively impaired arterial oxygenation in supine hypergravity.
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The heart-synchronous mechanical agitation of the lungs, as expressed by COS(flow), is highly dependent on peripheral-to-central blood shifts and COS appears relatively independent of this mechanical agitation and seems to be determined mainly by differences in intrapulmonary perfusion.
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Evidence now suggests that gravity has a less important role in the variation of regional distribution than structural features of the airways and blood vessels, and the application of these findings to conditions such as acute lung injury is discussed.
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Exposure of the healthy lungs to hypergravity can simulate key components of acute respiratory distress syndrome, a severe type of lung insufficiency, and recent preliminary data from a follow-up study suggest a protective role at lower hypergravity levels when the lung deformation is less pronounced.
Prone positioning acute respiratory distress syndrome patients.
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  • Medicine
    Annals of translational medicine
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Prone position is a key component of lung protective mechanical ventilation and should be used as a first line therapy in association with low tidal volume and neuromuscular blocking agents in patients with severe ARDS.
The effect of lung orientation on functional imaging of blood flow
TLDR
An image-based computational model of coupled tissue mechanics and pulmonary blood flow to enable predictions of pulmonary perfusion in various postures and lung volumes is developed and demonstrated a relatively consistent flow distribution in all postures indicating the large influence of branching structure on flow distribution.
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References

SHOWING 1-10 OF 27 REFERENCES
Effects of gravity on lung diffusing capacity and cardiac output in prone and supine humans.
TLDR
The finding of a more impaired diffusing capacity in the supine posture compared with the prone at 5 G supports the previous observations of more severe arterial hypoxemia in the Supine posture during hypergravity.
Effects of hypergravity on the distributions of lung ventilation and perfusion in sitting humans assessed with a simple two-step maneuver.
TLDR
It is concluded that not only large-scale ventilation and perfusion inhomogeneities, as reflected by phase IV amplitude, but also smaller-scale inhomogeneousities,As reflected by the ratio of COS to stroke volume, increase with hypergravity.
Protective effect of prone posture against hypergravity-induced arterial hypoxaemia in humans.
TLDR
It is speculated that mammals have developed a cardiopulmonary structure that favours function with the gravitational vector in the posterio-anterior direction.
Gravitational independence of single-breath washout tests in recumbent dogs.
TLDR
In recumbent dogs regional distribution of ventilation is not primarily determined by the effect of gravity, but by lung, thorax, and mediastinum interactions and/or differences in regional mechanical properties of the lungs.
Effects of hypergravity and anti-G suit pressure on intraregional ventilation distribution during VC breaths.
TLDR
Hypergravity increases overall but not intraregional intra-acinar inhomogeneity during VC breaths, presumably reflecting the consequences of basilar pulmonary vessel engorgement in combination with compression of the basilar lung regions.
The prone position eliminates compression of the lungs by the heart.
TLDR
The relative volume of lung located directly under the heart was measured in the supine and prone positions in seven patients to investigate a potential mechanism by which turning prone restores ventilation to dorsal lung regions without markedly compromising ventral regions.
Inhomogeneity of pulmonary ventilation during sustained microgravity as determined by single-breath washouts.
TLDR
The presence of a phase IV in microgravity is strong evidence that airway closure still occurs in the absence of gravity, as evidenced by the significant reductions in cardiogenic oscillations, slope of phase III, and height of phase IV for nitrogen and argon.
Inhomogeneity of pulmonary perfusion during sustained microgravity on SLS-1.
TLDR
The residual cardiogenic oscillations in expired CO2 imply a persisting inhomogeneity of perfusion in the absence of gravity, probably in lung regions that are not within the same acinus.
Effect of posture on the single-breath oxygen test in normal subjects.
TLDR
The data suggest a considerable similarity between the upright and prone positions in terms of lung filling and emptying and it is difficult to explain the failure of posture to alter phase IV solely on a model requiring a linear gradient of pleural pressure.
Single-breath washouts in a rotating stretcher.
TLDR
Of all body postures under study, the prone position most reduces the inhomogeneities of ventilation during a vital capacity maneuver at both inter- and intraregional levels, suggesting that phase III slope is partially due to emptying patterns of small units with different ventilation-to-volume ratios, corresponding to acini or groups of acini.
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