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Distributions of lu...
Distributions of lung ventilation and perfusion in prone and supine humans exposed to hypergravity
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- Rohdin, M (författare)
- Karolinska Institutet
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- Petersson, J (författare)
- Karolinska Institutet
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- Mure, M (författare)
- Karolinska Institutet
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Glenny, RW (författare)
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- Lindahl, SGE (författare)
- Karolinska Institutet
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- Linnarsson, D (författare)
- Karolinska Institutet
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(creator_code:org_t)
- American Physiological Society, 2004
- 2004
- Engelska.
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Ingår i: Journal of applied physiology (Bethesda, Md. : 1985). - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 97:2, s. 675-682
- Relaterad länk:
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http://kipublication...
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https://doi.org/10.1...
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Abstract
Ämnesord
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- 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: 1470–1477, 2004) were analyzed for vital capacity (VC), phase III slope, and phase IV amplitude, to analyze heterogeneities in ventilation (Ar) and perfusion [CO2-to-Ar ratio (CO2/Ar)] distribution, respectively. During hypergravity, VC decreased more in the supine than in the prone position (ANOVA, P = 0.02). Phase III slope was more positive for Ar ( P = 0.003) and more negative for CO2/Ar ( P = 0.007) in the supine compared with prone posture at 5 G, in agreement with the notion of a more severe hypergravity-induced ventilation-perfusion mismatch in supine posture. Phase IV amplitude became lower in the supine than in the prone posture for both Ar ( P = 0.02) and CO2/Ar ( P = 0.004) during hypergravity as a result of the more reduced VC in the supine posture. We speculate that results of VC and phase IV amplitude are due to the differences in heart-lung interaction and diaphragm position between postures: a stable position of the heart and diaphragm in prone hypergravity, in contrast to supine in which the weight of the heart and a cephalad shift of the diaphragm compress lung tissue.
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