Distribution of pulmonary blood flow as affected by transverse (+Gx) acceleration

Hoppin, F. G.; York, Elihu; Kuhl, David E.; Hyde, Richard W.

doi:10.1152/jappl.1967.22.3.469

Cited by 15 publications

(6 citation statements)

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“…In a study on supine humans exposed to hypergravity up to 8 G, Hoppin et al did not demonstrate any significant change in the distribution of regional lung blood flow. 118 In that study, a radioactive agent was administered during hypergravity exposure, followed by scanning at 1 G. This is in contrast to a later study by Glaister on supine humans exposed to 3 and 5 G. 111 In this study both administration and scanning of the radioactive agent marking regional blood flow were performed during hypergravity. The study demonstrated an increase in regional blood flow in the direction of gravity, reaching a maximum in the midlung followed by a decrease in the dependent part of the lung.…”

Section: Distribution Of Regional Lung Perfusion At Hypergravitymentioning

confidence: 98%

Regional lung ventilation in humans during hypergravity studied with quantitative SPECT

Karlsson

Sánchez-Crespo

et al. 2013

Respiratory Physiology & Neurobiology

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Section: Distribution Of Regional Lung Perfusion At Hypergravitymentioning

confidence: 98%

Regional lung ventilation in humans during hypergravity studied with quantitative SPECT

Karlsson

Sánchez-Crespo

et al. 2013

Respiratory Physiology & Neurobiology

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“…Invasive imaging techniques have been used in humans in different gravity conditions, but the results are difficult to interpret and cannot be compared with our results: injections took place either in an undistorted (0 G) or in an overdistorted lung (4 G, 8 G), whereas scanning was performed at 1 G. Thus what was measured was likely the distribution of pulmonary perfusion per vascular unit and not the spatial distribution in micro-and hypergravity per unit lung volume (29,42). Mostly due to mass and volume restrictions, high-resolution imaging techniques to provide three-dimensional topographical data are presently not suitable for inflight use.…”

Section: Intraregional Perfusion Heterogeneitymentioning

confidence: 73%

Residual heterogeneity of intra- and interregional pulmonary perfusion in short-term microgravity

Montmerle¹,

Sundblad²,

Linnarsson³

2005

Journal of Applied Physiology

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We hypothesized that the perfusion heterogeneity in the human, upright lung is determined by nongravitational more than gravitational factors. Twelve and six subjects were studied during two series of parabolic flights. We used cardiogenic oscillations of O(2)/SF(6) as an indirect estimate of intraregional perfusion heterogeneity (series 1) and phase IV amplitude (P(4)) as a indirect estimate of interregional perfusion heterogeneity (series 2). A rebreathing-breath holding-expiration maneuver was performed. In flight, breath holding and expiration were performed either in microgravity (0 G) or in hypergravity. Controls were performed at normal gravity (1 G). In series 1, expiration was performed at 0 G. Cardiogenic oscillations of O(2)/SF(6) were 19% lower when breath holding was performed at 0 G than when breath holding was performed at 1 G [means (SD): 1.7 (0.3) and 2.3 (0.6)% units] (P = 0.044). When breath holding was performed at 1.8 G, values did not differ from 1-G control [2.6 (0.8)% units, P = 0.15], but they were 17% larger at 1.8 G than at 1 G. In series 2, expiration was performed at 1.7 G. P(4) changed with gravity (P < 0.001). When breath holding was performed at 0 G, P(4) values were 45 (46)% of control. When breath holding was performed at 1.7 G, P(4) values were 183 (101)% of control. We conclude that more than one-half of indexes of perfusion heterogeneity at 1 G are caused by nongravitational mechanisms.

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“…Scintigrams performed on six sitting subjects during short-term microgravity showed that lung perfusion was more homogeneously distributed at 0 G than at normal gravity (119). On the other hand, recordings performed with the same technique on three subjects undergoing forward acceleration (injections at 1G x , 4G x and 8G x ) found that perfusion distribution was similar at all G loads (58).…”

Section: Background Classical Model Of Distribution Of Ventilation Anmentioning

confidence: 89%

Effects of gravity and blood volume shifts on cardiogenic oscillations in respired gas

Montmerle

Linnarsson²

2005

Journal of Applied Physiology

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During the cardiac cycle, cardiogenic oscillations of expired gas (x) concentrations (COS([x])) are generated. At the same time, there are heart-synchronous cardiogenic oscillations of airway flow (COS(flow)), where inflow occurs during systole. We hypothesized that both phenomena, although primarily generated by the heartbeat, would react differently to the cephalad blood shift caused by inflation of an anti-gravity (anti-G) suit and to changes in gravity. Twelve seated subjects performed a rebreathing-breath-holding-expiration maneuver with a gas mixture containing O2 and He at normal (1 G) and moderately increased gravity (2 G); an anti-G suit was inflated to 85 mmHg in each condition. When the anti-G suit was inflated, COS(flow) amplitude increased (P = 0.0028) at 1 G to 186% of the control value without inflation (1-G control) and at 2 G to 203% of the control value without inflation (2-G control). In contrast, the amplitude of COS of the concentration of the blood-soluble gas O2 (COS([O2/He])), an index of the differences in pulmonary perfusion between lung units, declined to 75% of the 1-G control value and to 74% of the 2-G control value (P = 0.0030). There were no significant changes in COS(flow) or COS([O2/He]) amplitudes with gravity. We conclude that the heart-synchronous mechanical agitation of the lungs, as expressed by COS(flow), is highly dependent on peripheral-to-central blood shifts. In contrast, COS([blood-soluble gas]) appears relatively independent of this mechanical agitation and seems to be determined mainly by differences in intrapulmonary perfusion.

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Distribution of pulmonary blood flow as affected by transverse (+Gx) acceleration

Cited by 15 publications

References 0 publications

Regional lung ventilation in humans during hypergravity studied with quantitative SPECT

Regional lung ventilation in humans during hypergravity studied with quantitative SPECT

Residual heterogeneity of intra- and interregional pulmonary perfusion in short-term microgravity

Effects of gravity and blood volume shifts on cardiogenic oscillations in respired gas

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