Adaptation of Systemic and Pulmonary Circulation to Acute Changes in Gravity and Body Position

Hoffmann, Uwe; Koschate, Jessica; Coriolano, Hans-Joachim Appell; Drescher, Uwe; Thieschäfer, Lutz; Dumitrescu, Daniel; Werner, Andreas

doi:10.3357/amhp.5300.2019

Cited by 10 publications

(14 citation statements)

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“…Levels of downward inertial force can be quantified as gravity (+Gz, also called G force). Hydrostatic pressure produced by G force causes blood to flow toward the lower body region, and hemodynamic parameters are affected in hypergravity environments [2][3][4][5]. If G stress surpasses the tolerance, military aircrew will probably experience visual disturbances and even G-induced loss of consciousness (GLOC) that will extremely threaten the flight safety [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

A Cardiac Force Index Applied to the G Tolerance Test and Surveillance among Male Military Aircrew

Chiang

Lin

et al. 2021

IJERPH

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Military aircrew are occupationally exposed to a high-G environment. A tolerance test and surveillance is necessary for military aircrew before flight training. A cardiac force index (CFI) has been developed to assess long-distance running by health technology. We added the parameter CFI to the G tolerance test and elucidated the relationship between the CFI and G tolerance. A noninvasive device, BioHarness 3.0, was used to measure heart rate (HR) and activity while resting and walking on the ground. The formula for calculating cardiac function was CFI = weight × activity/HR. Cardiac force ratio (CFR) was calculated by walking CFI (WCFI)/resting CFI (RCFI). G tolerance included relaxed G tolerance (RGT) and straining G tolerance (SGT) tested in the centrifuge. Among 92 male participants, the average of RCFI, WCFI, and CFR were 0.02 ± 0.04, 0.15 ± 0.04, and 10.77 ± 4.11, respectively. Each 100-unit increase in the WCFI increased the RGT by 0.14 G and the SGT by 0.17 G. There was an increased chance of RGT values higher than 5 G and SGT values higher than 8 G according to the WCFI increase. Results suggested that WCFI is positively correlated with G tolerance and has the potential for G tolerance surveillance and programs of G tolerance improvement among male military aircrew.

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Section: Introductionmentioning

confidence: 99%

A Cardiac Force Index Applied to the G Tolerance Test and Surveillance among Male Military Aircrew

Chiang

Lin

et al. 2021

IJERPH

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“…Their experiment showed that there is a decreased stimulation of volume receptors in microgravity. Furthermore, a minimal difference between pulmonary blood circulation and systemic blood circulation is seen in response to acute changes in gravity and body position relative to the force of gravity 3 . There are assumptions that there is a transient difference between right and left ventricular ejection fraction in response to acute gravity differences 3 20 21 .…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, a minimal difference between pulmonary blood circulation and systemic blood circulation is seen in response to acute changes in gravity and body position relative to the force of gravity 3 . There are assumptions that there is a transient difference between right and left ventricular ejection fraction in response to acute gravity differences 3 20 21 . The difference between the ejection fractions of the ventricles and the understanding of the effects of physical pressure (e. g., the Ex-Ex maneuver) on the pulmonary vasculature holds potential for diagnosis and further understanding of the pulmonary vascular disease, e. g. idiopathic pulmonary arterial hypertension (PAH).…”

Section: Introductionmentioning

confidence: 99%

“…The aim of this study is, in addition to the already processed data concerning the resting situation (see 3 ), to analyze the influence of Ex-Ex on the cardiovascular regulation after acute gravitational changes in comparison to resting breath situation. Three conditions of gravity changes to the body, tilt-seat, parabolic flight, and long-arm human centrifuge, will be compared.…”

Section: Introductionmentioning

confidence: 99%

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Cardiovascular Regulation During Acute Gravitational Changes with Exhaling on Exertion

et al. 2022

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During gravitational changes or changes in the direction of action in relation to the body, fluid displacements can be observed. In special cases different breathing maneuvers (e. g., exhaling on exertion; Ex-Ex) are used to counteract acute fluid shifts. Both factors have a significant impact on cardiovascular regulation. Eight healthy male subjects were tested on a tilt seat, long arm human centrifuge, and parabolic flight. The work aims to investigate the effect of exhaling on exertion on the cardiovascular regulation during acute gravitational changes compared to normal breathing. Possible interactions and differences between conditions (Ex-Ex, normal breathing) for the parameters V’O 2 , V’ E , HR, and SV were analysed over a 40 s period by a three-way ANOVA. Significant (p≤0.05) effects for all main factors and interactions between condition and time as well as maneuver and time were found for all variables. The exhaling on exertion maneuver had a significant influence on the cardiovascular response during acute gravitational and positional changes. For example, the significant increase of V’O2 at the end of the exhalation on exertion maneuver indicates an increased lung circulation as a result of the maneuver.

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“…A few studies have reported the use of centrifuges for simulation of parabolic flight involving human participants. [4,5] Human Centrifuge, as a simulation modality for parabolic flight, may serve as a training platform for the preparation of space crew for the subsequent actual parabolic flight and space missions by allowing their familiarization and physiological adaptation to such novel environments. The present study was undertaken to evaluate the feasibility of using human centrifuge for parabolic flight simulation.…”

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confidence: 99%

Cardiopulmonary responses to centrifuge simulated parabolic flight

Harshith

Nataraja

Dinakar

2021

IJASM

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Introduction: Parabolic flights, by producing short periods of weightlessness, closely simulate microgravity. However, they are still expensive, incur a significant logistics support, and occurrence of any adverse events during such simulation is undesirable. The present study was formulated to explore the feasibility of using a human centrifuge for simulation of parabolic flight to study the cardiopulmonary parameters as an alternative ground-based model. Material and Methods: Twelve healthy male volunteers were subjected to simulated parabolic flight, the profile of which involved exposure to 20 repetitions of hypogravity periods (+0.5 Gz), each interposed between periods of hypergravity phases (+2 Gz), using high-performance human centrifuge. Heart rate (HR), respiratory rate (RR), and arterial oxygen saturation (SpO2) were studied during such a simulation and analyzed using one-way repeated measures ANOVA. Motion sickness assessment questionnaire was administered to the participants after the run. They were also asked to rate their subjective feeling of weightlessness experienced during the run. Results: Comparison of HR revealed a significant difference (F = 22.167, P < 0.001) across 20 loops of different gravity phases. Post hoc analysis revealed that the mean HR of hypergravity phases was significantly higher compared with pre-run 1 G values and that of hypogravity phases. Similarly, HR showed a significant difference across pre-run 1 G, 10th and 20th loops of hypogravity phases (F = 5.672, P = 0.01). Post hoc analysis revealed a significant reduction in HR at 20th loop compared to both pre-run 1 G (P = 0.023) and 10th loop (P = 0.042) values. No significant differences were observed in both RR (F = 1.789, P = 0.148) and SpO2 (F = 1.708, P =0.199) across different gravity phases. The mean overall motion sickness score was found to be 23.6%. Participants rated their subjective feeling of weightlessness between 4 and 6 (mode = 5) on a scale of 1–10. Conclusion: It can be concluded from the results that HR increased during hypergravity conditions and reduced during hypogravity conditions, an expected outcome during parabolic flight. The significant reduction in HR during the 20th loop of hypogravity phase compared to 10th loop and pre-run 1 G conditions indicate a possible association with the duration of exposure. The centrifuge simulated parabolic flight profile designed in our study was able to emanate physiological changes similar to those experienced in actual parabolic flight for HR, RR, and SpO2.

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Adaptation of Systemic and Pulmonary Circulation to Acute Changes in Gravity and Body Position

Cited by 10 publications

References 0 publications

A Cardiac Force Index Applied to the G Tolerance Test and Surveillance among Male Military Aircrew

A Cardiac Force Index Applied to the G Tolerance Test and Surveillance among Male Military Aircrew

Cardiovascular Regulation During Acute Gravitational Changes with Exhaling on Exertion

Cardiopulmonary responses to centrifuge simulated parabolic flight

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