Acute and Chronic Effects of Hypobaric Exposure upon the Brain

Sherman, Paul M.; Sladky, John

doi:10.5772/intechopen.74231

Cited by 8 publications

(7 citation statements)

References 76 publications

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“…Although hypobaric chambers provided the initial tools to induce hypoxia, reduced oxygen breathing devices (ROBD) providing mask-on NH ( Sausen et al, 2001 ) and a combination of HH and mask-on NH (i.e., CADO; Singh et al, 2010 ) have more recently been incorporated into HRT to prevent potential adverse effects of barometric pressure reduction, such as decompression sickness ( Webb and Pilmanis, 2011 ), white matter hyperintensities ( McGuire et al, 2014 , 2019 ; Sherman and Sladky, 2018 ) and barotrauma. Additional advantages of ROBDs are their simplicity, ease of transport, reduced expense, and lower maintenance, and they can be the preferred mode of HRT for some individuals, particularly fighter pilots ( Artino et al, 2006 ).…”

Section: Training and Preparing For Hypoxic Incidentsmentioning

confidence: 99%

Hypoxic Hypoxia and Brain Function in Military Aviation: Basic Physiology and Applied Perspectives

Shaw

Cabre²

2021

Front. Physiol.

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Acute hypobaric hypoxia (HH) is a major physiological threat during high-altitude flight and operations. In military aviation, although hypoxia-related fatalities are rare, incidences are common and are likely underreported. Hypoxia is a reduction in oxygen availability, which can impair brain function and performance of operational and safety-critical tasks. HH occurs at high altitude, due to the reduction in atmospheric oxygen pressure. This physiological state is also partially simulated in normobaric environments for training and research, by reducing the fraction of inspired oxygen to achieve comparable tissue oxygen saturation [normobaric hypoxia (NH)]. Hypoxia can occur in susceptible individuals below 10,000 ft (3,048 m) in unpressurised aircrafts and at higher altitudes in pressurised environments when life support systems malfunction or due to improper equipment use. Between 10,000 ft and 15,000 ft (4,572 m), brain function is mildly impaired and hypoxic symptoms are common, although both are often difficult to accurately quantify, which may partly be due to the effects of hypocapnia. Above 15,000 ft, brain function exponentially deteriorates with increasing altitude until loss of consciousness. The period of effective and safe performance of operational tasks following exposure to hypoxia is termed the time-of-useful-consciousness (TUC). Recovery of brain function following hypoxia may also lag beyond arterial reoxygenation and could be exacerbated by repeated hypoxic exposures or hyperoxic recovery. This review provides an overview of the basic physiology and implications of hypoxia for military aviation and discusses the utility of hypoxia recognition training.

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Section: Training and Preparing For Hypoxic Incidentsmentioning

confidence: 99%

Hypoxic Hypoxia and Brain Function in Military Aviation: Basic Physiology and Applied Perspectives

Shaw

Cabre²

2021

Front. Physiol.

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“…However, despite these concerns, there have been no recorded cases of DCS in astronauts in pressurized space-suits during EVA, in contrast to altitude chamber technicians, who are much more prone to symptoms or signs of DCS. This might be explained by potential operational and gravitational benefits of the spaceflight upward fluid shift and pre-breathing exercise that induce faster denitrogenation ( Sherman and Sladky, 2018 ).…”

Section: Eva and Decompression Sickness (Dcs) Riskmentioning

confidence: 99%

Recent Progress in Space Physiology and Aging

Strollo¹,

Gentile²,

Strollo

et al. 2018

Front. Physiol.

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Astronauts coming back from long-term space missions present with different health problems potentially affecting mission performance, involving all functional systems and organs and closely resembling those found in the elderly. This review points out the most recent advances in the literature in areas of expertise in which specific research groups were particularly creative, and as they relate to aging and to possible benefits on Earth for disabled people. The update of new findings and approaches in space research refers especially to neuro-immuno-endocrine-metabolic interactions, optic nerve edema, motion sickness and muscle-tendon-bone interplay and aims at providing the curious - and even possibly naïve young researchers – with a source of inspiration and of creative ideas for translational research.

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“…Behavioral studies have shown high inter- and intra-individual variabilities in animals and humans in response to brain stimulation paradigms ( Fiske and Rice, 1955 ; Loevinger, 1957 ; López-Alonso et al, 2014 ; Wyrobek and Britten, 2016 ; Sherman and Sladky, 2018 ). These variabilities are manifested when the same subject responds differently in the ATSET if the test is done another time and may provide a potential explanation for rats with similar prescreen scores having different impairment labels.…”

Section: Discussionmentioning

confidence: 99%

“…While these statistical tests and plots are valuable, given the low sample size in such studies and the extent to which an affected individual score impacts the skewness of the population data, seen as the mean of the sample scores deviating significantly from their median, these averages alone likely represent an inadequate characterization of the change in the overall population performance. Furthermore, inter- and intra-individual variabilities in responses to brain stimulation paradigms ( Fiske and Rice, 1955 ; Loevinger, 1957 ; López-Alonso et al, 2014 ; Wyrobek and Britten, 2016 ; Sherman and Sladky, 2018 ) lead to inconsistent means across sample populations and disqualify their inferences on the general population.…”

Section: Introductionmentioning

confidence: 99%

Machine Learning Models to Predict Cognitive Impairment of Rodents Subjected to Space Radiation

Matar

Gökoğlu

Prelich

et al. 2021

Front. Syst. Neurosci.

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This research uses machine-learned computational analyses to predict the cognitive performance impairment of rats induced by irradiation. The experimental data in the analyses is from a rodent model exposed to ≤15 cGy of individual galactic cosmic radiation (GCR) ions: 4He, 16O, 28Si, 48Ti, or 56Fe, expected for a Lunar or Mars mission. This work investigates rats at a subject-based level and uses performance scores taken before irradiation to predict impairment in attentional set-shifting (ATSET) data post-irradiation. Here, the worst performing rats of the control group define the impairment thresholds based on population analyses via cumulative distribution functions, leading to the labeling of impairment for each subject. A significant finding is the exhibition of a dose-dependent increasing probability of impairment for 1 to 10 cGy of 28Si or 56Fe in the simple discrimination (SD) stage of the ATSET, and for 1 to 10 cGy of 56Fe in the compound discrimination (CD) stage. On a subject-based level, implementing machine learning (ML) classifiers such as the Gaussian naïve Bayes, support vector machine, and artificial neural networks identifies rats that have a higher tendency for impairment after GCR exposure. The algorithms employ the experimental prescreen performance scores as multidimensional input features to predict each rodent’s susceptibility to cognitive impairment due to space radiation exposure. The receiver operating characteristic and the precision-recall curves of the ML models show a better prediction of impairment when 56Fe is the ion in question in both SD and CD stages. They, however, do not depict impairment due to 4He in SD and 28Si in CD, suggesting no dose-dependent impairment response in these cases. One key finding of our study is that prescreen performance scores can be used to predict the ATSET performance impairments. This result is significant to crewed space missions as it supports the potential of predicting an astronaut’s impairment in a specific task before spaceflight through the implementation of appropriately trained ML tools. Future research can focus on constructing ML ensemble methods to integrate the findings from the methodologies implemented in this study for more robust predictions of cognitive decrements due to space radiation exposure.

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Acute and Chronic Effects of Hypobaric Exposure upon the Brain

Cited by 8 publications

References 76 publications

Hypoxic Hypoxia and Brain Function in Military Aviation: Basic Physiology and Applied Perspectives

Hypoxic Hypoxia and Brain Function in Military Aviation: Basic Physiology and Applied Perspectives

Recent Progress in Space Physiology and Aging

Machine Learning Models to Predict Cognitive Impairment of Rodents Subjected to Space Radiation

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