Could mild hypoxia impair pilot decision making in emergencies?

Legg, Stephen; Hill, Stephen; Mündel, Toby; Gilbey, Andrew; Schlader, Zac; Raman, Aaron

doi:10.3233/wor-2012-0156-198

Cited by 14 publications

(14 citation statements)

References 14 publications

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“…Generally, at high-altitudes, particularly above 15,000 ft (4,472 m; Petrassi et al, 2012 ), or with lower arterial blood oxygenation ( Ochi et al, 2018 ; Williams et al, 2019 ) or cerebral oxygenation ( Williams et al, 2019 ), there is greater and more predictable impairment to cognition. Complex and novel cognitive task performance may be impaired between 6,500 and 12,000 ft, which typically invoke an SpO 2 of 70–90% ( Legg et al, 2012 , 2014 ; Petrassi et al, 2012 ; Pilmanis et al, 2016 ). Whereas, simple cognitive task performance (e.g., card naming and/or sorting) may not deteriorate until below an SpO 2 of 65% ( Hoffman et al, 1946 ; Mitchell et al, 2019 ), which typically occurs following exposure above 18,000–25,000 ft.…”

Section: Hypoxia Brain Function and Performancementioning

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: Hypoxia Brain Function and Performancementioning

confidence: 99%

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

Shaw

Cabre²

2021

Front. Physiol.

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“…Hypoxia above 18,000 ft was mostly reported to cause obvious negative effects on cognitive functions (Asmaro, Mayall, & Ferguson, 2013;Malle et al, 2013;Neuhaus & Hinkelbein, 2014). However, hypoxia below this altitude is mild and moderate, and negative cognitive effects such as increased response time, short-term memory and working memory were observed but they were not obvious as seen at higher altitudes (Stephen Legg et al, 2012;Nesthus, Rush, & Wreggit, 1997;Pilmanis, Balldin, & Fischer, 2016). Moreover, there are also studies suggesting that mild and moderate hypoxia exposure do not have a signi cant negative effect on cognitive and psychomotor functions (Hewett, Curry, Rath, & Collins, 2009;SJ Legg et al, 2016).…”

Section: Discussionmentioning

confidence: 99%

Effects of Aerobic Capacity on Cognitive Functions During Hypoxia

SAVAS¹

2023

Preprint

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Objective We aimed to investigate the role of aerobic capacity on cognitive functions during hypoxic conditions. Background Possessing a mishap risk in aviation, acute hypobaric hypoxia has some negative effects on cognitive functions. Therefore, it is important to develop a hypoxia tolerance to preserve the mental functions of pilots against possible hypoxic conditions during flight. Method A total of 25 pilot candidates were included in this study. Subjects were dichotomized into two groups as High-fit and Low-fit according to aerobic capacities. Hypoxia was applied at an altitude equivalent pressure of 18,000 ft. Go/NoGo and Digit Span cognitive tests were applied two phases before hypoxia training and during hypoxia. Results In the Low-fit group, for the Go/NoGo test parameters mean R-Go reaction time increased significantly during hypoxia when compared to before hypoxia training. Also, in the Low-fit group for Digit Span test parameters the memory span and the sum of correct answers both decreased significantly during hypoxia. In the high-fit group, there has not been any significant difference between the two test parameters during hypoxia. Conclusion The results of this study indicate that if physical fitness has a positive effect on the deterioration of cognitive functions during hypoxia. It could be useful to suggest regular physical exercise habits for aircrew to increase their acute hypoxia tolerances in the aspect of cognitive functions.

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“…An adequate oxygen supply is crucial for correct cognitive functioning, and even mild degrees of hypoxia can alter cognitive abilities, including vision, attention, and memory ( Legg et al, 2012 ; Petrassi et al, 2012 ; Steinman et al, 2019 ; Shaw et al, 2021 ).…”

Section: Introductionmentioning

confidence: 99%

Hypoxia and risk preferences: Mild hypoxia impacts choices for low-probability high-payoff bets

et al. 2022

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Mild degrees of hypoxia are known to exert a detrimental effect on cognitive functions. In a lab study, we assessed the effect of mild hypoxia on risk-taking behavior. Participants (N = 25) were presented with pairs of bets of equal expected monetary value, one having a higher probability of winning/losing a lower payoff (safer bet) and one having a lower probability of winning/losing a higher payoff (riskier bet). We systematically varied the ratio of the probabilities (and corresponding payoffs) of the two bets and examined how this affected participants’ choice between them. Following a familiarization session, participants performed the task twice: once in a normoxic environment (20.9% oxygen concentration) and once in a mildly hypoxic environment (14.1% oxygen concentration). Participants were not told and could not guess which environment they were in. We found a higher preference for the riskier bet in the mild hypoxic than normoxic environment but only in the loss domain. Furthermore, as the probability ratio increased, mild hypoxia increased the preference for the riskier bet in the domain of losses but decreased it for gains. The present findings support that mild hypoxia promotes riskier choices in the loss domain and provide new insights into the impact of mild hypoxia in moderating the effect of probability ratio on risky choices.

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Could mild hypoxia impair pilot decision making in emergencies?

Cited by 14 publications

References 14 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

Effects of Aerobic Capacity on Cognitive Functions During Hypoxia

Hypoxia and risk preferences: Mild hypoxia impacts choices for low-probability high-payoff bets

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