Hypoxic Hypoxia at Moderate Altitudes: Review of the State of the Science

Petrassi, Frank; Hodkinson, Peter D.; Walters, Patricia L; Gaydos, Steven

doi:10.3357/asem.3315.2012

Cited by 116 publications

(109 citation statements)

References 35 publications

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“…The hypoxia literature, while inconsistent in terms of identifying specific cognitive functions most vulnerable to brief hypoxic exposure, raises the question of why a greater number of the BrainCheckers subtests failed to show an effect (Petrassi et al, 2012). This may be explained by the very mild nature of the concussed group’s symptoms.…”

Section: Discussionmentioning

confidence: 99%

Uncovering Latent Deficits Due to Mild Traumatic Brain Injury by Using Normobaric Hypoxia Stress

Temme¹,

Bleiberg²,

Reeves³

et al. 2013

Front. Neurol.

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Memory deficits and other cognitive symptoms frequently associated with mTBI are commonly thought to resolve within 7–10 days. This generalization is based principally on observations made in individuals who are in the unstressed environmental conditions typical of a clinic and so does not consider the impact of physiologic, environmental, or psychological stress. Normobaric hypoxic stress can be generated with normal mean sea level (MSL) air, which is about 21% oxygen (O2) and 78% nitrogen (N), by reducing the percentage of O2 and increasing the percentage of N so that the resultant mixed-gas has a partial pressure of O2 approximating that of specified altitudes. This technique was used to generate normobaric hypoxic equivalents of 8,000, 12,000, and 14,000 feet above MSL in a group of 36 volunteers with a mTBI history and an equal number of controls matched on the basis of age, gender, tobacco smoking consumption, weight, height, and body mass index. Short-term visual memory was tested using the Matching to Sample (M2S) subtest of the BrainCheckers analog of the Automated Neuropsychological Assessment Metrics. Although there were no significant differences in M2S performance between the two groups of subjects at MSL, with increased altitude, the mTBI group performance was significantly worse than that of the control group. When the subjects were returned to MSL, the difference disappeared. This finding suggests that the “hypoxic challenge” paradigm developed here has potential clinical utility for assessing the effects of mTBI in individuals who appear asymptomatic under normal conditions.

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Section: Discussionmentioning

confidence: 99%

Uncovering Latent Deficits Due to Mild Traumatic Brain Injury by Using Normobaric Hypoxia Stress

Temme¹,

Bleiberg²,

Reeves³

et al. 2013

Front. Neurol.

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“…Review of extant literature indicates possible effects on a variety of cognitive abilities (Petrassi, Hodkinson, Walters, & Gaydos, 2012; Virues-Ortega et al, 2004), including motor learning and memory (Denison, Ledwith, & Poulton, 1966), decision-making (Frisby, Barrett, & Thornton, 1973), reaction time (Kida & Imai, 1993; McCarthy, Corban, Legg, & Faris, 1995), attention and working memory (Malle et al, 2013), and cognitive flexibility and executive functions (Asmaro, Mayall, & Ferguson, 2013). …”

Section: Introductionmentioning

confidence: 99%

Mechanisms of Memory Dysfunction during High Altitude Hypoxia Training in Military Aircrew

Nation

Bondi

Gayles

et al. 2016

J Int Neuropsychol Soc

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Objectives Cognitive dysfunction from high altitude exposure is a major cause of civilian and military air disasters. Pilot training improves recognition of the early symptoms of altitude exposure so that countermeasures may be taken before loss of consciousness. Little is known regarding the nature of cognitive impairments manifesting within this critical window when life-saving measures may still be taken. Prior studies evaluating cognition during high altitude simulation have predominantly focused on measures of reaction time and other basic attention or motor processes. Memory encoding, retention, and retrieval represent critical cognitive functions that may be vulnerable to acute hypoxic/ischemic events and could play a major role in survival of air emergencies, yet these processes have not been studied in the context of high altitude simulation training. Methods In a series of experiments, military aircrew underwent neuropsychological testing before, during, and after brief (15 min) exposure to high altitude simulation (20,000 ft) in a pressure-controlled chamber. Results Acute exposure to high altitude simulation caused rapid impairment in learning and memory with relative preservation of basic visual and auditory attention. Memory dysfunction was predominantly characterized by deficiencies in memory encoding, as memory for information learned during high altitude exposure did not improve after washout at sea level. Retrieval and retention of memories learned shortly before altitude exposure were also impaired, suggesting further impairment in memory retention. Conclusions Deficits in memory encoding and retention are rapidly induced upon exposure to high altitude, an effect that could impact life-saving situational awareness and response.

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“…In a review, Petrassi et al [1] noted that there is considerable individual variability in the extent of cognitive impairment at altitude, but there is strong evidence for some learning impairment at altitudes as low as 8,000 ft (2,438 m). A variety of different types of cognitive assessments have been used at altitude, including number- and letter-sequence recognition, word association/generation tasks, and short- and long-term memory [2,3].…”

Section: Introductionmentioning

confidence: 99%

Cognitive and psychomotor responses to high-altitude exposure in sea level and high-altitude residents of Ecuador

Davis

Wagner

Garvin

et al. 2015

J Physiol Anthropol

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BackgroundHigh-altitude inhabitants have cardiovascular and respiratory adaptations that are advantageous for high-altitude living, but they may have impaired cognitive function. This study evaluated the influence of altitude of residence on cognitive and psychomotor function upon acute exposure to very high altitude.FindingsEcuadorians (31 residing at 0–1,500 m [LOW], 78 from 1,501–3,000 m [MOD], and 23 living >3,000 m [HIGH]) were tested upon their arrival to a hut at 4,860 m on Mount Chimborazo. Cognitive/psychomotor measurements included a go-no-go test (responding to a non-visual stimulus), a verbal fluency test (verbalizing a series of words specific to a particular category), and a hand movement test (rapidly repeating a series of hand positions). Mean differences between the three altitude groups on these cognitive/psychomotor tests were evaluated with one-way ANOVA. There were no significant differences (p = 0.168) between LOW, MOD, and HIGH for the verbal fluency test. However, the go-no-go test was significantly lower (p < 0.001) in the HIGH group (8.8 ± 1.40 correct responses) than the LOW (9.8 ± 0.61) or MOD (9.8 ± 0.55) groups, and both MOD (97.9 ± 31.2) and HIGH (83.5 ± 26.7) groups completed fewer correct hand movements than the LOW (136.6 ± 37.9) subjects (p < 0.001).ConclusionsBased on this field study, high-altitude residents appear to have some impaired cognitive function suggesting the possibility of maladaptation to long-term exposure to hypobaric hypoxia.

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Hypoxic Hypoxia at Moderate Altitudes: Review of the State of the Science

Cited by 116 publications

References 35 publications

Uncovering Latent Deficits Due to Mild Traumatic Brain Injury by Using Normobaric Hypoxia Stress

Uncovering Latent Deficits Due to Mild Traumatic Brain Injury by Using Normobaric Hypoxia Stress

Mechanisms of Memory Dysfunction during High Altitude Hypoxia Training in Military Aircrew

Cognitive and psychomotor responses to high-altitude exposure in sea level and high-altitude residents of Ecuador

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