A re-evaluation of the minimum altitude at which hypoxic performance decrements can be detected

Fowler, Barry; Paul, Michel; G, Porlier; Elcombe, D. D.; Taylor, Marla

doi:10.1080/00140138508963198

Cited by 26 publications

(20 citation statements)

References 7 publications

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“…Denison et al (1966) hypothesized that it was the novelty of the Mannikin test that made it particularly sensitive to hypoxia. It might therefore be argued that a somewhat lower threshold would have been found in the present experiment if the SCRT had been novel, since the threshold for the Mannikin test has only been determined to lie between 8000 and 12000 feet (Fowler et al, 1985). However, there are two problems with this argument.…”

Section: Discussionmentioning

confidence: 82%

The Threshold for Hypoxia Effects on Perceptual- Motor Performance

et al. 1987

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The hypoxia threshold for a decrement in perceptual-motor performance was determined with six subjects using a serial choice response time task at two levels of stimulus brightness. Low-oxygen mixtures were used to reduce SaO] (arterial oxyhemoglobin saturation) to hypoxic levels ranging from 86% to 76% in steps of2%. These values correspond to altitudes ranging from 8900 ft to 11 400 feet. Response time was slowed in a dose-dependent manner with a significant effect becoming apparent at an SaO] of 82% (10 000 feet). The slope of the dose-response function was steeper for the low than for the high brightness condition. These results provide a threshold estimate of9750 feet for performance decrements due to hypoxia and point to the disruption of vision as a factor influencing this decrement.

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Section: Discussionmentioning

confidence: 82%

The Threshold for Hypoxia Effects on Perceptual- Motor Performance

et al. 1987

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“…They concluded that the findings of Denison and colleagues 122 probably resulted from unusually low arterial Pao 2 , caused by the resistance of breathing through a facial mask, which became more significant during hypoxia, exercise, and hypoventilation. Hence, Fowler and colleagues 125 concluded that 2,438 m was substantially lower than the actual altitude threshold that affects performance. Their investigation also suggested that new learning is no more vulnerable than prior learning to the effects of hypoxemia.…”

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confidence: 99%

Cognitive performance, mood, and neurological status at high terrestrial elevation

Banderet¹,

Shukitt-Hale²

2002

PsycEXTRA Dataset

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. ABSTRACT (Maximum 200 words)Cognitive and psychomotor performance and mood states, including many critical behavioral functions such as sleep, memory, ■ reasoning, and vigilance, are significantly impaired by ascent to HTE higher than 3,000 m. Impairments in behavior caused by HTE can degrade military operations because the judgment and rate and accuracy of performance of military personnel can be affected. Such adverse effects have distinct and measurable time courses; onset of some effects is immediate (cognitive performance), whereas the onset of others is delayed (symptoms of AMS or adverse moods). The behavioral consequences of HTE are primarily dependent on the level of altitude, the duration of exposure the rate of ascent, an individual's state of physiological acclimation or acclimatization, characteristics of the task performed, and characteristics of the individual such as hypoxic sensitivity. Military history documents that the adverse effects induced by HTE need to be considered when military operations at altitude are planned and undertaken. Current research indicates that some performance decrements induced by ascent to extremely high mountains (e.g., Mount Everest, 8,848 m) may persist for a year or longer after return to lower elevations. Psychological, operational, and medical strategies have been employed to minimize these adverse effects. Psychological strategies often involve training and familiarization with the adverse effects that will be experienced at high altitude. Operational strategies include staging at intermediate altitudes, acclimatizing, and using supplemental oxygen from tanks of oxygen generators. Medical strategies often involve the use of medications to improve functioning at altitude and techniques to avoid complications. In most situations, multiple strategies are employed. The strategies now available and new developments to come will ensure that high-altitude military operations in the future will be less affected by adverse changes in cognitive and psychomotor performance and mood.14. SUBJECT TERMS high altitude, hypoxia, cognitive performance, moods, symptoms, time course of altitude effects, behavior NUMBER OF PAGES 3516. PRICE CODE

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“…Traditionally it has been accepted that visual functions (predominately dark adaptation) are particularly sensitive to hypoxia with effects on the visual threshold being found at an altitude as low as 5,000 ft (Fowler et al, 1985). However, the altitude at which these visual decrements, along with direct effects of hypoxia on neural tissue, influence performance on more complex tasks is equivocal.…”

Section: Minimum Altitudementioning

confidence: 96%

“…By investigating arterial oxygen saturation (SaC^) values, Fowler et al (1985Fowler et al ( , 1987 attempted to examine the discrepancies between the studies listed above. By modulating the breathing mixtures of the subjects to reduce their Sa0 2 values in 2% increments, they found that response times slowed in a step-dependent manner.…”

Section: Minimum Altitudementioning

confidence: 99%

Actual and perceived cognitive performance during acute altitude exposure

Terry¹

2002

PsycEXTRA Dataset

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The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing, the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Observations by aviators and mountain climbers who attempt to ascend above 10,000 to 14,000 ft will often include references to impairments of cognitive abilities.Although known cognitive impairments occur at altitude, little has been done to research the perception of such decrements in performance. The purpose of this study was to evaluate potential differences in actual and perceived cognitive performance at moderate altitude (10,000 ft and 14,000 ft) under several environmental conditions. Ten subjects were exposed to each altitude condition on separate days and asked to perform a computer test, SYNWIN, while at rest at ground level (5,000 ft), at rest at altitude, after 10 minutes of exercise at altitude, and while breathing supplemental oxygen at altitude.Before and after each test at altitude, subjects were asked to provide pre-and post-test estimates regarding their performance on the cognitive test by rating their performance on a five-point scale, as compared to the most recently completed test. It was hypothesized that cognitive performance at 14,000 ft would be worse than that at 10,000 ft, with the difference exacerbated after exercise, but then eliminated by supplemental oxygen. It was also hypothesized that over-confidence would also manifest itself, to degrees corresponding to the hypothesized decrements in performance.Actual performance on the test was significantly greater at 10,000 ft compared to both ground level and 14,000 ft while at rest. Performance at 10,000 ft was also in significantly greater than that at 14,000 ft after exercise and oxygen supplementation.Post-exercise scores were significantly greater than pre-exercise scores, regardless of altitude. Performance while breathing supplemental oxygen was significantly greater than without oxygen, also regardless of altitude.Subjects were unable to accurately predict their performance on the test prior to taking the test regardless of test condition. Under-estimation was prevalent for the resting and post-exercise test, while over-estimation was common while breathing supplemental oxygen. After taking the test, the subjective performance estimates showed better correlations with actual performance changes, but no obvious trends (such as marked blocks of correlations while breathing supplemental oxygen) were apparent.Based on the improvements in performance following exercise and oxygen, both protocols could be recommended to pilots prior to or during crucial portions of the flight.Although over-confidence tendencies whi...

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A re-evaluation of the minimum altitude at which hypoxic performance decrements can be detected

Cited by 26 publications

References 7 publications

The Threshold for Hypoxia Effects on Perceptual- Motor Performance

The Threshold for Hypoxia Effects on Perceptual- Motor Performance

Cognitive performance, mood, and neurological status at high terrestrial elevation

Actual and perceived cognitive performance during acute altitude exposure

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