Temporary threshold shift after noise exposure in hypobaric hypoxia at high altitude: results of the ADEMED expedition 2011

Fehrenbacher, Kerstin; Apel, Christian; Bertsch, Daniela; Giet, M. S. van der; Giet, Simone van der; Graß, Maren; Gschwandtl, Carina; Heussen, N.; Hundt, Nina; Kühn, Christian; Morrison, Alistair; Müller-Ost, Miriam; Müller-Tarpet, M.; Porath, S.; Risse, Julia; Schmitz, S.; Schöffl, Volker; Timmermann, Lars; Wernitz, Knut; Küpper, Thomas

doi:10.1007/s00420-021-01715-w

Cited by 5 publications

(15 citation statements)

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“…For example, basic auditory sensitivity, as measured with pure-tone audiometry, appears to be relatively unaffected by low-oxygen exposure ( Burkett and Perrin, 1976 ; Watson et al, 2000 ; but also see, McAnally et al, 2003 ; Lucertini et al, 2020 ). However, other aspects of auditory processing may be affected by hypoxia such as vulnerability to noise ( Fehrenbacher et al, 2021 ) or sound localization ( Rosenberg and Pollard, 1992 ). These other aspects of auditory performance, like sound localization are especially relevant in an aviation environment when considering how hypoxia may affect in-cockpit spatial audio cueing systems.…”

Section: Introductionmentioning

confidence: 99%

Effects of Acute Hypoxia on Early Visual and Auditory Evoked Potentials

Blacker

McHail

2022

Front. Neurosci.

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Reduced levels of environmental oxygen lead to hypoxic hypoxia and are a primary threat in tactical aviation. The visual system is particularly vulnerable to hypoxia, and its impairment can severely impact performance. The auditory system is relatively spared by hypoxia, although which stages of auditory processing are most impacted by hypoxia remains unclear. Previous work has used electroencephalography (EEG) to assess neural markers of cognitive processing for visual and auditory stimuli and found that these markers were sensitive to a normobaric hypoxic exposure. In the current study, we assessed whether early sensory evoked potentials, that precede cognitive activity, are also impaired by normobaric hypoxia. In a within-subjects design, we compared visual (P100) and auditory evoked potentials (sensory gating for the P50, N100, and P200) in 34 healthy adults during normoxic (21% O2) and two separate hypoxic (9.7% O2) exposures. Self-reported symptoms of hypoxia were also assessed using the Hypoxia Symptom Questionnaire (HSQ). We found that P100 mean amplitude was not reduced under hypoxic compared to normoxic conditions, suggesting no statistically significant impairment of early visual processing. The sensory gating ratio for auditory stimuli was intact for paired responses of the P50 and N100. However, the P200 sensory gating ratio was attenuated under hypoxic compared to normoxic conditions, suggesting disruption of the auditory system specific to the level of allocating attention that follows basic auditory processing. Exploratory analyses of HSQ scores identified a robust effect of hypoxia. However, consistency of symptoms reported between the two hypoxia exposures exhibited high intra-individual variability, which may have implications for the theory that individuals have a consistent hypoxia signature or reliable constellation of responses to hypoxia. These findings suggest that early sensory processing is not impaired during hypoxia, but for the auditory system there is impairment at the level of attentional processing. Given the previous findings of impaired visual performance under hypoxia, these results suggest that this impairment does not stem from early visual processing deficits in visual cortex. Together these findings help focus the search on when and where hypoxia-induced deficits occur and may guide the development of countermeasures for hypoxia in tactical aviation.

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Section: Introductionmentioning

confidence: 99%

Effects of Acute Hypoxia on Early Visual and Auditory Evoked Potentials

Blacker

McHail

2022

Front. Neurosci.

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“…Some previous hypoxia studies have excluded female participants entirely ( Kowalczuk et al, 2016 ; Dart et al, 2017 ; Steinman et al, 2017 ; Bouak et al, 2018 ; Bustamante-Sánchez et al, 2019 ; Lucertini et al, 2020 ). Whereas those that did include females lacked a large enough sample size to look at sex comparisons ( Blacker et al, 2021 ; Fehrenbacher et al, 2021 ; Leinonen et al, 2021 ). Temme et al (2010) and Kasture et al (2021) do not specify participants’ sex, referring to them as pilots or volunteers.…”

Section: Introductionmentioning

confidence: 99%

Sex comparisons in physiological and cognitive performance during hypoxic challenge

2022

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Within the tactical aviation community, human performance research lags in considering potential psychophysiological differences between male and female aviators due to little inclusion of females during the design and development of aircraft systems. A poor understanding of how male and female aviators differ with respect to human performance results in unknown potential sex differences on aeromedically relevant environmental stressors, perchance leading to suboptimal performance, safety, and health guidelines. For example, previous hypoxia studies have excluded female participants or lacked a sizeable sample to examine sex comparisons. As such, progress toward sensor development and improving hypoxia familiarization training are stunted due to limited knowledge of how individual differences, including sex, may or may not underlie hypoxia symptoms and performance impairment. Investigating sex differences bridges the gap between aerospace medicine and operational health, and addressing hypoxia is one of many facets yet to be studied. In the current study, we retrospectively examined N = 6 hypoxia studies with male-female participant samples (total, N = 189; male, n = 118; female, n = 71). We explored sex as a predictor of physiological response, sensory deficits, the severity of cognitive performance declines, and symptom manifestation via linear and binary logistic regression models. We found that the female sex predicted lower peripheral oxygen saturation and the likelihood of headache reporting in response to hypoxic challenge, yet explained little variance when combined with age and body mass index. The sensory and cognitive performance models did not converge, suggesting high intra-individual variability. Together, sex, age, and body mass index were not the most robust predictors in responses to hypoxic challenge; we cannot infer this for sensory deficits and cognitive performance within an experimentally induced hypoxic environment. The findings have implications for improving hypoxia familiarization training, monitoring sensor development, and emergency response and recovery protocols in case of a hypoxia occurrence suitable for all aircrew. We recommend continuing to elucidate the impact of sex and intrapersonal differences in hypoxia and other aeromedically relevant stressors in tactical aviation.

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“…The eight studies evaluating the effects of HA on the inner auditory function in a real environment are shown in Table 3 . Among these studies, three performed PTA [ 11 , 42 , 43 ], three characterized OAE [ 35 , 41 , 42 ], and three analyzed AER [ 15 , 16 , 40 ]. Only one study analyzed the effects of a chronic exposure at HA [ 43 ], while all the others investigated a pattern of acute exposure to HA with a period of acclimatization involving physical exercise.…”

Section: Resultsmentioning

confidence: 99%

“…Different techniques may have diverse sensitivity to the stages and pathways of auditory processing. On the other hand, different regions involved in audition may be diversely susceptible to the effect of hypoxia in terms of magnitude and mechanisms [ 11 , 15 , 16 ]. Environmental conditions, such as lower air pressure (i.e., hypobaria), may exert physical effects and alter the mechanisms of sound transmission and transduction, affecting measurements such as pure tone auditory thresholds [ 10 ].…”

Section: Introductionmentioning

confidence: 99%

“…Environmental conditions, such as lower air pressure (i.e., hypobaria), may exert physical effects and alter the mechanisms of sound transmission and transduction, affecting measurements such as pure tone auditory thresholds [ 10 ]. Together with experimental variability factors, data interpretation is further complicated by the incomplete knowledge of the mechanisms of oxygen supply to the inner ear and the effects of hypoxia on these mechanisms [ 11 , 17 , 18 ]. Finally, a reduction in cognitive performance may by itself have repercussions on auditory function, when this is investigated via subjective tests [ 19 ].…”

Section: Introductionmentioning

confidence: 99%

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Auditory function in humans at high altitude. A scoping review

Masè,

Viziano,

Strapazzon

et al. 2023

PLoS ONE

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Purpose High-altitude (HA) affects sensory organ response, but its effects on the inner ear are not fully understood. The present scoping review aimed to collect the available evidence about HA effects on the inner ear with focus on auditory function. Methods The scoping review was conducted following the guidelines of the Preferred Reporting Items for Systematic Review and Meta-Analysis extension for scoping reviews. PubMed, Scopus, and Web of Science electronic databases were systematically searched to identify studies conducted in the last 20 years, which quantified in healthy subjects the effects of HA on auditory function. Results The systematic search identified 17 studies on a total population of 888 subjects (88.7% male, age: 27.8 ± 4.1 years; median sample size of 15 subjects). Nine studies were conducted in a simulated environment and eight during real expeditions at HA. To quantify auditory function, six studies performed pure tone audiometry, four studies measured otoacoustic emissions (OAE) and eight studies measured auditory evoked responses (AER). Study protocols presented heterogeneity in the spatio-temporal patterns of HA exposure, with highly varying maximal altitudes and exposure durations. Conclusion Most studies reported a reduction of auditory function with HA in terms of either elevation of auditory thresholds, lengthening of AER latencies, reduction of distortion-product and transient-evoked OAEs. Future studies in larger populations, using standardized protocols and multi-technique auditory function evaluation, are needed to further characterize the spatio-temporal pattern of HA effects along the auditory pathways and clarify the pathophysiological implications and reversibility of the observed changes.

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Temporary threshold shift after noise exposure in hypobaric hypoxia at high altitude: results of the ADEMED expedition 2011

Cited by 5 publications

References 24 publications

Effects of Acute Hypoxia on Early Visual and Auditory Evoked Potentials

Effects of Acute Hypoxia on Early Visual and Auditory Evoked Potentials

Sex comparisons in physiological and cognitive performance during hypoxic challenge

Auditory function in humans at high altitude. A scoping review

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