Physical and Physiological Effects on Otoacoustic Emissions in Hypobaric Hypoxia
Physical and Physiological Effects on Otoacoustic Emissions in Hypobaric Hypoxia
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DOI：
10.1159/000310352
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发表时间：
2010-01-01
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影响因子：
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通讯作者：
Ogawa, Kaoru
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作者：
Ide, Rika;Harada, Tatsuhiko;Ogawa, Kaoru
耳鸣和头晕是急性高山病的症状。通过测量常压常氧（1，013 hPa; 760 mm Hg）和低压缺氧（540 hPa; 405 mm Hg）条件下的瞬态诱发耳声发射（TEOAE）和畸变产物耳声发射（DPOAE），探讨了高原（即低压缺氧）影响内耳功能的机制。使用鼓室图排除了气压对咽鼓管影响我们研究结果的可能性。低压缺氧对TEOAE和DPOAE的非生理效应也用耳模拟器进行了评估。在低压缺氧条件下，TEOAE和DPOAE水平均降低。TEOAE的总回波功率和信噪比以及DPOAE的2f（1）- f（2）元素水平的降低量约为4 dB。使用耳模拟器测量的刺激水平在低压缺氧条件下也降低了约4 dB。这些结果并不表明刺激水平影响TEOAE和DPOAE水平，因为这些水平实际上只受到刺激水平变化的轻微影响。相反，这种降低可能是由于鼓膜发出的声压的非生理性低压效应。我们的结论是，低压缺氧对耳蜗功能的影响是可以忽略不计的压力高达540百帕。版权所有（C）2010 S. Karger AG，巴塞尔
Tinnitus and dizziness are symptoms of acute mountain sickness. We investigated the mechanism by which high altitude (i.e. hypobaric hypoxia) affects inner ear function by measuring transient evoked otoacoustic emissions (TEOAE) and distortion product otoacoustic emissions (DPOAE) under conditions of normobaric normoxia (1,013 hPa; 760 mm Hg) and hypobaric hypoxia (540 hPa; 405 mm Hg). The possibility that air pressure effects on the eustachian tube impacted our findings was excluded by the use of tympanograms. The nonphysiological effects of hypobaric hypoxia on TEOAE and DPOAE were also assessed using an ear simulator. Under conditions of hypobaric hypoxia, both TEOAE and DPOAE levels were reduced. The amount of reduction that occurred was approximately 4 dB in the total echo power and signal-to-noise ratio of the TEOAE, and in the 2f(1) - f(2) element level of the DPOAE. Stimulus levels that were measured using an ear simulator were also reduced by approximately 4 dB under conditions of hypobaric hypoxia. These results do not indicate that stimulus levels affected TEOAE and DPOAE levels because these levels were actually only slightly affected by changes in the stimulus level. Instead, this reduction was likely due to the nonphysiological hypobaric effects of the sound pressure emitted from the tympanic membrane. We conclude that the impact of hypobaric hypoxia on cochlear function was negligible up to pressures of 540 hPa. Copyright (C) 2010 S. Karger AG, Basel