gms | German Medical Science

79th Annual Meeting of the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery

German Society of Oto-Rhino-Laryngology, Head and Neck Surgery

30.04. - 04.05.2008, Bonn

Article

Send article

Level alterations of the 2f1-f2 distortion product due to hypoxia in the guinea pig depend on the stimulus frequency

Meeting Abstract

Search Medline for

German Society of Oto-Rhino-Laryngology, Head and Neck Surgery. 79th Annual Meeting of the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery. Bonn, 30.04.-04.05.2008. Düsseldorf, Köln: German Medical Science; 2008. Doc08hno32

The electronic version of this article is the complete one and can be found online at: http://www.egms.de/en/meetings/hno2008/08hno32.shtml

Published: July 8, 2008

© 2008 Olzowy et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.

Outline

Text

Introduction: Increased intracranial pressure (ICP) is known to affect the levels of distortion product otoacoustic emissions (DPOAEs) in a frequency-specific manner. DPOAEs might therefore be used for monitoring ICP non-invasively. Hypoxia can also cause alterations of DPOAE levels, which can only be distinguished from ICP-related changes if their characteristics, in particular a frequency-specificity, are known in detail.

Methods: DPOAEs at f2 = 2, 4, 8, 12 and 16 kHz and oxygen saturation (SaO2) were continuously monitored in 9 spontaneously breathing guinea pigs during respiration of a gas mixture of N2O and O2 containing either 30% O2 or 13% O2.

Results: 14 hypoxic intervals in 8 animals were included into final data analysis. Characteristic hypoxic level alterations with a level decrease and a remarkable level destabilization during hypoxia, and a pronounced reversible level decrease after re-oxigenation were observed at the frequencies 4, 8 and 16 kHz. At 2 and 12 kHz the only reproducible effect of hypoxia was an increased fluctuation of the DPOAE level, which was significantly less pronounced compared to the other frequencies (p<0,05 for 12 kHz vs. 16 and 8 kHz and for 2 kHz vs. 16 kHz).