Document Detail

Level alterations of the 2f (1)-f (2) distortion product due to hypoxia in the guinea pig depend on the stimulus frequency.
MedLine Citation:
PMID:  19629511     Owner:  NLM     Status:  MEDLINE    
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 the ICP non-invasively. Hypoxia can also cause alterations of DPOAE levels, which can be distinguished from ICP-related changes only, when their characteristics, in particular frequency specificity, are known in detail. DPOAEs at f (2) = 2, 4, 8, 12 and 16 kHz and oxygen saturation (SaO(2)) were continuously monitored in nine spontaneously breathing guinea pigs, anaesthetized by i.m. administration of midazolam, medetomidin and fentanyl, during the respiration of a gas mixture of N(2)O and O(2) containing either 30% O(2) or 13% O(2). Fourteen hypoxic intervals in eight 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 reoxygenation were observed at the frequencies of 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 with the other frequencies (P < 0.05 for 12 vs. 16 and 8 kHz and for 2 vs. 16 kHz). DPOAE level alterations due to hypoxia depend on the frequency in guinea pigs. Studies in human are warranted to improve non-invasive ICP monitoring with DPOAE by the detection of hypoxia-related changes.
Bernhard Olzowy; Gregor von Gleichenstein; Martin Canis; Nikolaus Plesnila; Sebastian Strieth; Christoph Deppe; Klaus Mees
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-07-21
Journal Detail:
Title:  European archives of oto-rhino-laryngology : official journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS) : affiliated with the German Society for Oto-Rhino-Laryngology - Head and Neck Surgery     Volume:  267     ISSN:  1434-4726     ISO Abbreviation:  Eur Arch Otorhinolaryngol     Publication Date:  2010 Mar 
Date Detail:
Created Date:  2010-01-26     Completed Date:  2010-04-22     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9002937     Medline TA:  Eur Arch Otorhinolaryngol     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  351-5     Citation Subset:  IM    
Department of Otorhinolaryngology, Head and Neck Surgery, Ludwig Maximilians University of Munich Medical Center, Marchioninistr. 15, 81377 M?nchen, Germany.
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MeSH Terms
Anoxia / physiopathology*
Guinea Pigs
Intracranial Pressure / physiology*
Monitoring, Physiologic
Otoacoustic Emissions, Spontaneous / physiology*
Reference Values
Signal Processing, Computer-Assisted*
Sound Spectrography

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