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Trans-mucosal inert gas exchange constants for the monkey middle ear
W J Doyle1, C M Alper, J T Seroky
1Department of Otolaryngology, Children's Hospital of Pittsburgh, PA 15213-2583, USA. Doylewj@chplink.chp.edu
Auris, Nasus, Larynx
|March 17, 1999
Summary
This study quantifies Argon and N2 exchange constants in monkey middle ear mucosa. Findings suggest a slow gas exchange rate, implying infrequent Eustachian tube function is needed to prevent middle ear effusion.
Area of Science:
- Otolaryngology
- Physiology
- Biophysics
Background:
- Middle ear pressure regulation is crucial for hearing.
- Understanding gas exchange across the middle ear mucosa informs models of pressure dynamics.
- Inert gas exchange rates are key parameters for these models.
Purpose of the Study:
- To determine the exchange constants for Argon and Nitrogen (N2) across the middle ear mucosa in monkeys.
- To provide data for mathematical models of middle ear pressure regulation.
Main Methods:
- Anesthetized monkeys underwent tympanic membrane perforation.
- A probe was inserted into the ear canal, and the middle ear was flushed with Argon.
- Gas samples were analyzed over time using mass spectrometry to calculate exchange constants.
Main Results:
- The average trans-mucosal exchange constant for Argon was 0.0007/min and for N2 was 0.0003/min.
- The ratio of Argon to N2 exchange constants was approximately 2.6, consistent with perfusion-limited gas exchange.
- These values indicate a slow rate of inert gas exchange across the middle ear mucosa.
Conclusions:
- Gas exchange across the middle ear mucosa is slow and perfusion-limited for N2 and other inert gases.
- The Eustachian tube likely needs to open only about once per day to prevent middle ear effusion.
- These findings have implications for understanding and modeling middle ear fluid dynamics.