Trans-Middle-Ear Mucosal Gas Exchange Project 1, Specific Aim 1

Completed · Phase 1

Conditions studied: Middle Ear Gas Exchange

In brief

This study will measure the speed at which gases move between the middle-ear air-space and the blood flowing through the middle-ear lining. The middle ear is a rigid biological gas pocket located behind the eardrum and is filled with the same gases as in air, primarily oxygen (O), nitrogen (N) and carbon dioxide (CO2), but in different proportions. The middle ear is lined by a thin layer of cells overlying tissues that surround blood vessels. The blood that flows through the middle-ear lining also contains these same gases but at different proportions from both the atmosphere (room air) and middle ear. Because of the differences in the proportions of these gases, each gas tends to flow between the middle ear and blood trying to make the proportions of gases in those compartments the same. This flow of gases to and from the middle ear changes the middle-ear pressure. If the middle-ear pressure decreases much below the air pressure of the atmosphere, the ability to hear sounds is impaired and fluid can build up in the middle ear. It is expected that each different gas will move between the middle ear and blood at a different speed, but it is not known what those speeds are for any of the gases. It is also expected that those speeds will be different for ears that have had middle-ear disease and those that have not. In this study, we will measure the speed of nitrogen, oxygen and carbon dioxide exchanges in both directions between the middle ear and blood. To do this, the gas mixture in the middle ear will be changed so that there is movement of only one gas for each experiment and then measure the change in the amount of the gas in the middle ear. This can be done using a special instrument called a mass spectrometer if there is an open, working tympanostomy (ventilation) tube, a small plastic tube, in the eardrum. For all participants in this study, we will conduct 6 experiments lasting about 2 hours each to measure the speed of nitrogen, oxygen and carbon dioxide flow. Subjects with and without tympanostomy tubes will be recruited. Those without a tube will have a tube inserted in one ear for study purposes and it will be removed at the end of the study; these subjects will be followed weekly until the hole in the eardrum (where the tube was) is closed.

Key facts

Study ID: NCT01925482
Run by: Cuneyt M. Alper
People needed: 16
Starts: 2014-05-13
Expected to finish: 2015-05-19
Last updated by the study team: 2019-02-19

Who can join

Age: 18 and older, up to 50. Sex: any. Healthy volunteers: accepted.

You may qualify if…

Otherwise healthy adults aged 18 to 50 years
No history of significant ME disease; intact tympanic membrane (Group 1 only)
Functional tympanostomy tube or chronic perforation after tube extruded; tube placed for middle-ear effusion/Eustachian tube dysfunction (Group 2)
No history of past ME surgeries other than ventilation tubes (Group 2),
Able to comprehend study risks and provide written Informed Consent

You may not qualify if…

Have any chronic health problem
Have ME fluid or otitis media (OM)at the time of presentation for ventilation tube insertion (Group 1 only)
Have drainage through the ventilation tube at the time of testing
Have a cold or allergic rhinitis at the time of testing
Taking any prescription drug with the exception of those for birth control
Have a known or suspected allergy/adverse reaction to any of the study drugs use to prepare the tympanic membrane for ventilation tube insertion (Group 1 only)
Have a hearing threshold >15 dB or a >10 dB air-bone gap at any of the speech frequencies (Group 1 only)

Where it is running

Middle Ear Physiology Laboratory, University of Pittsburgh — Pittsburgh, Pennsylvania, United States

Full record on ClinicalTrials.gov

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