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

Summary

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.

Conditions

• Middle Ear Gas Exchange

Interventions

DRUG

6%CO2, 25%O2, balance N2

exposure of middle ear to gas

DRUG

6% CO2, 0%O2, balance N2

exposure of middle ear to gas

DRUG

20%CO2, 6%O2, balance N2

exposure of middle ear to gas

DRUG

0%CO2, 6%O2, balance N2

exposure of middle ear to gas

DRUG

6% CO2, 6%O2, balance N2

exposure of middle ear to gas

DRUG

6%CO2, 6%O2, 0%N2, balance argon

exposure of middle ear to gas

Sponsors & Collaborators

• National Institute on Deafness and Other Communication Disorders (NIDCD)

  collaborator NIH

• Cuneyt M. Alper

  lead OTHER

Principal Investigators

• Cuneyt M Alper, MD · University of Pittsburgh

Study Design

Allocation

NON_RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

NONE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Max Age

50 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2014-05-13

Primary Completion

2015-04-24

Completion

2015-05-19

FDA Drug

Yes

Countries

• United States

Study Locations