Gas Supply, Demand and Middle Ear Gas Balance -- Preliminary Protocol
| Status: | Recruiting |
|---|---|
| Healthy: | No |
| Age Range: | 18 - 50 |
| Updated: | 10/17/2018 |
| Start Date: | October 2013 |
| End Date: | June 2019 |
| Contact: | Julie Banks, BS |
| Email: | Juliane.Banks@chp.edu |
| Phone: | 412-692-3595 |
Gas Supply, Demand and Middle Ear Gas Balance -- Project 1, Specific Aim 4, Protocol 1
The purpose of this study is to gather more information on Eustachian tube function and
middle-ear pressures during flying. Ten subjects with tympanostomy tubes (plastic tubes
inserted in the eardrums) in their ears or holes in their ear-drums will undergo flight
simulation in a pressure chamber. Their middle-ear pressures and Eustachian tube function
will be monitored at various chamber pressures.
middle-ear pressures during flying. Ten subjects with tympanostomy tubes (plastic tubes
inserted in the eardrums) in their ears or holes in their ear-drums will undergo flight
simulation in a pressure chamber. Their middle-ear pressures and Eustachian tube function
will be monitored at various chamber pressures.
There are individuals who experience severe barotrauma/barotitis during airplane flights
and/or free or tanked diving. Previously, one of the investigators modeled the change in
middle-ear (ME) pressure during simulated airplane flights for ears with normal Eustachian
tube function (ETF) and with different degrees of Eustachian tube (ET) dysfunction (Kanick
SC, Doyle WJ. Barotrauma during air travel: predictions of a mathematical model. J Appl
Physiol. May 2005;98(5):1592-1602). That model provided a number of important insights into
the pathogenesis of ME barotrauma but included two assumptions that have not been validated:
1) in the absence of ET opening, ME pressure is relatively stable (ignoring tympanic membrane
volume induced changes) over wide ranges of ambient pressures, and 2) ET periluminal
pressures track local ambient pressures. Other, less rigorous, descriptions of ME pressure
behavior during flight and diving make different assumptions: 1) ME pressure changes with
changes in ambient pressure and 2) ambient and ET mucosa pressures are incompletely coupled.
Modeling ME pressure behavior using the two sets of assumptions predicts different ME
pressure trajectories and explanations for barotitis/ME barotrauma during flight and diving.
Because the behavior of ME pressure during flight (or diving) constrains the interventions
that could be used to prevent barotitis/ME barotrauma, it is important to determine which, if
either, model is correct.
Ten otherwise healthy subjects aged 18 to 50 years with unilateral or bilateral eardrum
perforations or ventilation tubes will be enrolled after obtaining Informed Consent. Complete
histories will be taken with a focus on ear-related problems and they will have an ENT
examination including tympanometry to document the patency of the ventilation tube and
absence of drainage through the tube (disqualifiers). Eligible subjects will be studied in
the pressure chamber during a typical flight simulation with periodic interruptions during
ascent and descent. During the simulation, one ME will be fitted with an ear-canal probe
attached to a pressure transducer and the other with a probe attached to the Forced-Response
test system. ME pressure will be continuously monitored in the one ear and the
Forced-Response test will be done at chamber pressures of atmospheric, on decreasing
pressures (ascent in a flight) at 500 daPa intervals, during stable "cruising" cabin
pressure, on increasing pressures (descent in a flight) at 500 daPa intervals and then at
atmospheric pressure. All transducers will be referenced to chamber pressure and signals
routed via an A-D box to the memory of a computer for on-line display and storage. Outcome
variables will consist of the continuous measures of ME pressure in one ear and the periodic
measures of ET opening pressure, closing pressure, passive resistance and dilatory efficiency
in the contralateral ear.
Under this model, it is expected that, between active/passive ET openings, ME pressure will
be relatively stable and not affected by changing chamber pressure and that the measures of
ET periluminal pressures (opening pressure, closing pressure and passive resistance) will
track chamber pressure.
and/or free or tanked diving. Previously, one of the investigators modeled the change in
middle-ear (ME) pressure during simulated airplane flights for ears with normal Eustachian
tube function (ETF) and with different degrees of Eustachian tube (ET) dysfunction (Kanick
SC, Doyle WJ. Barotrauma during air travel: predictions of a mathematical model. J Appl
Physiol. May 2005;98(5):1592-1602). That model provided a number of important insights into
the pathogenesis of ME barotrauma but included two assumptions that have not been validated:
1) in the absence of ET opening, ME pressure is relatively stable (ignoring tympanic membrane
volume induced changes) over wide ranges of ambient pressures, and 2) ET periluminal
pressures track local ambient pressures. Other, less rigorous, descriptions of ME pressure
behavior during flight and diving make different assumptions: 1) ME pressure changes with
changes in ambient pressure and 2) ambient and ET mucosa pressures are incompletely coupled.
Modeling ME pressure behavior using the two sets of assumptions predicts different ME
pressure trajectories and explanations for barotitis/ME barotrauma during flight and diving.
Because the behavior of ME pressure during flight (or diving) constrains the interventions
that could be used to prevent barotitis/ME barotrauma, it is important to determine which, if
either, model is correct.
Ten otherwise healthy subjects aged 18 to 50 years with unilateral or bilateral eardrum
perforations or ventilation tubes will be enrolled after obtaining Informed Consent. Complete
histories will be taken with a focus on ear-related problems and they will have an ENT
examination including tympanometry to document the patency of the ventilation tube and
absence of drainage through the tube (disqualifiers). Eligible subjects will be studied in
the pressure chamber during a typical flight simulation with periodic interruptions during
ascent and descent. During the simulation, one ME will be fitted with an ear-canal probe
attached to a pressure transducer and the other with a probe attached to the Forced-Response
test system. ME pressure will be continuously monitored in the one ear and the
Forced-Response test will be done at chamber pressures of atmospheric, on decreasing
pressures (ascent in a flight) at 500 daPa intervals, during stable "cruising" cabin
pressure, on increasing pressures (descent in a flight) at 500 daPa intervals and then at
atmospheric pressure. All transducers will be referenced to chamber pressure and signals
routed via an A-D box to the memory of a computer for on-line display and storage. Outcome
variables will consist of the continuous measures of ME pressure in one ear and the periodic
measures of ET opening pressure, closing pressure, passive resistance and dilatory efficiency
in the contralateral ear.
Under this model, it is expected that, between active/passive ET openings, ME pressure will
be relatively stable and not affected by changing chamber pressure and that the measures of
ET periluminal pressures (opening pressure, closing pressure and passive resistance) will
track chamber pressure.
Inclusion Criteria:
- adults 18-50 years of age
- have unilateral or bilateral holes in the eardrums/patent tympanostomy tubes
- otherwise healthy
- ability to read and comprehend English
Exclusion Criteria:
- drainage through either tube or hole in the eardrum
- cold or allergic rhinitis on presentation
- syndrome predisposing to otitis media
- history of ossicular reconstruction
We found this trial at
1
site
Pittsburgh, Pennsylvania 15213
Principal Investigator: Cuneyt M Alper, MD
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