Gas Supply, Demand and Middle Ear Gas Balance -- Fly/Dive Simulation
| Status: | Recruiting |
|---|---|
| Healthy: | No |
| Age Range: | 10 - 50 |
| Updated: | 10/17/2018 |
| Start Date: | October 2013 |
| End Date: | June 30, 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 2
This study will determine if newly developed and more standard tests of Eustachian tube
function can identify those persons who have ear pain (barotrauma) or develop middle-ear
inflammation and/or fluid (barotitis) when they are exposed to rapid changes in air pressure
as, for example, during airplane flights or scuba diving. Up to 150 adults and children
(10-50 years old) who fly or dive at least 1-2 times and experience ear pain or develop
middle-ear fluid during those activities and approximately 60 adults and children who fly or
dive but do not experience these problems will undergo Eustachian tube function testing
during simulated flight and diving.
function can identify those persons who have ear pain (barotrauma) or develop middle-ear
inflammation and/or fluid (barotitis) when they are exposed to rapid changes in air pressure
as, for example, during airplane flights or scuba diving. Up to 150 adults and children
(10-50 years old) who fly or dive at least 1-2 times and experience ear pain or develop
middle-ear fluid during those activities and approximately 60 adults and children who fly or
dive but do not experience these problems will undergo Eustachian tube function testing
during simulated flight and diving.
Subjects will be recruited who only experience symptoms or present signs interpretable as
Eustachian (ET) dysfunction (ETD) when exposed to rapid changes in ambient pressure as, for
example, during flights in airplanes (in the absence of a concurrent cold/active nasal
allergy) or during free and tanked diving. In general, subjects presenting to physicians with
these conditions are diagnosed with poor ET function (ETF) based solely on symptom/sign
presentation. However, it is not known how to identify those persons who will experience
these symptoms/signs at a future time which is the goal of this study or how to prevent those
presentations in susceptible individuals. To calibrate the test protocol, 20 subjects/age
ranges of 10-19, 20-29 and 30-50 years (total=60 control subjects) who are in good health,
fly and/or dive frequently but report no ear-related problems on ascent or descent, will be
recruited. One hundred fifty symptomatic subjects in general good health aged 10 to 50 years
with the lower age limit chosen to assure good communication between the subject and
investigators, will also be recruited. These and the control subjects will have intact
tympanic membranes since subjects with non-intact tympanic membranes do not experience
barotrauma but maintain ambient middle-ear (ME) pressures throughout a flight.
A general history with a focus on the specific symptomatic complaints and the maneuvers
performed in attempting to relieve any otologic symptoms during airplane flight/diving will
be taken, an ear, nose and throat (ENT) exam, including tympanometry, done to confirm intact
tympanic membranes and a disease-free ME and nasal exam done to rule out concurrent nasal
inflammation. Then, sonotubometry, the 9-step test, tubomanometry and the "sniffing",
Valsalva and Toynbee maneuvers will be done to establish baseline ETF. If a patulous (by
observation of synchronized breathing and tympanic membrane movements) or physically
obstructed ET (by an inability to transfer gas through the ET at normal driving pressures) is
suggested by the results of these tests, the subject will be dismissed from further ETF
testing and will be referred to their ENT physician or to the ETD clinic at Children's
Hospital of Pittsburgh if they want to pursue a more complete workup to evaluate the
underlying cause of the condition and possible treatment options. Those who are able to
continue will have the ET stress test. Briefly, the presence/absence of ET openings by
swallowing will be assessed by sonotubometry at stepped decreases from 2500 daPa (ref.
ambient) to local ambient to determine the relative efficiency of muscle-assisted ET opening.
The highest applied pressure at which the ET can be opened will be the outcome variable. If
the individual completes the applied pressure sequence without experiencing a problem in
opening their ET by swallowing or other maneuvers typically used by him/her to open their ET,
the subject will have a simulated flight/dive relevant to their expected exposure.
Flight Simulation: The standard flight simulation parameters are based on those for a Boeing
747 but can be modified to simulate other, including personal, aircraft. For the simulations,
we assume that the airport is at sea level, the maximum cabin pressurization is equal to the
atmospheric pressure at 7000 feet and the ascent/descent rate is 350 ft/min (for the cabin
altitude). With the subject seated comfortably in the pressure-chamber, chamber pressure is
decreased from ambient to ambient minus 2280 daPa (gauge pressure=-2280 daPa) over a 15
minute period, maintained at ambient-2280 daPa for 15 minutes (cruising) and then increased
to ambient over a 15 minute period. The subject reports symptoms throughout and middle-ear
pressure is measured bilaterally by tympanometry periodically.
Diving Simulation: The standard dive simulation assumes sea level ambient pressure and, to
avoid the possibility of the bends, is limited to a simulated maximum depth of 20 feet and a
maximum "dive" duration of 1 hour. We make a first assumption that the diver rapidly descends
to 5 feet at which point they attempt to equalize ME-ambient pressure and then proceed to the
maximum depth of 20 feet within 5 minutes (These parameters can be modified depending on the
diver's experience and the chamber pressure can be increased to simulate a dive to 30 feet).
We also assume that the return to the surface is approximately 10 feet per minute. With the
subject seated comfortably in the chamber, pressure is increased to 1500 daPa+ambient (gauge
pressure =1500 daPa, approximately depth of 5 feet), the subjects middle-ear pressures are
measured by tympanometry and any symptoms/signs evaluated. If these assessments are normal,
the chamber pressure is increased to 6100 daPa+ambient (approximate depth of 20 feet for sea
and fresh water), maintained at that pressure for 20 minutes and then decreased to ambient
(ascent to surface). The rate of change in depth is set at 5 ft/minute. The subject reports
symptoms throughout and middle-ear pressure is measured bilaterally by tympanometry
periodically.
The simulations will be interrupted at the first report of an inability to "clear" their ears
by swallowing or other maneuvers typically used for that purpose. At that pressure, the
subjects will again attempt to equalize the ME-chamber pressure by swallowing, and if
unsuccessful, will attempt to open the ET using a Valsalva maneuver, jaw movements/rotations
and voluntary yawning. If these maneuvers are unsuccessful, instrumented nasopharyngeal
overpressures using the "ear popper"® or Otovent® devices will be tried. If successful, the
simulation will be continued, else the chamber pressure will be reduced to atmospheric and ME
pressure equalized with ambient pressure. Then, only in subjects entered as symptomatic
subjects, a video-nasoendoscopic exam of the nasopharynx will be performed to diagnose nasal
and nasopharyngeal pathologies and physical obstruction of the ET orifice.
All subjects in the symptomatic group who pass the simulation without symptoms/signs of
barotrauma will be retested using the appropriate simulation on a second day to confirm
"symptom-free" flights/dives. For those subjects who fail this test and/or cannot complete
the simulation without otologic symptoms/signs, we will refer them to their physician or to
the ETD clinic if they want to pursue further work-up and treatment. We expect that all of
the control subjects will successfully complete both the test protocol and simulation while
the majority of subjects reporting flight/diving related symptoms will fail the stepped ETF
test and not be able to complete the simulation without symptoms/signs of ME barotrauma. The
sensitivities, specificities and accuracies of the ET stress test and the simple ETF tests
done at baseline with respect to predicting a failed/successful simulation will be
calculated.
Eustachian (ET) dysfunction (ETD) when exposed to rapid changes in ambient pressure as, for
example, during flights in airplanes (in the absence of a concurrent cold/active nasal
allergy) or during free and tanked diving. In general, subjects presenting to physicians with
these conditions are diagnosed with poor ET function (ETF) based solely on symptom/sign
presentation. However, it is not known how to identify those persons who will experience
these symptoms/signs at a future time which is the goal of this study or how to prevent those
presentations in susceptible individuals. To calibrate the test protocol, 20 subjects/age
ranges of 10-19, 20-29 and 30-50 years (total=60 control subjects) who are in good health,
fly and/or dive frequently but report no ear-related problems on ascent or descent, will be
recruited. One hundred fifty symptomatic subjects in general good health aged 10 to 50 years
with the lower age limit chosen to assure good communication between the subject and
investigators, will also be recruited. These and the control subjects will have intact
tympanic membranes since subjects with non-intact tympanic membranes do not experience
barotrauma but maintain ambient middle-ear (ME) pressures throughout a flight.
A general history with a focus on the specific symptomatic complaints and the maneuvers
performed in attempting to relieve any otologic symptoms during airplane flight/diving will
be taken, an ear, nose and throat (ENT) exam, including tympanometry, done to confirm intact
tympanic membranes and a disease-free ME and nasal exam done to rule out concurrent nasal
inflammation. Then, sonotubometry, the 9-step test, tubomanometry and the "sniffing",
Valsalva and Toynbee maneuvers will be done to establish baseline ETF. If a patulous (by
observation of synchronized breathing and tympanic membrane movements) or physically
obstructed ET (by an inability to transfer gas through the ET at normal driving pressures) is
suggested by the results of these tests, the subject will be dismissed from further ETF
testing and will be referred to their ENT physician or to the ETD clinic at Children's
Hospital of Pittsburgh if they want to pursue a more complete workup to evaluate the
underlying cause of the condition and possible treatment options. Those who are able to
continue will have the ET stress test. Briefly, the presence/absence of ET openings by
swallowing will be assessed by sonotubometry at stepped decreases from 2500 daPa (ref.
ambient) to local ambient to determine the relative efficiency of muscle-assisted ET opening.
The highest applied pressure at which the ET can be opened will be the outcome variable. If
the individual completes the applied pressure sequence without experiencing a problem in
opening their ET by swallowing or other maneuvers typically used by him/her to open their ET,
the subject will have a simulated flight/dive relevant to their expected exposure.
Flight Simulation: The standard flight simulation parameters are based on those for a Boeing
747 but can be modified to simulate other, including personal, aircraft. For the simulations,
we assume that the airport is at sea level, the maximum cabin pressurization is equal to the
atmospheric pressure at 7000 feet and the ascent/descent rate is 350 ft/min (for the cabin
altitude). With the subject seated comfortably in the pressure-chamber, chamber pressure is
decreased from ambient to ambient minus 2280 daPa (gauge pressure=-2280 daPa) over a 15
minute period, maintained at ambient-2280 daPa for 15 minutes (cruising) and then increased
to ambient over a 15 minute period. The subject reports symptoms throughout and middle-ear
pressure is measured bilaterally by tympanometry periodically.
Diving Simulation: The standard dive simulation assumes sea level ambient pressure and, to
avoid the possibility of the bends, is limited to a simulated maximum depth of 20 feet and a
maximum "dive" duration of 1 hour. We make a first assumption that the diver rapidly descends
to 5 feet at which point they attempt to equalize ME-ambient pressure and then proceed to the
maximum depth of 20 feet within 5 minutes (These parameters can be modified depending on the
diver's experience and the chamber pressure can be increased to simulate a dive to 30 feet).
We also assume that the return to the surface is approximately 10 feet per minute. With the
subject seated comfortably in the chamber, pressure is increased to 1500 daPa+ambient (gauge
pressure =1500 daPa, approximately depth of 5 feet), the subjects middle-ear pressures are
measured by tympanometry and any symptoms/signs evaluated. If these assessments are normal,
the chamber pressure is increased to 6100 daPa+ambient (approximate depth of 20 feet for sea
and fresh water), maintained at that pressure for 20 minutes and then decreased to ambient
(ascent to surface). The rate of change in depth is set at 5 ft/minute. The subject reports
symptoms throughout and middle-ear pressure is measured bilaterally by tympanometry
periodically.
The simulations will be interrupted at the first report of an inability to "clear" their ears
by swallowing or other maneuvers typically used for that purpose. At that pressure, the
subjects will again attempt to equalize the ME-chamber pressure by swallowing, and if
unsuccessful, will attempt to open the ET using a Valsalva maneuver, jaw movements/rotations
and voluntary yawning. If these maneuvers are unsuccessful, instrumented nasopharyngeal
overpressures using the "ear popper"® or Otovent® devices will be tried. If successful, the
simulation will be continued, else the chamber pressure will be reduced to atmospheric and ME
pressure equalized with ambient pressure. Then, only in subjects entered as symptomatic
subjects, a video-nasoendoscopic exam of the nasopharynx will be performed to diagnose nasal
and nasopharyngeal pathologies and physical obstruction of the ET orifice.
All subjects in the symptomatic group who pass the simulation without symptoms/signs of
barotrauma will be retested using the appropriate simulation on a second day to confirm
"symptom-free" flights/dives. For those subjects who fail this test and/or cannot complete
the simulation without otologic symptoms/signs, we will refer them to their physician or to
the ETD clinic if they want to pursue further work-up and treatment. We expect that all of
the control subjects will successfully complete both the test protocol and simulation while
the majority of subjects reporting flight/diving related symptoms will fail the stepped ETF
test and not be able to complete the simulation without symptoms/signs of ME barotrauma. The
sensitivities, specificities and accuracies of the ET stress test and the simple ETF tests
done at baseline with respect to predicting a failed/successful simulation will be
calculated.
Inclusion Criteria:
- bilaterally intact tympanic membranes
- flyer or diver with middle-ear symptoms
- flyer or diver without middle-ear symptoms (controls)
- generally good health
- no recent history of non-activity related otitis media
Exclusion Criteria:
- existing middle-ear disease
- allergic rhinitis symptoms or "cold" on day of testing
- 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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