OTITIC BAROTRAUMA

Aero-otitis media / Aviation pressure deafness

•1783 - Charles Hydrogen Balloon

•World War I - Sidney Scott

•World War II - Increase of Air power

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Mention anatomy of ET

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Boyle’s law

• Volume is inversely proportional to pressure in fixed mass of gas

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MECHANICS OF BAROTRAUMA

Relationship between altitude and barometric pressure

• As altitude ↑ environmental pressure ↓

• At 18000 ft pressure is half that of sea level, and at 34000 ft ¼

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• As depth increases during diving , pressure increases

• One atmospheric pressure increase for every 10 mtrs

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MECHANICS OF BAROTRAUMA

Cross-section of Cartilagenous part ofEustachian tube

•Medial end is slit like, lies collapsed, in close proximity to lymphoid tissue

• Opens on swallowing (pressure equalises) (effect of tensor & levator palati)

LEARN DIAGRAM

elastin

Ostman pad of

fat

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MECHANICS OF BAROTRAUMA

Middle Ear

Nasopharynx

At high altitude ME pressure is higher than env pressure, therefore air from middle ear escapes passively along ET equalising pressures

ASCENT

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MECHANICS OF BAROTRAUMA

Middle ear

Nasopharynx

DESCENT

• During descent environmental pressure is higher than ME pressure, therefore we need to aerate the ME actively by VALSALVA manouvre/other methods

• If the tube does not open and the pressure gradient increases beyond 90 mm of Hg, tube gets locked

•Similar during deep sea diving & hyperbaric chamberwww.nayyarENT.com 8

Aetiology of Otitic Barotrauma

• Healthy subjects– Rapid descent – No attempt at auto-inflation– Sleep; sedation; position– Effect of alcohol– Anatomical differences

• Pathological states– Acute infection oedema of ET mucosa– Chronic ET obstruction infected tonsils/nasal

polypi /allergic rhinitis/ DNS/nasal allergywww.nayyarENT.com 9

OTITIC BAROTRAUMA

Clinical Features

• Mild – Fullness/ slight hearing loss

• Moderate – Pain/ deafness/ interstitial hemorrhage/

fluid

• Severe – Severe pain/ deafness/ rupturewww.nayyarENT.com 10

Tubal Occlusion

OTITIC BAROTRAUMA- EARLY

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Findings Grade

Symptoms (pain, nausea, vomiting, etc.) Without changes in the tympanic membrane

0

Injection of the tympanic membrane (may be most noticeable along the handle of the malleus)

I

Injection plus mild haemorrhage within the tympanic membrane II

Gross haemorrhage within the tympanic membrane III

Free blood in the middle ear (tympanic membrane blue and bulging)

IV

Perforation of the tympanic membrane (commonest in AI quadrant) Vwww.nayyarENT.com 13

Other possible features• Middle ear

– Ossicular disruption– Stapes avulsion– RW membrane rupture– 7th nerve barotrauma

• Inner ear– Perilymph fistula

• Implosive mechanism forceful valsalva patent ET Implosive damage to RW

• Explosive mechanism forceful valsalva blocked ET ↑ CSF pressure explosive damage to RW

• Oval window in stapedectomized patients

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OTITIC BAROTRAUMA

Treatment - Curative• No flying• Reascent & gradual descent• ET catheterisation• Antibiotics• Analgesics• Nasal + oral decongestants• Myringotomy• Grommets• Eliminate septic foci

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Treatment

• TM rupture no active management, remove clots if not healed by 3 mths myringoplasty

• Perilymph fistula Bed rest, head elevation, labyrinthine sedatives, stool softeners, cough suppressant, Acetazolamide

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• Decompression chamber run on enrolment• Education of aircrew/ divers• Flying discipline• Auto-inflation techniques – frenzel’s manouvere for

pilots

Prevention

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