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OTITIC BAROTRAUMA. Aero-otitis media / Aviation pressure deafness 1783 - Charles Hydrogen Balloon World War I - Sidney Scott World War II - Increase of Air power. Mention anatomy of ET. Boyle’s law. Volume is inversely proportional to pressure in fixed mass of gas.
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OTITIC BAROTRAUMA • Aero-otitis media / Aviation pressure deafness • 1783 - Charles Hydrogen Balloon • World War I - Sidney Scott • World War II - Increase of Air power www.nayyarENT.com
Mention anatomy of ET www.nayyarENT.com
Boyle’s law • Volume is inversely proportional to pressure in fixed mass of gas www.nayyarENT.com
MECHANICS OF BAROTRAUMA • As altitude ↑ environmental pressure ↓ • At 18000 ft pressure is half that of sea level, and at 34000 ft ¼ Relationship between altitude and barometric pressure www.nayyarENT.com
As depth increases during diving , pressure increases • One atmospheric pressure increase for every 10 mtrs www.nayyarENT.com
MECHANICS OF BAROTRAUMA elastin • 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 Ostman pad of fat Cross-section of Cartilagenous part of Eustachian tube www.nayyarENT.com
MECHANICS OF BAROTRAUMA ASCENT At high altitude ME pressure is higher than env pressure, therefore air from middle ear escapes passively along ET equalising pressures MiddleEar Nasopharynx www.nayyarENT.com
MECHANICS OF BAROTRAUMA • 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 chamber Middle ear DESCENT Nasopharynx www.nayyarENT.com
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 allergy www.nayyarENT.com
OTITIC BAROTRAUMA Clinical Features • Mild – Fullness/ slight hearing loss • Moderate – Pain/ deafness/ interstitial hemorrhage/ fluid • Severe – Severe pain/ deafness/ rupture www.nayyarENT.com
OTITIC BAROTRAUMA- EARLY Tubal Occlusion www.nayyarENT.com
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 www.nayyarENT.com
OTITIC BAROTRAUMA Treatment - Curative • No flying • Reascent & gradual descent • ET catheterisation • Antibiotics • Analgesics • Nasal + oral decongestants • Myringotomy • Grommets • Eliminate septic foci www.nayyarENT.com
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 www.nayyarENT.com
Prevention • Decompression chamber run on enrolment • Education of aircrew/ divers • Flying discipline • Auto-inflation techniques – frenzel’s manouvere for pilots www.nayyarENT.com