Aero-otitis media / Aviation pressure deafness 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 Middle Ear 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

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Injection plus mild haemorrhage within the tympanic membrane Findings Grade Symptoms (pain, nausea, vomiting, etc.) Without changes in the tympanic membrane 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) V 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