1. Aero-otitis media / Aviation pressure deafness
OTITIC BAROTRAUMA
Aero-otitis media / Aviation pressure deafness
Charles  Hydrogen Balloon
World War I - Sidney Scott
World War II - Increase of Air power

2. Mention anatomy of ET

3. Boyle’s law
Volume is inversely proportional to pressure in fixed mass of gas

4. MECHANICS OF BAROTRAUMA
As altitude ↑ environmental pressure ↓
At ft pressure is half that of sea level, and at ft ¼
Relationship between
altitude and barometric pressure

5. As depth increases during diving , pressure increases
One atmospheric pressure increase for every 10 mtrs

6. 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

7. 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

8. 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

9. 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

10. OTITIC BAROTRAUMA Clinical Features
Mild – Fullness/ slight hearing loss
Moderate – Pain/ deafness/
interstitial hemorrhage/ fluid
Severe – Severe pain/ deafness/ rupture

11. OTITIC BAROTRAUMA- EARLY
Tubal Occlusion

13. 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

14. 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

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

16. 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

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