Otitic Barotrauma

MUHAMMAD ALI RAZA

Definitionsy Barotrauma : an injury produced by mechanical forcescaused by a change of pressure in a gas filled space

y Otitc Barotrauma : this type of injury in ear and relatedstructures

Aetiologyy Air travel

y Scuba (self contained underwater breathing apparatus)diving

y Slap injuries y Blast injuries y Professional jet pilots

Understanding Pathophysiologyy Pressure / volume relationship : inverse relationy Boyle s law

y Charle s law

Understanding Pathophysiology

Understanding Pathophysiologyy Ambient Pressure : external pressure is uniformlydistributed over an object provided there are no air spaces in it.

y Middle ear : air filled bony cavity

Understanding Pathophysiology

Physiological consequences of Compression (Decent)

Contd

Contd.

Contdy Tympanic membrane perforation

y Perilymphatic fistula

y A rigorous caloric vertigo

Physiological consequences of Decompression (Ascent)y If eustachian tube function absent : y If both eustachian tube are function normal : then onlysymptoms of decompression illness are observed

y If eustachian tube function suboptimal :mucosal edema and haemorrhage passive ventilation does not occur positive middle ear pressure with more ascent chances of perilymphatic fistula are high

Clinical features of otitic barotraumay Compression injuries

y Injuries at stable pressure

y Decompression injuries

Compression (Decent) injuriesy External ear barotrauma :y Due to air trapped in EAC y Pain increases in proportion to compression y Prevention : avoid occlusive ear plugs y Treatment : y Clear external meatus y Antibiotic drops y Surgical repair if perforation and spontaneous healing fail y Advice : complete resolution observed and causative factors corrected prior to further flying diving

Middle ear barotraumay Common during flight and scuba diving y Speed of compression is important risk factor y Perceive ability to equalize is useful predictor y Symptoms :y y y yEar discomfort or pain Dizziness Hearing loss Sense of fullness in ears

y Diagnosis :specific history:pain on decent

otoscopic appearance

audiometry: CHL

Tympanic membrane appearance in Middle Ear Barotrauma

Grade 0 Symptoms without signs

Grade I Injection of the tympanic membrane and along the handle of Malleus

Grade II Injection plus slight hemorrhag e within the substance of the tympanic membrane

Grade III Gross hemorrhag e within the substance of tympanic membrane

Grade IV Free blood in the middle ear , bluish drum and bulging

Grade V Perforation of the tympanic membrane

Middle ear barotraumay Prevention :y Oral decongestants y Otovents

y Treatment :y y y y yConservative/symptomatic initially Elective repair of TM and or ossicles Treat nasal conditions Consider septal surgery Myringotomies +/- ventilation tubes for flying

y Advice to patient :y No flying or diving with URTI y Complete resolution expected in mildcases

y Identify those at risk:y Aymmetric equalizers y Inability to equalize at sea level(divers)

y Scuba diving contraindicated ifpersistant problems

y Decongestants brfore diving/flying

y Nasal obstruction

Caloric vertigoy Asymmetric exposure of each ear to cold stimulus

y Short lived and self correcting

y Vomiting may occur

y Life saving manoeuvre:inflation of buoyancy vest

y Management as for middle ear trauma

Inner ear barotraumahistopathological studies demonstrated three entities

y Inner ear haemorrhage : y Labyrinthine tears : y Perilymphatic fistula :y y y y yMuffled hearing (SNHL) Dysequlibrium ( with manoeuvres which increase ICP) Vertigo / tinnitus Tullio phenomenon / History of pressure/time profile of incident is important

y Should be distinguished from inner ear decompression illness

D/D of inner ear barotraumaMiddle ear barotrauma Phase of dive/flight Difficulty equalizing middle ear pressure Assosiated middle ear barotrauma vertigo Sensorineural hearing loss Effect of recompression on symptoms Hearing loss None None Worsened CHL decent Yes Inner ear barotrauma decent Yes Usual Usual Frequent Worsened Mixed Inner ear decompression illness ascent Not usual Not usual Usual Frequent Improvement SNHL

Injuries at stable depthy High pressure nervous syndromey Occurs with extreme pressure exposures y Usually occurs on changing inspired gas mixtures y Characterized byy Tiredness y General dizziness y tremor y May progress to include vertigo, ataxia and myoclonus y Permanent vestibular damage may occur without hearing loss

Decompression (Ascent) injuriesy Alternobaric vertigo:y Caused by asymmetric middle ear overpressure y Common in divers and aircrew y Often has preceding history of unilateral difficulties equalizing y Usually occurs with decompression or within 2 minutes ofsurfacing

y Maximum 10 mins duration of sympotoms y There are no permanent sequelae

Contd .y Barotraumatic facial palsy:y Caused by middle ear overpressure during ascent y It involves neuropraxia secondary to compression of vasa nervosa y No other neurological signs y Often associated with middle ear barotrauma y Rapid spontaneous resolution is expected y Other causes of facial palsy be ruled out y Myringotoies for persistance when bulging tympanic membrane isidentified

Decompression illness and hyperbaric mediciney Pathophysiology :decompression vascular damage

y Hyperbaric treatment : y Increases amount of gas in solution y Highly effective in decompression illness and gas embolism y Adjuvant role in gangrenes, crush injuries y Failure to give hyperbaric oxygen treatment in decompression illnessis associated with permanent functional damage

Contd .y Inner ear decompression illness :

y Middle ear and inner ear barotrauma secondary tohyperbaric oxygen treatment :

y Cerebral air gas embolism :

Historic perspectivey 323 BC : Alexander the great used first diving bell

y 1640 AD : First modern bells

y 1788 AD : Caissons

y 1837 AD : SCUBA (self contained underwater breathingapparatus)

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