Trapped Gases Flashcards

1
Q

Describe the physiological mechanisms underplaying trapped gas disorders

A

Pascal’s principle - pressure applied to an incompressible liquid will be transmitted equally throughout the liquid
Pressures are transmitted equally through body fluid to all body cavity

Boyle’s law’s- Pressure is inversely volume at contrast temperature

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2
Q

Demonstrate how to perform a Valsalva Manoeuvre

A

Moderately forceful attempted exhalation against a closed airway
Forces air up Eustachian tube and increases pressure in the middle ear
Ineffective if pressure differential exceeds 90-120mmHg

When testing must be brisk, easy and symmetrical - equal

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3
Q

Describe methods to prevent trapped gas disorders

A
Do not fly with URT congestion
Do not self medicate
See you if ill or unsure
Equalise pressure frequently on descent
Avoid gas producing foods and carbonate beverages before flight
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4
Q

Where would you have more issues with trapped gas and why

A

In take off and landing due increase rate of change

Pressure at altitude

  • 0-3000 = 27mmHg per 1000ft
  • 3000-10000 = 23mmHg
  • 10000 - 18000 = 18 mmHg
  • 18000 -25000= 17mmHg
Volume
3000 - 10% increase
8000 - 30% increase
18000 - Double size 
34000 - four times larger
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5
Q

Body cavities affect by trapped gas

A

Ears
Sinuses
Teeth
Lungs: Coughing, straining, Valsalva, pneumothorax, air emboli, CAGE
GUT - pain, distension and fainting eg small bowel
Anywhere after surgery or trauma

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6
Q

Managing gas in the gut

A
Stand
Stretch
Massage abdomen
Avoid soft drinks
Monitor types of food
No crewing gum
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7
Q

How to equalising ear pressure

A

Swallowing
Chewing yawning
Valsalva manoeuvre

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8
Q

Grades of Otic barotrauma

A

Grade 0 symptoms without signs
Grade 1 injection of TM
Grade 2 Injection plus mild haemorrhage of TM
Grade 3 Goss haemorrhage within TM
Grade 4 free blood in middle ear, bulging of TM
Grade 5 Perforation of TM

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9
Q

Symptoms of barotrauma

A
Symptoms on descent
Fullness
Hearing loss
Pain
Pressure lock
Rupture
Ear perforation
- take 6-8 weeks to heal TMUFF
- gets alternobaric vertigo
- risk of infection
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10
Q

Immediate management of otic barotrauma

A

Immediate

  • slow or halt descent, ascend if possible
  • attempt to Valsalva and descend more slowly
  • use vasoconstrictor nasal spray
  • Hand over control if pain is distracting/severe
  • seek medical attention on landing
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11
Q

Managing of otic barotrauma once landed

A
If perforation the TMUFF 6-8 weeks
Monitor for infection nad treat if needed
Tympanometry
\+/- audiology (required by CASA)
Imaging 
\+/- ENT referral
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12
Q

Symptoms of sinus barotrauma

A
Typically on descent 
Commonly frontal
Less common than otic barotrauma
Severe pain
Sinus tenderness
Epistaxis
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13
Q

In flight and post flight Mx of sinus barotrauma

A

Manage altitude and descent rates
Topical vasoconstrictors
Hand over if possible
Declare PAN if incapacitating

Post flight
TMUFF
Analgesia
Decongestants
Antibiotics if indicated
Imaging
Referral if recurrent
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13
Q

Aeromedical evacuation consideration

A

Trapped gas

Endotracheal tubes
Ventilators
Pumps
Infusions
Air splints
IV bags and lines
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13
Q

Organs effected by pressure changes on ascent

A

Teeth
Lungs
Gut
Surgery/trauma

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14
Q

Areas effected by pressure changes on descent

A

Sinuses

Ears

15
Q
The sinus most likely to succumb to acute barotrauma is 
A. The frontal sinus
B. The Maxillary sinus
C. The mastoid air cells
D. The sphenoid also sinus
A

A. The frontal sinus