Trapped Gases Flashcards
Describe the physiological mechanisms underplaying trapped gas disorders
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
Demonstrate how to perform a Valsalva Manoeuvre
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
Describe methods to prevent trapped gas disorders
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
Where would you have more issues with trapped gas and why
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
Body cavities affect by trapped gas
Ears
Sinuses
Teeth
Lungs: Coughing, straining, Valsalva, pneumothorax, air emboli, CAGE
GUT - pain, distension and fainting eg small bowel
Anywhere after surgery or trauma
Managing gas in the gut
Stand Stretch Massage abdomen Avoid soft drinks Monitor types of food No crewing gum
How to equalising ear pressure
Swallowing
Chewing yawning
Valsalva manoeuvre
Grades of Otic barotrauma
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
Symptoms of barotrauma
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
Immediate management of otic barotrauma
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
Managing of otic barotrauma once landed
If perforation the TMUFF 6-8 weeks Monitor for infection nad treat if needed Tympanometry \+/- audiology (required by CASA) Imaging \+/- ENT referral
Symptoms of sinus barotrauma
Typically on descent Commonly frontal Less common than otic barotrauma Severe pain Sinus tenderness Epistaxis
In flight and post flight Mx of sinus barotrauma
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
Aeromedical evacuation consideration
Trapped gas
Endotracheal tubes Ventilators Pumps Infusions Air splints IV bags and lines
Organs effected by pressure changes on ascent
Teeth
Lungs
Gut
Surgery/trauma
