Flashcards in Exam Revision Deck (159)
What height is considered to be the Physiological Zone?
MSL - 10000feet
What height is considered to be physiologically deficient zone?
What is considered to be the Space Equivalent Zone?
50000 feet and above
What is the break down of the atmosphere?
1% other gases (ozone, CO2, methane etc)
Does the percentage of gases in atmosphere change?
No, pressure may change but percentage relationship stays the same
What height is pressure approximately half that of atmosphere?
What is hypoxia?
Lack of 02 to tissue sufficient to cause impairment of function
What are the four types of hypoxia?
Hypoxic hypoxia (due to low o2 levels)
Anaemic Hypoxia (insufficient blood)
Stagnant (lack of flow, g force)
Histotoxic hypoxia (poison)
At 33000 feet on 100% oxygen, what is this equivalent to?
Sea level on air
At 40000 feet on 100% oxygen, what is this equivalent to?
10000 feet on air
What are some signs of hypoxia?
Loss of judgement
Loss short term memory
Slower reaction times
Mental 'Tunnel vision"
Hot flushes, (cherry cheeks)
Sense of euphoria
Muscular in-coordination and tremors
Loss of peripheral, colour and night vision
What factors will increase risk of hypoxia?
Rate of ascent
Exercise/fitness (lack there of)
Drugs and alcohol (hangover)
How do you 'recover' from hypoxia?
O2 mask, 100% oxygen
Descend below 10000 feet
Breathe normal rate and depth
What is oxygen paradox?
Worsening of symptoms following re-introduction of O2 after period of exposure to hypoxia
What is you useful level of conciousness at FL180?
What is your useful level of conciousness at FL250?
What is your useful level of conciusness at FL300?
What is your useful level of conciusness at FL350?
What is your useful level of conciusness at FL400?
What is your useful level of conciusness at FL430?
What are some post hypoxic symptoms?
What are some causes of hyperventilation?
Excessive G forces
Voluntary over breathing
Environmental stressors (high temperatures)
What are some symptoms of hyperventilation?
Unconsciousness then recovery
What are some body cavities that contain gas?
Post op sites
Gas expansion in lungs can lead to what illnesses?
Air embolism (air bubbles)
What can lead to gas expansion in the lungs?
Pressure changes and holding your breath
When is pain in the ears likely to occur?
Where in the ear are you likely to feel affects of pressure change?
Middle ear (known as barotrauma)
Why do we feel pain in the ear?
Air cannot easily escape Eustachian tube to equalise pressure