oxygen oxygen

OxygenOxygen – the ‘Breath of Life’

“How high can I make it without extra O2?”

harry oxer

copyright Harry Oxer 5/2003

2

How much oxygen in air?

At ground level:

• Nitrogen 78%

• OxygenOxygen 21%

• Others 1% (mostly Argon)


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How much oxygen in air?

At 30,000’:• Nitrogen 78%

• OxygenOxygen 21%

• Others 1% (mostly Argon)

Same percentages, BUT:


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But……

• Oxygen needs pressure to get into solution in the body

• And the pressure is MUCH lower as you get higher!

• Need a partial pressure of at least 60mmHg to force oxygen into solution in the body


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Compare carbon dioxide

• 1000 L of CO2 in an average room

• But all water doesn’t turn to soda water!

• CO2 only dissolves if injected under PRESSURE

• If reduce the pressure enough – i.e. take the top off – all the CO2 comes out of solution

• In space, even if lungs full of oxygen, you would suffocate, because all oxygen comes out of solution – no pressure to keep it dissolved!


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Relevance of this?

• As you climb in sailplane, or any unpressurised a/c, the ambient pressure FALLS, and so does the partial pressure of oxygen

• Partial pressure – that % of the total pressure exerted by the oxygen, i.e. 21%

• CO2 and water vapour further reduce the pressure available for oxygen


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Pressure available to push oxygen into solution

Pressure altitude – (ft)

Atmospheric pressure mmHg

Ambient O2 pressure

Alveolar(lung) O2 pressure

0 760 159 103

5000 632 133 81

10,000 523 110 61

12,000 483 101 54

13,000 465 97 51

14,000 447 94 48

15,000 429 90 45

20,000 350 73 34

25,000 282 59 30


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Oxygen pressure cascade

• Air 150 mmHg

▼• Alveolae of lungs 100 mmHg

▼• Tissues average 40mmHg

• If inspired pressure of O2 less than 40mmHg, O2 comes OUT of body!


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flying

• Must maintain alveolar partial pressure of O2 at least 60mmHg (more than 40 to push)

• How?• Increase inspired partial pressure, by

increasing %.

• e.g. 50% O2 pressure 760/2 = 380 mmHg – 300mmHg in lungs! Plenty of pressure.

• Add oxygen to increase the driving pressure


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10,000’

• Lung O2 pressure 61 mmHg – above the tissue 40mmHg

• OK if you are fit and healthy!

12,000’• Lung O2 pressure 54 mmHg – just

above the tissue 40mmHg – not much force to get O2 in to solution!

• Above this level, RAPID decline!


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Effects of hypoxia – low oxygen

• Insidious• First to go is the ability to assess oneself• Over-confidence and under-competence!• Like alcohol• CAN’T detect own symptoms!• Use oxygen always, and early• No room for under-performing pilots who

don’t realise it - or dead heroes!


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hypoxia

• Up to 10,000’ - normal individual: effects rarely significant

• 10,000-12,000’ – rapid decrease:– Complex eye-hand coordination

decreases 10-12% @ 12,000’, 30% @ 15,000’.

– Vision decreases from 8,000’– Some > unconscious @ 16,000’!

AND YOU DON”T KNOW!


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hypoxia

The most dangerous aspect of hypoxia is that the

individual experiencing it does not and can not detect the decrement in function,

and loses the ability for critical judgement


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When to use oxygen

•You MUST use it above 10,000’10,000’

• All the time• If oxygen fails, or any doubts,

DESCEND!Fly another day


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When should I consider oxygen earlier?

• Anaemia, lung disease, older, heart problems, smoking, hang-over.

• Cold (Shivering increases O2 consumption up to 20 times!)

• Illness• Medications?


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Summary

If climbing, commence If climbing, commence oxygen oxygen byby 10,000’ 10,000’

Maintain until well below 10,000’Maintain until well below 10,000’

Check flow and contents oftenCheck flow and contents often

If in doubt about flow, duration, If in doubt about flow, duration, DESCEND!DESCEND!

KNOW YOUR EQUIPMENT THOROUGHLY before you fly.

Using oxygen for gliding

EDS-D1 system


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Mountain High

Oxygen supply


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EDS-D1

Aviation

Oxygen

system


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Using oxygen

Check:• Cylinder – security, sufficient

contents, turned ON• Battery in unit and working. Cold

reserve?

• Unit connected to O2 and to nasal prongs or mask – reachably stowed


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Using oxygen

• All settings will automatically give sufficient oxygen – or more – for the flight altitude

• F 10 settings ADD a flow equivalent to that which you’d get at 10,000’

‘D’ settings:D 5 - - - O2 comes on at 5000’

D 10 - - - O2 comes on at 10,000’

D 12 - - - O2 comes on at 12,000’Flow increases automatically with height


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Press to set

Oxygen flow alarm

Non-breathing alarm


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Using oxygen

• MUST be on by 10,000’• Above 18,000’ FAI recommend full mask

rather than just nasal prongs • MUST trigger oxygen with each breath –

this usually means breathe IN through nose

• Alarms sound if 45 seconds with no flow –either not sniffing, not breathing, oxygen run out, battery run out.


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25


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Press nose clip

to fit

Pull elastic

both sides to snug fit

Place elastic

below ears

Only mask above 18.000 with EDS 1


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•If you wear a beard, a good mask seal is difficult

•You risk hypoxia at altitude!


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Using oxygen

• If alarm sounds, and oxygen not flowing,

• press to last button position – R/M mode (reserve/manual) – gives half second oxygen pulses (longer)

• airbrakes, and GET DOWN!


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Using oxygen - summary

Use “D” from 10,000’ If older, chest problems etc.

use “F” settingsCheck and KNOW your

Oxygen system

It is your LIFE above 10,000’.

Harry Oxer

oxygen oxygen – the ‘breath of life’ “how high can i make it without extra o 2 ?” harry...

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