Oxygen the Breath of Life How high can

Oxygen – the ‘Breath of Life’ “How high can I make it without extra O 2? ” copyright Harry Oxer 5/2003 harry oxer

How much oxygen in air? At ground level: • Nitrogen 78% • Oxygen 21% • Others copyright Harry Oxer 5/2003 1% (mostly Argon) 2

How much oxygen in air? At 30, 000’: • Nitrogen 78% • Oxygen 21% • Others 1% (mostly Argon) Same percentages, BUT: copyright Harry Oxer 5/2003 3

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 60 mm. Hg to force oxygen into solution in the body copyright Harry Oxer 5/2003 4

Compare carbon dioxide • 1000 L of CO 2 in an average room • But all water doesn’t turn to soda water! • CO 2 only dissolves if injected under PRESSURE • If reduce the pressure enough – i. e. take the top off – all the CO 2 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! copyright Harry Oxer 5/2003 5

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% • CO 2 and water vapour further reduce the pressure available for oxygen copyright Harry Oxer 5/2003 6

Pressure available to push oxygen into solution Pressure altitude – (ft) Atmospheric Ambient O 2 pressure mm. Hg pressure Alveolar(lung) O 2 pressure 0 5000 760 632 159 133 103 81 10, 000 12, 000 13, 000 14, 000 523 483 465 447 110 101 97 94 61 54 51 48 15, 000 20, 000 25, 000 copyright Harry Oxer 5/2003 429 350 282 90 73 59 45 34 30 7

Oxygen pressure cascade • Air 150 mm. Hg • Alveolae 100 mm. Hg ▼ ▼ • Tissues average 40 mm. Hg • If inspired pressure of O 2 < 40 mm. Hg, O 2 comes OUT of body! copyright Harry Oxer 5/2003 8

flying • Must maintain alveolar partial pressure of O 2 at least 60 mm. Hg (more than 40 to push) • How? • Increase inspired partial pressure, by increasing %. • e. g. 50% O 2 pressure 760/2 = 380 mm. Hg – 300 mm. Hg in lungs! Plenty of pressure. • Add oxygen to increase the driving pressure copyright Harry Oxer 5/2003 9

10, 000’ • Lung O 2 pressure 61 mm. Hg – above the tissue 40 mm. Hg • OK if you are fit and healthy! 12, 000’ • Lung O 2 pressure 54 mm. Hg – just above the tissue 40 mm. Hg – not much force to get O 2 in to solution! • Above this level, RAPID decline! copyright Harry Oxer 5/2003 10

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! copyright Harry Oxer 5/2003 11

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! copyright Harry Oxer 5/2003 12

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 copyright Harry Oxer 5/2003 13

When to use oxygen • • You should consider it at 10, 000’ You MUST use it from 12, 000’ All the time If oxygen fails, or any doubts, DESCEND! Fly another day copyright Harry Oxer 5/2003 14

When should I consider oxygen earlier? • Anaemia, lung disease, older, heart problems, smoking, hang-over. • Cold (Shivering increases O 2 consumption up to 20 times!) • Illness • Medications? copyright Harry Oxer 5/2003 15

Summary Above 10, 000’ consider oxygen If climbing, commence oxygen On oxygen by 12, 000’ Maintain until below 10, 000’ Check flow and contents often If in doubt about flow, duration, DESCEND! KNOW YOUR EQUIPMENT THOROUGHLY before you fly. copyright Harry Oxer 5/2003 16

Using oxygen for gliding EDS-D 1 system copyright Harry Oxer 5/2003

EDS-D 1 Aviation Oxygen system copyright Harry Oxer 5/2003 18

Using oxygen Check: • Cylinder – security, sufficient contents, turned ON • Battery in unit and working. Cold reserve? • Unit connected to O 2 and to nasal prongs or mask – reachably stowed copyright Harry Oxer 5/2003 19

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 - - - O 2 comes on at 5000’ D 10 - - - O 2 comes on at 10, 000’ D 12 - - - O 2 comes on at 12, 000’ Flow increases automatically with height copyright Harry Oxer 5/2003 20

Press to set Oxygen flow alarm copyright Harry Oxer 5/2003 Nonbreathing alarm 21

Using oxygen • MUST be on by 12, 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. copyright Harry Oxer 5/2003 22

Press nose clip to fit Pull elastic both sides to snug fit Place elastic below ears copyright Harry Oxer 5/2003 Only mask above 18. 000 with EDS 1 25

• If you wear a beard, a good mask seal is difficult • You risk hypoxia at altitude! copyright Harry Oxer 5/2003 26

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! copyright Harry Oxer 5/2003 27

Using oxygen - summary Use “D” from 10, 000’ If older, chest problems etc. use “F” settings Check and KNOW your Oxygen system It is your LIFE above 12, 000’. Harry Oxer copyright Harry Oxer 5/2003 28