{"id":13700,"date":"2016-12-08T15:57:06","date_gmt":"2016-12-08T14:57:06","guid":{"rendered":"https:\/\/www.dg-flugzeugbau.de\/en\/?page_id=13700"},"modified":"2017-01-05T11:22:53","modified_gmt":"2017-01-05T10:22:53","slug":"the-correct-usage","status":"publish","type":"page","link":"https:\/\/www.dg-aviation.de\/en\/library\/the-correct-usage","title":{"rendered":"The Correct Usage of Oxygen"},"content":{"rendered":"

This article came as an e-mail from Steele Lipe and is published with his friendly agreement.
\nThe first photo comes from the “Segelfluggruppe Winterthur”.
\nThe second photo is made by Ruud Rozendaal in the southern French Alps.<\/p>\n

Question:
\n“I’ve been using an A14A system for a long time, and am tempted to change to the EDS set-up.\u00a0\u00a0 I have contacted Mountain High, and spoken to suppliers; what I would like is feedback from actual users of the system.\u00a0 What is it’s ceiling (I think MH says 30,000 feet), and how do you find consumption compared to a good demand system.\u00a0 The ceiling seems a long way below an A14A, and I wonder is the claimed consumption saving only relative to a constant flow system.\u0094<\/em><\/p>\n

Answer:
\nFirst of all I am an Physician Anesthesiologist and have studied oxygen, its absorption, uptake, distribution, and utilization in our bodies extensively.\u00a0 In addition, I have flown gliders (DG-100 and now a DG-600M) innumerable times over 18,000 feet with my highest level 37,400 feet.\u00a0 My ship is equipped with 4 different regulators and delivery systems (A14 {USAF military surplus}, EDS, low flow for Conserve cannulas, and high flow for a Sierra mask) and two different sources with automatic crossover in case of freeze up, exhaustion, or loss of pressure.\u00a0 I have personally studied oxygenation of the human body while in flight using newer methods of investigation than those used by the U. S. Air Force during W.W.II upon which FAA decisions and regulations are based.\u00a0 I have also spoken at the San Diego and the Reno SSA Conventions on the use of oxygen at altitude by pilots with particular interest to glider pilots.
\nEssentially, the FAA in its FARs require:<\/p>\n

Oxygen must be used by a pilot (not speaking of passengers) any time above 14,000 feet and above 12,500 feet in excess of 30 minutes.<\/p>\n

The use of cannulas has been approved by the FAA for use up to but not including 18,000 feet, but to be legal (FAR 25) the pilot must also carry a full face fitting mask when a cannula is used.\u00a0 The mandated flow to the cannula must be 1.0 liter\/minute\/10,000 feet or more.\u00a0 A waiver (in so many words) of these restrictions was given by the FAA to Ted Nelson and the oxygen system he popularized using lower flows and the oxygen conservation cannula.\u00a0 The Conserve cannula was initially developed for the breathing impaired but has been used also in aviation.\u00a0 The trick with these cannulas is the pouch on each side that allows the cannula to accumulate the constantly flowing oxygen until it is needed during inhalation.\u00a0 Therefore, the gas flow during exhalation (breathing out) and the normal pause before the next inhalation is not wasted.\u00a0 Using the conserve cannula, the flow may be reduced to between 300 and 400 cc\u0092s per minute (about 1\/3 of the FAA requirement for non conservation cannulas).\u00a0 I ran the experiments and was the guinea pig for Ted Nelson when he tested the low flow version of his flow meter system.
\nI have measured oxygen saturation (% of oxygen carried by the red blood cells compared to the amount of oxygen the blood is capable of carrying) on myself during numerous flights at altitudes in the approved FAA altitude envelope and above.\u00a0 According to Mountain High, whose information is to my knowledge anecdotal, their initial aim was to provide oxygenation for hang glider pilots using an apparatus with minimal weight.\u00a0 Instead of using a pouch reservoir to accumulate oxygen, Mountain High\u0092s EDS regulator, calculates the amount of oxygen that should be delivered and delivers it in a high flow at the beginning of the following breath.\u00a0 Thus, theoretically, the same amount of oxygen is delivered from the EDS as from the conservation cannula.\u00a0 There may possibly be a slight loss of gas from the conserve cannula that is probably not lost when using the EDS system especially at altitudes above 18,000 ft..\u00a0 Therefore, the EDS system may be slightly more efficient.\u00a0 I have used both systems extensively and have realized no great savings of oxygen when using the EDS unit.
\n\"OxygenThere are two disadvantages with the EDS system.\u00a0 First, it is more expensive
\nand secondly it requires a battery.\u00a0 I believe others have discovered, as have I, that the battery may fail at the wrong time.\u00a0 I have had to cancel or abort flights because of battery failure and thus the failure of the EDS system.\u00a0 Its advantage is it is automatic and within the confines of the FAA regulations user friendly.\u00a0 The Nelson regulator (now sold by AirOx) requires operator attention to keep the flow at least at the recommended level.\u00a0 When climbing in wave conditions or flying above 10,000 feet (I suggest using oxygen at 10,000 feet) I have usually set the flow regulator to a level above my present level so that I do not need to adjust it too often.\u00a0 The waste of oxygen is no more than 5 to 10%.
\nAbove 18,000 feet the FAA requires a full fitting face mask such as the Sierra mask with a reservoir bag and a flow of 1.0 liter\/min\/10,000 feet.\u00a0 In theory, and in my observations, this system is sufficient for our needs up to about 39,000 feet at which time better control of the oxygen concentration requires an A14 type system or similar.\u00a0 The A14 system adjusts the inspired concentration of oxygen by barometric means and at about 43,000 feet 100% oxygen is delivered.\u00a0 It is not automatic.\u00a0 At higher altitudes adequate oxygenation may only be provided with pressure breathing or an external pressurization system such as a pressurized cockpit or pressure suit.\u00a0 Pressure breathing is very fatiguing and unless practiced it should not be attempted.
\nFor those outside of the USA (FAA) my personal use of both the EDS and conserve cannula systems has provided me with adequate oxygenation at altitudes of 24,000 to 25,000 feet.\u00a0 (I have not been higher than 25,000 feet with either because of FAA wave window control, so I can not attest to the altitude where each system has reached its maximum effectiveness.)\u00a0 The pouches on the conserve cannula, in actuality, will hold the amount of gas that is needed at about 18,000 feet without wastage.\u00a0 Above that altitude, in theory, the resultant higher flow will be lost to overflow.\u00a0 At levels above 18,000 the EDS may be beneficial.\u00a0 I should not hazard a guess as to the maximum effective altitude of the EDS unit but I would surmise that it might be usable up to the very low 30,000s.\u00a0 To my knowledge, this has not been measured at this time.
\n\"PhotoTherefore in the USA, to be legal, either system will provide the pilot adequate oxygenation up to positive control.\u00a0 The choice really depends upon the pilot’s pocket and the trust in batteries vs. the necessity of paying attention to the flow regulator.
\nAs far as efficiency is concerned, the EDS and the conserve cannula are the most efficient but are altitude limited (18,000 feet in the USA by FAA Regulation).\u00a0 Next, at a flow rate about 3 times higher is the standard mask and reservoir systems (Sierra and others) which are good to about 39,000 for a well functioning unit without leaks.\u00a0 The A14 to my knowledge is the most wasteful but probably not much more than the high flow mask and bag, but it is not altitude limited unless you fly above 43,000 feet at which time pressure breathing needs to take place.
\nThere is only one recommendation I would like to make.\u00a0 Whenever, you as a pilot use an oxygen system please keep it on and active until you have landed and stopped your aircraft.\u00a0 There seems to be (not substantiated) evidence that there may be a time of significantly lowered blood oxygen in a pilot following removal of the system.\u00a0 In any case, the approach and landing is the most stressful time in any glider flight and the pilot should be as oxygenated as possible.\u00a0 Because of this observed \u0093hypoxia\u0094 I recommend VERY STRONGLY that a pilot not remove the oxygen mask of cannula until after landing.
\nThe above express my philosophy and my investigations and in the case of oxygen my ongoing interest.\u00a0 Thank you for hearing me out.\u00a0 I welcome comments and arguments.<\/p>\n

Just remember to be safe and to fly as safely as you can.
\nOxygen is sure a lot cheaper than your glider or your Life!<\/p>\n

– Steele Lipe – 11\/1998 \u0096 Revised 6\/2002 –<\/p>\n

The copyrighted talk given before the Soaring Society of America in San Diego, California and again in Reno, Nevada
\nis available in PDF format by contacting the author, Steele Lipe.<\/p>\n

\n

A Note from the Editor:<\/h2>\n

We had an interesting question lately:<\/p>\n

Why does a human not simply breath at a higher frequency if he or she suffers from a lack of oxygen?<\/em><\/p>\n

The answer lies in the way of the oxygen measurement within the human body. The body does not measure the O2<\/sub> concentration. Instead it measures the CO2<\/sub> concentration within the blood and automatically regulates the breathing frequency. It works flawless on the ground. A high CO2<\/sub> level relates to a high use of O2<\/sub> and therefore results in accelerated breathing. When flying we remain quiet within our airplane. The CO2<\/sub> concentration in our blood does not rise. Only the O2<\/sub> concentration drops down significantly. Unfortunately a manually controlled increase in the breathing frequency does not help us either. We have only half the amount of O2<\/sub> in the air at 16,000 ft and the transformation of oxygen into the blood is done under pressure. That pressure – you all know that – is not as high as at MSL. Therefore it is not possible to enrich the O2<\/sub> concentration within the blood to a normal level even if on breathes twice as fast. One will suffer from a lack of oxygen. This is visible from high’s of 9.000 ft and upwards.
\n<\/a><\/p>\n