Oxygen

[pkofman]

This is not specifically a mooney question but i do have o2 in my plane. I was curious if anyone has ever used o2 in the plane at low altitude when fatigue sets in.

Im curious as this came up on another board. Obviously if you are  tired you should land but i found this interesting.  Is there any benefits. So what are your thoughts on this . I use a cannula. Is there any particular danger in using o2 at low altitudes. 

Thoughts.. Peter

[gsxrpilot]

If you've got it, no reason not to use it. It's only the cost involved to refill. But no detrimental effect using O2 at any altitude.

@cnoe knows a lot about using O2 at all sorts of very low altitudes.

[StevenL757]

Peter, I would say, generally-speaking, that using oxygen at any altitude would be beneficial, however, once fatigue sets in, oxygen may not help you as much as you'd like.  Cannulas also provide a limited amount of O2, especially at higher altitudes, so you should consider investing in a properly-fitting mask.

You should probably review your flight prep checklist (IMSAFE) before you undertake any flight.  If you've done that and still find yourself fatigued after a certain period of time, you should land, rest, and continue only when rested as you said.  Oxygen is not a bandaid to combat the "F" in that acronym, but to allow you mainly to counteract the effects of hypoxia.  Flying fatigued is preventable.  Review IMSAFE, and if you feel fatigued, use oxygen if you want, but your first priority should be to land and rest.

[yvesg]

When I borrow my friend's oxygen tank on a long multi-day trip (in case I need to fly high altitude), I would systematically use it 8K and above. I found out that it PREVENTS becoming tired when I fly long that high. (3 - 4 hour legs) I do not know if using it after will get rid of the tireness but I doubt it.

Yves

[peevee]

Good point. If you're like me you don't want to worry about bathroom breaks and you dehydrate yourself. Exacerbated by the altitude.

[donkaye, MCFI]

At night vision goes first, so I use O2 from the ground up at night.  During the day, anytime time over 7,500 or over 5,000 for more than an hour.  If you consider a situation stressful, at any altitude.  I check the pulse oximeter every 10-15 minutes and turn the O2 up whenever it gets below 96.

The BENDS can be an issue when flying even in the teens.  Mitigation;1. Pre-breath O2,  2. Take an aspirin before flight, 3. Drink plenty of water (hydration). 4. Slow Ascent.  Additionally you can acclimate overnight at an elevated altitude.  I have found time aloft makes the most difference, so limit high altitude flight when flying with a person susceptible to the BENDS to no longer than 2.5 hours.

[peevee]

20 minutes ago, Hyett6420 said:

These are the RESTOP bags i use.  RESTOP 1.  Work REALLY well.  And no i don't care if someone else is in the plane, they can look out of the window if they are shy or don't want to be embarrassed about how small theirs is. . 

http://restop.com/?v=79cba1185463 

I carry a similar product and they work very well

[slowflyin]

1 hour ago, peevee said:

I carry a similar product and they work very well

I've been using the Travel John brand for years.   They work great.  No spills and no odor.   https://www.amazon.com/TravelJohn-Disposable-Urinal-18-pack/dp/B000NVBYD8/ref=pd_lpo_vtph_468_tr_t_3?_encoding=UTF8&psc=1&refRID=X0DCAJ71Q2GP0NXKTRA1

[jaylw314]

There is only one possible problem with using oxygen at low altitude.  If you are chronically hypoxic (usually from pulmonary disease, so presumably for months or years, not hours), sudden administration of oxygen can actually cause you to stop breathing.

I think it's a good bet you're not chronically hypoxic if you're flying so I think you'd be ok.  Look at all the athletes and crazies who believe in hyperbaric or superoxygenated therapy.  Okay, maybe not a good example...

[KLRDMD]

1 hour ago, jaylw314 said:

There is only one possible problem with using oxygen at low altitude.  If you are chronically hypoxic (usually from pulmonary disease, so presumably for months or years, not hours), sudden administration of oxygen can actually cause you to stop breathing.

Theoretically true, but the increased FiO2 (fraction of inspired oxygen) of 1-1.5 LPM (liters per minute) of supplemental oxygen through a nasal cannula versus "room air" is insufficient to cause apnea due to a preexisting hypoxic drive. Now, if you're talking full face mask, non-rebreather with 10 LPM of oxygen, then the FiO2 is high enough to do that.

[cnoe]

I use a cannula. Is there any particular danger in using o2 at low altitudes. 

Don's post is spot-on.

Using a cannula below 10K' has almost zero risk and a good deal of upside.

I might add that even at modest altitudes (well below 10K') relaxed shallow breathing can cause a significant drop in one's O2 saturation level. Rather than having to consciously think about taking a deep breath now and then, donning a cannula will keep my levels in the mid-90s even with a minimal flow-rate (.5-1.5 lpm).

I also believe it's a good idea to "pump" one's calf muscles occasionally on long flights to thwart the possibility of DVT (https://en.m.wikipedia.org/wiki/Deep_vein_thrombosis).

[tigers2007]

I have only made one r/t 10k+ flight with no O2 and I did feel beat. I have a setup now with the cheap Oxymizer cannual that'll be using. Refilling the tank (which is currently full) will be the tough part; I have plenty of physician friends that can write me a script.
On the topic of portajohns, I really REALLY had to go the other day and considering the rough turbulence, it would have been a terrible mess. Once you start you cant stop!


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[cnoe]

Refilling the tank (which is currently full) will be the tough part; I have plenty of physician friends that can write me a script.

 

 

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Aviator's breathing oxygen doesn't require a prescription but medical suppliers will often balk at filling cylinders for pilots. Ideally the cylinder should be marked as ABO and not USP oxygen.

 

This .pdf has some useful info.

 

http://www.mhoxygen.com/index.php/component/attachments/download/629

 

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[jaylw314]

5 hours ago, KLRDMD said:

Theoretically true, but the increased FiO2 (fraction of inspired oxygen) of 1-1.5 LPM (liters per minute) of supplemental oxygen through a nasal cannula versus "room air" is insufficient to cause apnea due to a preexisting hypoxic drive. Now, if you're talking full face mask, non-rebreather with 10 LPM of oxygen, then the FiO2 is high enough to do that.

Didn't want to get that technical, but yes, it would be practically impossible 

[jlunseth]

I am certified as a technical diver (decompression diving).   It never occurred to me that someone might incur the Bends (we call it decompression sickness or DCS) in a climb to the teens.  That is a change of just half an atmosphere (to 18K from sea level).  I suppose it would depend on how rapidly you climb, DCS is caused partly by how rapid the pressure change is.  However, there is a DCS-type issue that might help explain the fatigue.  DCS is caused by the formation of nitrogen bubbles in the blood stream and tissues.  When it gets to the point where you feel pain in joints or numbness you have DCS and you are in trouble.  But before that point micro-bubbles form, and while they do no damage they create fatigue.  For divers, it is particularly a problem during cold water or arduous dives, when the diver is working hard or stressed.  We do essentially what you are suggesting, we increase the percentage of O2, which replaces the N in the mix and thus reduces N bubble formation.  My son and I dive together, and several years ago we switched to nitrox for all our diving, it is a higher O2 percent mix than air.  Its 32% (Nitrox 1) or 36% (Nitrox 2), and it makes quite a bit of difference in how tired we don't feel after a dive.  I have done a couple of cold water dives on standard air where I could hardly keep my eyes open afterwards in the middle of the afternoon.  Nitrox fixes it.  First aid for DCS is to put the diver on pure O2 as soon as possible.  

At any rate, I don't feel any effect in my aircraft, but if someone does, it is certainly worth going on O2.  The pressure changes are not what we experience in diving (every 33 feet is 1 ATM), but there is the potential in any environment where pressure changes rapidly. If you have the built in system it will last about forever at 8k.

[jaylw314]

7 hours ago, cnoe said:

 

Aviator's breathing oxygen doesn't require a prescription but medical suppliers will often balk at filling cylinders for pilots. Ideally the cylinder should be marked as ABO and not USP oxygen.

 

This .pdf has some useful info.

 

http://www.mhoxygen.com/index.php/component/attachments/download/629

 

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I got my portable oxygen cylinder from here

https://www.cramerdeckermedical.com/category.php?category_id=2

You can order them with a low-profile CGA-540 valve for $11 that takes up much less space than the typical CGA-540.  It looks a lot like the valves Aerox uses on their regulators.

Industrial gas and welding supplies will refill tanks with CGA-540 valves.  It cost me $12 to refill a D size tank

Edited April 30, 2017 by jaylw314

[Tom]

The "oxygen can cause you to stop breathing" idea is, practically speaking, a myth and has nothing to do with aviation.

Shallow breathing coupled with supplemental oxygen is not a good idea as, all else equal, this is a recipe to increase CO2 in the blood.  Some C02 is normal.  Increased C02 causes fatigue, headache, concentration impairment, sleepiness...  

It never hurts to practice good sitting upright posture while flying to try to establish more normal chest excursion while breathing--especially if you're well-endowed in the midsection. 

As Don said, it's recommended to use oxygen at night if you can, especially over 5-6k, if only for improved vision functions.

I bought a used Inogen G2 concentrator with 3 extra batteries off Craigslist for $800.  I've only had it to 15k but it kept my sats over 92%.  I use it routinely, even when I don't need to at lower altitudes if I'll be up longer than a couple hours.  Basically zero hassle to use (no refills, etc).

Edit: to more precisely answer the OP question, no medical problems using supplemental 02 at lower altitude while flying. 

Edited April 30, 2017 by Tom

[larryb]

Regarding the thickness of the tank, a little math can answer that. The pressure inside the tank is 2000 psi. The pressure outside at sea level is 14.7psi. The pressure at 18,000 feet is 7 psi. The pressure differential between the inside of the tank and the outside of the tank is what matters. That 7 psi difference between sea level and 18,000 feet is insignificant. The tank would be fine even in outer space.

The regulator is what you set for the number of people and altitude. It fits a certain tank valve, typically CGA540. So as long as a tank has the CGA540 valve you can use it with any standard aviation regulator.

I use the Mountain High pulse system with the head-set mounted canula arm. Previously I used an Aerox system with standard canula that fits over the ears. The MH system is so much better in terms of comfort and efficiency. I typically fly at 10,500 to 14,500. With the Aerox system I would try to fly below 10,000 so I didn't have to use it, as it started to get uncomfortable after an hour or so. The MH canula is much more comfortable. With it I now plan almost every flight above 10,000 feet because using oxygen is no longer a pain.

Larry

 

http://www.mhoxygen.com/index.php/portable-pulse-demand

http://www.mhoxygen.com/index.php/face-masks/cannulas/82-ez-breathe-ii

[cnoe]

6 hours ago, Hyett6420 said:

Are these cylinders as thick as the aerox ones? What I mean by that is, the aerox ones KNOW they are going to go up to FL180 and therefore are designed not to explode because the air pressure is less.  Are these ones as well?  I obviously know that the pressure inside must be HUGE so they must be pretty strong.

Cylinders are essentially unaffected by the increased altitude. The pressure reduction from sea-level to outer-space is less than 15 psi. Over-filling a tank to 2,030 psi rather than 2,015 psi imparts more stress on it than flying to FL600.

11 minutes ago, Tom said:

Shallow breathing coupled with supplemental oxygen is not a good idea as, all else equal, this is a recipe to increase CO2 in the blood.

I agree that shallow breathing can elevate CO2 levels, even with supplemental oxygen. But inspiring more oxygen should have no detrimental effect on CO2 levels all other factors being equal. If there is evidence to dispute this I'm very interested to see it.

I'd rather be using a cannula at 10K' with an O2 sat of 97% than breathing only air with an O2 sat of 87%.

I also agree that improving one's breathing habits is a noble goal and proper posture is certainly a part of that. It also doesn't hurt to take a slow deep breath from time to time (which has a noticeable effect on one's pulse oximeter reading).

9 hours ago, jaylw314 said:

Industrial gas and welding supplies will refill tanks with CGA-540 valves.  It cost me $12 to refill a D size tank

That is indeed the case; getting a CGA540 tank filled is no problem. I'm not familiar with Aerox systems or other aviation oxygen systems. If the delivery systems can mate with a CGA540 then this is simple.

[cnoe]

larryb and I must have been typing at the same time. But he gave some great additional information! It's good to know that the aviation delivery systems are compatible with CGA540 valves.

[Tom]

35 minutes ago, cnoe said:

I agree that shallow breathing can elevate CO2 levels, even with supplemental oxygen. But inspiring more oxygen should have no detrimental effect on CO2 levels all other factors being equal. If there is evidence to dispute this I'm very interested to see it.

I should not have intimated that the increase 02 would somehow increase C02, all else equal. 

I should have said "shallow breathing can increase C02" which can itself cause deleterious effects to similar low oxygen.  

The concern to highlight is that someone who is shallow breathing on supplemental oxygen with good oxygen saturations may think that they're doing good, but in reality they're resolving one problem (low oxygen) while possibly (if shallow breathing for hours at a time) creating another...(elevated C02 with associated issues).

I don't mean to over-blow (mild pun intended) the C02 concern.  Just don't be a slouch in the cockpit.  Deep breath every now in then.  Work on the posture.

36 minutes ago, cnoe said:

I'd rather be using a cannula at 10K' with an O2 sat of 97% than breathing only air with an O2 sat of 87%.

Agreed.

On a related point, not good to hyperventilate to keep saturation up as this causes other wonky things to happen.  Bottom line, if you find your sats dropping and you're breathing normally...as you would be sitting breathing in an office chair...time for supplemental 02.

[ilovecornfields]

Agreed.

On a related point, not good to hyperventilate to keep saturation up as this causes other wonky things to happen.  Bottom line, if you find your sats dropping and you're breathing normally...as you would be sitting breathing in an office chair...time for supplemental 02.

 

Actually, increasing oxygen concentration (FiO2) does increase CO2 levels, especially in people with lung disease. The mechanism is somewhat complicated but it has to do with hypoxic pulmonary vasoconstriction and the fact that blood vessels in the lungs normally constrict and direct blood away from areas of the lung with low partial pressures of oxygen. If you increase the FiO2 (fraction of inspired oxygen concentration) then it counteracts this effect and in areas where the lung is poorly ventilated, blood flow will increase to those areas, creating a right to left shunt and allowing blood that has not had the opportunity to exchange CO2 into the systemic circulation. This causes an increase in CO2 levels, proportional to the degree of lung disease and the FiO2. In young healthy lungs, this effect is small but as you deviate away from that the effect is significant. The curves below illustrate this effect starting with healthy lungs at the bottom and severe COPD at the top.

 

How does this apply to you? Don't use more oxygen than you need in order to maintain normal oxygen saturation.

 

 

 

 

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[ilovecornfields]

Sorry, picture didn't go through on the previous post.




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[jaylw314]

1 hour ago, Tom said:

I bought a used Inogen G2 concentrator with 3 extra batteries off Craigslist for $800.  I've only had it to 15k but it kept my sats over 92%.  I use it routinely, even when I don't need to at lower altitudes if I'll be up longer than a couple hours.  Basically zero hassle to use (no refills, etc).

Holy smokes, now there's a good PIREP.  I wasn't sure if portable concentrators could work at altitude, that's good to know.

8 hours ago, Hyett6420 said:

2.  Th reducing valve on the aerox ones has that clever thing that says "how many people" and "what altitude are you at" Me not being a doctor type I would not know from a normal medical valve what flow rate I would need at what altitude   Is there data for that or could one use the aerox valve on these cylinders?  

The aerox valve is a fixed pressure regulator (I'm guessing 25 PSI but they don't say).  The actual flow is adjusted by a needle valve in the line with a flow meter.

Most medical regulators are also pressure regulators, but each setting is calibrated to a flow rate, presumably at sea level.  I use this medical regulator without a needle valve

[cnoe]

 
Actually, increasing oxygen concentration (FiO2) does increase CO2 levels, especially in people with lung disease. The mechanism is somewhat complicated but it has to do with hypoxic pulmonary vasoconstriction and the fact that blood vessels in the lungs normally constrict and direct blood away from areas of the lung with low partial pressures of oxygen. If you increase the FiO2 (fraction of inspired oxygen concentration) then it counteracts this effect and in areas where the lung is poorly ventilated, blood flow will increase to those areas, creating a right to left shunt and allowing blood that has not had the opportunity to exchange CO2 into the systemic circulation. This causes an increase in CO2 levels, proportional to the degree of lung disease and the FiO2. In young healthy lungs, this effect is small but as you deviate away from that the effect is significant. The curves below illustrate this effect starting with healthy lungs at the bottom and severe COPD at the top.
 
How does this apply to you? Don't use more oxygen than you need in order to maintain normal oxygen saturation.
 

 
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That's interesting and technical information but I'll assume you're not making an argument that in-flight use of a nasal cannula by normally healthy pilots is detrimental.

Certainly extended exposure to high-level oxygen concentrations can be harmful but these aren't the levels of exposure typically experienced by GA pilots.

I just don't want people getting the idea that using O2 in their planes is a bad thing.


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