Blood Oxygen levels during flight

Again, I'm testing for hopefully many long distance trips in the RV. Along with the endurance of the plane, I'm trying to figure out the effect on my wife and I spending 6 or 8 hours a day at altitudes that shouldn't require oxygen, but are high enough for the blood oxygen levels to have dropped. This is all pretty new to me and hopefully there are some folks here that have some knowledge to share on this.

Finding sources to read about this is proving to be somewhat limited. One of the providers for oxy systems states that if the blood oxygen level drops to 95% you should consider oxygen to prevent headaches and fatigue. If levels drop to 90% they recommend going on the bottle to come back to at least 95% or better. 85% and headaches and nausea are most likely going to occur and decisions are starting to be slower and likely not your best ones.

Armed with a new blood oxygen and heart rate monitor off I went today for a flight. On the way to the airport I slipped it over my finger and got a sea level reading. (140 feet above sea level) The oxygen saturation was at 99% and my heart rate while driving was 72. Okay the thing works and was reading what it should on the ground. Level at 5500' with density altitude of 6800' per my Garmin my blood oxygen saturation was at 96% and my pulse was again at 72. Basically this is the highest I can fly per the manufacturers of the oxygen systems without suffering ill effects. Later on the return trip I climbed up to 8500' and waited about 1/2 hour and tested again. This time the density altitude was 9704' and my blood oxygen level was at 91% and the pulse at 90. As the flight progressed the level dropped as low as 86% and when it would I tried taking several large breathes and it didn't seem to help. What did seem to help was relaxing and breathing thru my nose. This natural breathing would bring it back to 90-91%. Every time I breathed thru my mouth the levels would drop again????

Are there any charts or tables out there that anybody knows about that could be added to a POH? Do any of you have experience with these contraptions that you slip over your finger and second guess yourself? Is it crazy to go on oxygen and try to maintain 95% or better at levels? This would mean having a cannula stuck in your nose for essentially low level flights.

Thanks,

RE O2 Sat Long

Look Here

Unfortunately Av Web now requires you to "sign in" but it is well worth the read.

Oxygen

Bryan,
I've had the same results. In flying a Long EZ home to Davis from Long Island I flew between 9,500 and 12,500 and used a demand type system and the low cost finger indicator. Saw pretty much what you did today.

A doctor from Sac gives a good talk on oxygen at Golden West and convinced me of the need even at lower altitudes. They found healthy young Air Force pilots had the same crummy responses after an hour at 8,500' as they did after 20 minutes over 12,000' without oxygen. And visibility really goes down at night even at lower altitudes. A few minutes on the bottle and things get a lot brighter and clearer.

This is a good site for Oxygen info on sytems and high altitude research:
http://www.dg-flugzeugbau.de/sauerstoff-e.html

I like my Mountain High?s EDS setup. I check the voltage on the battery before any long high flights and carry a backup. It is light, works very well and saves oxygen. Hardly used 1/2 bottle all across the country.

Save flying,
Dave

Recomended ox levels

I've spent a bunch of time in hospitals and they almost always use 90% as the threshold for putting a patient on oxygen. For airplane and altitude issues, you'll never get too much oxygen. I wouldn't worry if your above 90%. between 85 and 90 is ok as long as it's not for extended periods or durring high workloads (like night imc). The other affect of using oxygen is to be much more awake and rested when you land.

10,000'

The cabin altitude in most commercial airliners is around 8,000'. Sometimes you can suffer that for 16hrs on an Ulltra Long haul.

If there is a cabin depressurisation in a commercail airliner, oxygen is required for the CREW whilst the CABIN Altitude is above 10,000' and for the passengers whilst the cabin Altitude is above 14,000'.
That should be a pretty good guide.

Perhaps a more significant cause for concern is to ensure what you are breathing does contain ANY CO (Carbon Monoxide) That will put you out quicker than too high an altitude.

I would install a CO monitor before Oxy for flights around 10,000'

Pete.

I haven't yet purchased a pulse oximeter for aviation use but I use pulse oximetry every day at sea level as an anesthesiologist. I am unaware of any published limits for oxygen saturation applicable to aviators. The limits you mention may be anecdotal based on someone's experience. You may have to find your own limits, but be aware that you will be a very poor judge of your abilities at altitude.

Pulse oximetry displays the percentage of hemoglobin that is saturated with oxygen. Hemoglobin is the molecule in the blood (in the red cells, actually) the carries oxygen to the tissues. The whole point is to deliver oxygen to the tissues. Pulse oximetry measures only one factor in that process, and it measures it indirectly, ie: it can be fooled. Here are just two ways it can give false but reassuring data. Anemia (low blood count) will render normal pulse oximetry readings but the total oxygen carrying capacity of the blood is decreased and so less oxygen gets to the tissue. Abnormal hemoglobin can't carry as much oxygen. The most common cause of abnormal hemoglobin is probably smoking, which poisons a percentage of the hemoglobin with carbon monoxide and makes it useless for transporting oxygen. The list goes on.

Here is a pearl, a take home message: The quantity of oxygen carried in the blood is NOT directly related to saturation. In other words, the difference between 99% sat and 95% sat is trivial. The difference between 95% and 90% is much greater physiologically, and the difference between 90% and 85% is huge. I would personally add supplemental oxygen well before I saw 90% sat. Fortunately, a very small amount of added oxygen can raise the sats back into the normal range. I would be interested to hear of other's aviation experiences with pulse oximetry.

Bryan: The important altitude for physiology is pressure altitude, not density altitude. The air temp does not matter. I don't know why breathing through your nose raised your sats. I can conjecture that you developed atelectasis (small areas in your lungs that collapsed...pretty common) from lack of activity and shallow breathing (cool aviator that you are). Deep breathing and coughing would tend to re-expand those lung areas and raise your sats back up. Look for this phenomenon next time and report back. Also, the knick-knack on your finger cost, what, $400? The ones I use costs thousands. Maybe they works better.

Euphoria

I am pretty sure when you finger tips are turning blue and you feel super happy its bad. (if you are a smoker you are screwed)

Oxygen

Bryan,
This is just my personal experience over the past six months and about 175 hours in my recently completed RV-4. Most of my flying is in the range of 300-400 mile legs and I really prefer 10,500' -11,500' altitudes. I like these altitudes because 1.) It's so easy to get there now , 2.) almost no Cessna or other traffic to speak of, so I don't feel the need for flight following. 3.) fuel burn is about 8.5gph or so.

BUT...I found that without oxygen, I was arriving tired, and sometimes with a headache. My finger monitor said I was at about 85-90% at best and this caused me to consider either flying lower or getting my own portable oxygen bottle. I opted for the oxygen and use it nearly every flight now. I even bought my own refilling tank and do it myself as needed. Cost was fairly high up front (AEROX about $650 plus my refilling tank and transfilling lines another $350), but now I fill up for less than $5 in the hanger...no need to find an FBO with oxygen or pay the minimum $35 charge they need to even carry/offer it. Another benefit of on-board oxygen...if necessary for cloud tops or mountain ranges, you can easily go even higher.

I like the Aerox equipment and you can call them direct and order at a significant discount.

Ron P.
N8ZD

Bryan:

I like having O2 in my airplane on all flights that are more than one leg. I refuse to carry O2 when I have smoke oil in my smoke oil tank as both would then be in the baggage compartment at the same time.

I like to use O2 anytime I am at or above 9,500. To save O2, I have been know to not use the O2 till 30 minutes before landing.

I find I am MUCH more alert when I use O2. If I have ample O2 for a round trip flight, I use O2 at and above 9500 or anytime my O2 drops below 90%. Yes my pulse also gets very high as altitude goes up and has been above 90. I have a large O2 tank in my hangar and do refill my own.

After 6 hours of flying in one day at altitudes of 9500 or higher, I am tired and many times have a headache. With the use of O2 and keeping my saturation level at or above 90%, I am not tired nor do I have a headache.

I think my experiences are similar to yours. Unfortunately, I know of no charts. Please share if you find some.

A few minor points

I think Steve is our expert here but I would like to add a couple of points. Seeing you are from the San Jose area I'm guessing your base field is well under 1,000 ft MSL. All other things being equal, you will probably experience a greater impact at 9,000 ft cruise altitude on your alertness that I would since I live at 6,000 ft MSL. My blood probably has more hemoglobin than yours. I was skiing at Copper Mountain today and didn't have any problems on their 12,000 to 9,800 ft MSL ski runs.

Second, your age will have a big influence on the level of degradation in alertness at these altitudes. If you are 20 years old you will probably fair much better than I would, being in my mid-50's.

All that said, I have a semi-perminant 22 cu ft O2 system ready to install in the rear baggage compartment of my RV-8A. I will be using a 4 ft high pressure hose from the bottle to bring the Mountain High regulator up where I can see it. Mountain High is, in my opinion, the best (and most expensive) system out there. I plan on going to O2 when I am over 10,000 MSL or 4,000 AGL with a mask, not a canula, for anything longer than a couple of minutes.

Al Thomas
N880AT
RV-8A
Finishing kit

Al,
Do you have any pictures of your installation? If so, could you please email them to me at n97ap -at- comsouth.net?

Thanks,

If you are concerned split the seam on one finger of a glove and check your finger nail. If its getting very blue come down or take a puff of O2. If at night and you start to feel a need to turn up the panal lights do somthing....RB

O2 Install in RV-8A

Tony,
I have my flooring and baggage area skins all out right now for starting to run a battery cable, antenna coax and such. I'll send you a pic once things are back in place in a week or so.

Here's what I'm using:

Jumbo D 22 cu ft aluminum cylinder with CGA 540 valve ($76) and 48" flexible pigtail ($28) from Cramer Decker Medical (877-222-0200).
CMK Omega Cylinder 5.25" brackets ($75) from Craggy Aero (530-905-0062)
Mountain High FPR 4 place regulator for CGA-540 valve with gauge ($315) from Cumulus Soaring (952-445-9033)

I am also using an older Nelson A-3 (?) flow meter and Scott face mask that I've had since the 1970's. The Scott mask doesn't have a mic in it but I can flip it off easily when I need to talk on the radio or get some water. I did have to get two male CPC connectors to connect the flow meter/mask assembly to the MH regulator. I don't use a cannula because I've had problems with nose bleeds from the dry O2 during long periods at altitude. Finally, I purchased a double male CGA-540 coupler for the pigtail to regulator connection.
The cylinder brackets are mounted to a 1/16" thick 8"x14" aluminum doubler which is then mounted to the rear baggage area floor right behind the rear seat with six platenuts. I have the cylinder mounted side-to-side for safety reasons.

I'm still working on the best routing path for the pigtail up to the front and some sort of bracket on which to mount the regulator. Worse case I'll just put a clamp around the regulator.

Hope that info helps.

Albert Thomas
N880AT
RV-8A
Finishing kit

Thanks, Al. Just one more thing for me to research at SNF this year.

Other considerations in O2 installations

A couple of other things I didn't mention earlier on my semi-perminent O2 installation.

The six platenuts used in the my rear baggage floor cylinder mount are actually two each in the F-818L, F-818R and F-807 bulkheads, not on the baggage floor itself. I am comfortable I have a strong mount.

I have two potential routes in mind for the pigtail to bring the regulator up where I can access it in flight. I am holding off on this decision until all the wiring is in place. I want to keep the O2 hose and connections as far away from anything electrical as I can. I also don't want any of the connections to be below the floor. If I every had a slight O2 leak I do not want the O2 to concentrate anywhere within the plane.

Al Thomas
N880AT
RV-8A
Finishing kit

Question for Dr Lindberg...

Dr Lindberg -

Could you comment on how donating blood might affect one's fitness for flight - are less blood or red blood cells going to further limit my safe altitude or increase my need of supplemental oxygen?

Thanks

John Babrick

Stephen Lindberg said:

... I don't know why breathing through your nose raised your sats....

Click to expand...

How about this for a guess?
Breathing through your nose increases the humidity level of the air in your lungs and the gas transport process across the lung wall works better at higher moisture levels???

-mike

Nose Breathing

Quote:
Originally Posted by Stephen Lindberg
... I don't know why breathing through your nose raised your sats....

I think that exhaling through the nose increases the pressure in your lungs, thus increasing the partial pressure gas exchange into the blood.

Maybe we should do a little valsalva move with every breath at high altitudes.

Hans

hemoglobin

OldAndBold said:

Dr Lindberg -

Could you comment on how donating blood might affect one's fitness for flight - are less blood or red blood cells going to further limit my safe altitude or increase my need of supplemental oxygen?

Thanks

John Babrick

Click to expand...

Perhaps I can help. There is a drop in the total oxygen carrying capacity of blood after one donates.
Supposing you are a healthy male, your hemoglobin (hgb) is 14-16 g/dl. Donating a pint (unit) of blood will drop your hemoglobin by about 1 g/dl. So if you are in the midrange of normal, say 15 g/dl you have dropped your total oxygen carrying capacity by 1/15 or 6.67%. Keep in mind that red blood cells live for about 90 days. Everyone is different on the regenerative capabilities for replacing the donated blood. So to say when a particular individual would be flying with "full tanks" is difficult to predict but about 90 days.

Would you need oxygen earlier? the answer is probably yes if you maintain the same flight characteristics ~ altitude and flight time. An oxygen sensor only calculates the amount of oxygen on the red blood cells - period. This is a qualitative and NOT a quantitative measurement.

For example, consider a person with a hgb of 15 and an oxygen saturation of 90%. This person has a far greater total oxygen "availablility" than that of a person with a hgb of 10 with an oxygen saturation of 95%

At some point, with an extremely low hgb, you could conceivably have a saturation of 100% with tissue starvation occuring.

Brad Bush

Here are a few links to articles on flying with supplimental oxygen. The one that explains why density altitude is not used to determine when to go on the bottle is included. This is pretty interesting as to why density altitude has no affect.

http://www.dr-amy.com/rich/oxygen/

www.flightstat.nonin.com/documents/Hypoxia, Oxygen and Pulse Oximetry.pdf

http://members.eaa.org/home/medical/articles/Oxygen For The Pilot.asp?

Best,

Quick replies to those who responded:

Mike: Inspired air is 100% saturated and at body temp before it gets to your lungs whether in the arctic or Sahara, nose or mouth breathing. BTW, bottled oxygen has 0% humidity, hence the dried out nose/throat. Drink extra water while on the nose bag.

Hans: Good thought. There is such a thing as "physiologic PEEP" (positive end expiratory pressure) which you described, and it does help stave off atelectasis, but it is provided by your glottis which periodically closes without your conscious effort. Usual accepted value is 4 cm of H2O. You can help the process by coughing and deep breathing while watching the autopilot at altitude, just like you described. Mouth vs. nose breathing should ordinarily make no difference, however.

John B. : Brad's explanation is correct. Healthy people have compensatory mechanisms that can compensate for the loss of a unit of blood. Ususally you don't notice unless you stress the system. In my own experience, I have found that donating blood causes a noticable decrement in my gym performance, esp max performance cardio and 20 rep squats. Lasts about 3 weeks. Donating blood would have a negative effect on performance at altitude. How much, I don't know. Depends on your age/health and how high you (foolishly) fly without oxygen. Maybe you would black out 1000 feet lower after donating a unit, 18,000 instead of 19,000, or some such. Just a guess.

Bryan W: Good articles. If you understand that level of respiratory physiology I may have a job for you. You will be tested, of course.

With the advent of portable pulse oximetry I think we are going to find out that we have been flying around in a semi-stuporous state. We need supplemental oxygen at a lower altitude than previously thought, esp us semi-geezers and esp at night and IFR. Now we can collect real data. I encourage all of you with pulse oximetry to report your data. Maybe DR can set up a collection system. I will buy a pulse oximeter when I finish this RV and start flying long high trips again. Don't need it in a Cub. Between that and trying to run LOP, I should stay busy.

Military Jet Jockeys

I have read that there is a breathing technique that is used to help overcome the effects of high G maneuvers. If you O2 system is having a problem is there a government recommended procedure to help maintain brain function at altitude?

I will be installing an O2 system in my plane before venturing into the upper part of the sky, but just encase of a failure, is there a breathing technique that I can use to help me get back down?

Kent

kentb said:

I have read that there is a breathing technique that is used to help overcome the effects of high G maneuvers. If you O2 system is having a problem is there a government recommended procedure to help maintain brain function at altitude?

I will be installing an O2 system in my plane before venturing into the upper part of the sky, but just encase of a failure, is there a breathing technique that I can use to help me get back down?

Click to expand...

Maintaining blood flow to the brain under g, and maintained oxygen flow at high altitude are completely different problems, with different solutions. If you are pulling a bunch of g, you need to raise the blood pressure, so it can push the blood up to the brain, while the high g is trying to pull it back down. You can increase the blood pressure by using an anti-g straining technique, but this won't help you increase the oxygen in the blood.

The government recommended procedure if your O2 system devlops a problem is to do an emergency descent. You need to get down before you go to sleep.

The FAA is here to help!

See, they really are here to help:

http://www.faa.gov/pilots/safety/pilotsafetybrochures/media/PT_06272005_web.pdf

I've heard that this is a great course, and I think it's free! I think to experience the effects this thread talks about first hand and under a controled environment instead of at 10k feet above the clouds in the plane by yourself would be priceless.

It's definitely on my "to-do" list while I wait for my fus and wings to show up.

An emergency method for breathing in low oxygen environment is to take deep breaths and breath out of your mouth with the air restricted so that you increase the air pressure in your lungs.

DBone said:

See, they really are here to help:

http://www.faa.gov/pilots/safety/pilotsafetybrochures/media/PT_06272005_web.pdf

I've heard that this is a great course, and I think it's free! I think to experience the effects this thread talks about first hand and under a controled environment instead of at 10k feet above the clouds in the plane by yourself would be priceless.

It's definitely on my "to-do" list while I wait for my fus and wings to show up.

Click to expand...

Yes, I think it would be priceless, too, but in the above pdf file on page 3, under "Applying," there is a mention of a fee.

"There is a course fee, which is non-refundable and is not
transferable."

If not too expensive, it would be worth doing. Maybe they offer group rates!

Don

Oxygen and Hypoxemia

I just found this article which was published today. Bottom line...91% is the number to remember.

http://www.ifr-magazine.com/oxygen-and-hypoxemia.html

I wish I had known about the information in this article and re-read this thread before a four-hour cross-country to Florida this past week.

Although I didn't experience any ill-effects (no headaches, nausea, etc. and I stayed on course and altitude) I was surprised at the numbers from my oximeter (bought from Sporty's awhile back).

After planning the trip with the most impressive Weathermeister web site ala Dan Checkoway, I planned to fly non-stop at 11,500 MSL. My RV-7 is not complete so I flew in my reliable but slow C172. I had 25 knot tailwinds and clear smooth air so it was a satisfying trip.

Here's what now alarms me...my saturated oxygen levels as measured by the oximeter were consistently below 80% and, of course, my pulse rate was elevated...typically up around 100. In my rush to plan and execute the trip I had not taken the time to read this or similar threads. If I had, I would have flown at say 9500 or even 7500 even if it meant a stop for fuel.

I'm posting this as a data point...not as a post recommending you can safely fly at low blood oxygen saturation levels. I don't think the oximeter is faulty although I realize it's probably not as accurate as more expensive ground based units. On the ground it indicates very believeable numbers. BTW, on the return trip I flew at lower altitudes (4500 and 6500 MSL) because of headwinds and the sat levels were in the low nineties and pulse readings were only slightly faster and were crosschecked the old fashioned way.

Also, the linked article above indicates the body typically increases heart rate to adjust for the decreased oxygen in the blood. Makes sense, huh?

YMMV...just a data point. And yes, I do plan to install a oxygen system in my RV-7.

Don

Thanks for the reference

This was very useful. My wife and I have been thinking about getting an oxygen system (and oximeter). This article decided it in the affirmative. Again, thanks.

Ed

Aviation Physiologist

I am a board certified aviation physiologist, have run over 70,000 aviators through the altitude chamber and here is the bottom line. Consulted on the Payne Stewart mishap as well as many others.

Their is no magical PAO2 for performance degradation which is why I dont allow students to take a pulse oximeter into the chamber. I have seen pulse ox as low as 58% and still had the student activate the regulator and recover. He obviously couldnt recover a jet however.

Symptoms, recognition, recovery and TUC time of useful consciousness is different for everyone, which is why we do this training. If everyone was similar we could publish the answer and require folks to comply. unfortunately it isnt that easy.

Slow insidious onset is actually more dangerous than a rapid decompression. Unfortunately hypoxia doesn't hurt, if it did we wouldnt have a problem.

Please dont experiment and dont bet your life on a pulse oximeter. I will prove to you in the controlled environment of an altitude chamber that your performance is degraded at 8,000 ft for those un acclimatized to high altitude.

After preflighting your plane do a human preflight and determine whether you are prepared to handle an emergency procedure, if not dont fly.

What is the correct alveolar oxygen pressure to maintain
optimal performance after being awake for 8 hours with a mediocre sleep last night and non recent flight currency. I have no idea and dont want to find out and wouldnt trust a pulse ox to tell me any more than the 80 or so divers I had to put in the hyperbaric chamber because they believed their dive computer would prevent decompression sickness.

Go to the FAA at OK city or any Air Force or Navy Altitude chamber and learn first hand what hypoxia feels like IN YOU. Oh you'll also learn alot about spatial D also. Here is the link, class costs $25 for FAA liability insurance. Hope to see you in my class.

http://www.faa.gov/pilots/safety/pilotsafetybrochures/media/PT_06272005_web.pdf

Efficacy of Medical Regulators at Altitude

Anybody have any adverse information or data indicating that medical regulators will not work properly at altitude? Many on this forum have advocated for their use and I am planning to do the same. Just want to see if anybody (e.g. flight surgeons, aviation physiologists, anesthesiologists ) is aware of an altitude-induced failure or deficiency of one of these medical units or potential design issues which would make them unsuitable for aircraft use.

Blood O2 saturation

So I just got my finger pulse oximeter ready for my western oregon to Colorado trip next week ..I mean for $64 why not?

Anyway I just wondered what O2 saturation level to aim for...Both me and the Wife are at 97% at sea level so what level of drop is allowable for good health and sharpness Vs. wasting O2?

Should we ba aiming to keep at 97% or allow a drop to some lower number and what is THAT number?

Thanks

Frank

Thanks

That was a good read..I guess 90% (approx) is the answer.

frank

Planning to go high if the winds are right.

What about an EP

Lets ask this a different way.

What would be the appropriate O2 saturation in order to appropriately handle an emergency procedure at altitude? Me thinks 110%.

Be careful up there.

Indeed

But then it might be more cost effective to feed the engine supplimental O2 and get there a whole lot quicker..

Frank

Frank,

I use a pulse ox unit in my office on a regular basis. I consider a normal saturation level for my patients to be above 95% and prefer to see 98 to 100% in a healthy person. I am at sea level here in Florida.

At 10000 ft the O2 level can drop to between 88 and 93%,
13000 ft is 83-88%,
16000 ft is 75-80%
20000 ft is as low as 70-75%

I would take care to keep the O2 level above 90% and preferably 93%. Once into the mid to lower 80's bad things can start to happen.

You should be careful and take into account your overall fitness and health as well as your home altitude (Denver people handle altitude with activity a little better than a flatlander like me)

Hope this helps

Little off this topic but during my sleep study to check for sleep apnea I got down to 63% and 120 interuptions per hour...Needless to say I love my CPAP machine. I found flying after getting this problem fixed was much better but that may be because I was actually sleeping again. I can tell you that O2 deprivation on that scale was ruining my life and health. My RV-10 has a Mt. High 4 place pulse demand system. I plan to use it for anything more than short hops around the pasture.

And...if you even think you may have this problem...ask your mate how bad you snore and if you stop breathing at times...get yourself to the Doc, it may save your life.

What we do

Consistent with any high altitude activity we stay well hydrated and snack.

On a long flight we like to use oxygen above 10,000 for daytime. Otherwise, as others have pointed out already, we end up feeling fatigued and a bit nasty at the end.

We use 90% as the threshold to indicate when I need to crank up the flow. In the mid-to-high teens we check O2 levels frequently. More than once we have found low levels related to kinked or disconnected hose. This seemes to especially happen on long trips with a lot movement in the cockpit to eat, pee, etc.

At night or IFR I go on O2 at a lower altitude to keep the brain sharp.
A few years back I got myself into a weather jam and ended up spending too much time at 13,000+ without oxygen. I couldn't get settled. I checked all the gauges, com, position, etc, all ok, but something didn't seem right. Then I do it again, and again, and ........

When I eventually went to a lower altitude everything seemed to magically fall into place and make sense again.

Acclimation matters. Coming back home from a week or two our daughters in Littleton (~6000) CO we deal with altitudes much better that usual. Even overnight acclimation makes a big difference and after 2 or three days the improvements become more subtle.