Oxygen saturation on normal skydives

[billvon 2,402]

Starting about two years ago I've started to notice hypoxia a bit more. At first I didn't think anything of it; it would happen at Lost Prairie where we regularly go to 17,000 feet MSL. I think almost everyone on those loads is hypoxic most of the time.

But then I started noticing it happening at Perris, too, going to only 14K MSL. Was I just getting old? How come I was having trouble and that fat smoker guy wasn't? I was in fairly good shape, didn't smoke, resting heart rate around 65, no problems with cardiovascular exercise or lung capacity (I bike to work.) It would hit me about 5 seconds after exit and get worse for another 10 seconds, then gradually improve. Usually it was just general fuzziness, but sometimes I'd lose color and start to get tunnel vision as well. It started to affect my skydiving - on video I could tell when I started to fuzz out and when I recovered. I'd get sloppy and slow.

Oddly, it did not occur during wingsuit jumps (longer at higher altitudes, generally more exertion) and it never affected me on skyvan jumps. Also, on really high loads (25K on oxygen) I was fine. After a while I figured out that the big factor was crouching down. If I was in the first group and had to crouch by the door, or was on the right side of the plane when they needed the bench up, it would affect me. My theory on this was that a) crouching meant a lot of exertion and b) when I'm crouched, circulation is worse in my legs, so deoxygenated blood gets stored down there, which all hits me as soon as I get into freefall and the pressure is relieved.

But why did it start all of a sudden?

To find out I got a pulse oximeter and tested my own saturation levels on several test jumps. (I didn't really jump; I'd just go up then land with the plane.) The first thing I learned was that my personal limit of hypoxia is around 80%. Below that and I really start to feel it.

The second thing I learned was something that contradicted previous learning. When I first learned to use oxygen, the guy going over its use told us that it was essential to breathe normally. Breathing too deeply/rapidly can cause hyperventilation which carries its own set of problems. But after some further research, I discovered that that's not a good idea for normal full altitude (12K or so) jumps without supplementary oxygen. The problem is that your respiratory drive is normally driven by your CO2 concentration, not your O2 concentration. In other words, your body can be doing just fine at getting rid of CO2, but not getting enough oxygen, and your respiration rate won't pick up until you're _really_ hypoxic. When it does pick up it picks up bigtime for a while, then slows down again. This sort of breathing is called Cheyne-Stokes breathing, and is what your body will do naturally at high altitude. Mountain climbers breathe like this when they sleep; very shallow breathing followed by periods of very deep breathing.

This sort of breathing can cause transient hypoxia, because you can almost stop breathing for short periods. Normal (i.e. shallow) breathing can also cause hypoxia because during normal breathing, you don't exchange about 40% of the air in your lungs/throat/nose. So you're effectively getting only 60% of the available oxygen.

So on one of the tests I tried breathing more slowly (about 6 breaths a minute) but more deeply to see if that would affect it. As the data below shows, it made a significant difference.

last jump of the day
Ground 98%
6K 95%
9K 90%
13.5K 80%
13.5K after moving around a lot 78% (start of fuzziness)

Morning load
Ground 97%
6K 96%
9K 90%
12.5K 86%
12.5K after moving around a lot 80% (no fuzziness)

Very next load
Ground 98%
6K 95%
9K 91%
12.5K 82%
12.5K after moving around a lot 81%
12.5K after deep breathing 89%

So now I have a new tool to deal with hypoxia - deeper but slower breathing. (Deep fast breathing can lead to hyperventilation.) This makes sense since I'm getting more air exchanged overall.

For a good overview of oxygen use/breathing for pilots at the altitudes we use, check out http://www.avweb.com/news/aeromed/181934-1.html

[FrogNog 1]

Can you clarify your data numbers to show saturation percentages at certain places with and without deep breathing?

Without the actual hard evidence, I found out that anything that squishes my torso can lead me to hypoxic symptoms. Unfortunately, I usually couldn't readily discern them from "young skydiver terror" symptoms, so I can't swear it's hypoxia. But the common link I found to being folded wrong in the 182, worrying too much, or wearing the "small" student rig with the teeny harness was that I would not breathe deep at all. Solution: breathe slow and deep, and everything seemed to get better.

On a separate note, do you have any opportunity to perform these experiments using supplemental oxygen?

-=-=-=-=-
Pull.

[Swooopa-x 0]

Very interesting post. Thanx for the link too.
check out these two martial arts : Tai chi and chi-kung. Dont have any links for you but have been
involved and practicing for close on twenty years. (certainly chi-kung).
Loads of valuable info on how to optimise the breathing technique you are touching on.
good luck and enjoy

People dont care how much you know until they know how much you care.

[tombuch 0]

Interesting post. I’ve also found that forcing more of the residual air out of my lungs before taking another breath at altitude helps manage hypoxia. (For anybody who is interested in more detail, follow the link Bill provided: http://www.avweb.com/news/aeromed/181934-1.html).

Your thought that age might be part of the process is also a good one. I noticed that I get hypoxic much sooner now than when I was younger, and that is especially apparent in a chamber. The last time I did physiological flight training in a chamber the staff confirmed that as we age hypoxia manifests faster. They explained that symptoms will remain the same over time, but that they will manifest earlier.

Your note about NOT being hypoxic in a Skyvan touches on a point I’ve often wondered about. When we load Skyvans it is usually a fast process. When we load Otters some of us end up standing outside the door for a minute or two, breathing in the hot smelly exhaust. Is there any chance we are filling hemoglobin with CO, increasing our risk of hypoxia? When I was doing tandems I noticed hypoxia a lot more than on regular jumps, probably because I was working so hard in the airplane, and talking to my students so much. I also associated standing outside the door for a while with increased hypoxia at altitude, so now I try to stay away from the area that is especially hot or smelly.

I don’t know much about the gas mixture within the exhaust of a turbine engine. Typical pulse-ox meters simply measure filled hemoglobin, not actual oxygen saturation levels, so CO will usually show as oxygen saturation because it is bound to the hemoglobin. CO also binds faster than oxygen, and remains attached to hemoglobin much longer. The best way to check for CO in the blood is with an actual blood test, but a CO test of ambient air in the boarding area might tell us if there is an exposure risk. It’s an interesting thought worth investigating if a mechanic wants to address exhaust gas mixtures from a turbine engine.

There are also a few other tactics we can all use to reduce our risk of hypoxia. Since hypoxia is caused by not enough oxygen being carried by the hemoglobin, we can improve the ability of our blood to carry oxygen by staying well nourished and well hydrated throughout the day. Those are simple things that we should all do anyway, but the management of hypoxia adds an extra reason to eat and drink well throughout the day.

Tom Buchanan
Instructor Emeritus
Comm Pilot MSEL,G
Author: JUMP! Skydiving Made Fun and Easy

[councilman24 36]

Also Bill, when your crouched you can't take even normally deep breaths. The movement of your diaphram and or ribs may be resticted. While some muscles may be working hard and contributing, you're also probably not moving as much air. In a skyvan, with "standing" exits you wouldn't be constricted.

Note the problems the Pope is having moving air because of the hunch caused by the parkensons.

I'm old for my age.
Terry Urban
D-8631
FAA DPRE

[billvon 2,402]

> Can you clarify your data numbers to show saturation percentages at
>certain places with and without deep breathing?

The first two flights were without deep breathing. The last one was with.

>On a separate note, do you have any opportunity to perform these
>experiments using supplemental oxygen?

Yeah, I have a small O2 system, but haven't had the chance yet to fill it and try it. I have a feeling the results will not be that interesting, at least on normal altitude jumps; O2 sat will go to 98% and sit there.

[kallend 1,632]

I've noticed exactly the same thing about crouching down at altitude, so I try to avoid the need to do it. It typically happens if, say, someone treads on my bootie as we're getting ready and I have to fix it at altitude.

...

The only sure way to survive a canopy collision is not to have one.

[flyangel2 2]

I always try to get a seat on the side of the Otter where the bench can't be lifted up.

May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view. May your mountains rise into and above the clouds. - Edward Abbey

[wmw999 2,123]

I'm short enough to simply bend some at the waist, without crouching at all. It was easier when I used to put static line students out of the 182, also.

Wendy W.

There is nothing more dangerous than breaking a basic safety rule and getting away with it. It removes fear of the consequences and builds false confidence. (tbrown)

[mfrese 0]

Great thread!

Working at a DZ that regularly does 18K tandems, I've had to change the way I approach my breathing for some time now. I've always made it a policy to breath deeply during the climb to altitude, and I've started having my students do it as well. For 18K loads we start supplemental O2 at about 7K, so I breath slow and deep up to that point, then switch to a 3-4 shallow, 1 deep pattern. This seems to keep hypoxia symptoms down, even on days where I do 5 or more 18K loads.

I also try to make sure I do most of the hard work (attaching and tightening laterals and such) by 10K, and I keep the O2 on until we start moving toward the door.

If you do any more experiments, please post the results...maybe you can get a smoker to try the same experiment as well, and get data from them. It might convince a whole lot of people to quit!

Thanks, Mike

Doctor I ain't gonna die,
Just write me an alibi! ---- Lemmy/Slash

[Zenister 0]

hmm nice data.. and good info..

a habit i learned from kenjitsu was to set up a base breathing pattern by exhaling for a 10 count and inhaling for a 10 count (beginners should start with 5s) with a bit of practice your body continues the base pattern even after you've stopped thinking about it, and reverts back into it after sudden exertion fairly quickly.

i sort of reverted to it on instinct when (for some reason) i was feeling very nervous on my third AFF dive and it made a HUGE difference, my instructor even pointed out the difference on the debrief

now whenever i'm anxious about a dive or move i cant seem to get, taking a moment or two to focus on how i'm breathing is incredibly useful to help insure successful dive. I was sure some of the effect was mental clarity from just relaxing but its great to have proof the actual breathing pattern helps as well...

____________________________________
Those who fail to learn from the past are simply Doomed.

[voodoo78 0]

Try pre-breathing your O2 system before the loads check your results,or do a hard day of jumping with out any O2 and then repeat that same amount of jumps the vary next day using pre-breathing or @ alt and see what the effects are and how you feel at the end of the day.

[skiskyrock 0]

Quote

So on one of the tests I tried breathing more slowly (about 6 breaths a minute) but more deeply to see if that would affect it. As the data below shows, it made a significant difference.

reply]

I read about positive pressure breathing on a mountaineering thread in another forum recently. Evidently you exhale through pursed lips, boosing the pressure in your lungs slightly, theoretically increasing blood oxygenation. A poster quoted a reduction in perceived altitude of 2000 feet, and other testimonials to great effectiveness and utter worthlessness were offered. As long as you are wiring yourself up, it might be an interesting variable to add to the mix.

• Quote

[gerrcoin 0]

Although I don't have very much knowledge on the subject, I seem to remember hearing from a comercial pilot who was also a scuba diving instructor about the partial pressure of oxygen at altitude having an effect, in addition to the lower air density. This is why hyperventilating does nothing to increase your oxygen saturation.

Deeper slower breathing on the other hand may well help. When you take a deep breath and hold it you tend to relax the intercostal muscles and the diaphragm, which may increase the static pressure slightly in your lungs and allow a greater exchange of oxygen.

[Deuce 1]

I'm wondering if there is a cumulative effect on tissue that goes beyond the blood values you've collected.

I am often really wiped out after a day of 10 14K skydives that goes beyond just the physical demands of skydiving that much. I really noticed the difference when we did the sequential record in FLA with O2. After a very long day of dirt diving and skydiving on oxygen, I felt much better that a similar day without it. Especially on jump run.

[Praetorian 1]

The long day thing (most likely) includes other factors, carbonmonoxide from exaust, dehydration, and redcell turnover ... redblood cells "die" faster when you blood goes acidic (too much CO2). These same things still occur but to a lesser extent when you run on O2 all day Breathing O2 will drive CO out of your blood faster than just normal air, will also HELP keep your blood PH from dropping

Good Judgment comes from experience...a lot of experience comes from bad
judgment.

[mjosparky 3]

Yes, it does have a cumulative effect even when supplemental O2 is used.

Sparky

My idea of a fair fight is clubbing baby seals

[jumpwally 0]

Bill,,,as fucking usual,you've hit a home run base's loaded,,,,great info. Thanks wally

smile, be nice, enjoy life
FB # - 1083

[IanHarrop 37]

I found this to be a very interesting thread and I am going to use this information whenever I can.
In fact I think this is the kind of information that needs to spread around for the benefit of everyone.

On the other hand, there was one point in the original post that I have an issue with.

The comment was "I was in fairly good shape, didn't smoke, resting heart rate around 65, no problems with cardiovascular exercise or lung capacity (I bike to work.)"

Now Bill may indeed "bike" to work but I refer you to the post below where there is a description and a picture of his "bike".

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=1450842#1450842

Fess up Bill, you're on the road to being old and feeble like the rest of us and use a power assisted bike to get to work!

"Where troubles melt like lemon drops, away above the chimney tops, that's where you'll find me" Dorothy

[IanHarrop 37]

As I thought about this some more it occurred to me that Bill should look at having this posted as an article. In that way perhaps more people would read it and benefit by it.

There are a lot of dropzones in places where the ground level altitude is already high enough that once you put people on an Otter the loads are going pretty high. All of these people would benefit from reading this.

"Where troubles melt like lemon drops, away above the chimney tops, that's where you'll find me" Dorothy

[Beerlight 0]

Quote

Although I don't have very much knowledge on the subject, I seem to remember hearing from a comercial pilot who was also a scuba diving instructor about the partial pressure of oxygen at altitude having an effect, in addition to the lower air density. This is why hyperventilating does nothing to increase your oxygen saturation.

Deeper slower breathing on the other hand may well help. When you take a deep breath and hold it you tend to relax the intercostal muscles and the diaphragm, which may increase the static pressure slightly in your lungs and allow a greater exchange of oxygen.

Deep slow breathing? maybe not... It's really all about oxygen transfer at the aveolar level. ie. The law of gaseous diffusion. You can breathe slowly and deeply all you want, but if the pressure across the fence is higher than what's in your lungs, ineffective transfer will occur. At least a reduced transfer.

Trying to artificially increase lung pressure via a muscle contraction will not be effective either. To few oxygen molecules to compress and you can't hold the contraction long enough to be effective anyway. (It's actually counterproductive) Your useful conciousness time will be reduced due to increased metabolic function from the muscle contraction. ie., your burning oxygen to increase oxygen transfer?

Tom Buck hit the nail on the head. Stay out of the exhaust fumes of turbine and recip engines (yea right) and Hypemic Hypoxia will be lessened. No smoking prior to unpressurized flight, no booze 12 hours prior to jump, staying hydrated, fed, plenty of sex, and it all equates to a better tolerance to reduce partial pressure of oxygen at altitude.

RTF-- STS 114........

[wmw999 2,123]

Quote

RTF-- STS 114.......

Coming soon
Wendy W.

There is nothing more dangerous than breaking a basic safety rule and getting away with it. It removes fear of the consequences and builds false confidence. (tbrown)

[billvon 2,402]

>You can breathe slowly and deeply all you want, but if the pressure
>across the fence is higher than what's in your lungs, ineffective transfer
>will occur. At least a reduced transfer.

The issue here is dead space. Typically during normal breathing you only exchange about 60% of the volume in your lungs. That means 40% of the air in your lungs hasn't seen the light of day for a bit and is lower in O2 concentration (and higher in CO2 concentration) than the outside air. Normally you have no problem with this; your respiration rate automatically adjusts to deal with the slightly lower O2 content and the slightly higher CO2 content. (Side note - this is why people breathe into paper bags when they're hyperventilating. The artificial increase in dead space helps restore the 'normal' CO2 balance in their blood.)

At higher altitudes, the normal 60% of exchanged air is insufficient to keep your blood 100% (or even 95%) oxygenated. Breathing more deeply will help you exchange more air and thus increase the ppO2 of the air in your lungs.

[gerrcoin 0]

Quote

Trying to artificially increase lung pressure via a muscle contraction will not be effective either. To few oxygen molecules to compress and you can't hold the contraction long enough to be effective anyway. (It's actually counterproductive) Your useful conciousness time will be reduced due to increased metabolic function from the muscle contraction. ie., your burning oxygen to increase oxygen transfer?

I didn't say anything about using muscle contraction to artificially increase pressure in the lungs. In fact I considered the opposite to be effective - ie. relaxation of the intercostal muscles and diaphragm, which would allow the ribcage to return to its normal position. In addition with constricting the trachea (or however the body prevents exhalation) this might cause a slight increase in static pressure in the lungs over the ambient and thus provide a more favourable differential and delaying the effects of of hypoxia. The deeper the breath the greater the deflection of the ribcage and thus the greater the compression when relaxed. This is just my theory, feel free to shoot it down.

Of course meditation techniques demonstrate that slow deep breathing relaxs the body and can slow the heart and metabolic rate. The factors you have also mentioned would have a drastic effect too.

[mjosparky 3]

I think you might to listen to what "Beerlight" has to say about the physiology of high altitude. He knows his shit.

Sparky

My idea of a fair fight is clubbing baby seals