Supplemental O2

[gowlerk 2,249]

Someone here knows this, probably several people. What is the source and composition of the supplemental O2 typically given to skydivers on high altitude loads? Is it just compressed air, or is it higher in O2 than that?

(I just found this, it does not leave me feeling all that confident in the systems we use!)

https://www.aopa.org/training-and-safety/pic-archive/pilot-and-passenger-physiology/oxygen-use-in-aviation

Always remember the brave children who died defending your right to bear arms. Freedom is not free.

[Slimrn 6]

I do anesthesia for a living and I can tell you that it's going to have to be something with a higher Oxygen content than compressed air. It's probably a green O2 E-cylinder or larger.

[gowlerk 2,249]

  Slimrn

I do anesthesia for a living and I can tell you that it's going to have to be something with a higher Oxygen content than compressed air. It's probably a green O2 E-cylinder or larger.

That's what I was thinking. But someone recently told be otherwise. With O2 in the atmosphere being only 20% I can't see how sticking that little tube in your face or even under you helmet is going to make much difference.

Always remember the brave children who died defending your right to bear arms. Freedom is not free.

[Slimrn 6]

Right, so the higher you go, the partial pressure of Oxygen molecules remains the same, but the atmospheric pressure drops. Basically you get fewer oxygen molecules per breath. You have to offset that by breathing in MORE oxygen before you leave the plane. It's like filling up your gas tank before going on a road trip.

[billvon 3,066]

It is almost pure O2 with almost all the moisture removed (important for aviation.) When I get it here, all the oxygen (medical, aviation, welding) comes from the same source - a big tank of liquid oxygen.

There are a lot of debates about how to use O2 in skydiving. Sticking the hose in the space between your face and the helmet is probably the worst way. Nasal cannula and sticking it in your mouth are probably the best.

[Slimrn 6]

+1 to nasal canula....I mean why not deliver oxygen the way we do in hospitals right?

[Anachronist 2]

Check this out Note the flow rates though. At lower rates the nasal cannula outperforms the simple mask because there isn't enough flushing out of the mask with O2 in between breaths. At a high flow rate you will get a high percent either way.

[billvon 3,066]

>+1 to nasal canula....I mean why not deliver oxygen the way we do in hospitals right?

Well, we have a slightly different environment than hospitals.

Let me add another caveat to the above - if you are using bailout oxygen (not just supplemental in the aircraft) either hose-in-mouth or full face demand mask are the two ways to go. Cannulas are less effective when 120mph of wind gets involved.

[Slimrn 6]

I'm sorry if anyone could take me to have meant that a nasal canula is adequate outside the aircraft- ha. You need a closed circuit when in the wind.

[northrun 0]

  Slimrn

Right, so the higher you go, the partial pressure of Oxygen molecules remains the same, but the atmospheric pressure drops.

Mmm...

As you go higher the _percent_ of oxygen remains the same while the total pressure drops. As the total pressure drops, so does the partial pressure of every component, including Oxygen.

Partial Pressure O2 = Percent O2 * Total Pressure

Partial pressure of oxygen is the primary driver of (loss of) consciousness at altitude. By raising the percentage of oxygen, you raise the partial pressure of oxygen, which is what you need to stay conscious and functional. The more oxygen you consume, the higher the partial pressure.

Incidentally, consuming compressed air will do absolutely nothing useful. It's still 20.9% oxygen, and you'll go unconscious just as fast breathing it out of a can as you would out of the air.

(Tech diver... monitoring partial pressure is what we do. Pure O2 too deep, you die. Bottom mix too shallow, you die. All based on the differences in partial pressure.)