Nitrogen and Oxygen

[tarponchik]

I don't believe the original post mentioned anything about HBO therapy or anything about the treatment of DCS
"How does oxygen promote evacuation of nitrogen? What is the mechanism?"

I do not believe the original post mentioned anything about HBO therapy or anything about the treatment of DCS either. Even more, I know this for a fact. So?..

 

[tarponchik]

To clarify, my question was about giving a suspected patient of DCS a 100% oxygen vs any other gas mixture.

Bingo!

 

[scubadada]

I do not believe the original post mentioned anything about HBO therapy or anything about the treatment of DCS either. Even more, I know this for a fact. So?..

Bingo!

Take it easy Yuri, you'll blow a gasket. The original post did not mention DCS or HBO, was just saying. SB is not a competition.

Easy for me to say relax, I'm in Bonaire, diving with my wife. Today was day 7, 3 more glorious days to go. If you remember the solo diving with Dive Friends discussion, no one enforces anything. My wife's asthma kicked up one afternoon and I simply went solo off the Den Laman/Sand Dollar dock.

Good diving, Craig

 

[Kevrumbo]

EDIT:

How does oxygen promote evacuation of nitrogen? What is the mechanism?

To clarify, my question was about giving a suspected patient of DCS a 100% oxygen vs any other gas mixture.

Goals of Oxygen Therapy in suspected DCS Syndrome case:
-Bubble Resolution through Denitrogenation (bubble contents almost pure nitrogen).
-Surround bubble with high oxygen environment
-Diffuse Nitrogen out of bubble into blood.
-Nitrogen transported to the lungs and exhaled.

Augmented with Hyperbaric Oxygen Therapy (HBO) in a Recompression Chamber, the goals are:
-Bubble size reduction (vital in suspected case of AGE).
-Hyperbaric oxygenation of hypoxic tissues.
-Reduction of tissue edema.
-Rehydration (e.g. Oral hydrating fluids or IV Normal Saline during Treatment).

Bubble size Reduction:
Decompression Sickness, small bubbles:
-Treatment starts at 2.8 ATA pressure breathing 100% Oxygen, with theoretical 70% reduction of Original Bubble Diameter.

Arterial Embolism, large gas bubbles:
-Treatment starts at 6.0 ATA pressure breathing 47% to 50% Nitrox or 50/50 Helium-Oxygen (for a ppO2 of around 2.8 to 3.0) with 55% reduction of Original Bubble Diameter.

 

[TrimixToo]

Glad you said that......so here's my "de-rail" question

Why does helium make us talk funny when we inhale a balloon?

Because the latex blocks your airway, and that makes it hard to talk?

 

[Akimbo]

Take it easy Yuri, you'll blow a gasket. The original post did not mention DCS or HBO, was just saying. SB is not a competition.

(concurring and adding perspective)
It is also not entirely inappropriate. The physics and physiology are about the same. Most of the same principals also apply to aviators in unpressurized aircraft, who can also get bent. That why the chambers at NEDU's Ocean Simulation Facility are rated from 2,250'/690M of sea water to an altitude of 150,000'/46Km.

 

[tarponchik]

@Kevrumbo The high pressure only reduces the size of the bubbles to ease the suffering. If you take the pressure away, the bubbles will expand back.

Take it easy Yuri, you'll blow a gasket. The original post did not mention DCS or HBO, was just saying. SB is not a competition.

Easy for me to say relax, I'm in Bonaire, diving with my wife. Today was day 7, 3 more glorious days to go. If you remember the solo diving with Dive Friends discussion, no one enforces anything. My wife's asthma kicked up one afternoon and I simply went solo off the Den Laman/Sand Dollar dock.

Good diving, Craig

Good for you, Craig. 3 weeks ago Andreas at AlWest caught me diving solo (for similar reason) and lectured us with "we do not appreciate solo diving here" stuff. So I just found some good instabuddies next time.

And now I am in bed, recovering from an "unknown virus" attack. This is what the doctors called it after examining me for 9 hrs Wednesday night, failing to find any other explanation for the 102 F fever switching with chills, severe stomach pain, and blood pressure down to 85/55 sometimes, while everything looked good in the scans. Well, I was pretty much sure from the start this was some kind of virus, an unknown [to me, but] known [to the doctors], but now I know this is an unknown unknown, in Donnie Rumsfeld's terms.

Anyway, I hope your trip ends well and you make it home safe.

 

[tursiops]

Decreased density of gas increases the speed over your vocal cords and raises the pitch.

Umm, not exactly. There are two separate questions here. (1) How does the pitch change with increasing speed of sound in the gas? (2) Why is the speed of sound in helium faster than in air?

(1) The sound travels by compression waves (molecules bunching up and getting farther apart), not by the movement of the gas. The vocal cords actually vibrate at the same rate, air or helium, but the sound waves produced by resonance in the throat/neck/mouth are shorter wavelength (thus higher frequency) in a higher sound-speed gas. The helium molecules are smaller and lighter so are easier to move around more quickly. If you made the throat smaller, you'd get a higher pitch too. Thus, women and children tend to have higher pitched voices.
(2) The sound speed is inversely proportional to the compressibility of the gas, and to its density. A "spongy" gas (highly compressible) will have a lower sound speed; the compression waves are more sluggish. A denser gas will have a lower sound speed; the molecules are harder to move around thus compression waves move around more sluggishly.

On balance, air and helium are similar in compressibiity, but are greatly different in density, so the less dense helium has a higher sound speed than air, by a factor of about 2.9.

By the way, the difference in the speed of sound in N2, O2 is the basis for a gas analyzer that someone built. If you know the combined speed of sound in the mixture, you can calculate the fraction of each gas. You can make this even more complicated by adding in a third gas, like He, and measuring one of the gases, like O2. Then you can calculate how much N2 and He are there by knowing the combined sound speed of the whole mixture. You get the sound speed by measuring the pitch of the sound produced by resonating in a chamber of known dimensions.

 

[TrimixToo]

<snip>

By the way, the difference in the speed of sound in N2, O2 is the basis for a gas analyzer that someone built. If you know the combined speed of sound in the mixture, you can calculate the fraction of each gas. You can make this even more complicated by adding in a third gas, like He, and measuring one of the gases, like O2. Then you can calculate how much N2 and He are there by knowing the combined sound speed of the whole mixture. You get the sound speed by measuring the pitch of the sound produced by resonating in a chamber of known dimensions.

That'd be the Divesoft. I have one, and like it a lot.

 

[scubadada]

Umm, not exactly. There are two separate questions here. (1) How does the pitch change with increasing speed of sound in the gas? (2) Why is the speed of sound in helium faster than in air?

(1) The sound travels by compression waves (molecules bunching up and getting farther apart), not by the movement of the gas. The vocal cords actually vibrate at the same rate, air or helium, but the sound waves produced by resonance in the throat/neck/mouth are shorter wavelength (thus higher frequency) in a higher sound-speed gas. The helium molecules are smaller and lighter so are easier to move around more quickly. If you made the throat smaller, you'd get a higher pitch too. Thus, women and children tend to have higher pitched voices.
(2) The sound speed is inversely proportional to the compressibility of the gas, and to its density. A "spongy" gas (highly compressible) will have a lower sound speed; the compression waves are more sluggish. A denser gas will have a lower sound speed; the molecules are harder to move around thus compression waves move around more sluggishly.

On balance, air and helium are similar in compressibiity, but are greatly different in density, so the less dense helium has a higher sound speed than air, by a factor of about 2.9.

By the way, the difference in the speed of sound in N2, O2 is the basis for a gas analyzer that someone built. If you know the combined speed of sound in the mixture, you can calculate the fraction of each gas. You can make this even more complicated by adding in a third gas, like He, and measuring one of the gases, like O2. Then you can calculate how much N2 and He are there by knowing the combined sound speed of the whole mixture. You get the sound speed by measuring the pitch of the sound produced by resonating in a chamber of known dimensions.

Didn't I say that my dolphin friend?