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Offlinedefcheck
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Hyperbaric Chamber
    #5476732 - 04/03/06 09:21 PM (17 years, 9 months ago)

Any one here know anything about sleeping in 100% pressurized oxygen? I here of some crazy ass actors doing it. Is there science behind sleeping in one? I know of the Hyperbaric Oxygen Therapy, and its benefits, but can't find any recommendations on sleeping in a chamber.


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OfflineSeussA
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Re: Hyperbaric Chamber [Re: defcheck]
    #5477989 - 04/04/06 04:34 AM (17 years, 9 months ago)

Sleeping in pressurized 100% oxygen will lead to oxygen toxicosis, quickly followed by death. When a person is bent (has nitrogen gas bubbles in their body), they are put into a hyperbaric chamber for treatment. The pressure is increased in the chamber forcing the bubbles in their body to dissolve back into the tissues. Pure oxygen is breathed to reduce the partial pressure of nitrogen in the body thus speeding up the gas exchange of nitrogen out of the body. However, the percentage of oxygen in the blood is closely monitored and the patient is switched back to regular air from time to time to prevent oxygen toxicosis.

Even regular air, under pressure, can lead to oxygen toxicosis. As the pressure increases, there are more oxygen atoms available in the lungs, which can be thought of as an increase in percentage of oxygen available in the air being breathed. Aside from decompression problems, this is the main factor that limits the maximum depth of recreational scuba divers. Somewhere around 100 feet of sea water, the diver on regular air is taking in as much oxygen per breath as they would on the surface breathing pure oxygen.

Although 100% oxygen at ambient atmospheric pressure will not lead to oxygen toxicosis, it is still hard on the body with prolonged (>12 hours) exposure. Lemme do some digging real quick...

Quote:

The potential risks and risk-benefit ratio of hyperbaric oxygen have often been underemphasised in therapeutic trials. The side effects are often mild and reversible but can be severe and life threatening. In general, if pressures do not exceed 300 kPa and the length of treatment is less than 120 minutes, hyperbaric oxygen therapy is safe. Overall, severe central nervous system symptoms occur in 1-2% of treated patients, symptomatic reversible barotrauma in 15-20%, pulmonary symptoms in 15-20%, and reversible optic symptoms in up to 20% of patients.

Reversible myopia, due to oxygen toxicity on the lens, is the commonest side effect and can last for weeks or months. Epileptic fits are rare and usually cause no permanent damage. A suggested carcinogenic effect of hyperbaric oxygen has not been substantiated in extensive studies.




Quote:

Acute: Pure oxygen, especially if not properly humidified, may cause mucous membrane irritation and pulmonary edema after 24 hours. Air normally contains 20-21% oxygen. As exposure to higher concentrations and/or greater than atmospheric pressure continues symptoms of toxicity may develop and increase in severity. Respiratory system effects may include a progressive decrease in vital capacity, tightness in the chest and discomfort, coughing, congestion, tracheobronchitis, pneumonia, edema atelectasis and increased depth of respiration, rapid panting or asthma-like attacks, apnea in inspiratory position, fibroblastic proliferation, and hyperplasia of alveolar cells. Cardiovascular system effects may include bradycardia, hyperthermia or hypothermia and peripheral vasoconstriction. The nervous system may be affected with mood changes, nausea, dizziness, slowing of mental processes, malaise, hilarity, apprehension, paresthesias including tingling of fingers and toes, fasciculation of the lips and face, muscular twitching, visual and auditory hallucinations, general convulsions and epileptic seizures, loss of consciousness and collapse. At increased atmospheric pressures, vision may be affected. Symptoms may include photophobia, amblyopia, mydriasis, bilateral progressive constriction of visual acuity was found after breathing pure oxygen for four and one-half hours at normal atmospheric pressures. Animal studies indicate exposure to oxygen under high pressure has caused hemolytic anemia. In pregnant women exposed to 100% oxygen for 20 minutes, the response was a fetal cardiac rate which decreased and became variable.

Chronic: Inhalation of pure oxygen for periods up to 16 hours per day for many days at atmospheric pressure has caused no observed injury to man. Administration at atmospheric pressures at concentrations of 60-80% may be followed by adverse effects, including severe cough, acute chest pain associated with a decrease in vital capacity, intra-aveolar edema and atelectasis. It is possible that prolonged low-level injury may produced severe fibrotic changes in the lungs. However, after a human was exposed to high concentrations of oxygen for 150 days, severe irreversible retinal atrophy occured. Dogs exposed to pure oxygen for 48 hours were found to develop retinal and choroidal detachments. Reproductive effects have been reported in animal studies.




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Offlinecybrbeast
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Re: Hyperbaric Chamber [Re: Seuss]
    #5479798 - 04/04/06 04:34 PM (17 years, 9 months ago)

I though deep scuba divers used heliox to prevent oxygen poisoning. Heliox, mixture of air and helium.


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InvisibleDiploidM
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Re: Hyperbaric Chamber [Re: cybrbeast]
    #5480321 - 04/04/06 07:37 PM (17 years, 9 months ago)

Actually, most scuba divers breathe ordinary air, which is safe to breathe down to 130 feet. At that depth, the 21% oxygen in air become equivalent to 100% oxygen partial pressure at sea level and the danger from acute oxygen toxicity becomes significant. That's why it's limited to 130 feet.

Some advanced recreational divers enrich their breathing air with extra oxygen. This is called Nitrox and compared to air at 21% oxygen, can have up to 40% oxygen. The extra oxygen displaces the nitrogen in the air and allows the diver to remain at depth longer without having to decompress, which recreational divers don't do. The extra oxygen also limits the depth at which Nitrox can be breathed safely. Too deep and you will convulse from the oxygen toxicity. These convulsions aren't especially dangerous on dry land, but at depth, you would drown immediately. This is why Nitrox divers undergo extra training in the safe use of oxygen-enriched air.

Beyond that are technical and cave divers who perform long duration deep dives well beyond 130 feet. At those depths, oxygen has to be carefully controlled and the gas of choice is called Trimix. It's composed of helium, nitrogen, and oxygen. With Trimix, helium is used to displace the nitrogen in the air which beyond 130 feet deep has a narcotic effect. Helium has no narcotic potential. If you've ever done nitrous oxide, you know what nitrogen narcosis is like.

During decompression, technical divers do breath typically 50% oxygen / 50% helium starting at 70 feet on up to 20 feet where they switch to 100% oxygen until they surface. Breathing 100% oxygen deeper than 20 feet (or for too long) leads to oxygen toxicity, convulsions, and certain drowning. Trimix technical divers undergo extensive training to learn how to dive safely.

This all may be more than you want to know, but I teach this stuff for fun, so I can't help myself.  :wink:

Here's a pic of a room at the back of a cave 480 feet underwater in north-central Florida. I'm in the upper left:



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Republican Values:

1) You can't get married to your spouse who is the same sex as you.
2) You can't have an abortion no matter how much you don't want a child.
3) You can't have a certain plant in your possession or you'll get locked up with a rapist and a murderer.

4) We need a smaller, less-intrusive government.


Edited by Diploid (04/04/06 07:51 PM)


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OfflineHagbardCeline
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Re: Hyperbaric Chamber [Re: Diploid]
    #5480681 - 04/04/06 09:14 PM (17 years, 9 months ago)

Four hundred and eighty fucking feet!?!  That's crazy!  :crazy:

How long can you stay down in a cave like that? 

What does the pressure feel like at that depth?  I've free dived to around 35 feet and that was nearly unbearable.  Is it easier to cope with air?


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I keep it real because I think it is important that a highly esteemed individual such as myself keep it real lest they experience the dreaded spontaneous non-existance of no longer keeping it real. - Hagbard Celine


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OfflineSeussA
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Re: Hyperbaric Chamber [Re: HagbardCeline]
    #5481656 - 04/05/06 05:46 AM (17 years, 9 months ago)

Are you on a closed circuit back there?  I see bubbles from the guy in the foreground, but not from you.  Of course, it is hard to tell with the washout from the light.  How long did it take you to plan that dive?  I have always wanted to get into tech diving, but the thought of hanging out on a line decompressing never really set well.  I get bored during a three minute safety stop... :grin:

> Four hundred and eighty fucking feet!?! That's crazy!

Only crazy if done without the proper training, planning, and equipment.  Trust me, a lot of time goes into preparing for something like this.  It isn't the type of thing that you wake up and call up your buds to go diving today 'cause it looks nice out.

> How long can you stay down in a cave like that?

Until you run out of gas.  These are decompression dives, so they are not limited by NDLs (non-decompression limits).  They decompress as they slowly (with many long waits at various depths) surface.  Again, a huge amount of planning goes into this type of dive.  It takes a lot of skill, a lot of training, and a lot of courage to do a dive like this.

> What does the pressure feel like at that depth?

No different than at the surface, once equalized.  Things like neoprene will compress, making thermal protection less efficient.

> I've free dived to around 35 feet and that was nearly unbearable.

Be careful!  You are not equalizing and are risking a blown ear drum, or worse.  If you equalize as you decend, there is no pain from pressure differences between the inside and outside of the eardrum.


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InvisibleDiploidM
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Re: Hyperbaric Chamber [Re: HagbardCeline]
    #5483369 - 04/05/06 03:46 PM (17 years, 9 months ago)

How long can you stay down in a cave like that?

The limits are set by:

1. How much breathing gas you can take with you
2. How much calcium and sodium hydroxide CO2 absorbent your rebreather can hold
3. How much time you're willing to spend decompressing on your way up (very boring)

A typical dive in that particular cave is about 35 minutes bottom time and 140 minutes decompressing.

What does the pressure feel like at that depth? I've free dived to around 35 feet and that was nearly unbearable. Is it easier to cope with air?

Other than feeling the pressure change in your ears the same as you feel in an airliner or diving to the bottom of a swimming pool, it's not noticeable because humans are made of mostly incompressible materials.

If you feel pain in your ears when diving, you're not equalizing them properly and you're risking damage to your eardrum. Next time, try putting your tongue flat up against the roof of your mouth, sticking your chin out and swallowing as you descend. That should equalize your ears.


--------------------
Republican Values:

1) You can't get married to your spouse who is the same sex as you.
2) You can't have an abortion no matter how much you don't want a child.
3) You can't have a certain plant in your possession or you'll get locked up with a rapist and a murderer.

4) We need a smaller, less-intrusive government.


Edited by Diploid (04/05/06 04:10 PM)


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InvisibleDiploidM
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Re: Hyperbaric Chamber [Re: Seuss]
    #5483443 - 04/05/06 04:01 PM (17 years, 9 months ago)

Are you on a closed circuit back there?

Yes. I dive CCR for anything below about 300 feet, both for safety and for logistical reasons.

How long did it take you to plan that dive?

If I were diving there for the first time, I'd spend several hours easy the evening before designing the custom decompression tables, selecting the ratios of oxygen/helium/nitrogen in the Trimix, and working out dozens of other details. That's not counting the time required to calculate all the gas pressures, mix and test all the gasses, and pack the truck for the trip.

But, as it happens, that's actually a routine dive I do all the time, so I have all the logistics ready to go on a moment's notice. That particular cave is very dangerous because of the depth and a tight restriction on the way down. As such, only highly trained and experienced divers are even allowed in there, and they have to go with one of three designated instructor-guides, of which I'm one.

No different than at the surface, once equalized. Things like neoprene will compress, making thermal protection less efficient.

Although we dive wetsuits during warm summer months in the ocean off Florida, all our cave dives are done in drysuits due to the long time we spend in the constant year-round 70F water in Florida caves.

I have always wanted to get into tech diving

Well, as you know, you have a standing invitation if you're ever in south Florida.  :wink:


--------------------
Republican Values:

1) You can't get married to your spouse who is the same sex as you.
2) You can't have an abortion no matter how much you don't want a child.
3) You can't have a certain plant in your possession or you'll get locked up with a rapist and a murderer.

4) We need a smaller, less-intrusive government.


Extras: Filter Print Post Top
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