Does Oxygen REALLY not contribute to DCS

[pescador775]

Cripes, breathing air the human body is only capable of dissolving less than a 1/2 liter oxygen per ATMA. Given such a small amount, the body has no trouble keeping the O2 tension below 2 ATMA. It takes some real gymnastics to create an O2 bend. Forget it, that is unless you know a diver who is diving O2 to depths below 100 feet, staying on bottom to SATURATION, and is surfacing in less than a minute.

 

[dsteding]

Well that might be it. The Henry's law constant of O2 is, what, about half of nitrogen's? Given that there is 2-3 times the amount of nitrogen in your breathing gas, you would have a quarter of the amount of O2 in solution at any one time. Combined with metabolism of O2, and you may not be able to get there at scuba conditions.

 

[rjack321]

Well that might be it. The Henry's law constant of O2 is, what, about half of nitrogen's? Given that there is 2-3 times the amount of nitrogen in your breathing gas, you would have a quarter of the amount of O2 in solution at any one time. Combined with metabolism of O2, and you may not be able to get there at scuba conditions.

This is my understanding as well. You need to way exceed 1.4 ppO2 and race to the surface.

 

[lamont]

This is my understanding as well. You need to way exceed 1.4 ppO2 and race to the surface.

The goats were on 100% O2 at 70 fsw or greater and went to the surface at 70 fpm...

 

[rjack321]

That might do it

Of course they might have toxed and then embolized? Wonder what a toxing goat looks like?

 

[dsteding]

The goats were on 100% O2 at 70 fsw or greater and went to the surface at 70 fpm...

Wow. Those are some unlucky goats.

 

[TSandM]

1) Oxygen is very poorly soluble in plasma. Nitrogen is much more soluble.

2) Most oxygen carried in the bloodstream is carried on hemoglobin. The reason you have hemoglobin is because oxygen is so poorly soluble. In the normal, healthy adult with normal lungs, hemoglobin will be 99 percent saturated at .21 ATA of O2.

3) Oxygen toxicity is primarily related to oxidative damage. High oxygen tensions destroy surfactant, which is the substance which reduces surface tension in the alveoli (small air sacs) and helps prevent them from collapsing. Some oxidative damage may be carried out by free radical formation; some may be from oxidation of proteins or fats and resulting changes in their behavior. If it weren't midnight, I'd go do some Medline searches to see what I could find from the laboratory bench about this.

4) You can undoubtedly produce some type of O2 bends, if you are willing to create the laboratory conditions. In practice, it's not going to happen diving, simply because your central nervous system won't tolerate the partial pressures of O2 necessary to dissolve enough gas in plasma to create bubbles, even with rapid ascents.

 

[Dr Deco]

Hello readers:

Nitrogen Bubbles

There have been many responses to this query and most have been on the mark. Nitrogen causes DCS because it forms a free gas phase and small bubbles. These cause various pathological processes depend on where they form or where they migrate. Dissolved nitrogen in inert at conditions found in the body.

Oxygen Toxicity

Dissolved oxygen is a very reactive molecule. It forms “reactive oxygen intermediates" [ROI] that are normally eliminated by the body’s defensive enzymes. When diving and using compressed oxygen, more oxygen enters the cells and produces more ROIs than the body can handle. These accumulate with time and produce problems in all tissues. The brain and lungs are target organs that are first noted but all organs are damaged. [If one anesthetizes an animal to prevent seizures and holds it at high oxygen pressure for a long period, the animal will never recover.]

Oxygen Bends

This interesting “event” occurs when oxygen is added on top of a dose of nitrogen almost sufficient to prod bends by itself. The oxygen bends remit within a few minutes.

Dr Deco :doctor: