Nitrox question

[BugHunterNY]

Willie... You're a real doctor? Like one of the ones on TV? The Chiropractor passing out flyers near my subway calls himself a doctor too...

I'm just teasing. I agree with you 100% that armchair divers are not in a place to give concrete medical advice - however, sometime, like this poster - he was specifically asking for anecdotal recommendations and he's already under the supervision of an M.D.

Hope you don't take offense - just good natured SB ribbing...


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[freewillie]

Yes, real MD. I've been around SB long enough to enjoy most of the banter but it helps to have thick skin.

Normally don't like smileys or emoticons since I equate that with my teenage daughter's texts but it does have some relay nonverbal emotions which is hard to convey sometimes in writing.

 

[TSandM]

Although I doubt anyone is seriously interested, there is actually a good answer to the saturation/Henry's law question.

Oxygen is pretty poorly soluble in aqueous solution, which is what plasma is. That's why we have hemoglobin in the first place -- regardless of the inspired oxygen concentration, and even with hyperbaric oxygen, if you have no hemoglobin, you can't carry enough oxygen in your blood to survive. Doubling the inspired oxygen tension results in virtually no additional oxygen on hemoglobin, in the presence of normal lungs, and although it doubles the ppO2 of oxygen in the plasma, the oxygen CONTENT (the number of oxygen molecules traveling around dissolved in the liquid) changes very little, simple because little additional oxygen dissolves.

Where breathing Nitrox might be helpful is where the level of exertion is high enough that the tissues are removing oxygen at a maximal rate from the blood. In that case, very desaturated blood is returning to the lungs, and having a higher inspired oxygen concentration might increase the gradient for oxygen diffusion sufficiently to avoid the arterial desaturation that has been documented in conditioned athletes. In us usual folks, I'm not sure what difference it would make. But polari, partial pressure and gas content are different, and for oxygen, this matters a lot.

 

[Polari]

Although I doubt anyone is seriously interested, there is actually a good answer to the saturation/Henry's law question.
Oxygen is pretty poorly soluble in aqueous solution

Iam interested
Yes, maybe Oxygen is poorly soluble but is interesting that is more soluble than Nitrogen.

Doubling the inspired oxygen tension results in virtually no additional oxygen on hemoglobin, in the presence of normal lungs, and although it doubles the ppO2 of oxygen in the plasma, the oxygen CONTENT (the number of oxygen molecules traveling around dissolved in the liquid) changes very little, simple because little additional oxygen dissolves.

Yes i see and i understand what you and freewillie trying to say.But what iam saying is that the oxygen in solution in divers is more because of the Hernys law.Hernys says that oxygen in solution is directly proportional to the partial pressure.
If this law is correct then it can be 6 times more.I know is not much if you compare it with the oxygen on hemoglobin but is still almost 1/10th of the total.So now we have this dissolved oxygen which can help supplying and maintain the tissue with fuel.If iam wrong please correct me.

In us usual folks, I'm not sure what difference it would make. But polari, partial pressure and gas content are different, and for oxygen, this matters a lot.

What do you mean by gas content? Other than Nitrogen and oxygen or the amount?
Maybe is something i cant comprehend right .My understanding is again :that oxygen in solution is directly proportional to the partial pressure.Means that the higher the partial pressure the higher the amount of gas dissolving in solution.In our case,we are talking about oxygen in blood.

 

[ev780]

Iam interested
Yes, maybe Oxygen is poorly soluble but is interesting that is more soluble than Nitrogen..

Lets see if a paramedic can help interpret. I can't remember if Oxygen is and "more" soluable or not but the concept of EAN diving is that there is less absolute nitrogen to be absorbed.

Yes i see and i understand what you and freewillie trying to say.But what iam saying is that the oxygen in solution in divers is more because of the Hernys law.Hernys says that oxygen in solution is directly proportional to the partial pressure.
If this law is correct then it can be 6 times more.I know is not much if you compare it with the oxygen on hemoglobin but is still almost 1/10th of the total.So now we have this dissolved oxygen which can help supplying and maintain the tissue with fuel.If iam wrong please correct me. .

I think what the docs are trying to say is that dissolved oxygen is essentially worthless, The machine that is your body needs oxygen in the form of oxyhemoglobin, which is oxygen bound to hemoglobin in your blood. It is really the only way your body's chemical engine can use it effectively. Once you are saturated then that is that. All the more is not really going to help much in the otherwise healthy person. Docs, did I get that essentially right? P-school was a long time ago and I have been driving a desk for a bit now.

 

[sphyrnidus]

http://www.umich.edu/~projbnb/cvr/O2transport.pdf
There is actually very little oxygen dissolved in the blood. Yes it's the oxyhemoglobin that does the trick.
And yes I doc

 

[boulderjohn]

I don't think this is a SB question, but is one that should be saved for a physician with a specialty in dive medicine and cardiology.

SB is actually a pretty good source for this. If this thread was in the Diving Medicine section, it might have gotten the attention of a specific member of our medical moderating staff, Doug Ebersole. Doug is both a cardiologist and a technical diving instructor. He has written articles on the heart and diving for DAN's Alert Diver magazine. I will let him know this thread exists so that he can jump in if he is not too busy.

 

[Polari]

the concept of EAN diving is that there is less absolute nitrogen to be absorbed.

True indeed.Also another benefit of EAN which in some dives is more important than controlling the nitrogen not to be absorbed is the offgassing of nitrogen due to the larger potential difference of the inert gas and the tissue.

---------- Post added September 12th, 2014 at 02:01 PM ----------



I google the subject we are talking here and is true what the docs saying but the main issue here they are not take into consideration hernys law. I found some examples that are self-explanatory.Here is just one :




Oxygen Solubility

As chamber pressure increases, PO₂ in the breathing media also increases. For instance, Using Dalton’s Law , air at sea level pressure (760mm Hg) contains 21% oxygen with a PO₂ of 160 mmHg. When the chamber is pressurized with air to 3 ATA PO₂ is 479 mmHg which is equivalent of breathing 63% oxygen at sea level. As the chamber is pressurized with air to 5 ATA, PO₂exceeds 798 mm Hg, which is greater oxygen pressure than can be attained breathing 100% oxygen at sea level!

Oxygen is transported by the blood from the lungs into the tissue by two methods: Bound to hemoglobin, and physically dissolved in the plasma. At normal sea level pressure where alveolar oxygen pressure is about 100 mm Hg, hemoglobin is already 97% saturated (Oxyhemoglobin) and yields an oxygen content of about 19.8 ml of oxygen per dl blood. When PAO₂ (alveolar oxygen partial pressure) reaches 200mmHg, hemoglobin then becomes fully saturated with oxygen. Therefore further increases in pressure will not increase the amount of oxyhemoglobin, thus oxygen transport via hemoglobin is not improved with hyperbaric oxygen therapy. Instead oxygen is dissolved into the plasma and carried to the tissues in physical solution. A person breathing air at sea level pressure has only 1.5% of the oxygen physically dissolved in plasma. Oxygen transport by plasma is the key to hyperbaric oxygen therapy, for even poorly perfused tissue can receive oxygen as the hyperoxygenated plasma seeps across⁴ it. As the chamber is pressurized, the elevated alveolar oxygen tension in the lungs drives oxygen into the plasma of the pulmonary circulation and it’s subsequent transport throughout the body. Unlike hemoglobin saturation, which has an S-shaped curve, the amount of dissolved oxygen increases linearly as PO₂ increases.⁴
Oxygen solubility is defined by Henry’s Law which looks at the relative quantity of gas entering solution as related to the PAO₂, but does not define the absolute amount of gas in solution. The absolute amount of gas varies with different fluids and is determined by the solubility coefficient of gas in fluids, which is temperature dependent. Oxygoen solubility in whole blood at 37^oC is 0.0031 ml of O₂ per dl blood per mmHg PAO₂. Breathing air at sea level arterial oxygen tension is about 100 mmHg, therefore the blood carries about 0.31 ml of dissolved oxygen per dl whole blood. When breathing 100% oxygen at sea level the amount of dissolved oxygen increases to about 2.1 ml of O₂ per dl blood. Breathing 100 percent oxygen at 2 ATA results in a PAO₂ of 1433 mmHg ( 4.4 ml of dissolved oxygen per dl of blood). At 3 ATA provides a PAO₂ of about 2200 mmHg and adds about 6.8 ml O₂ to each dl of blood. A healthy adult human at rest uses about 6ml of oxygen per dl of circulating blood. Thus HBO at 3 ATA provides sufficient plasma oxygen to exceed the body’s total metabolic requirement. The dissolved content of 6ml oxygen per dl of blood is equivalent to the sea level oxygen capacity of 5 grams of hemoglobin.. This phenomenon is the reason Dr. Boerma was able to sustain pigs life without blood in his study “Life Without Blood”.^4,6







---------- Post added September 12th, 2014 at 02:21 PM ----------

Iam sorry for this post but i find this situation really funny.If Herny was alive was going to say this

 

[sphyrnidus]

But this statement is about 100% Oxygen. Recreational mixtures do not exceed 36%.

 

[BugHunterNY]

But this statement is about 100% Oxygen. Recreational mixtures do not exceed 36%.

40%...


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