Preventing Bends?

[Dr Deco]

Dear devjr:

You question on the exact anatomy of the micronuclei is a difficult one to answer. Assuredly, they are not plain, naked air bubbles. This is because the body fluids contain a large number of dissolve biomacromolecules that can adhere to the air/liquid surface of a bubble. This will lower the surface tension that in turn will:

[sp]-- prolong its lifetime and
[sp] -- make it easier to expand when in a supersaturated [sp][sp][sp]fluid.

The microbubbles may or may not be attached to some other solid structure. They are much more commonly found in tissue fluids than in blood (although they are quite common on the capillary endothelium (= cells that comprise the capillary walls).

It is not known how long the micronuclei persist in the body but some things are probably true.

1. They are not in equal concentration in all tissues,
2. Movement in a tissue seems to produce micronuclei,
3. They are probably distributed in size and number with many very small one (<0.1 micron), some medium size ones (about 1 micron) and a few large ones (about 3-5 microns).

Dr Deco :doctor:

 

[devjr]

If I remember correctly, some beer manufacturers have used additives to suppress foaming. Has any research of this nature been attempted on humans or animals, or whole blood? For example, it might be of interest to test for variations in blood samples by shaking(soda test), or/and testing various agents in vivo while decompressing test subjects.

 

[Dr Deco]

Dear devjr:

Yes, indeed, additives are added to beer to enhance form stability (rather than break up the foam). Too much stability will lead to what is referred to in the beer industry as “gushing” and mostly foam will issue from the barrel. This is wasteful and foam stabilizers are closely monitored. Guinness has even added a small device (the Widget) that will create bubbles in the can or bottle by hydrodynamic cavitation when pressure in the container is reduced.

As far as bubble reduction in humans, this is only in the nascent stage. While readers of this FORUM are well aware of the importance of micronuclei in the etiology (=cause) of DCS, this is not commonly recognized by scientists in the world of barophysiology. We see here an example of individuals (divers) who are not saddled with classical theory and bias, as are the scientists.

While my colleagues and I have yet to actually perform the experiments, we have certainly given this topic considerable thought over the past five years. One problem in humans is that there is a restriction on what drugs can be given, especially when we are discussing only a recreational problem. Not everything that will work with a lab rat would be suitable for humans.

If one examines the question in the light of micronuclei concentration, it appears to be true that some people contain fewer of these in their tissues and they posses a shorter lifetime than in other divers. [Another possibility is that some divers take on and excrete inert gas faster than others.] Since microbubbles are stabilized by surfactants in the tissues, the lower the concentration of surfactant will result in a greater surface tension (the tension will approach that of pure water = 72 dynes/cm). As one increases their water intake, the surface tension will rise in the bodily fluids as surfactants are diluted.

This was demonstrated in an experiment performed during WW II by Warwick (and described in Fulton’s Decompression Sickness) on 1,211 subjects. It was based on a questionnaire from test subjects on water intake and followed by altitude chamber studies to assess their susceptibility to DCS.

Glasses Water/ Day[sp][sp]Per Cent With DCS
3-5 [sp][sp][sp][sp][sp][sp][sp][sp]67
6-8[sp][sp][sp][sp][sp][sp][sp][sp] 64
9-11[sp][sp][sp][sp][sp][sp][sp][sp]58
12-14[sp][sp][sp][sp][sp][sp][sp][sp]44
15-17[sp][sp][sp][sp][sp][sp][sp][sp]26
18-20[sp][sp][sp][sp][sp][sp][sp][sp]0

For those who have an undying interest in this, my two-day class is in June at USC Wrigley Biological Station on Catalina Island.

Dr Deco :doctor:

Advanced Decompression Phsiology, June 22-23, 2002
http://wrigley.usc.edu/hyperbaric/advdeco.htm

 

[devjr]

Dr Deco:

I guess that explains why water laced with detergent blows better bubbles than water alone.

All this raises questions to the lay person. For example, how would lung function be affected by reduction of surfactants systemically? I believe I read that lung tissue depends on surfactant for effective gas exchange; also, that some persons who have been rescued with water in lungs subsequently die because of wash out. Perhaps the answer lies with cetacians or similar.

Has anyone looked at the blood of whales or seals? Evolutionists believe that whales are related to the hippopotemus. Comparisons of blood or tissue might be of interest. Perhaps the military would have an interest as well as NASA.

Thanks again for your time.

Dennis

 

[Dr Deco]

Dear Dennis:
You bet! Soapy water is much better for making bubbles.

People have studied the diving capabilities of cetaceans (whales, etc), but believe that their ability to resist DCS lies in the fact that they are breath hold divers. The nitrogen uptake in all of their tissues is actually quite small. Whether there are other characteristics of the fluids of their tissues and blood, I do not know.

The alveoli of lungs are indeed coated with surfactant that reduces the surface tension to the lowest in the body. The material produces a surface tension of about 0.5 dynes/cm compared to pure water that is 72 dynes/cm.. This makes the expansion very easy under normal conditions.

Dr Deco :doctor: