Hydration

[kazinvan]

Can anyone explain to me *why* hydration helps prevent DCI? Or why being dehydrated promotes it? Everyone tells me "keep hydrated", but no one ever tells me why.

Thanks,
Mike

 

[jbd]

Can anyone explain to me *why* hydration helps prevent DCI? Or why being dehydrated promotes it? Everyone tells me "keep hydrated", but no one ever tells me why.

Thanks,
Mike

http://www.scubaboard.com/showthread.php?t=33161&page=1&pp=10

There were some thoughts and some doubts in this thread.

 

[Dr Deco]

Hello readers:

Hydration and DCS

The classical reason given is that fluid is necessary for good blood flow. Inert gas is carried in the blood stream entirely in solution (except when decompression bubbles are present). As far as gas exchange goes, it is not necessary to have red blood cells in the blood. It is necessary to have fluid.

Circulation is volume dependent. The most obvious consequence of fluid loss is shock since oxygen is not available to the body, especially the heart. A fluid deficit (hypovolemic shock) for a period of time will result in the swelling and death of cells of the body and “irreversible shock.” Many of the body’s functions are very dependent on an adequate hydration level.

Inert gases are moved around the body in the blood plasma. In the absence of adequate fluid, inert gas washout is reduced. The body will preferentially shunt blood to the heart and brain and shut down blood flow to the muscles (and tendons and ligaments).

Surface Tension

While it is by no means proven in the body, surface tension certainly affects small gas bubbles in vitro. The concept here is that pure water has a higher surface tension than water with the biomacromolecules [from the body]. The less water present, the more concentrated the biomacromolecules are. They will reduce (in principle, at least) the surface tension and allow microbubbles to expand (grow) more easily. Surface tension is an inward-directed pressure and helps to keep bubbles smaller than they would be in its absence. It is as if there was a small pressure chamber around each bubble because of surface tension. The greater the surface tension, the greater would be the pressure in this imaginary, tiny pressure chamber.

The greatest surface tension (largest constricting pressure) would occur if the body were pure water with no biomacromolecules (surfactants). This can not happen, but you can approach this salubrious condition by drinking water and staying well hydrated.

Dr Deco :doctor:

 

[kazinvan]

Thanks Dr. Deco, it's an interesting argument. What I'm wondering is how much difference there is in blood plasma volume when an individual is not fully hydrated. I'm not talking a person who is showing signs of serious dehydration. Is there really *that* much difference in surface tension and blood plasma levels in an individual before and after drinking two quarts of Gatorade? The body obviously deals with excess fluid very quickly. If I drink two quarts and end up urinating 1.5 shortly after, I don't see the benefit of 0.5 quarts of extra fluid in my body. It is possible that a small effect makes a big difference, that I don't know.

If you are at the point where you stop sweating, your body is shunting blood away from the muscles and into the core, and you are showing serious signs of clinical dehydration then I don't think going for a dive is your primary concern.

I'm still going to play it safe, drink my water, OJ, or Gatorade before and after dives, but I'm wondering if this is a bit overrated.

Mike

 

[Wildcard]

It's an intresting argument? Some claim to know a lot, this IS Dr Deco. I doubt there is more than one or two world wide that know more about this than him. Dr Deco isn't a brag title. Look at his back ground. Cripes! Thanks Doc for providing you time to answer our questions.

 

[pilot fish]

Hello readers:

Hydration and DCS

The classical reason given is that fluid is necessary for good blood flow. Inert gas is carried in the blood stream entirely in solution (except when decompression bubbles are present). As far as gas exchange goes, it is not necessary to have red blood cells in the blood. It is necessary to have fluid.

Circulation is volume dependent. The most obvious consequence of fluid loss is shock since oxygen is not available to the body, especially the heart. A fluid deficit (hypovolemic shock) for a period of time will result in the swelling and death of cells of the body and “irreversible shock.” Many of the body’s functions are very dependent on an adequate hydration level.

Inert gases are moved around the body in the blood plasma. In the absence of adequate fluid, inert gas washout is reduced. The body will preferentially shunt blood to the heart and brain and shut down blood flow to the muscles (and tendons and ligaments).

Surface Tension

While it is by no means proven in the body, surface tension certainly affects small gas bubbles in vitro. The concept here is that pure water has a higher surface tension than water with the biomacromolecules [from the body]. The less water present, the more concentrated the biomacromolecules are. They will reduce (in principle, at least) the surface tension and allow microbubbles to expand (grow) more easily. Surface tension is an inward-directed pressure and helps to keep bubbles smaller than they would be in its absence. It is as if there was a small pressure chamber around each bubble because of surface tension. The greater the surface tension, the greater would be the pressure in this imaginary, tiny pressure chamber.

The greatest surface tension (largest constricting pressure) would occur if the body were pure water with no biomacromolecules (surfactants). This can not happen, but you can approach this salubrious condition by drinking water and staying well hydrated.

Dr Deco :doctor:

How would 5 mg of ditropan affect diving/hydradtion?

 

[kazinvan]

It's an intresting argument? Some claim to know a lot, this IS Dr Deco. I doubt there is more than one or two world wide that know more about this than him. Dr Deco isn't a brag title. Look at his back ground. Cripes! Thanks Doc for providing you time to answer our questions.

I'm not doubting him, but he is saying:

"The classical reason given"
"While it is by no means proven in the body"
"in principle, at least"

Thus, to me it still seems like theory and speculation. Nothing seems proven to work (yet).

Mike

 

[Dr Deco]

Hello kazinvan:

What you have indicated is “the fine print.” These are all of the modifiers used by scientists to show such things as

• the limited data sets,
• the limited range of the data
• what parts of the conclusion are empirical and what parts are generalizations from theory,
• what portions of the conclusions are the interpretation of the author beyond what the data will sustain,
• what parts are the thoughts of the author and the fact that these might differ from the majority of scientists.

Yes, much of this is just an educated guess.

Dr Deco :doctor:

 

[kazinvan]

Thanks Dr. Deco. Overall, the explanation makes sense. As I said before, I will continue to drink lots of fluids before my dives regardless. Thanks for taking the time to reply.

Mike