DCS & Gear

[daisho]

Hello All,

I am reading much about DCS and Decompression and it seems that you run a higher risk by doing physical activity after a deco dive.

How big is that risk? I am wondering since after a deco dive you still have to lug around all your gear. Will doing this greatly increase your risk for post dive dcs?

Thanks,
Dai-Sho

 

[Dr Deco]

Dear Dai-sho:

How much of an increase in DCS risk is not clear since tables have never been tested in this manner. The test subjects always just walk around somewhat. In the studies that I performed for NASA concerning decompression for Extravehicular Activity (EVA), there was a big difference in the condition of walking (what would be the conventional test configuration) and sitting down (the test configuration that mimics individuals in the null gravity of space). The difference between DCS risk in these two conditions was 10 times. That would be, for example, 5% versus 50% DCS.

Now all dive tables are test for people who are walking since that is common on the ground. However, lifting tanks is another story. This is not a part of the dive table program. I believe that many of the “undeserved hits” could be traced to similar types of strenuous activity.

How long does the risk last? It depends on the gas loads. I could not give a good answer since it is dive dependent. Nevertheless, remember that the decompression is not over when you hit the surface.

Dr Deco :doctor:

 

[SaltyWhale]

Hi DrDeco

How about consuming alcohol or a hot shower imediately after a dive?

 

[The Iceni]

.. or a soak in a hot tub?


Alcohol causes dehydration and we all know the deleterious effects of dehydration on DCI.

I'll get the chamber ready now!

Gasses become increasingly less soluble with increasing temperature.

 

[Dr Deco]

Dear Salty:

The practice of drinking alcohol and soaking in hot tubs is much discussed. One study did indicate that Doppler-detectable gas bubbles were released into the blood stream after rewarming, but that this did not provoke decompression sickness. Others have commented in these forums that it seems harmless. The jury is out on this.

We have not checked this at NASA since astronauts do not take hot showers following EVA - - or following anything else in space for that matter.:martian:

The effect of dehydration is more than speculation. A direct relationship was found with water consumption and [altitude] decompression sickness by researchers during WW II. We have water loss through urination with alcohol (it inhibits the anti-diuretic hormone and cause un-needed water loss) and additionally immersion diuresis. All of this contributes to the so-called “undeserved hits.” With a reduction of body fluid comes reduced perfusion and an increse in the concentration of surfactants. The latter leads to more bubbles growing during decompression. :whack:

Keep chuggin’ that water.

Dr Deco:doctor:

 

[SaltyWhale]

Dr Deco

Thanks for the tip.
Will take these notes into considerations.

Cheers

 

[The Iceni]

I take your point, Mike.

Anecdotal I know, but I had been lead to believe that there have been numerous cases of skin bends caused by hot showers.

Not that "skin bends" is life-threatening!

 

[DocVikingo]

Hi Dr. Thomas,

Perhaps the statement, "Not that 'skin bends' is life-threatening!" could benefit from a little more discussion.

Admittedly the term "skin bends" is a somewhat loose one, but cutaneous DCS comes in at least two flavors. The most common involves transient itching or "crawling sensations," often accompanied by rash, and is seen in chamber treatment, dry suit diving & caisson workers. It generally is not considered worrisome nor is it generally the focus of treatment.

The second type, however, is more worrisome & some experts consider it an indication for recompression treatment. Cutis marmorata, or patchy, red & white marbled areas on the skin that can be intensely itchy, is caused by venous obstruction/vasospasm and may be an early sign of more serious DCS manifestations to follow.

What think?

DocVikingo

PS: I agree with you that the possible occurrence of "numerous cases of skin bends caused by hot showers" is at present best considered anecdotal.