Question DCS less likely if diver is cool?

[ABay Diver]

All other things being equal, are colder dive/divers less likely to get DCS due to slower on gassing? I know it means slower off gassing as well, but the less you take on, the less you have to breath off. Is this an argument for wetsuits over drysuits? Not being too “toasty” on a dive?

 

[arkstorm]

There is a correlation between being cold on the ascent (supersaturation phase) and increased incidence of negative outcomes.

I don't think that means being cold on the entire dive equates to reduced incidence of negative outcomes.

What this suggests is that if, e.g., you are using a heated vest, make sure to conserve the battery for the ascent as opposed to being warm on the descent and cold on the ascent.

I also recall somewhere in the "literature" that being cold in general increases the risk of DCS but I'm not sure what data there is to back that up.

 

[boulderjohn]

Yes, you are more likely to off-gas more slowly, and since you will likely get colder as the dive goes on and you are off-gassing, then it should make the situation worse.

But let's look at it from a different perspective. The odds of getting DCS are extremely low to begin with, especially on an NDL dive. Let's say, hypothetically, that you could indeed make a very, very minor improvement in that itty bitty percentage by being uncomfortably cold throughout your dives. Does that sound like a good trade off to you?

 

[rmorgan]

How (if at all) does this relate to the risks associated with a hot shower after a dive?

 

[JoeTPhilly]

Here is a link you might find interesting:

 

[boulderjohn]

How (if at all) does this relate to the risks associated with a hot shower after a dive?

The reason temperature is an issue during a dive is because of perfusion--the flow of blood through the body. When the body is colder, perfusion is more limited and inhibits the gas exchange that occurs as blood flows through the tissues.

The issue (which I consider minor) with warming after a dive has two parts, one positive and one negative. Here is the explanation from a DAN article:

If you are cold after diving, you will have diminished circulation in your limbs due to blood vessel constriction. Hot tubs (or hot showers) will warm your extremities and restore circulation faster. If your inert gas load is small, the warming will help eliminate gas more quickly because of the improved blood flow. Larger inert gas loads can cause more problematic responses. Since the solubility of gas is inversely related to temperature, tissues will hold less in solution as they warm. Warming tissues with significant gas loads can promote bubble formation. Because superficial tissues warm before the increased blood flow happens, bubbles formed then can be problematic. These develop before regular circulation can remove them harmlessly.​

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There is no simple formula to compute what constitutes a minor, significant or substantial peripheral inert gas load. The conditions vary based on the individual as well as their thermal protection, physical activity and dive profile.​

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In that article, DAN recommends delaying hot tub treatment 5-30 minutes after a dive. I would find it hard to get into a hot tub (or the like) in 5 minutes after a dive.

 

[Kendall Raine]

Cool (not cold) during working phase and warm(er, ish) on the hang.

If diving dry I close the exhaust value on ascent and dump gas in the wing until all buoyancy is in the suit. That way 1) I loft up for the hang, and 2) don't have to reheat suit gas.