Peeing in wetsuits

[kelemvor]

I've seen (and participated in) discussions about peeing in wetsuits many times on this forum. Until today I never saw anything that actually explained why you have to take a whiz so bad when you go diving.

Today I was reading an article in DAN's alert diver magazine (Summer 2014) about the effects of nitrox on fatigue in divers. While the article didn't seem to present any actual useful information on the topic at hand it did explain the "wetsuit pee" phenomenon better than I've ever seen it explained. If you've got a DAN membership, you should have the magazine. The article is on pp58-52. Basically it says that the pressure causes excess blood to be pushed into your heart. The body responds by suppressing a couple hormones. That suppression results in you having to pee in order to eliminate some of the extra fluid.

Here's a link to the article on the DAN website: Alert Diver | Air, Nitrox and Fatigue

Neal Pollock: Many people do not fully appreciate the physiological impact of being immersed in water. An immediate response to the hydrostatic pressure is that a substantial amount of blood normally remaining in the capacitance vessels (veins) of the legs is pushed to the central volume (in the chest). A well-known study of this effect found that an average of 700 mL of blood is pushed to the heart during the resting phase of the cardiac cycle. The heart is stretched by the increased blood volume and responds immediately by contracting harder and then, over a short period, by suppressing certain hormones to promote increased fluid elimination through the kidneys. This is a healthy response to the physiological perception of the presence of excess fluid volume. Practically, this is why people have to urinate even after fairly short periods of immersion.

Just thought I'd pass on an interesting tidbit I stumbled across. Enjoy.

 

[mjrob]

I thought that, if I were to pee in my wetsuit, I'd most certainly die. I think I read that here somewhere...

 

[Nemrod]

I think DAN, in this case, is all, er, wet!

N

 

[spectre184]

I go a lot whether I'm in the water or out. Wife hates it when we go on trips in the car. I chalked it up to having a small bladder!

 

[drrich2]

Now that's different. I thought that since (aside from internal air spaces) the human body was considered non-compressible due to roughly equal pressure being exerted on & through us in all directions, the pressure had no significant net effect.

I was also under the impression that the sequence of events went like this:

1.) Human, body temp. roughly 96 degrees, enters water - let's say 80 degrees and no wetsuit, or equivalent.

2.) Water is far denser than air and pulls heat off the body much faster than air. This leads to cooling the body surface.

3.) Body perceives this as a heat loss threat, and shunts blood from the periphery to the deep structures to maintain adequate core body heat.

4.) This net increase in fluid (blood) in the deep structures appears to the body to indicate excessive fluid build-up.

5.) The body reacts by triggering increased urine output to eliminate perceived 'extra' fluid.

That's the process I thought caused immersion diuresis. Was anyone else under this impression, also?

Richard.

 

[gopbroek]

Ah, justification, kinda like lower external pressure causing gas on an aircraft. I no longer have to suffer from guilt.

 

[spoolin01]

Imersion Diuresis

I can't argue with that analysis of dive physiology, but it also seems to me that dive-motivated peeing is a feature of wetsuit diving but not drysuit diving. That makes me think there's more to it than just the pressure and temperature effects.

Drysuit diving, I've never had an urge to pee that was anywhere near too strong to resist. On the other hand, during weeks-long trips to Hawaii, this pattern seems to always develop: for a week or 10 days, it's easy to manage that urge while wetsuit diving; after that comes a dive where I have to give in, and once that happens it's a feature of every dive and soon I'm peeing 3 or 4 times per dive and have no ability to resist the urge for even a few moments once it hits.

Some of that is no doubt capitulation of the will, but it seems like there's also some change in kidney function set-point that just generates urine at a higher rate while underwater. I don't recall it being the same during the surface intervals.

 

[kafkaland]

Now that's different. I thought that since (aside from internal air spaces) the human body was considered non-compressible due to roughly equal pressure being exerted on & through us in all directions, the pressure had no significant net effect.

I was also under the impression that the sequence of events went like this:

1.) Human, body temp. roughly 96 degrees, enters water - let's say 80 degrees and no wetsuit, or equivalent.

2.) Water is far denser than air and pulls heat off the body much faster than air. This leads to cooling the body surface.

3.) Body perceives this as a heat loss threat, and shunts blood from the periphery to the deep structures to maintain adequate core body heat.

4.) This net increase in fluid (blood) in the deep structures appears to the body to indicate excessive fluid build-up.

5.) The body reacts by triggering increased urine output to eliminate perceived 'extra' fluid.

That's the process I thought caused immersion diuresis. Was anyone else under this impression, also?

Richard.

I thought immersion diuresis was caused by being "weightless" in water. The blood that is usually in your legs is now evenly distributed over your body. The body senses this additional fluid load on your heart, and has an endocrinal reaction to get rid of the excess fluid. But your explanation related to a centralization of the circulation because of external heat loss makes sense, too. Or perhaps it;s a combination of the two.

 

[industrious95]

Obviously you've never been stuck in a car on the George Washington Bridge for a 2-1/2 hour traffic jam after having 4 cups of coffee at the diner.

 

[drrich2]

Spoolin01:

Thanks for that link; looks like the mechanism I had heard of before, rather than pressure-based, at least in that discussion.

Kafkaland:

Interesting idea! Hadn't considered that.

Richard.