Scuba Diving and Bodily Functions

[Scuba_Noob]

I find that near the end of dives, as I get shallower and when I get out of the water, I often have the strong urge to urinate (or sometimes an urge to poop ). At my bottom depth, I never feel these urges.

Is that something related to the water pressure? In other words, as you get deeper, the pressure might help control these urges more easily, but as you ascend, the release of pressure makes things within want to move outwards. Also, the increase of pressure may cause minor irritations to internal organs and make the urges more likely after the pressure is released.

Or is it just the passage of time? Even when I urinate immediately before a dive and feel completely comfortable down there, I still feel some level of 'urge' afterwards.

I'm talking out of my butt here , but I'm wondering if people who have a better knowledge of the relationship between pressure and the body have anything to say about it. Or does this happen only to me?

 

[freewillie]

There is something referred to as immersion diuresis. It is a reflex that is triggered while diving. As blood moves from your extremities to your core in attempt to preserve body heat the change fools the kidneys and they basically make more urine. Ergo you now need to pee.

 

[g1138]

Pre-game morning dunks will solve one issue.
As for the other....it could be worse. My friend gets the massive urge to pee everytime he smells neoprene.

And don't worry, I too feel this way about the pee.

 

[TSandM]

HERE's a nice piece from DAN on immersion diuresis. It isn't pressure-related, but more time and temperature. It's the concept underlying what I call "Brekke's rule", because a nice DM named Brekke once told me, "Go pee before you get in your dry suit, whether you think you need to or not."

 

[Hickdive]

Two factors at work;

Cold: so your body reduces blood flow to the extremities causing an apparent increase in blood in your core. The body interprets that as a signal to reduce blood volume by, amongst other things, peeing more.

Secondly: Immersion reduces or even eliminates the normal pressure gradient from head to toe when standing up. The vaso constriction your body reflexively maintains to keep more blood in your head and trunk relaxes. This again causes more blood to be retained in your core and the body responds as above. This is why rescue helicopters don't now normally winch casualties from the water with their legs hanging vertically and instead use a double strop or a basket to lift the casualty in a sitting or lying down posture. It was found after the Fastnet disaster that otherwise healthy people winched vertically from the water were dying of shock before they reached the aircraft door as the water pressure that had been keeping blood in their core was suddenly removed and their body couldn't compensate quickly enough.

 

[Cave Diver]

Secondly: Immersion reduces or even eliminates the normal pressure gradient from head to toe when standing up. The vaso constriction your body reflexively maintains to keep more blood in your head and trunk relaxes. This again causes more blood to be retained in your core and the body responds as above. This is why rescue helicopters don't now normally winch casualties from the water with their legs hanging vertically and instead use a double strop or a basket to lift the casualty in a sitting or lying down posture. It was found after the Fastnet disaster that otherwise healthy people winched vertically from the water were dying of shock before they reached the aircraft door as the water pressure that had been keeping blood in their core was suddenly removed and their body couldn't compensate quickly enough.

Does this lend itself to the possibility that someone standing up and exiting the water after a long technical dive runs the risk of going into shock? What sort of time period are we talking about for this scenario?

 

[JamesK]

Does this lend itself to the possibility that someone standing up and exiting the water after a long technical dive runs the risk of going into shock? What sort of time period are we talking about for this scenario?

Good question. It would be interesting to see any data/theory on this.

 

[Hatul]

The urine part was explained above. As far as the pooping it may be in part from expansion of gas in the bowel as you ascend stimulating the reflex.

 

[Hickdive]

Does this lend itself to the possibility that someone standing up and exiting the water after a long technical dive runs the risk of going into shock? What sort of time period are we talking about for this scenario?

I've not heard of any technical diver suffering from shock but it certainly increases the urge to pee, especially if you've been keeping well hydrated.

You can experience milder but similar symptoms if you stand up suddenly from a long soak in a bath or hot tub. That sudde

 

[jewelofnile69]

So if I had to pee while I was diving dry and I was nice and warm, it was likely due to the fact that I probably had to pee before I dove? Just curious....boy did I have to refrain from the urge to just let go in that suit!!!