Subclinical DCS and Deco Dives

[bamamedic]

Does it actually go fast enough to cause a sz? I thought things had to be blinking almost too fast to see to actually trigger one....

 

[Web Monkey]

Greetings Dr Deco!

It would appear that on many many dives I have the possibility of getting subclinical DCS. A typical profile would be ~70' for 20-25 minutes, a slow ascent with a minimum of a half stop for 2 minutes, followed by a slow ascent and an epic safety stop (~10 minutes). Total run time is usually around 45-55 minutes. All dives are done on nitrox, with appropriate mixes.

Both tables and your computer (if any) are based on a 30'/minute ascent rate. If it takes you 30 minutes to get back to the surface after a 70', 25 minute dive, you're way off the edge of the no-deco table for air

I'd suggest trying a dive that's well within the no-deco table limits, with a normal ascent rate (30'/minute) and a 3 minute safety stop, then see how you feel.

Terry

 

[Wormil]

Both tables and your computer (if any) are based on a 30'/minute ascent rate. If it takes you 30 minutes to get back to the surface after a 70', 25 minute dive, you're way off the edge of the no-deco table for air

I'd suggest trying a dive that's well within the no-deco table limits, with a normal ascent rate (30'/minute) and a 3 minute safety stop, then see how you feel.

Terry

That's what I started with, I felt like poo. I switched and felt like less poo. I'm also not diving air.

 

[Couv]

I think your avatar is wearing you down. Try something a bit more serene.

c

 

[DocVikingo]

Does it actually go fast enough to cause a sz? I thought things had to be blinking almost too fast to see to actually trigger one....

Hi Bamamedic,

In the clinical setting, strobe lights are sometimes used in an attempt to precipitate a seizure.

However, lower frequency photosensitivity also can be associated with seizures. For example, TV images and flickering sunlight through a line of trees or bridge supports or the like have been known to precipitate a convulsion.

Regards,

DocVikingo

 

[kaerius]

Lethargy following a dive has yet to be identified with a single cause. Some do refer to it as “subclinical DCS.” The belief is that it could result from gas bubble formation. What the bubbles would actually do is not specified.

Could be connected to something my EFR/O2/O2 instuctor instructor(hah, course director/dive medic technician, one of three course directors on my IDC as well), taught me; namely that bubbles in the bloodstream bounce on the bloodvessel walls, causing tiny bruises, these then swell up and then white bloodcells come and attach to them. This causes reduced bloodflow(and thus oxygen supply) to tissues.

I would hazard a guess that this would be one reason why subclinical DCS would tire you, as your oxygen supply is reduced. It also makes you more susceptible to going into shock.

I believe he in turn got it from the dive medic technician course or possibly a paramedic manual he showed us.

 

[amascuba]

Both tables and your computer (if any) are based on a 30'/minute ascent rate. If it takes you 30 minutes to get back to the surface after a 70', 25 minute dive, you're way off the edge of the no-deco table for air

I'd suggest trying a dive that's well within the no-deco table limits, with a normal ascent rate (30'/minute) and a 3 minute safety stop, then see how you feel.

Terry

That's what I started with, I felt like poo. I switched and felt like less poo. I'm also not diving air.

On EAN32, the NDL limit for 70' is about 45 minutes. Even with the insanely slow ascent your average depth is around 50' or so and your total run time still doesn't exceed the NDL of that profile.

Instead of doing a 2min. stop at half stop (I assume you mean half of your maximum depth, so around 35 feet?) and a 10 minute safety stop, try doing 1 minute stops every ten feet at half your depth to the surface. So for your 70' ft dive do a 1 minute stop at 30', 1 minute stop at 20', and a 1 minute stop at 10'. Your run time will be closer to 25 minutes. (When I mean minute, I mean get to your 30' stop wait for the minute to tick over, then move. Same for the 20', etc...)

More than likely your lethargy is related more to physical and mental exhaustion than it is to decompression stress.