DCS and possible causes

[Desert_Pirate]

I know of a diver who just got DCS. and my question is what is the primary onset? is it a matter of lots of small things wrong?

Subject is a male in his mid to late thirtees. he is in pretty good physical condition, He smokes, not clear if he drinks, and I dont have info on how well hydrated he was.

He was doing a training dive, with a police department. They had been diving some earlier in the day, however I dont know what his nitrogen level was. (what letter diver by tables, or how many diamonds he may have registered on his computer)

A fellow diver dropped a weight belt and it setteled in about 50 feet of water, approx 6000 ft elevation. he decides he will "bounce" and get it. When the belt was retrieved he is too heavy with his belt and theirs to resurface so he inflates his BC and his Dry suit and makes an haul a$$ ascent. i am told that he gained control around 8 feet so he hung out and did a safety stop for about 2 minutes. (dont kill the messenger here, I am just askin and tellin) he then surfaces.

Later that night he has a head ache but thinks nothing of it, the next day he does some pretty heavy aerobic work out and gains pain in his shoulder joint and then some numbness and tingling down into his hand.

after a trip to the hospital and a phone call to DAN he is treated for DCS. He was quoted to me saying that while in the chamber he felt a "release" when bubbles went back into solution and knew when he was cured. I have never heard anything like before... has anyone?

tonight I have my Search and Rescue meeting and this conversation is bound to come up. I would like some feedback on what probably, possibly, could have brought this on.

I have always been led to believe that De hydration is a huge factor and primary cause of DCS. I have been told that it is caused by too much bottom time and too fast ascent, or/and unproper Safety stop. Last night a very good friend and instructor told me he believes that possibly this onset was triggered by Physical exertion. Does anyone on the board have any answers or Ideas what may have happend. I know its oppinions but a little more understanding of DCS would be helpful to me tonight for our dive teams discussion.
Thanks!!

 

[PfcAJ]

Well, there isn't a simple "cause" of DCS. Its multifactoral.

Things that can increase your chances of DCS:

Poor ascent management
Bounce diving
Dehydration
PFO
Smoking
Poor physical condition (this is more than how a person looks, btw)
Body fat % (lower is better)
Lack of a safety stop
Dives approaching NDL or exceeding NDL
Cold during the ascent
Hot during the bottom phase of the dive
Post dive exertion
More stuff I can't think of at the moment. Some times, it just happens, too. No deco algorithm can guarantee that a diver will not experience DCS. The only way that can be accomplished is to not dive. Each one of those above variables is NOT weighted equally, either.

I'm not surprised your friend felt relief in the chamber, thats not uncommon.

It sounds like you work with this diver. I would take a look at your team's diving protocols and possibly rework some of them. Bounce diving is one thing I would cut immediately. I would also work on training so that everyone has precision buoyancy skills.

 

[Desert_Pirate]

Thanks, I dont work with him, this is a team in a neighboring county, and I am not sure of what the protocols are. I was more concerned because we have aided in several incidents when 3 or 4 counties have worked togather. The more education the better and was just curious if there was one that created a problem quicker than other. quite possibly i dont word my questions correctly,

My good friend was led to believe that this case was provoked by post dive exertion because of the sudden onset when the victim did it. however I guess it could have been set up with several poor judgment calls and that was the straw that bent the camels back?

 

[The Chairman]

I am not a human doctor: I cure sick networks... HOWEVER,

It would be my guess that the headache is incidental and has nothing to do with his DCS.

It would be my suggestion that his "strong aerobic workout" is the real culprit. Dr Deco has talked about the effects of exercise often and is in a better place to discuss it. Hopefully he will come along and correct my mistakes. When you work out all of your vessels dilate to accommodate the increased flow of blood. The pumping action associated with this kind of workout helps to create and grow micro nuclei bubbles which then get forced into the dilated capillaries. When work stops, these bubbles are trapped in the capillaries causing the DCS.

I avoid cardio workouts for at least 36 hours after a dive.

 

[Mr Carcharodon]

Depth, time and gas mixture are the most important things to look at. Fast ascents from depth especially if it not the first dive is a bad deal since you are changing pressure rapidly. It is the pressure difference between the dissolved gas in your tissues and ambient pressure that cause bubbles to grow. Of course if it is your first dive and you do a bounce there is not much dissolved gas to drive into bubbles in the first place. Post dive exertion is known to increase risk too. The theory there is that you make more small bubbles due to friction between your joints and those small bubbles can grow if there is a supersaturation of nitrogen. Dehydration may be a factor after losing several percent of your body weight, but most people are not that dehydrated most of the time. It would be a stretch to call it the primary cause of DCS.

A few suggestions: (1) get a lift bag for your team and, recommend the neighboring teams do the same; (2) keep ascent rates below 30 feet per minute; (3) dive nitrox; (4) spend 3-5 minutes between 30 feet and the surface and keep the last 10 feet of the ascent very slow (5) Get an oxygen first aid system.

 

[Bubbletrubble]

PfcAJ's list is a good one. I also agree that retrieval of the weight belt would have been safer using a lift bag.

I'd have to agree with your friend/instructor. With the case in question, if it was DCS, it's pretty clear that excessive post-dive exertion played a major factor. Why did the diver do a heavy aerobic work-out on the following day? That's a very poor decision based on published studies.

If you are curious how exercise can affect DCS pathogenesis, you are not alone. The prevailing hypothesis is that exercise, particularly activities involving joint-loading, can increase micronuclei activity which promotes bubble formation. Several published studies have looked at how the timing and intensity of exercise can increase or decrease DCS risk. Interestingly, Dujic et al. showed that a single bout of strenuous exercise 24 hrs prior to diving actually decreases venous gas emboli measured post-dive (vs. non-exercising controls). The authors speculate that this protective effect may involve a nitric oxide (NO)-mediated mechanism, i.e., exercise stimulates endothelial cells to release NO, which prevents leukocyte adhesion and platelet adhesion/aggregation.

FWIW, there is also a case report of a couple of instances in which physical exertion caused relapse in decompression illness.

The current recommendation is that intense physical exercise should be avoided 24 hrs before and after diving. During the compression and bottom phase of the dive, divers should aim for the lightest exercise possible. During the decompression phase of the dive, divers should be encouraged to do mild, low-intensity exercise. DAN has written a nice essay on exercise and diving.

Feel free to do a search using the key terms "exercise" and "decompression" on the Rubicon Research Repository. You'll get numerous hits.

 

[Desert_Pirate]

bubble, thanks I printed DANs report and will pass it on to my team

 

[Jim Lapenta]

Not to be real ignorant but what he did was just plain stupid. That can be a big factor in DCS that is not so easily fixed. What he did shows poor judgment, lack of skill, and poor buoyancy control. Be happy he is not on your team.

 

[drrich2]

...the next day he does some pretty heavy aerobic work out and gains pain in his shoulder joint and then some numbness and tingling down into his hand.

after a trip to the hospital and a phone call to DAN he is treated for DCS. He was quoted to me saying that while in the chamber he felt a "release" when bubbles went back into solution and knew when he was cured.

I'm surprised by this. I would've thought delayed onset DCS symptoms would be a matter of 'the damage was done' at the end of or in the hour or so after a dive (just guessing on time frame), and the symptoms took hours to manifest (perhaps due to tissue inflammation, for example).

I would not expect actual nitrogen gas bubbles to still be whirling around a diver's bloodstream, or lodged in his tissues, clear into the next day.

Does anyone know how long actual bubbles persist in the human body?

I'd think if they didn't, there'd be no point in putting him in a recompression chamber the next day, so obviously I'm missing something.

Richard.

 

[The Chairman]

Drrich2,

It depends on the half time of the tissue more than anything. Bones have the longest half time, while blood and neural fluids are very quick. Aerobic exercises provide a much larger amount of flow to these slower tissues and now all bets are off. It's impossible to make anything more than a guess as to where this sudden excess of Nitrogen will end up.