Increased risk of DCS severity?

[redrover]

A current discussion led me to the following question re: DCS severity risk.

This thread, ScubaBoard - Could you do it? has statements I’ve edited for the parts I’m asking about. The topic under discussion is risking personal harm to save another diver.

Beginning at Post#40:
If you are recreationally diving, your chances of getting bent are low. And if you do get bent you are likely to get fatigued first, followed by joint pain or skin bends long before you get type 2 DCS…….Recreational divers should stop agonizing over pulling regs out of people's mouths -- exhale to the surface and go onto O2 and hit the chamber if you have any symptoms. Stop being so terrified of DCS that you'll kill someone else rather than running the slightest risk of DCS

Post #46:
Well said, the tables computers are just guidelines that are designed with so much safety margin in them that it takes in the entire bell curve of responses. In normal diving stay within them and you have virtually no chance of DCS. In a rescue situation you have an enormous safety margin re DCS - skip the safety stop, exceed the ascent rate etc.

Post# 60:
Ask any Cayman DM/Instr who has been on the job for a little while, we all have had divers on our octo dragging us up, we've all slowed them down as much as possible but all ended up on the surface with a scared diver after the elevator ride. I can think of only a couple of times I've heard of this actually ending up in the chamber for the donor and that was when this happened on the forth dive of the day.

Post #68:
... but a fast assent doesn't equal being bent in every (or even very few) cases when you are looking at recreational limit diving.
Same thing on your comment on "blowing" a safety stop. Yup it is a great idea to do one, but it is a "safety" stop, not mandatory deco and 99.999% of the time not doing one doesn't have any bad effects.
.... the reality is that most divers on most days will get away with it. (otherwise in resort areas we would be having a diver death a day vs. the more normal one or two a year) When a diver does get bent doing one of these two 90% of the time a 6a treatment or two is all it takes to resolve. (boring....)

My understanding is there is increased risk of DCS factors such as (off the top of my head) age, fatigue, dehydration, caffeine, alcohol, body fat, stress, cold, pre-existing medical and nutrition. Can or do these additional factors also contribute to increased risk of DCS severity?
If so, is the severity increase in general reversible with treatment (severe fatigue, worse skin bends, more joint pain?) Or of a more serious permanent disability such as paralysis?

Please don’t get too technical, I’ve been reading about DCS and still have the question. I keep thinking all it takes is a big enough bubble in the right place…like spine, brain etc.
Mahalo

 

[Kendall Raine]

Could you please narrow and restate your question? The excerpts you quote bring up a number of themes and I can see this thread going in about ten directions at once.

Thanks, Kendall

 

[fisherdvm]

My understanding is there is increased risk of DCS factors such as (off the top of my head) age, fatigue, dehydration, caffeine, alcohol, body fat, stress, cold, pre-existing medical and nutrition. Can or do these additional factors also contribute to increased risk of DCS severity?[/COLOR]
Mahalo

I think it is like looking at an old house with old plumbings. All the factors you mentioned increased the risk of corrision build up in the pipes, and the weakness of the pipes, and sediment in the drains. The factors you listed also include the ability of the homeowner to repair the damage fast enough, before the basement is flooded (our immune system, which also is the repair system of the body). If you float a large enough wad through the drain, it will plug up. Pressure will build, and the drain will back up. Or the pipe freeze up, and will crack. If you don't have the resources to fix the drain and water problem, you will have a disaster.

All of these factors ties together .... obesity leads to diabetes and hypertension. These leads to vasculopathies and weakness and narrowing of blood vessels. Indirectly, they affect the immune systems and its ability to repair and control damages to injured tissue.

The assumption that a diver with an OK from a doctor to dive is saying that a house built and plumbed in the 18th century is going to have modern plumbings.... It ain't so... I would simply say, the older you are, the more conservative you should dive.

And definitely, older bodies heal slower than younger ones... Adding obesity, diabetes, hypertension, underlying vasculopathies from these conditions - certainly the severity is going to be higher.

You can not separate increase risk of DCS from increased severity of DCS... They go hand in hand.

 

[cerich]

My understanding is there is increased risk of DCS factors such as (off the top of my head) age, fatigue, dehydration, caffeine, alcohol, body fat, stress, cold, pre-existing medical and nutrition. Can or do these additional factors also contribute to increased risk of DCS <<<YES>>> severity?
If so, is the severity increase in general reversible with treatment (severe fatigue, worse skin bends, more joint pain?) Or of a more serious permanent disability such as paralysis?

More severe the "hit" the harder it is to reverse with treatment. Also the type of hit and location plays a huge part. The longer the hit" goes untreated the harder it is to treat, permanent damage may occur that otherwise may resolve with speedy treatment.

Some "hits" may do damage that is irreversible virtually immediately. This is relatively rare in recreational diving and normally only occurs with multi day and multi repetitive diving, mostly pushing the limits of NDL/assent rates and/or having a pre disposition factor such as you listed above. Sometime people get DCS with no apparant reason that remains a mystery.

Some people with major issues resolve virtually 100%, other with what may seem to be not as major have not resolved with dozens of treatments.

Unfortunately deco and DCS is NOT a hard science....

 

[redrover]

Apologize for the confusion. I wanted to ask in general in this forum, not specific to the thread. I included the statements simply as; where my question came from and not about will I try to help another diver. I wish I could figure it out from the technospeak about bubbles I’ve been reading but we can’t all be the sharpest knife in the drawer.

Cerich, you voiced what my understanding has been particularly; it is not an exact or hard science. I was surprised to see the statements I quoted, that us recreational divers don’t need to worry about DCS in a rapid ascent.

cerich and fisherdvm, given your answers here, would you say, “If you are recreationally diving, your chances of getting bent are low even with additional risk factors?

 

[fisherdvm]

I think that's a question for Dr. Deco to answer. As I understand, the diving tables were derived from a rather standard numbers of divers - likely male, young, and healthy.

When you try to extrapolate that to what we have now - very heterogenous - with different age, size, sex, body composition, and throw in a hand full of prescription drugs, recreational drugs, alcohol and tobacco.... My guess is that your chances of getting DCS is likely higher.

But again, Dr. Deco likely has read studies where the no deco tables and charts were derived.

My guess is - if you carry the additional risk factors, you would want to dive more conservatively than the most conservative dive computers and dive tables.... You might be outside of the bell curves....

 

[cerich]

The US Navy tables were developed from young healthy male divers . However it's been years since recreational divers used US Navy tables. Recreational tables in use are either US Navy based with extra conservatisim built in or based on newer studies.

One thing you can be sure of is that when this subject comes up people will always recomend caution, as it should be.

My observations from living and working in Cayman for 5 years are what I draw my conclusions from. The vast majority of people that get DCS fell into two categories, multi day repetitive toursist divers who get run down (tired and or have some drinks for dinner...) and on island instructors who either didn't take a day off that week or got drunk the night before. After those two groups are the ones that just don't make sense and divers that so pushed it it obvious.

For recreational diving this is my best advice for recreational no deco required diving

Have DAN Insurance

Practice a slow assent (30 fpm or less and slower if possible the last 30 feet) and agood 3-5 min safety stop on all dives and a further 1 min safety stop at half your max depth.

Be well rested and well hydrated.

Don't just "avoid" booze, just dont do it 48 hours before diving and 12 hours after diving.

If doing multi day multi dives take a day off after 4 days of diving.

 

[fisherdvm]

I think a person might be inside of the bell curve most of the times, but any factors which causes vasoconstriction or decreased blood vessel size could certainly aggravate DCS...

Diabetes - diabetic vasculopathy - small peripheral blood vessels
Hypertension - atherosclerosis - small peripheral blood vessels
Hypothermia - vasoconstriction - same
Tobacco use - nicotine induced vasoconstriction - same..
Obesity - hypertension and diabetes predisposition - same...
Use of decongestants - same...
Use of recreational drug like speed and cocaine - same result...

As you can imagine, most navy divers are healthy, young, and has no additional medical conditions (most cases)..

Then you wonder why we still get DCS

 

[cerich]

even still its fair to say that many recerational divers have at least one of those conditions, yet DCS is FAR from common in recreational divers.

Here is some stuff from DAN, my gut feeling is that as they only polled DAN members the results are biased high. Generally people that are frequent divers bother to join DAN, most once a year divers don't bother...

http://www.diversalertnetwork.org/medical/articles/article.asp?articleid=25

 

[Kendall Raine]

Apologize for the confusion. I wanted to ask in general in this forum, not specific to the thread. I included the statements simply as; where my question came from and not about will I try to help another diver. I wish I could figure it out from the technospeak about bubbles I’ve been reading but we can’t all be the sharpest knife in the drawer.

Cerich, you voiced what my understanding has been particularly; it is not an exact or hard science. I was surprised to see the statements I quoted, that us recreational divers don’t need to worry about DCS in a rapid ascent.

cerich and fisherdvm, given your answers here, would you say, “If you are recreationally diving, your chances of getting bent are low even with additional risk factors?

Let me try a different tack. Is the question: do predisposing factors increase the risk of 1) a hit, AND 2) the probable severity of the hit? If yes, the answer is maybe. For example, a large septal shunt or PFO-which allows venous bubbles to transit from the the venous side to the arterial side-correlate to an increased risk of a hit AND an increased risk of AGE? The answer is it should. Does this hold true for other predisposing factors? The answer is it depends. It depends on the person, the factor and the circumstances. The rule of thumb is the more predisposing factors, the more conservative should be the profile.

Rather than saying decompression science isn't a hard science, I prefer to think of it as akin to the science of predicting the weather. Lot's of "hard" science can be applied, but it's being applied to a relatively poorly understood and chaotic process.