Increased risk of DCS severity?

[Dr Deco]

Hello redrover:

“Hard Science” and DCS

I read often in SCUBA BOARD that decompression is not a hard science. Actually, the only hard science of which I am aware is analytical chemistry – and that only when all interfering substances are removed. There is variability in all science – and medicine.

Response of individuals to, e.g., an anesthetic, alcohol, or some medicine is variable. So it is with inert gas uptake and bubble formation/growth in diving. Unless a given individual has performed a decompression under specific conditions [before, during, and after deco – such as in a laboratory setting] can something be predicted.

A “random diver” will simply give a random result as predicted by a bell-shaped curve. That does not mean that we are not dealing with “hard science,” but rather that are more variables in decompression than estimated uptake and elimination. Even then, there also the variables associated with tissue blood flow and tissue nuclei number.

Conservative Tables

All tables are conservative in that the testing procedure identified the most sensitive subject and applied conservatism after that. Depending on how the data was viewed, there will be a different table generated. Divers will see the differences when they surface and different meters will yield different deco results.

“Animal Tables”

From time to time, I see it mentioned something to the effect that some tables were generated with data obtained from sheep and goats. This is not correct. All tables for humans are derived from humans. It is true that tests involving the relationship of different gas might have initial tests performed with animals, but ultimately human tests are performed.


Dr Deco :doctor:

 

[redrover]

Thank you all!
I have this nagging voice in my head that says; all it takes is one bubble big enough in the right place and ‘feces occurs.’ Consequently having the additional risk of age I factor it into my level of caution. Actually I was asking relative to beyond caution such as providing emergency response. What you said is what I could discern from the bubblespeak but not well enough to feel comfortable I ‘got it.’ I do have DAN fully expecting to never use it.:blinking:

I genuinely understand the problems (risks LOL) with providing internet advice, so anything offered is appreciated. Geeze it is difficult to figure out a way to fairy dance around the implications. I can only assure you I’m not looking for permission to do anything! I am looking for an answer to that naggy voice, but not to shut it up.

I’m surmising each individual situation (dive, additional risk factor(s) prior nitrogen load etc.) makes it impossible to predict when that bad bubble hits. The gist I see here is a more serious risk of depilating DCS would be expected in a less cautious general approach. Less caution being repetitive diving and multiple risks or advanced risks for example.

If my paraphrasing is an acceptable understanding, I can have a reasonable discussion with that naggy part of my brain.

Every time I read what I wrote I see more ways to interpret it, sigh. Suffice it to say I view each moment as it exists and make judgments or decisions in real time with an eye to the front for the big picture, and one to the rear keeping historical experience available.

 

[NJMike]

A very technical topic like this is first, hard to understand for anyone who does not devote the time and energy to read and evaluate what they read; second, as I read this thread, my mind kept going back to fisherdvm's analogy to the old house plumbing.

As untechnical as it sounds, I think it was a VERY good analogy to begin to understand and maybe should even be included in standard teaching! Just consider all the similiarities between the body and the house....both have plumbing, heating and cooling systems...both need proper maintenance...and you can surely find examples of how multiple things....like NOT cleaning a drain AND dumping the wrong thing in the drain...might combine to cause a problem....JUST LIKE multiple, repetitive days of diving AND drinking....

Anyway, fisherdvm, I thought that was a good post. Now, back to the techno side!