RBC's & PPN2

[scubadoc]

Both BillP and Lost Yooper bring up good points - the action of O2 on the red cell at the surface and depth probably cannot be compared.

I've not been able to find any articles that show that the rbc changes at depth are any different from those at the surface; even though we know that O2 under pressure causes marked changes in many most bodily systems (but at variable rates).

This question, like so many on this board, brings up many suppositions, speculations and opinions - but very few facts that have been subjected to rigid scrutiny. With a background in clinical medicine - I'm very reluctant to get into a 'spittin' contest with extremely knowledgeable researchers who have spent their lives investigating (usually) one subject.

Warm regards and good things!
Ern Campbell, MD
Diving Medicine Online
http://www.scuba-doc.com

 

[Dr Deco]

Dear Readers:

The posting by Lost Yooper concerning the divers making some “rather unconventional” dives and airplane flights bears some comments. This is almost in the line of a sermon - - here goes:

• As has been mention, there are not any true “bends/no bends” limits. It is in actuality a gradual progress where time at depth yields increase probability of DCS;
• in the construction work of the 1870's (St Loius Bridge), up to two hours of decompression were missed by most workers and many were fine - - but 13 died;
• in addition to increasing the probability of the bends, more time also increases the presentation of DCS making it worse as the gas loads increase;
• not all individuals have the same susceptibility to decompression sickness, and the reason for this is currently not known;
• differences in susceptibility to DCS were the reason for devising “selection tests” during WW II for bomber crews;
• by and large, these selection tests worked and were repeatable;
• as was true with airplane crews, we must assume that not all divers are the same;
• this being true, possibly a selection test could be made and individual tables for scuba derived;
• unfortunately, there are more variables in diving profiles than in those used by plane crews, and thus the selection tests might be almost worthless in actual operation;
• one way or another, the divers referred to have determined to their satisfaction that they have better dive procedures;
• to me, it is only evident that they have determined empirically that they are in the “resistant -to - DCS” group;
• it is therefore an egregious error to assume that you can also follow their dive techniques and obtain the same outcome.

The titration of individual susceptibility is not at all a common practice. I an loath to pursue this in any detail for fear that someone will actually use it. There is a saying “When it works, it works well. When it fails, it fails catastrophically.”

Dr Deco
:doctor:

 

[neil]

[*] one way or another, the divers referred to have determined to their satisfaction that they have better dive procedures;[*]to me, it is only evident that they have determined empirically that they are in the “resistant -to - DCS” group;


Not to mention pure dumb luck.

 

[100days-a-year]

neil,probly not dumb luck.These guys either invented or perfected deep stops,are responsilbe for the work done that became RBGM,write thier own deco programs,start thier own certifying agencies are responsible for a lot of the advances in rec diving.A major difference between a hunch and a hypothesis is 6 years + of school.Empirical evidence is usually accepted as evidence in court,not so for theory.

 

[neil]

Tony,
Yes, of course, but my flip little remark was intended to show that I agree with Dr. Deco that while these guys have methods that work (for them), none of their hypotheses have been proven in any substantial (scientific?) way that I know of, and the average diver should NOT be trying to do what these guys are doing. I am in no way downplaying the advances Irvine and his divers have made.

Anybody can start their own certification agency: Tony and Neil's Excellent Cert. Agency can be started tomorrow!

"A major difference between a hunch and a hypothesis is 6 years + of school."

Really? Tony, I don't mean to pick on you, but that is such a crock. As far as I know there aren't any degrees in decompression science, are there? I have college degrees, and while they may help my credibility when speaking on my subject, they don't make me an expert in my field. A hypothesis is just an advanced and properly worded hunch. PROOF is what is needed and you don't need a degree for that. You need data; you need to publish it; you need to have it reviewed. I'm no scientist, but isn't that how it's done?

Anyway, sorry, this is way off topic. Peace.
Neil

 

[Dr Deco]

Dear Readers:

The reply of mine was in no way meant to denigrate the efforts of the other divers. I do not know who they might be.

The bottom line is that many things work for one individual but tables are built to work for thousands under all conditions. The special cases presented here might not work under more varied circumstances. If one can examine just what is done, the method might be expanded and good things result for more divers.

It is naturally hearing about the more avant-garde methods that is my payback for writing these columns. I truly would be interested in hearing more about this – without counseling others just yet to perform the same type of dives.

Dr Deco

 

[100days-a-year]

neil,can we agree 1st to overcharge for classes,2nd break up every phase of training into specialties and 3rd teach a deep air course under a different name?I think there may be degrees in diving medicine...I was just illustrating the differences between theory and reality(I hope)Really I 'd hate for anyone un-trained to attempt this at home .I particularly like the disclaimer Ladydiver put on the Tek section.Off-topic is Ok by me ,pertinate is pertinate....

 

[neil]

Tony,
I got your point, I was just being difficult.
We should definitely charge way too much for classes, that will be our guiding business principle. I don't know about the deep air thing though, even my greed has it's limits. The hard part is going to be coming up with a really cool slogan for Tony & Neil's Excellent Cert. Agency. Maybe we should start a new thread for it.
"Tony & Neil's, All our dives have descents AND ascents! No extra charge!"
Neil

 

[Lost Yooper]

Everyone,

Irvine and those guys regulary tell others not to push things as far as they do. These guys are in top physical shape with a history of personnal experimentation. However, they do have a significant track record of safety among all of their divers that can't be ignored, IMO.

These guys aren't a DCS scientific research group per se -- they are extreme cave explorers. My only point is that there is more to the story of DCS than most people realize (including those in science), and there are very good indications that DCS can be beat using proper deco procedures, and if no preconditions exist.

I use many of the techniques the WKPP use but with my own safety factors put in place. In truth, I have never felt better after a dive than I do when I use their techniques. Learning from them has done wonders in improving my safety and enjoyment of the underwater world.

Take care.

Mike

 

[100days-a-year]

neil,the deep air class was a tongue in cheek reference back to LY who started the post.The certifying agency thing was a poke at Put Another Dollar In.I'd be a bigger fan of an agency that was small.The larger ones often have little control over what's done in thier name.We have a local instructor here that I wouldn't let snorkel in my pool and some I really respect and they teach outta the same agency and shop.