Deco stops

[MHK]

Genesis once bubbled...
some SCIENTIFIC, peer-reviewed studies on this matter.

Right now all we have is anecdotes. That's unfortunate, but it is the way of the world for now....

One can only hope that there will, sometime in the future, be an OPEN study made by some of the proponents. Not "proprietary anecdotes", but real, honest-to-god study.

There you go signing the same one note that you always sing.. Perhaps if you put into context George's statements, and perhaps if you consider that George's motivation isn't to satisfy you, you'll perhaps understand why George doesn't have a peer-reviewed studyhandy everytime you ask for one..

I am a member of the WKPP, and I'm there often when they do these dives that exceed the NOAA recommendations by nearly 10,000%. Accordingly if you are looking for peer-review please see Rutkowski or Hamilton.. Then ask yourself why Hamilton, Rutkowski and Morgan show up at Wakulla to learn from George and JJ..

When NOAA adopted their time limits, depending on whether you are talking about Pulmonary or CNS toxicity you'll look either to the Repex studies or the NOAA studies. The underlying presumption in those studies provides for a 90 minute half-time decay recovery theory. BTW, there is no peer review study for why Rutkowski and/or Hamilton used 90 minute half-time decay recovery it was just an accepted recovery time. Once you accept that 90 minutes is the "wrong" recovery time, you can then move on and see why at the WKPP we exceed NOAA by 10,000%.. George, and/or the WKPP isn't interested in providing you with peer-review studies every single time you make a post. Perhaps if you made an effort to understand what is involved, rather then simply claiming everything we do is junk science and screaming the same one note "peer-review" you'd have greater success with our responses.

According to the very peer review study that you want a diver should spend 45 minutes at 1.6.. Did it ever occur to you to wonder how it is that George and JJ did in excess of 4 hours and nearly 10,000% in excess of what your peer reviewed studies provide for??? Could it just be that the peer-reviewed study is flawed and by adjusting the recovery life half-time that we can achieve far greater results??? I guess what you don't understand is that George isn't out to convice you that what he does every week is correct. He doesn't care if you accept it without peer-review. What he does is report what is done every week at Wakulla. Some will look at the information and learn from it, other's will stand aside and ask for peer-review because they refuse to accept that they are much more efficient ways to do things.. The choice is yours which you want to do, but every time you ask for peer review I crack up because it tells me that you can't think on your own and you need other's to do your thinking for you.. Just like you claims of in excess of 8% hemoglobin binding would mean emphesemya, even though I provided several Cancer Society peer-reviewed studies offering up to 20% in smokers.. If what you were trying to say in your last peer-review mantra was that the "carboxyhaemoglobnin levels" is smokers range up to 8% I would have agreed with you, but that isn't what you were saying. You didn't understand teh difference between binding hemoglobin and reducing 02 transport and the psychomotor effects within the Carboxyhaemoglobnin levels.. All you did was cry about peer-review.. You did the same thing on the other board when you ceeded that the molecular weight of Helium is lower but yet couldn't understand why that transcended into reduced C02 accumulation, and you are doing the same theing here.. You don't understand what you are talking about so your knee-jerk reaction is to demand peer-review..

Ask yourself why is it that George and JJ spent 4 hours when NOAA said they should only spend 45 minutes.. Then provide me with a peer-review study when you figure it out..

Later

 

[MHK]

Diver0001 once bubbled...


Any idea why an air break would help in decompression?

R..

Oxygen is a vaso constrictor so by backing off the 02 [ ie; air break] you actually allow the constriction to reduce which in turns when you go back on 02 will mean less constriction. As such, you will more efficiently allow the transport of 02 and thus more efficiently decompress..

Later

 

[MikeFerrara]

Slam Dunk...

 

[Genesis]

just a bunch of anecdotes.

Second, we KNOW that succeptability to tox (acute) and DCI varies from individual to individual and even day to day. This is why you can do the same profile 100 times, and on time 101, get hammered.

The "accelerated deco" that GI3 preaches, as has been noted, appears to include the backgas breaks into the total time - without penalty for the lower gradient. That's aggressive. It works for him. It might not work for someone else.

There is a way to find out how much nitrogen is taken up and offgassed in a specific time, but it requires some pretty extreme scientific instrumentation and probably would have to be done in a chamber, because I don't know if you could manage to "make it work" underwater. But it IS possible.

It would be very interesting to find out whether the claims that nitrogen (or helium/nitrogen, in the case of trimix) offgassing is impaired by pulmonary impairment are true and the breaks are a net help or harm, all-up.

That someone BELIEVES a thing does not make it true. That someone gets away with something does not make it science - it makes it an anecdote and something that works for that ONE individual.

The problem is that such a thing does not necessarily translate to other people and THEIR ability to successfully use the same rules without getting hammered.

Right now we don't have that, and we probably won't have that. So we have to live with what we DO have, which is a bunch of anecdotes - by various people - and a bunch of competing theories, none of them with scientific validation.

This is not JUST a prod at GUE; its a prod at ALL of the proclaimers of the "one true way"!

 

[Dr Deco]

Dear Readers:

Reversal of Vasoconstriction

It is true that oxygen is a vasoconstrictor, although that can be completely offset by rather easy movements of the arms and legs during the oxygen-breathing phase. Slow movements are always useful during the off gassing period, as has been mention many times on this Forum by me. This is not speculation but is based on laboratory research at NASA and at DCIEM.

Oxygen-induced Vasoconstriction

While oxygen might constrict the capillaries, the effect is quite rapid. From first principles, I would imagine that breathing a low-oxygen gas would increase the capillary flow and allow more of the diluent (e.g., nitrogen) to be taken up by the tissues. Upon returning to the high-oxygen breathing gas, the washout of nitrogen would be restricted. The overall effect would be one of a reduction in the rate of nitrogen elimination.

Testing

The only real way to test this is to make a side-by-side comparison (i.e., a “cross-over” study) of methods using pure and nitrogen-diluted breathing gases. In the few cases where this has been done (and the studies are not without their problems), the results have not indicated an improvement in performance with “nitrogen leaks.”

So what?

This is not to say that possibly there is something to this. If I had the resources, I would be willing to test it. Unfortunately, the research climate is not going to make this happen in early 21st century America. We can hope that better days are ahead, but I doubt it. That is one reason why I, sadly, am looking forward to my retirement. Those who have the experience do not have the power, and those who have the power do not have the experience.

Dr Deco :doctor:

 

[boomx5]

I would like to see what BRW has to say about all this.

 

[MHK]

Genesis once bubbled...
just a bunch of anecdotes.

Genesis,

It's clear to me that your only interest isn't in sharing ideas and exchanging thoughts.. It's clear that you and I and you and the WKPP approach things from a different perspective. I totally respect your right to approach your diving in any way you see fit, but where I take issue with your approach is that just because you don't understand a concept that we do, you term it junk science and demand a peer-review study.

The problem with your knee-jerk reaction is that you can't demand peer-review for somthing that has never been done before, that is the very essence of exploration and ground breaking achievements.. It is the equivalent of asking for a map for a territory that is unexplored..

I have no problem if you want to stay with 45 minutes at 1.6, but when George or JJ routinely spend 4 or 5 hours I would suggest to you that rather then worry about what peer-review study George produces why not question the very study that you are relying on that only provides for a mere 45 minutes when every week at the WKPP we do 4 or 5 hours. The problem with you is that you are challenging the wrong people to back up their efforts.. You've lost a lot of crdibility in my eyes, and I'm therefore less likely to engage in back and forth with you because you are looking for the faults rather then appreciating what can be learned from the accomplishments.. Explorer's don't sit around waiting for peer-reviewed studies tell them what the limitations are, they go out and push the limits and find the barriers that other's who sit around in lab's say can't be done..

I'll give you a perfect analogy, I spent last weekend at Duke University doing a flying after study commisioned jointly by the US Navy and DAN. I've also spent the better part of the last 2 1/2 years getting right out of the water and right on to a plane. As you know DAN recommends anywhere from a 12 hour to a 24 hour waiting period.. Now you are free to wait 24 hours if you want, the study data has already been delievered to the US Navy, but your peer-reviewed study isn't expected to be released for 2 years.. So in this case if I said wait 4 hours before you fly, you'd be screaming junk science, demanding peer-review studies and while you spend the next ywo years of your life waiting for other's to tell you how to dive, we will have moved on to other projects and then when you catch up you'll accept the same premise because someone other then the WKPP said it..

Lee Iaococca used to say " Lead, follow or get out of the way".. You can choose your direction but we plan on leading and sooner or later someone else will "prove" to you that what we have been saying all along is correct, you'll just be a few years behind waiting for the studies.

I don't mean any of the above harshly, but just a realistic overview of our limited exchanges..

Later

 

[100days-a-year]

MHK,Those who can.....Do.
Those who can't.......Teach
Those who can do niether.....ridicule.
Faith and belief are for those intelligient enough to see thier own limitations and do not believe themselves to be the ultimate incarnation of rational thought.Your detractor tried this at another less moderated forum and was soundly trounced.I appreciate your remaining active here as well as BRW and especially Dr Deco to give actual anecdotal evidence vs. anecdotal derision.

 

[The Iceni]

MHK once bubbled...
There you go signing the same one note that you always sing. . .

I am a member of the WKPP, and I'm there often when they do these dives that exceed the NOAA recommendations by nearly 10,000%.

Ask yourself why is it that George and spent 4 hours when NOAA said they should spend no more than than 45 minutes.. .

Then provide me with a peer-review study when you figure it out..

Later

It appears as if this thread is getting a tad emotionally charged, which in itself is not good science.

As you may know, I for am no great advocate of the NOAA CNS toxicity limits because of the considerable variability but tended to accept the pulmonary limits because I understood, apparently quite wrongly, that the observations were repeatable. If the WKPP divers do regularly exceed these limits by a factor of 100 times (10,000%) it seems to prove that the NOAA pulmonary limits are somewhat conservative, to say the least.

This brings me to ask about 90 minute recovery times. To what exactly does this refer? This is genuinely from a position of ignorance. If this is recovery of vital capacity or FEV1, this unlikely to be related to a reduction and subsequent recovery of pulmonary gaseous exchange because there is so much spare capacity, which is not necessarily directly related to lung volume or peak flows.

I understand helium is used in respiratory labs to measure gas transfer, but do not know how it is done (yet). Perhaps gas transfer could be measured in decompressing trimix divers with another inert gas? Perhaps hydrogen. Would that be possible do you think?

Sadly, advances in "traditional" medicine and science are somewhat hampered by the need for expensive, double-blind placebo controlled studies and a requirement for peer review. In consequence I sometimes fear complimenary medicine and pseudoscience are on the ascendancy and in moments of despair, I fear we are heading to a new age of ignorance, where innovators are alternatively considered "heretics" or "experts" according to the whim of the observer simply because of the absence of "proof", whatever that means.

It seems to me there are few organisations capable of a genuine claim to be the peers of the innovators of WKPP. To an unbiased observer this is not helped by the attitudes expressed in the writings of certain of the WKPP participants (not you MHK!).

I share exasperation expressed by Dr Deco.:doctor:

 

[Genesis]

with characterizing exposures exactly (or figuring out if claims are right) is putting together ACTUAL PO2s during a dive.

Its simple to know what the PO2 is during a deco stop, and thus figure out the OTUs, but for the bottom gas its not quite so simple. This is doubly true when it comes to recreational-style exposures.

One of the issues that is raised by the claims and experience of some of these folks is just how the "recovery" actually works, and whether it applies ONLY to pulmonary tox or whether it affects the "clock" from a standpoint of risk of a CNS hit as well.

These questions aren't really answerable at this point.

The anecdotes of a handful of people do not present as a model that necessarily translates to reality for others, and certainly not for the diving population as a whole.

There are (probably) ways to scientifically answer some of these questions, but certainly not all of them, and not with certainty for anyone other than the subjects modelled. However, an understanding of some of the boundaries of individual response would definitely help to shape protocols for the diving public as a whole.

I, like you Paul, doubt we'll see it though.