Deep Stops Increases DCS

[ajduplessis]

You suggested, in very strong terms, that a diver might want to rethink their decompression strategy if their present approach produces a lot of bubbles.

I have pointed to evidence that your approach produces a lot of bubbles.

I can't put it any more simply.



I never mentioned the NEDU study in this exchange with you or drew any parallels with it. I am merely pointing out the apparent irony in your unrelenting defense of a decompression strategy proven to produce high bubble counts after strongly advising someone else that they should rethink their approach under similar circumstances.

Simon M

Did you actual bother reading things end to end? Obvious not, yet you still do pure guessing.

Firstly, My comment around the existence of real bubbles is that I personally would not shoot shallow and ignore deepstops, but merely suggested considering them being real vs imaginary. The Other thing that I did make 100% clear is that the study IMO only confirmed what we already know. The longer and deeper you stay the greater risk to injury.

Yet you continue to fabricate your own conclusions.

Yes, you never mentioned NEDU and neither did I mention bubble models or or drew any parallels with it.

 

[rossh]

Once again: I wrote that the bubble models' bubbles are imaginary. The real world bubbles in your blood, brain, ... are real. You need to distinguish between reality and model, particularly if the bubble model has never been calibrated by controlled experiments, because then you cannot assume any correlation between bubbles in the model and bubbles in reality. I'm not at all surprised about the findings in the paper by Ljubkovic et al., measuring a lot of real bubbles after a dive planned with VPM.

The Ljubkovic et al test procedure was to use settings in the fast position - highly efficient profile, with managed high stress. The result was a complete success - no injury. The testing confirmed the model calibration is spot on for this segment of the dive spectrum. It's a fantastic result for VPM-B.

I don't undestand the fuss. If we want to go fast, it involves higher levels of stress, and that's exactly what we saw.

.

 

[UWSojourner]

The Ljubkovic et al test procedure was to use settings in the fast position - highly efficient profile, with managed high stress. The result was a complete success - no injury. The testing confirmed the model calibration is spot on for this segment of the dive spectrum. It's a fantastic result for VPM-B.

As best I can determine from figure 1 in the article, Dive 1 appears to be about 63m 15min Tx16/45 EAN50@21m with a runtime around 68min.

What "high stress" VPM-B settings produce a 68min RT for this dive?

 

[Dr Simon Mitchell]

Did you actual bother reading things end to end? etc

Your post was very simple and easy to interpret. Your responses to my point are an obvious attempt to avoid having to provide a direct answer and to create uncertainty. Fine. People can judge for themselves.

 

[Dr Simon Mitchell]

Ross,

Your post demonstrates there is almost nowhere you won't go in an attempt to obfuscate the meaning of research whose results are negative to your product.

The Ljubkovic et al test procedure was to use settings in the fast position - highly efficient profile, with managed high stress.

Where do they say this? You are rewriting the paper in an attempt to lessen its negative impact on your position. And even if, for argument's sake, they had used nominal VPM, the result would still be a demonstration that a bubble model does not control bubble formation very well.

The result was a complete success - no injury. The testing confirmed the model calibration is spot on for this segment of the dive spectrum.

The experiment was not designed to confirm the "model calibration for this segment of the dive spectrum". I would have expected someone who markets a decompression algorithm to have a deeper insight into the requirements such testing. They performed 21 dives across 3 profiles. This is insufficient to compartmentalise the risk of DCS associated with those profiles below a level any of us would consider acceptable.

It's a fantastic result for VPM-B.

I find it hard to see how a study that demonstrated consistently high bubble grades after surfacing can be a "fantastic result" for a bubble model. You will recall that the bubble grades we are talking about (3 and 4) were the ones that led to explicit rejection of profiles in the development of the DCIEM tables.

Simon M

 

[lowviz]

You will recall that the bubble grades we are talking about (3 and 4) were the ones that led to explicit rejection of profiles in the development of the DCIEM tables.

Simon M

Dr. Mitchell,

Is this (below) the present grading protocol?

"The previously reported clinical VGE grading system (I-IV) was refined and calibrated as follows in VGE signals per second: Ia rare, Ib less than 1, IIa 1-10, IIb 10-100, IIIa 100-1,000, IIIb greater than 1,000, and IV uncountable."

 

[ajduplessis]

Is it not the Spencer scale?

 

[lowviz]

Yes, I copied that from the 1979 Spencer scale.

However, it is reasonable to ask if this is today's standard for grading one's level of bubbling.

 

[ajduplessis]

I believe so, but you asked Simon.

 

[lowviz]

Well, yeah, I did. But I'm happy for an answer from anyone who knows...

It just seems to me that logistic scoring would be way more appropriate for bubbling. But then, this may very well be a case of "good enough is good enough". (Difference between “Exponential Growth” and “Logistic Growth” – Explained!)