Decompression controversies

[Storker]

This video popped up in my social media stream the other day, and I can't see that it's been posted here before. It's a presentation by Simon Mitchell about gas content models vs bubble models, and the (in)famous NEDU study. I found it rather interesting.

 

[lermontov]

this is a very good lecture by simon mitchell well worth a watch

 

[Kevrumbo]

At 39:07 --> ". . .that Fast Tissue Supersaturation doesn't seem to matter . . .that Buhlmann knew years ago that you can tolerate much more supersaturation in fast tissues. . ."

So the next big question & implication that needs addressing as a result of the NEDU Study, how much can we empirically tolerate supersaturating our Fast Tissues over time & still remain asymptomatic -or lesser chance of acute symptoms- with regards to neuro type II DCS?

 

[tbone1004]

long story short

deep stops suck, vpm sucks, as proven by science


Kevrumbo, note that they were simulating 40/70 gradient factors, so it's not putting you through that much super saturation with that low of a GF-low. Pure Buhlmann is a bit more intense

 

[Storker]

---

---

A ScubaBoard Staff Message...

Duplicate threads merged

---

 

[Pao]

GF LOW 50?

 

[Pao]

Here is the original article from which the talk was based on:
http://spums.org.au/sites/default/files/DHM Vol43 No2 compact.pdf
The NEDU study is on pp 98-100

 

[Diver0001]

GF LOW 50?

Makes sense to me. The whole point of the research shows that you pay for too much time deep (including deep stops) by higher saturation in the slower tissues later on. Getting off the bottom (50/70) makes more sense, given the evidence, than using 30/70.

I'm glad I ran across this. This is a great presentation. I hadn't seen the heat diagrams before but they really seem to illustrate the issue. When Simon was on here arguing with Ross about it, I was focused on why they used what looked like a highly unconventional ascent and it wasn't clear to me that the same principle would apply to real world dives as well as it does.

Very interesting.

R..

 

[Diver0001]

long story short

deep stops suck, vpm sucks, as proven by science

I don't see any judgement calls about specific models here. What I see is a demonstration of how the models ACTUALLY work, which is different than what we've been lead to believe.

What I'm hearing him say is that the logic of avoiding bubbles works as advertised but that the logic is being applied to the wrong tissues. It's the slower tissues that seem to make the difference in whether or not you get DCS and we're putting all the effort in deep stops into avoiding bubbling in fast tissues.

R..

 

[tbone1004]

yeah, the problem is the way they're implemented. VPM implements by favoring shallow tissues. I didn't say the bubble model sucks, I said deep stops and VPM suck, very different