More Deco Reading?

[TSandM]

AquaQuest: "DEEPER INTO DIVING, 2nd Edition" By John Lippmann & Dr. Simon Mitchell

Lippmann & Mitchell have a 2nd edition of their book, although this website currently lists it as unavailable.

There really isn't a whole lot of research going on into decompression theory, at least at the whole body level. I spent a fascinating evening talking with several research guys from NEDU, as well as Gene Hobbs. There is some very interesting stuff being done at the cellular level, looking at whether there is a component of DCS operating below the level of the systemic circulation. But there is very little money for the large-scale research projects that are required to evaluate things like decompression algorithms at different depths and times, or against one another.

 

[LiteHedded]

The issue with a lot of deco theory is that there are not a lot of real scientific tests to back up some of it (like s-curves vs linear vs exponential, o2 window, deep stops, variable ascent rates, etc) so its hard to make an official recommendation.

I'm not above experimenting a little. For me, deeper stops with a variable ascent rate with extended stop times when I switch gas works very well. No chamber rides yet, and I usually feel like a champ after deep dives.

nothing worth missing practice over

 

[Bubbletrubble]

I just read another paper that people might be interested in...

The essay is entitled "Gas Exchange, Partial Pressure Gradients, and the Oxygen Window" written by Johnny E. Brian, Jr., M.D. (former Assoc. Prof., Univ. of Iowa; currently in private practice, I think). I have to warn everyone of at least one rather glaring error in Brian's calculation (level of "unsaturation" of venous blood relative to ambient pressure during pure O2 breathing at 1 ATA, p. 9; should be ambient pressure [760 mmHg] minus total venous pressure [142 mmHg] = 618 mmHg [oxygen window], as depicted in Figure 6). Don't let that throw you off.

It's freely available on several websites. Here's a link to the Google Docs version of the PDF hosted on the Ocean Wreckers site. Here's a link to the Technical Reference webpage on the Ocean Wreckers site that contains PDFs of several useful papers.

 

[rjack321]

I just read another paper that people might be interested in...

The essay is entitled "Gas Exchange, Partial Pressure Gradients, and the Oxygen Window" written by Johnny E. Brian, Jr., M.D. (former Assoc. Prof., Univ. of Iowa; currently in private practice, I think). I have to warn everyone of at least one rather glaring error in Brian's calculation (level of "unsaturation" of venous blood relative to ambient pressure during pure O2 breathing at 1 ATA, p. 9; should be ambient pressure [760 mmHg] minus total venous pressure [142 mmHg] = 618 mmHg [oxygen window], as depicted in Figure 6). Don't let that throw you off.

It's freely available on several websites. Here's a link to the Google Docs version of the PDF hosted on the Ocean Wreckers site. Here's a link to the Technical Reference webpage on the Ocean Wreckers site that contains PDFs of several useful papers.

I've read that before, its more of the "milk truck" concept whereby there's a "space" created in the venous blood from O2 into which N2 offgasses. But it misses the fact that gases behave independently of one another (which is why IBCD doesn't really exist in sport diving - although it starts to at obscene depths where everything goes non-linear and for some rediculous gas switches).

 

[Bubbletrubble]

I've read that before, its more of the "milk truck" concept whereby there's a "space" created in the venous blood from O2 into which N2 offgasses. But it misses the fact that gases behave independently of one another (which is why IBCD doesn't really exist in sport diving - although it starts to at obscene depths where everything goes non-linear and for some rediculous gas switches).

@rjack321: Is it possible that you are mistaking this paper for a different one? The author clearly states in pages 1-3 that the on-/off-gassing behavior of one gas occurs independently of other gases.

 

[rjack321]

@rjack321: Is it possible that you are mistaking this paper for a different one? The author clearly states in pages 1-3 that the on-/off-gassing behavior of one gas occurs independently of other gases.

Well I didn't re-read the whole thing so I might have been off-base... But the figures are what I remember and they show a large venous vacancy which is "created" by O2 which doesn't jive with the independence of gases.

I'll re-read soon and see if I'm just confused

 

[PfcAJ]

Here's a good one by Doolette and Mitchell regarding inner ear DCS. Makes a case for 50/25 for long+deep dives.

Rubicon Research Repository: Item 123456789/8179

 

[Bubbletrubble]

Well I didn't re-read the whole thing so I might have been off-base... But the figures are what I remember and they show a large venous vacancy which is "created" by O2 which doesn't jive with the independence of gases.

I'll re-read soon and see if I'm just confused

Please re-read the essay when you get the chance.
You might find pages 11 and 12 to be very interesting.

 

[rjack321]

Please re-read the essay when you get the chance.
You might find pages 11 and 12 to be very interesting.

Well that's where the significant error is in the graphics & text for that matter. O2 is practically insoluble and the figure 9 is inaccurate. There's really no more "space" in the venous blood for an inert from the metabolic consumption of O2 from the dissolved state vs. the hemoglobin bound state. The inert (He or N2 doesn't matter) and O2 are independent.

And regarding page 11, the last paragraph there along with the text starting on page 12 is correct (and inconsistent with the figures). Figure 11 on page 13 is a disasterous mixup of terms and conventions.

Dr. Deco's discussions in the 2004 thread linked earlier are vastly better than this paper.

 

[craracer]

Try "Deeper into Diving" by John Lippmann.

I just started reading this book (first ed.), and a quick check of the index shows no entries regarding the oxygen window.

Sure, right after I get this book, TSandM pops up with a newer version. I'm always a dollar short and a day late.