How to switch with 2 deco bottles?

[TotDoc]

his article was not about ICD, it was about IEDCS, two very different things, position of the C and D are important. One often causes the other, but you can get inner ear hits without helium.

The article proposes counter diffusion as the mechanism of isolated IEDCS:
In the intro:

the development of deeper diving techniques involving breathing of helium-oxygen gas mixtures has been associated with the occurrence of “pure” or “isolated” IEDCS (7), especially when switches to air or other nitrogen-rich breathing gas mixtures are made to accelerate decompression (3). Indeed, isobaric switches of inspired gas, made while the diver is held at a constant ambient pressure, have precipitated symptoms of IEDCS in the absence of any decompression.

In the discussion:
The case described here typifies the type of technical recreational diving that is becoming increasingly widespread. It also illustrates the potential for isolated IEDCS to occur in a seemingly random fashion during an otherwise uneventful deep technical dive that has gone according to plan. As we will discuss below, this case and others like it suggest that some decompression algorithms for deep technical dives, particularly those incorporating switches to nitrogen-rich breathing gas, may need to be modified to avoid such events. It certainly seems possible that isolated IEDCS will become more common as technical diving grows in popularity.

note that I said I'd be shocked if the gas switch was determined to be a contributing factor, ergo the gas switch was not relevant unless he dil flushed whcih there was no mention of.

The breathing-gas switch results in a transient elevation of vascular compartment and endolymph gas tensions above ambient pressure; such supersaturation is required for bubble formation. The peak vascular compartment gas tension was 37.8 atm (0.4 atm supersaturation) occurring at 2 min after the gas switch.

And later in the discussion section...
However, IEDCS is clearly associated with switching breathing gas from helium-rich to nitrogen-rich mixtures (4, 10), and the present model suggests that such gas substitution may cause bubble formation in the membranous labyrinth and endolymph. The model implicates transient supersaturation resulting from a counterdiffusion mechanism in which helium transfer from the perilymph to the other compartments temporarily exceeds the washout of helium in the venous blood.

[floridabob]

TotDoc. It's refreshing to read your educated and intellectual posts where you actually try to reference an article/paper from a known expert.

However, it should be clear to you that all of us know more when placed by a keyboard than some PhD. I mean, hell, how much data could he have by using ALLLLL dives versus us using our 7 dives last year over 3 hours??

Duh. Go away. Go read some more silliness and let the experts continue to tell you what they know to be anecdotally true. Most of us actually have 2 deco gas mixes in our garage, never mind if we use them.

[tbone1004]

@totdoc, also in the discussion

"The present model of dissolved inert gas kinetics is not a complete model of inner ear decompression; for instance, it does not explain the 50-min delay between predicted maximum supersaturation and onset of symptoms of IEDCS in the present case report. This delay may be related to the dynamics of bubble growth due to gas influx and expansion during decompression or biological processes induced by bubbles that are not considered in the present model."

The delay in symptoms and the failure to mention a dil flush when they mention the O2 flush is why I'm not convinced that was an ICD incident and from the excerpt above as well as the rest of the discussion they appear to be making the conclusions that the issue is more that the models are not factoring in the ~9minute tissue that would represent the inner ear vs the actual gas switch.

https://apps.dtic.mil/dtic/tr/fulltext/u2/a112779.pdf
this is a bit dry, but this is the basis of our understanding of ICD with sections on how it relates to IEDCS

Beckner, Totdoc isn't the only one with a doctorate participating in this thread, nor is he the only one with published peer reviewed research papers... I'm a believer in ICD and make rational gas switches, but I do not believe that the paper originally cited is the right one to use to argue a point on ICD when it was clearly written about IEDCS.

[TotDoc]

https://apps.dtic.mil/dtic/tr/fulltext/u2/a112779.pdf
this is a bit dry.

I laughed when I read this. Simply because it's a good disclaimer for pretty much every text related to this material

I do not believe that the paper originally cited is the right one to use to argue a point on ICD when it was clearly written about IEDCS.

While I agree that the article is about IEDCS, the purposed mechanism by Dr Mitchell for the case in this article was ICD. I posted it as a case, in response to a comment that there were zero cases of ICD, particularly when I stated my concern about these gas switches was ICD, particularly as it relates to the inner ear.
I understand ICD. But since I have a side gig as a hyperbaric doc, I do lots of reading on this type of stuff. It just so happened I had this article open, and it was relevant to the current discussion, so I included it. It was never meant to be a primer on what ICD is.
If you feel this case didn't represent an ICD mechanism, you are welcome to argue that with Dr Mitchell, as that is what HE proposed. It wasn't my article, after all.

[TotDoc]

And for the record, I'm very much not an expert in ICD, IEDCS, or DCS in general. I'm just a baby hyperbaric doc who loves diving and has a life long obsession with physiology. I'm really not wanting to argue with anyone about this stuff... I'm LOOKING for information here. That said, I really appreciate it that the conversation has been continuing... just not necessarily in a fashion helpful to the initial thread.

[OFG-1]

Look at the bajillions of successful dives

Can you convert that to SI units?

[tbone1004]

Can you convert that to SI units?

mcf*ckton

[Arctic Mike]

mcf*ckton

How about metric?

[tbone1004]

How about metric?

touche, SI equivalent is metric f*ckton