How to switch with 2 deco bottles?

I have a question for those who do 2 bottle deco, say 50% and 100%. When you reach the second, shallower switch, what do you do with the deco reg that is already in your mouth? Do you

a) prefer to clip it to the right D ring where the primary is clipped and allow it to remain there until you surface.

b) prefer to switch to back gas to give yourself an air break, stow the 50% reg and then make the switch to pure O2?

c) prefer to switch to pure O2 from 50% and then stow it while breathing O2?

I will be drilling second bottle management so I would like to know your recommendations.

Switching directly from one deco gas to the next is asinine. Back gas, stow, switch.

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Originally Posted by grantctobin

Switching directly from one deco gas to the next is asinine.

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asinine..? Please explain.

direct deco gas switching is super messy. High risk of hoses getting twisted and it's just generally a PITA. When you leave your 30ft stop and head to 20, then you switch to backgas, stow the 50% bottle, then deploy the 100% bottle. I usually nose clip the dead bottles or put them on a leash.

I like this approach.
https://youtu.be/ATfl-ou2_Yc

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Originally Posted by tbone1004

direct deco gas switching is super messy. High risk of hoses getting twisted and it's just generally a PITA. When you leave your 30ft stop and head to 20, then you switch to backgas, stow the 50% bottle, then deploy the 100% bottle. I usually nose clip the dead bottles or put them on a leash.

I like this approach.
https://youtu.be/ATfl-ou2_Yc

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Out of curiosity - why leash the 3rd bottle to the hip d-ring and not butt d-ring?

Interesting! In 27 years of trimix diving I have always switched directly from 50% to O2. I will have to try going to back gas between 30 and20. It seems to make sense.

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Originally Posted by RGU

Interesting! In 27 years of trimix diving I have always switched directly from 50% to O2. I will have to try going to back gas between 30 and20. It seems to make sense.

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Its definitely a much cleaner way to go. Even when diving stages and one deco bottle I used to keep the stage hose wrapped around my neck. I stopped and now do it as described above and am much happier. Unfortunately I wasnt taught that way either and I also as never taught the most ideal switch procedures. I had to learn through mentors and experience.


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Direct switch from 50% to 100% then stow the hose and reg on the 50%. Guess I don't get how its such a mess to do that way. I don't live in cave country so when I'm doing this its coming up a line from a wreck often times with current.

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Originally Posted by mndiver67

Direct switch from 50% to 100% then stow the hose and reg on the 50%. Guess I don't get how its such a mess to do that way. I don't live in cave country so when I'm doing this its coming up a line from a wreck often times with current.

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Direct switch = 3 2nd stages hanging around (50 + 100 + BG)

Switch to BG = 2 2nd stages hanging around (50 + BG) then (BG + 100)

It's just about eliminating risk. Breathing the wrong gas is still a considerable root cause of too many diving related accidents. This, along with proper bottle marking and buddy verification, helps minimize the risk.

Switch from 50 to 100, stow the 50 regulator afterwards. No need to make mountains out of molehills.


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It occurs to me that many of the dives over the years have required keeping the 50% around for "air" breaks.

I'll add my voice to the ones who have already stated that they go back to the BG reg between the two bottles. It's not so much about the air break as it is the simplicty. There are a few other things I would mention considering in this whole equation though. Such as where do you position the bottles? I have all my bottles on my left side. I try to think ahead with regard to bottom stages, 02 and any other deco gas and consider where I'll be placing them so that I can stow the hose for the bottle I'm coming off of cleanly and properly be able to verify the labeling on the bottle that I'm switching to. For instance a more common scenario for me would be returning to my 02 bottle at the end of a dive and breathing from a stage. I would come off the stage before I picked up the 02 bottle to ease in stowing the hose and then pick up the bottle (now on BG) and stow it outboard of the stage so that when I get up to 20 feet I can easily read the labeling on the 02 bottle and verify my gas before switching on to 02.

With just two gasses it doesn't make sense to be moving bottles around too much if you're not in a cave where you're dropping them on the line. On a recent OW dive I used 2 deco gasses and a bottom stage. I had the deep deco gas inboard, and the stage outboard in front of me. I had the 02 bottle clipped on a leash. When I came off the stage I was able to stow it easily. When I began my ascent I used the time at a deep stop (before my first gas switch) to clean up my bottles a little bit and I took my leash out clipped the empty stage to the leash and took the 02 bottle off the leash. I clipped the leash off and actually clipped the 02 bottle inboard of the deep deco gas. When I got up to the deep deco gas switch I was able to easily read the bottle deploy the hose and switch off back gas. When I came up to my 02 stop I switched off the deep deco gas at 30' was easily able to stow the hose and get onto O2 at the end of the dive. I surfaced with the O2 reg still in my mouth.

I could see someone making an argument that another way to do the sequence above would be to wait until after I was on the deep deco gas to rearrange the bottles. I could still verify the deep deco gas with the stage outboard, and it keeps the O2 completely out of the picture at that first gas switch. I think that's a valid argument.

Again with only two bottles it makes sense that you wouldn't want to have to rotate bottles if you didn't have to so thinking about the arrangement ahead of time to make sense for your dive is important. I know a lot of instructors teach a rule of some sort, rich on one side, and lean on the other or rich inside of lead or vice versa. It's important that the diver understand the "why" behind those rules, and that they are able to meet all the real necessary and important aspects of the gas switch (verifying the bottle you're breathing from, verifying the regulator you're about to breath from is connected to the bottle you've verified, stowing unnecessary hoses, etc)

Switch to BG, stow the deep deco reg, switch to O2.

Cleaner, minimizes risk of switching to incorrect mix, minimizes clutter/complications.

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Originally Posted by TraviTheDiver

Out of curiosity - why leash the 3rd bottle to the hip d-ring and not butt d-ring?

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not scalable when you get more bottles, and I find the leash easier than the butt d-ring. All "dead" bottles go on the leash which makes surfacing a lot easier.

You guys haven't picked it up yet. This is a guy who is trying to use the internet to train him. He has repeatedly come in here asking questions that should be answered by an *INSTRUCTOR*. Check his post history.

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Originally Posted by lord1234

You guys haven't picked it up yet. This is a guy who is trying to use the internet to train him. He has repeatedly come in here asking questions that should be answered by an *INSTRUCTOR*. Check his post history.

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yeah, but this is one of the only interesting discussions we have had in a long time on this forum, so whether he's trying to use the forums to train himself or not, it has us discussing useful things

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Originally Posted by lord1234

You guys haven't picked it up yet. This is a guy who is trying to use the internet to train him. He has repeatedly come in here asking questions that should be answered by an *INSTRUCTOR*. Check his post history.

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Idk why people get so upset and just tell people to call their instructor. People like to have a knowledge base before they take a class (be it good or bad) and the internet is one of the places to do it. I had a ton of mentors that helped guide me before I took certain classes. One instructor actually even set me up with the mentor as he knew he?s teach me how the instructor wanted.
If the guy takes advice here then konks himself so be it. Its not going to fall back on you.
I just wish the immediate shutting these things down with call your instructor would stop. I even think the op said that was his goal. But I?m too lazy to go back to the top to confirm.


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As far as minimizing risks goes - you deploy your O2 reg, show your buddy the tank, follow the full length of the hose with your hand to confirm reg/tank. You know you have the O2 reg in your left hand. No matter which reg (backgas or 50%) you take out of your mouth with your right hand, you know which one you'll put in your mouth with the left. I don't see how there's more risk of switching to incorrect mix if it's the 50% that you've just pulled out of your mouth.

I prefer to switch directly from the deep deco gas to the next deco gas. If you follow your verification procedures correctly it would be very difficult to switch to the wrong bottle. Your BG long hose should be clipped off, your secondary BG reg is on your necklace, richer O2 mix is in your hand current leaner O2 mix is in your mouth. You switch from leaner to richer then stow the leaner. Your hoses should not get tangled up, even if they did it would not be a big deal to untangle the two deco hoses. Personally i feel if you switch to back gas you would be adding a bit of risk, as it would be possible for you to not have your next deco gas in you hand at all times after the verification with your buddy. To do it safely you would have to reach your next stop depth, switch to BG, stow the lean mix, verify the rich mix, deploy the rich mix, then stow the BG reg. This seems more complicated to me than just verifying the rich mix, deploy, and stow the lean mix. Either way if done properly is safe, i think it mostly comes down to how you were trained and what you are most comfortable doing. Just my two cents.

One issue that has been described to me by hyperbaric physicians is the nitrogen "slam" when going from a low N2 mix to a higher N2 mix, then back to a low N2 mix.

Swapping from BG EAN32 to EAN50 and then to BG again - has PN2's of: 1.29 to .95 then back to 1.29 before switching to PN2 0.

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Originally Posted by Randall

If you follow your verification procedures correctly it would be very difficult to switch to the wrong bottle.

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Not to pick on you, but it's not the first time for someone to say something to the extent of, "as long as you do everything right, nothing can go wrong". There's nothing incorrect in your statement and I'm just using it as an example, but this is a dangerous train of thought. Risk management is about minimizing risks when things do go wrong (if they haven't, you haven't dove enough). Protocol will (and does) get broken all the time and our procedures should account for this as much as reasonably possible. The first time a real emergency happens, our brain shuts down and we react. I'd rather not have 3 regs to choose from if my buddy is OOG and I need to donate one...hell I've seen people try to donate their necklace in an "emergency" instead of their long hose and that's just with 2 regs and a 50/50 chance of getting it right. I've seen instructors stop whatever they're doing (including gas switches) because someone dropped their spool or light, it happens, it's instinctual for some.

I'm always going to screw something up, so let me reduce the amount of things I can possibly screw up as much as reasonably possible. Everyone has their own risk tolerance.

I think this all sounds very reasonable if your back gas is 32... but what if you're doing a dive at eagles nest, and your back gas is a high percentage helium mix?

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Originally Posted by Randall

Personally i feel if you switch to back gas you would be adding a bit of risk, as it would be possible for you to not have your next deco gas in you hand at all times after the verification with your buddy. To do it safely you would have to reach your next stop depth, switch to BG, stow the lean mix, verify the rich mix, deploy the rich mix, then stow the BG reg.

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Yes you're right you come off the deep deco gas and get on back gas, stow your hose before you even begin with the deployment. The idea is to have all the other tasks done so that when you switch to the shallow deco gas it's the same procedure you always always use. A lot of people get stuck on the how many hoses are around the neck, but the other aspect is that my mechanical movement to keep my left hand on the valve, and the right hand on the reg, and then swapping with the reg in my mouth and clipping off that reg stays constant.

Two fine points I would offer for this method that you can take or leave, is that I will typically come off my deep gas at the end of the previous deco stop. So for instance I would come off of 50% after having completed my 30 ft stop, I would ascend from 30 to 20 with my BG reg in my mouth. That way when I get to 20 to perform the gas switch it's a very familiar and consistent series of actions. Second, I keep my left hand on the valve and right hand on the reg after I verify the bottle I'm switching to because I can do one last dummy check. Right before I breath from the reg I'll purge the reg to see pressure drop on the SPG I have on the bottle my left hands on (not depressurize, just a tap so the needle deflects). Then when I turn the bottle on the SPG goes back to full pressure and I can check the bottle one more time and start breathing.

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Originally Posted by TotDoc

I think this all sounds very reasonable if your back gas is 32... but what if you're doing a dive at eagles nest, and your back gas is a high percentage helium mix?

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what are you worried about with the high helium mix?

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Originally Posted by tbone1004

what are you worried about with the high helium mix?

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Isobaric counter diffusion, particularly as it relates to the inner ear.

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Originally Posted by TotDoc

Isobaric counter diffusion, particularly as it relates to the inner ear.

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not relevant for O2 gas breaks

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Originally Posted by TraviTheDiver

Not to pick on you, but it's not the first time for someone to say something to the extent of, "as long as you do everything right, nothing can go wrong". There's nothing incorrect in your statement and I'm just using it as an example, but this is a dangerous train of thought. Risk management is about minimizing risks when things do go wrong (if they haven't, you haven't dove enough). Protocol will (and does) get broken all the time and our procedures should account for this as much as reasonably possible. The first time a real emergency happens, our brain shuts down and we react. I'd rather not have 3 regs to choose from if my buddy is OOG and I need to donate one...hell I've seen people try to donate their necklace in an "emergency" instead of their long hose and that's just with 2 regs and a 50/50 chance of getting it right. I've seen instructors stop whatever they're doing (including gas switches) because someone dropped their spool or light, it happens, it's instinctual for some.

I'm always going to screw something up, so let me reduce the amount of things I can possibly screw up as much as reasonably possible. Everyone has their own risk tolerance.

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Na you are not picking on me at all. I get it, every one has a different opinion of the best way to do something. It is definitely good to discuss these things, hopefully that's how we learn. I don't necessarily disagree with the point you are making. I generally keep an open mind as far as different ways to do something is concerned. The point I was making is, it seems more complicated to me to make two gas switches instead of one. Not saying it is wrong at all. Just not how I like to do things.



The idea of having 3 regs to choose from in a OOG situation, I understand. But you donate what you are breathing. I've been in situations where it has hit the fan. Fortunately for all involved training and practice kicked in, and everything was fine. I know that is not always the case.


I think the biggest issue with gas switches, and switching to the wrong gas, is not enough people practice theses skills when they are not actively using them. It comes back to the point you were making of, "Whelp I'm certified to do this now, now we just go do it". Too many times people get complacent with what they consider "mundane" skills. That leads to major issues when you brain shorts out.


There are always multiple ways to do something. When it boils down to it use the method that you and your team is most familiar with.

Even if you switch directly from one deco mix to the other, you still stow the first regulator immediately afterwards. Technically you don't even need to have 3 regs around your neck at any point in time, because you can take the reg out of your mouth and from around your neck at the same time, then immediately wrap the next hose around your neck and put it in your mouth.

Yes, protocols get broken, but they can get broken with either option. What grounds are there to claim, that putting a confirmed reg into your mouth has different levels of risk, depending on the reg you're taking out?

If you've confirmed the reg, both options are "safe". If you have not (or you've gone and fetched a reel in the middle of the switch), both are dangerous. You can't take a general risk and apply it to one situation only.

I think the best solution would be to dive CCR. None of those dangerous and apparently very complicated gas switches.

Now someone can chime in about stepping down your high He diluent as you ascend and then the required discussion about nitrogen uptake w/He outgassing and the benefits of one vs the other.....

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Originally Posted by floridabob

I think the best solution would be to dive CCR. None of those dangerous and apparently very complicated gas switches.

Now someone can chime in about stepping down your high He diluent as you ascend and then the required discussion about nitrogen uptake w/He outgassing and the benefits of one vs the other.....

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What Bob said... LOL

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Originally Posted by floridabob

I think the best solution would be to dive CCR. None of those dangerous and apparently very complicated gas switches

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100% agree... unless you have to bail out, effectively turning you into an open circuit diver for the purposes of your deco.

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Originally Posted by tbone1004

not relevant for O2 gas breaks

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Who is talking about o2 gas breaks? Aren't we discussing gas switches between deco mixes when multiple bottles are involved?
The reason I brought up deep dives with a heavy helium mix as back gas is because this may now be a 3 mix decompression plan, and because gas SWITCHING, not gas breaks, is exactly the time that ICD becomes a problem... particularly for the inner ear.

In real life, switches between sensible gases don't cause ICD issues.

Look at the bajillions of successful dives out there making switches from gasses like 15/55 and 18/45 to 50%. No issues.

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Originally Posted by TotDoc

Who is talking about o2 gas breaks? Aren't we discussing gas switches between deco mixes when multiple bottles are involved?
The reason I brought up deep dives with a heavy helium mix as back gas is because this may now be a 3 mix decompression plan, and because gas SWITCHING, not gas breaks, is exactly the time that ICD becomes a problem... particularly for the inner ear.

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10/70 or 12/65 or whatever to first deco mix of likely 35/25 or 30/30 or something around there is not going to cause ICD. Put helium in your ~100ft deco gas and then you don't have an issue. I wouldn't go from 10/70 to EAN32 though, that's a bad idea.

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Originally Posted by PfcAJ

In real life, switches between sensible gases don't cause ICD issues.

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^^This

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Originally Posted by PfcAJ

In real life, switches between sensible gases don't cause ICD issues.

Look at the bajillions of successful dives out there making switches from gasses like 15/55 and 18/45 to 50%. No issues.

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Not entirely true... in this article discussing ICD, there's a case included of an individual experiencing inner ear DCS related to a seemingly benign gas switch. Mind you, it was a rebreather diver, but the mechanics are no different...
https://journals.physiology.org/doi/...iol.01090.2002

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Originally Posted by TotDoc

Not entirely true... in this article discussing ICD, there's a case included of an individual experiencing inner ear DCS related to a seemingly benign gas switch. Mind you, it was a rebreather diver, but the mechanics are no different...
https://journals.physiology.org/doi/...iol.01090.2002

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i haven't read the whole thing, but it doesn't seem to be the case.
it reads like it was a 1.3 setpoint the whole way and he got bent in the ear at 9 meters. not after any gas switch

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Originally Posted by TotDoc

Not entirely true... in this article discussing ICD, there's a case included of an individual experiencing inner ear DCS related to a seemingly benign gas switch. Mind you, it was a rebreather diver, but the mechanics are no different...
https://journals.physiology.org/doi/...iol.01090.2002

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I'm with Litehedded, the gas switch probably didn't cause any issues, his tissues were probably quite unhappy after being at 1.3 for 2 hours *rough time when ambient pressure was 2ata's since graph resolution isn't great*. It's one thing on OC where your ppO2 falls drastically until gas switches. Says he switched from 8/60 to air at 30msw, so at 4ata he would be been at 4*8=.32ppO2, 4*60=2.4ppHe, 4*.32=1.3ppN2 switching to 4*.21=.84ppO2, 4*.79=3.1ppN2. Instead, he was running constant ppO2 of 1.3 through that and his tissues were likely quite aggravated and not offgasing efficiently.
Also, 8/60 is a stupid gas, and switching to air that deep is probably not the most brilliant of gas switches, but since his body would have been dumping He into the loop I'd be shocked if the gas switch was determined as a contributing factor since he was on a CCR and there is no mention of doing a dil flush when he made that gas switch.

Rule of fifths says that you get to increase ppN2 by 1 for every drop of ppHe by 5. 18/45 has 37% Nitrogen so switching to 50/50 has ppHe going down by 45 which means ppN2 can go up by 9 so technically that would be a max of 46 and 54/46 is a weird mix so it is deemed close enough and is deemed a "sensible gas switch.

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Originally Posted by tbone1004

I'm with Litehedded, the gas switch probably didn't cause any issues, his tissues were probably quite unhappy after being at 1.3 for 2 hours *rough time when ambient pressure was 2ata's since graph resolution isn't great*. It's one thing on OC where your ppO2 falls drastically until gas switches. Says he switched from 8/60 to air at 30msw, so at 4ata he would be been at 4*8=.32ppO2, 4*60=2.4ppHe, 4*.32=1.3ppN2 switching to 4*.21=.84ppO2, 4*.79=3.1ppN2. Instead, he was running constant ppO2 of 1.3 through that and his tissues were likely quite aggravated and not offgasing efficiently.
Also, 8/60 is a stupid gas, and switching to air that deep is probably not the most brilliant of gas switches, but since his body would have been dumping He into the loop I'd be shocked if the gas switch was determined as a contributing factor since he was on a CCR and there is no mention of doing a dil flush when he made that gas switch.

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So... he didn't switch to air, he switched to air as his diluent. I absolutely know people who have been taught to make that switch around 100 feet to help with helium wash out. I also know people that lie to their computer to tell it they made that kind of switch to decrease their helium penalty, even if no actual switch was made.
That said, your calculations don't really hold up for his nitrogen exposure, since air was dil, not directly inspired gas. Since the diver was holding 1.3, he would have needed to add o2 at 30m, thus decreasing the relative concentration of nitrogen in the loop.
As far as if this relates to an ICD issue or not, all I know is that Simon Mitchell felt it was, and that's why he included it as a case in his article about ICD. I don't pretend to know more about this issue than he does.
I do propose, however, that their must be SOME known problems related to ICD, otherwise why would they bother including it in curriculum for trimix diving?
As a final note... all of this is a big drift from the initial topic. The reason I asked my initial question was to see if people would treat the gas switching problem differently if high % helium trimix was involved. If a change of procedure would be needed based on the composition of the back gas, then I personally wouldn't really entertain a change in procedures involving other mixes, since consistency is paramount to folks like me that don't dive nearly as often as I would like. Admittedly, I don't really give much thought to this type of diving, anyway, as I suspect open circuit trimix diving is likely becoming less common with the high cost of helium and ready access to rebreathers. I personally won't be loading a set of doubles with high % helium any time soon...

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.
Also 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.

Your last comment however is actually very relevant as the rebreather running too high of a constant ppO2 is likely to be a contributing factor to his IEDCS and that would not have been an issue on OC or SCR. Be careful about what ppO2 you are running on those dives and don't be afraid to let it decay on the way up

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Originally Posted by tbone1004

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.

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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.

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Originally Posted by tbone1004

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.

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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.

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.

@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.

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Originally Posted by tbone1004

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

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

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Originally Posted by tbone1004

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.

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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.

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.

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Originally Posted by PfcAJ

Look at the bajillions of successful dives

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Can you convert that to SI units?

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Originally Posted by OFG-1

Can you convert that to SI units?

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mcf*ckton

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Originally Posted by tbone1004

mcf*ckton

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How about metric?

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Originally Posted by Arctic Mike

How about metric?

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touche, SI equivalent is metric f*ckton