Ccr Diver From Ohio Died In Ginnie Springs Today...

[JohnN]

Here is the article i was referring to in my earlier post, click here. CO2 Sensing in Rebreathers.

Excellent article. Thanks for the link.

Pulse/Oximeters are now very inexpensive. Would it be possible to detect increased CO2 loading in the blood by monitoring the O2 saturation level? (I'm thinking of something like a clip on the ear lobe)

 

[KenGordon]

Ken, If this were actually true then why have there been multiple fatalities on eCCRs with 2 x current limited cells?
See Dual Sensor Failure at Lake Mead National Recreation Area - TEKDiveUSA

Are you suggesting that two cells being current limited is a failure which had not been previously characterised? Or that RB instructors have no suggestion as to what to do when that happens? They do not have a little plastic card labelled 1.7, 1.1, 1.1 to hold up under the water when practicing this on a course?

Ken, a thread discussing the fatality of a rebreather diver is neither the time nor appropriate place to discuss your issues with the links I posted. But in the interest of correcting your sledge: Yes, I am a Director of OSEL, a company that manufacturers, sells and ships the rebreathers designed, tested and certified as Functionally Safe to EN61508 SIL3 by Deep Life. All public knowledge and irrelevant to the publishing of links that can help those interested learn more about rebreathers in general.

If you have a problem with the testing done by Deep Life feel free to provide readers with a better source of rebreather testing!

QinetQ? SGS?

You have a product to sell, ok maybe you don't have a product but you do have a marketing campaign. You are now using this thread as part of that campaign.

Your campaign is to create fear, uncertainty and doubt about the other manufacturer's products. People should know that when following your links.

To anyone reading this thread. Google APOC and take a look at the history of OSEL, Deep Life, Brad Horn and Alex Deas.

 

[JohnnyC]

You can say I missed the biggest point, but what you posted was misleading and patently false. Without the appropriate caveats, your two quoted statements are mutually exclusive and I want to make sure that everyone is clear about this. You are not guaranteed any warnings at all.

Divers, if you're so intellectually broke that you can't pay attention to your PPO2, you should stay away from rebreathers. A few minutes of inattention and bang, you're dead.

Nothing I posted was misleading nor "patently false." You simply failed to clearly parse the important caveat, which I did point out. No big deal, it happens. You didn't need to get defensive about it but I can understand why. I certainly don't hold it against you. Rebreather diving is serious business and we should strive for accuracy. We are in complete agreement about many things regarding the use of rebreathers, most importantly, if you're not capable of keeping your PO2 in check you shouldn't be on a rebreather.

 

[The Chairman]

if you're not capable of keeping your PO2 in check you shouldn't be on a rebreather.

On this we agree.

 

[TONY CHANEY]

Excellent article. Thanks for the link.

Pulse/Oximeters are now very inexpensive. Would it be possible to detect increased CO2 loading in the blood by monitoring the O2 saturation level? (I'm thinking of something like a clip on the ear lobe)

No. It just does not work that way. You can have a SpO2 100% and have a PaCO2 of 90 mmHg. There is really no defined method to determine CO2 within the body by measuring a persons SpO2 which is just the % of hemoglobin that is saturated with oxygen. I feel too many divers really do not know the difference between end tidal PCO2, PaCO2. SpO2 and PaO2. Throw in CO in a bad mixed gas and it really gets crazy. i.e. A patient has a SpO2 of 100% but the Pt is cyanotic. Why, because the red blood cell's (hemoglobin) 4 receptor sites are saturated with CO instead of O2 but the pulse oximeter cannot detect what is loaded on the receptor site. OBTW, the red blood cells (hemoglobin) binding affinity for CO is 250 times greater than its affinity for oxygen. So basically you die of hypoxia instead of CO poisoning. But, it is rather an eye opening experience to read how divers view CO2, O2 and CO.

 

[lamont]

Besides, sanity breaths do not exist. The idea that switching to open circuit will somehow restore mental capacity in the span of a few inhalation/exhalation cycles is not true. There are plenty of reasons to bail out, and many that will give you time to solve a problem and go back on the loop in one form or another. However, bailing out due to compromised mental acuity will do nothing in the span of several breaths to allow you to go back on the loop. If you bailed out because you recognized your mental state declining, you have a gas-compromised loop, and going back to a gas-compromised loop is a sure way to punch your ticket.

I've had CO2 issues due to overexertion on OC. Chasing after a buddy with long legs and big fins in a cave class. We dropped down to 70-ish feet at one point so I got a bit of a narc on, and the instructors watched my perceptual awareness narrow and then threw some **** at us and we completely screwed it all up. The issue there wasn't the gas I was breathing, but my own fitness and how hard I was pushing myself -- lesson learned.

Similarly I know of someone who bailed out in a CCR class. The diver later went back onto the loop because the problem was similar. It was trying to keep up with the instructor (who kinda likes to swim fast to stay warm). Since the loop wasn't the issue when the diver's head cleared they realized what the issue was and switched back onto the loop and was fine.

So... Sanity breaths don't really exist. But there are more reasons than a gas-compromised loop to feel hypercapnia -- it might not be your loop and might just be how hard you are breathing. Of course, if you're working hard because your loop is going south it could be hard to tease that one apart so the safest thing to do would be to stay off of it...

 

[The Chairman]

I feel too many divers really do not know the difference between end tidal PCO2, PaCO2. SpO2 and PaO2

Why would they need to understand this? I certainly don't! I don't believe that rebreather divers need to understand this and I doubt you could line up a half a dozen instructors who could describe the relationships even casually.

EDIT>>> After having thought about this for a moment, while I may not need to understand what's happening on a molecular level, I certainly would like to know. @TONY CHANEY , please start a thread on this for us. I would like a clear understanding of the pulmonary functions as well as the blood chemistry going on.

 

[Reku]

Thanks for the crosslink, @DA Aquamaster . Very informative and sobering given the amount of cave diving experience Diver B had.

I presume with just over 1 year on the o2ptima, that he wouldn't really be considered "new" or "still learning" the unit, right? I ask out of ignorance. I have read there is a very steep learning curve and seen several post about hundreds of hours being needed on a unit to get to know the HUD light signals for example.

It sounds to me like there is no standard method for towing another distressed diver with a scooter. Maybe some agency could develop some sort of "scooter rescue" procedure to help in an event such as this? If possible, it may be a good way to help prevent other tragedies. Especially since Brent explicitly states it's not the first or even second time he's seen such a situation.


Also, thank you very much for the links and book information. With the costs of rebreathers and training being what they are, those books are a reasonable first step.

In terms of using the o2ptima for over a year it would depend on how much someone actually used it. Rebreather experience is based off 'hours on the unit' as in the number of hours underwater operating the unit. I could of had the unit for over a year but put little hours into it - In that case I would be an inexperienced operator but I would have owned it for a year. One rebreather dive can span several hours if you have enough bailout/deco gas.

 

[TONY CHANEY]

Why would they need to understand this? I certainly don't! I don't believe that rebreather divers need to understand this and I doubt you could line up a half a dozen instructors who could describe the relationships even casually.

EDIT>>> After having thought about this for a moment, while I may not need to understand what's happening on a molecular level, I certainly would like to know. @TONY CHANEY , please start a thread on this for us. I would like a clear understanding of the pulmonary functions as well as the blood chemistry going on.

Pete, please stop taking each and everything that anyone post as it was directly aimed you. I just sit back and watch and only jump in where I feel it is needed or wanted. I really cannot believe that you stated, "Why would they need to understand this? I certainly don't! I don't believe that rebreather divers need to understand this...."

Thanks for proving my point. I simply cannot believe that other diver like you post. My post is about breathing. Because that is what we do! Breathe! Without breathing nothing else is going to happen. If you do not know what is going on within your body how in the heck can you tell what is happening? Even from your first post you are talking about increased CO2 / hypercapnia, but then you say "Why would they need to understand this?"

I am glad that you edited your post to ask for, "a clear understanding of the pulmonary functions as well as blood chemistry going on." I might just start a thread based on your request.

 

[The Chairman]

Pete, please stop taking each and everything that anyone post as it was directly aimed you.

That's a fallacious statement. If you don't like what I post, then put me on ignore. I don't mind challenging statements that I don't understand or seem to be false. Too many frauds who act like they know it all when the only thing they have going for them is their confidence. You can either back up the claims with fact or not. Then I'll know what your confidence is based on.

I don't have to have a doctor's understanding of the physics and biology of respiration in order for my breathing to be effective above or below the water. If that were the case, little kids would suffocate. While I understand what hypercapnia, hypoxia and hyperoxia are, and what to do when I encounter them, I certainly don't pretend to understand them on a molecular level. Again, I doubt that you could find 6 instructors who could describe this in any detail unless they were a researcher, a physician or in the medical field.