'Clinically dead' rebreather diver dragged from quarry - and then revived

[DandyDon]

The compression only approach has long since been recognized as inappropriate for drownings:

Or small children. Why do so many here point out the difference for drowning victims but ignore that difference?

 

[rjack321]

Or small children. Why do so many here point out the difference for drowning victims but ignore that difference?

Because that wasn't what was asked about, would be great if can dig up the pediatric guidelines

 

[hroark2112]

Are you saying it's like a single-engine airliner - perfectly safe and a great fuel saver, if you're 100% focused on flying and maintain it 100% intact 100% of the time?

I'm saying that if you don't assemble it properly every time, or you exceed your training, or if you don't dive it properly, you're probably going to be someone we read about in the accidents & incidents forum one day.

Very experienced instructors have done very dumb things and ended up very dead. Diving with years old O2 sensors is one of those things you're told never to do in your very first class, yet it has been done with the expected outcome.

 

[Dr Simon Mitchell]

Very interesting, Simon. I can appreciate that having the lungs full of water will of course prevent them from functioning, but I've never heard this discussed in a CPR class--including one given by a municipal parks department, which operates several pools. Presumably in a drowning rescue someone would have tried to empty the airway and put the victim in a rescue position before starting to whale away on them, but it seems that not "air enough"?

Can you point me to a link to those guidelines, so I can look further into them?

Hello Rred,

I think you are missing the essential point. In any sort of asphyxia (like drowning) the cause of cessation of breathing is hypoxia, but this comes before cardiac arrest. Thus, there is a window for effective lifesaving by restoring oxygenation. If you can restore oxygenation before cardiac arrest occurs then there is a very good chance of saving the victim. If you intervene with compression only CPR in this window, then oxygenation will not be restored and cardiac arrest will follow. If that occurs, the chances of saving the victim are small, no matter what method of CPR you subsequently use. The accident scenario described here is almost certainly a great example of this principle in action.

I would be very surprised if a resuscitation course designed for swimming pool attendants advocated compression only CPR for drowning, and if it did they are wrong.

I have uploaded the UHMS guidelines which address the compression only CPR issue. rjack has linked to the European Resuscitation Guidelines in his post above.

Simon M

 

[Blasto]

It's not perfectly safe.
It obviously has some advantages over open circuit because otherwise why would anyone accept the additional cost, work of setup and breakdown, training and risk?

Of course. It has the advantages of being better at mitigating the risks of hard overhead environments and offering a more optimal gas mix for decompression from deep dives. So there are dives for which it's the better option with less total risk, or at least a more reasonable option than a dozen bottles to match it.

But to consider it as safe as OC and place all blame on user error would be too far. Something that doesn't turn into a danger to the user even if half its hardware fails or mistakes are made is clearly safer, by itself, than something that does.

 

[doctormike]

Of course. It has the advantages of being better at mitigating the risks of hard overhead environments and offering a more optimal gas mix for decompression from deep dives. So there are dives for which it's the better option with less total risk, or at least a more reasonable option than a dozen bottles to match it.

But to consider it as safe as OC and place all blame on user error would be too far. Something that doesn't turn into a danger to the user even if half its hardware fails or mistakes are made is clearly safer, by itself, than something that does.

Who said it was as safe as OC...?

 

[JohnnyC]

Who said it was as safe as OC...?

I don't think anyone said that it was as safe. I think the general attitude is that it is safer in certain scenarios, because of the specific risks of certain dives, not because the hardware is safer at a base level.

And those responses arose out of "OMGREBREATHERSAREDEATHBOXESOFDOOM!!!!!"

 

[KenGordon]

Of course. It has the advantages of being better at mitigating the risks of hard overhead environments and offering a more optimal gas mix for decompression from deep dives. So there are dives for which it's the better option with less total risk, or at least a more reasonable option than a dozen bottles to match it.

But to consider it as safe as OC and place all blame on user error would be too far. Something that doesn't turn into a danger to the user even if half its hardware fails or mistakes are made is clearly safer, by itself, than something that does.

There are two reasons that people die OC. First, their time has come. If they waited until next week and carried the cat up the stairs it might happen then. Second, user error.

Which bit of an OC set can fail without posing a danger to the user? Which mistakes don’t make a dive less safe? The kit all has a purpose, the protocols are to reduce risk. Break them or ignore them and you are exposed to greater danger.

CC diving is about risk mitigation too. The failure modes are different and so there are pros and cons. If I get in on OC with 100 bar because I can’t be bothered to change the cylinder and the dive I see only simple and shallow, but then my buddy has a problem and drowns due to me having too little gas, is that the fault of OC kit or an idiot diver? If I drive my car with a leaky master cylinder and can’t stop is that an issue with cars or the driver? Should we go back to cable or rod operated brakes because they require less maintaince?

For me the hardest thing in CCR is cleaning the lungs. I really don’t like it, it is fiddly and to do it properly you need to take the thing to bits, it will be some nasty fungal disease that gets me. Changing the cells is easy. Replacing the sorb is easy. Carrying about the sorb is a bit a pain, getting rid of a load of 25l chemical containers is a nuisance. On the other hand I don’t have to worry about gas. This weekend I will waste about 100l of helium diving 18/45 to 20m. This will cost about the same as the coffee I buy on the drive to the boat. If are blown out and I am doing 30m or 40m next weekend I will still have 18/45. If I was using a twinset it would be air or maybe the left over 20/10 because that is what is practical. If I did get a proper twinset fill for a 30 or 40m dive it would cost about £50 and a load of driving about. For a 50 or 60m dive I would do that, but not for 40m. So on OC I will be narced in a way I will not be on CC. OC you spend most of the dive very heavy, so buoyancy has some extra difficulty.

In the UK when you get on a boat doing vaguely deep stuff people mostly use rebreathers. Past 60 bottom time and cost are big limits for OC, ignoring the logistics. If anything goes wrong on OC that restricts surfacing you are in big problems very soon. I get very timid about dives like that, but I am way more comfortable about them CC. I know what the possible failures are and so long as I pay attention I know I can solve them.

It is fair to say that on a shallow pretty fishes dive the extra attention maybe too much, however you need to practice to be able to do the stuff where CC is really to only choice.

 

[Blasto]

Which bit of an OC set can fail without posing a danger to the user?

Any of them, except for the manifold.

Granted, there are three O2 sensors as well, but they have been known to fail simultaneously with the same mode.

 

[KenGordon]

Any of them, except for the manifold.

Granted, there are three O2 sensors as well, but they have been known to fail simultaneously with the same mode.

I think you miss where the issue lies. If you contend that an OC failure is ok because of redundancy then so to is any CC failure. I carry better redundancy for a CC dive than an OC one.

The crucial failures are those of the diver not noticing if the kit has failed. A bit like the OC failure of not practicing shutdowns enough.