Thread split: CNS toxicity limits

[Vicko]

A realistic open circuit dive with 2 hours of decompression will put you at least close to the 100% cns limit.
If the cns limit was halfway accurate every other tec diver would cough up pieces of his lungs daily.

 

[stuartv]

A realistic open circuit dive with 2 hours of decompression will put you at least close to the 100% cns limit.
If the cns limit was halfway accurate every other tec diver would cough up pieces of his lungs daily.

A CNS limit and coughing up pieces of your lungs are two completely separate things...

 

[steinbil]

A realistic open circuit dive with 2 hours of decompression will put you at least close to the 100% cns limit.
If the cns limit was halfway accurate every other tec diver would cough up pieces of his lungs daily.

Don't you mean "every other tec diver would drown from a CNS toxicity seizure"? Am I still confused or is it very common to conflate CNS and pulmonary toxicity? This has confused me a lot in the past, and it has happened several times in this thread. Is there something I'm not getting? Are you implying a link between the CNS limits and OTUs and making a shortcut? Or is somebody saying the CNS limits are helpful to limit pulmonary toxicity because both OTUs and CNS clock tracks PPO2 exposure over time?

 

[boulderjohn]

There are also plenty of examples of divers taking a CNS hit even though they were within the limits prescribed by the tables.

Great! This is helpful. Please post some links to these.

 

[Vicko]

I'm being facetious and overly dramatic to point out how little we actually know about cns problems.
For example I keep ignoring the cns in the cns oxygen toxicity which shows how little I know, but my point still stands.
Pretty much any tec dive over 80m will result in high cns, and funnily enough I see the pulmonary toxicity a lot more than the cns one (I never actually saw a cns ox tox in diving).
I pity the admin who will be cleaning this one up, but not enough to stop with the off topic.

 

[cerich]

I am shocked how many instructors in this thread are confusing CNS Oxygen tox with Pulmonary Tox.


To those in the learning phase, there is VERY little value in the oxygen tox discussions the last few pages.

 

[Pavao]

And that is just rubbish. Millions of dives happen within the bounds of the tables and without CNS hits. Millions of very fun dives with very enjoyable amounts of bottom time. Those tables give a very safe baseline that MOST divers can and do use for enjoyable dives without incident.

I mean, he is telling you that the real limit is beyond the published limit, then your response is to say millions of dives happen without incident below the established limit, which he told you is likely way below the real limit!
How do you even respond to that?

 

[billgraham]

Regardless of where the data came from, it’s not a useful tool.

“100%” of the limit doesn’t really mean anything. Also, being below the limit doesn’t mean anything either. Passing 100% doesn’t mean anything. It doesn’t give you and information of value as to your risk of experiencing a CNS toxicity episode.

Yes, people have been saying that for years. Twenty something years ago, I had Kees' RGBM table software on my computer and a friend asked me to run out some tables for an upcoming dive. I did, and when I looked at it, his CNS % was way way over and I told him I wasn't going to give him the tables, he freaked out and we had this exact argument!

 

[Capt Jim Wyatt]

I am shocked how many instructors in this thread are confusing CNS Oxygen tox with Pulmonary Tox.

I'm not.

 

[Brett Hatch]

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A ScubaBoard Staff Message...

I have split this thread off from around page 30 or so in a recent A&I thread. I think there is some value in this discussion on CNS limits etc, it just didn't belong on the A&I forum. The discussion thus far is a little heated here, so I would like to remind you all to play the ball and not the man. I'd rather not have to clean up this new thread. Cheers.

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