Doc Deep dies during dive.

[Germie]

The latest research indicates that oxygen is less narcotic than nitrogen.

Is Oxygen Narcosis A Thing?

There’s been a long running debate as to whether oxygen is a narcotic diving gas. Training agencies CMAS, GUE, PADI and PSAI include O2 in their equivalent narcotic depth (END) calculations. Others like BSAC, IANTD, NAUI and TDI do not. The problem has been reliably measuring gas narcosis. Enter...

gue.com

But I'm not interested in going to 134m to test that theory.

Some people think you stay alive at 30.0m END and die at 30.2m END. Happely the boundery is not that hard. Getting narced is not only a process of N2, but also of CO2. This means that an END let's say 30 at 30m depth is different from an END of 30m at 134m depth. Ok, the END maybe not, but factors as CO2 are different
I mentioned O2 narcotic and O2 not narcotic as this is still not completely understood. O2 is a strange gas in your body, it is used for you metabolism also. So some believe it is as narcotic or a little bit more narcotic as N2 (due to the atomic mass is an idea for example). But because of you use it also, a lot is still not completely understood. The last idea is that it is maybe less narcotic than N2, but more research must be done. So to talk about END, I normally give O2 not narcotic and narcotic.
If getting narced is due to all inert gases that need to leave your body over the lungfilter, and CO2 is also a narcotic gas, this means that you probably produce more CO2 due to a higher breathing resistance. And that is the gasdensity, EADD.
But also if you go down fast on let's say air to 50m, there is a chance you get more narced than that you go slower. This has to do with the PN2 between gas and body. And people state that if they go down and get narced and they wait a little bit time, the extreme narced feeling will go away.
I have felt narced at 44m and felt nothing at 65m on air. So it is a strange process. It already changes between the hour of the day.

But if breathing resistance also gives a (little bit) higher CO2 production, the WOB is higher when diving a rebreather. This is something to think about when using a ccr.

HPNS is something that is also still not completely understood. It has to do with too less or no inert gases in your breathing mix. Inert gases don't do anything, right? But there is something why a body 'needs' them. If you are a professional diver, normally they go down slow. Hydrogen (we cannot use as normal divers) and N2 are added a little bit to prevent hpns. This means a 3/97 gas gives you a higher change of hpns then a 3/95 for example. The compressing rate, how fast you go down, has to do with the way how fast or severe hpns will come. But if we dive, we cannot go that slow as commercial divers can do. You drain tanks really fast when diving oc over 200m depth. For sure if you go to 300m. Also staying longer at depths over 100, even if you go down further, your decompression will increase. The diver that does extreme dives dives alone at the highest depth. Safety divers will come between 100 and 150m (I don't know the exact plan of that record dive as I am not interested in doing records). This means any mistake down there alone can only be corrected by yourself.

So think on every deep dive you want to make, is it safe enough for me to accept the risks? And take the steps down to new 'personal depth' records slowly. I write personal records as there is still a 'deepest personal' dive. I don't mean that every diver needs to set records. For some divers going below 30m for the first time is a big step. And also that step has some risks. If you don't trust yourself, even if the dive is 'shallow', don't make it.
And if you sign up for a trimixcourse, think about this: Normally an instructor who teaches you a trimixcourse can teach you how to conduct deep decompression dives as safe as possible. But no instructor can say you will never get bent. Even if you followed a good plan, there is some risk left.

Another point if you ever want to do really deep dives or are asked to help:
Recorddives like this can only be done with the help of a big amount of help. Not only at surface but also in the water. The safetydivers in the water must be really good solodivers. I call it solodivers because they normally don't act in a team in the water, they handle alone. But you must not only be self sufficient enough to take care of yourself, you must be able to handle a lot of extra cylinders easely and must be able to follow a really strickt plan. Even if the recorddiver himself is good enough to perform a dive to 300+m, if the safetydivers are not good enough, a lot can go wrong. Just done some 100+m dives will not make you a good safety diver. And don't forget, the deep safetydivers also need shallow support from other safety divers. It is not only the recorddiver that needs safety divers. So if you ever get asked to act as a safety diver, ask yourself the question: am I good enough to perform this really important task?

And if you do dives at 100-130m, it is not bad to think already about safetydivers. Can you hold enough reserves for bailout or buddy if you do a 20 minute bottomtime at 100m?

Remember going deep is not difficult, but to get up to the surface safe again is the problem. For me, I don't feel any need to do a worldrecord dive.

 

[The Chairman]

focused on solving the problem

Too often, people work on assigning blame, which can make the situation worse.

Recorddives like this can only be done with the help of a big amount of help.

No! You're missing the big point here. Record dives like this are stupid and should not be undertaken. You simply cannot outthink compressive arthralgia and the only way around it is staged saturation. The USN already does this and has had open circuit divers below 1'000FSW, so what's the point? Vanity kills. There's nothing down there worth dying for. Stop the madness.

 

[Germie]

Too often, people work on assigning blame, which can make the situation worse.

No! You're missing the big point here. Record dives like this are stupid and should not be undertaken. You simply cannot outthink compressive arthralgia and the only way around it is staged saturation. The USN already does this and has had open circuit divers below 1'000FSW, so what's the point? Vanity kills. There's nothing down there worth dying for. Stop the madness.

I don't state that I agree with recorddives like this. I will never do such dives and do not support them. But it is a fact that money opens doors and that there always will be people who want to go further, extremer, etc. There is no way to stop them. And they always will find people to help them. Maybe sad, but true. That the usn has done such dives on oc, true. But then people refer to 'commercial' diving, etc. And that means for some people that it is not 'thrillseeking' enough. Just going deep and risk lives for just a record is stupid, I agree.

 

[ofg-1]

There's nothing down there worth dying for. Stop the madness.

But...But you get your name in a book. Right next to the most weight puled with eye sockets, most straws stuffed in your mouth, largest collection of belly button lint, most time spent in an ice bath, longest high wire walk in high heels. All are obviously more important than life itself. Personally, I am training for the loudest burp record.

 

[kammel78]

Sure, all good ideas. And yet when I had a problem with (I think) CO2 I was using a proper gas mix (15/55 trimix) going down the descent line at only about 100 ft, had streamlined gear, was riding a scooter, and had a fitness level higher than most tech divers. But I still got myself into a little trouble because I made some other mistakes including wasting too much time screwing around on the surface in rough conditions getting my gear squared away, and then tried to rush the descent instead of taking a moment to relax. It worked out fine in the end but if I had panicked then I could have had a real problem.

I'm not any kind of great diver but I think similar problems can creep up on anyone in the wrong circumstances.

Absolutely. I'm not implying we can 100% prevent CO2 related issues...merely pointing out the low hanging fruit. And to your point, proper gas mix, fitness level, etc. probably made the difference between a "little trouble" and a "real problem"

 

[kammel78]

There is a pretty direct connection between elevated CO2 and panic, however, for some it takes a little, and others a lot. That may be where the experience/mental toughness comes in.

No - this is EXACTLY the myth we need to stop perpetuating. The difference is individual's tolerance of CO2. We acknowledge this constantly with alcohol...oh, he's just a lightweight, can't hold his liquor, he can hold his liquor better than anyone I know. And no one is going around saying being drunk is an measure of mental toughness.

And it's been tested and proven...direct quote from Warkander DE and Shykoff BE. Combinations of Breathing Resistance and Inspired CO2: Effects on Exercise Endurance, NEDU TR 14-14, Navy Experimental Diving Unit, Feb 2015...."an experienced Navy diver described a sudden sense of panic as his PETCO2 climbed from about 60 to 65 Torr."

 

[Lorenzoid]

The difference is individual's tolerance of CO2. We acknowledge this constantly with alcohol...oh, he's just a lightweight, can't hold his liquor, he can hold his liquor better than anyone I know. And no one is going around saying being drunk is an measure of mental toughness.

I'm picturing a cartoon of a panicked diver with the caption, "Oh, he's just a lightweight--can't hold his CO2."

If it is a myth, there is the same sort of myth about holding one's alcohol being a measure of mental toughness. The tough guy in the movie can always hold his liquor.

 

[The Chairman]

The phrase "I can drink him under the table..." comes to mind. We all have our fantasies about what makes us 'special'. Some of those fantasies are dangerous and nigh on to stupidly fatal. Trying to set a record in deep diving is farm animal stupid. If the outcome might include inclusion or a special mention in the Darwin awards, I think I'll pass.

 

[kammel78]

I hate to keep derailing this thread, but I think CO2 is the single most misunderstood factor in diving atm and some of the replies support my theory.

Picture CO2 as pushing a ball up the hill. The higher the PCO2, the higher up the hill the ball goes and if the ball crests the hill and starts rolling down the other side, you have "panic". So, if the ball gets to the top and sits precariously on the crest, if you've had training to recognize the dangers of elevated CO2 and are prepared, you can most certainly make every effort to keep the ball balanced on the crest and keep it from rolling off the other side into "panic".

But, if PCO2 continues to increase the ball will go over the edge regardless of your efforts. They proved this in people with the condition where their amygdala doesn't function properly and prevents them from feeling fear by simply jacking up their PCO2 and guess what? They had panic attacks. Feinstein, J. et al. Nature Neurosci. http://dx.doi.org/10.1038/nn.3323 (2013).

Now, just imagine that the size of that hill, the height of the crest, differs for every single person and you understand why "some people are just more prone to panic" than others.

 

[Bob DBF]

Now, just imagine that the size of that hill, the height of the crest, differs for every single person and you understand why "some people are just more prone to panic" than others.

Now if you can tell me why it differs from one person to another. Why does the level of panic seem to be affected, to a certain degree, by training? Also, why do people panic without a CO2 hit? There seems to be a lot of variables, and you are taking one off the table without evidence.

I agree that at a certain point one will succumb to CO2 with panic and/or death, but how it is reacted on the way up the hill will make a difference.