Another fatal record attempt in Lake Garda, Italy

[Akimbo]

Does anyone know if v.deep saturation diving recycles exhaust gas from the helmet, or is it just vented off? That's a lot of gas lost if its vented as the bottom time would be a whole working shift, or measured in hours at least.

See #2 above. Open circuit sat diving was pretty common in the 1970s and early 80s. All gas including Helium was a consumable, like the DSV's fuel, and was a client paid item on all contracts. Gas recycling systems were experimented with since the mid-1960s. Cousteau's Conself III experiment used one in their habitat at 102.4m/336' in 1965. Here is an image of Cousteau testing his "push-pull" regulator.

 

[Degenerate]

@Superlyte27 — What set point do you plan with for a v.deep bounce dive? Also do you switch diluent to reduce helium loadings?

Planning with Bulhmann yields enormous CNS and OTU levels. Switching to lower helium mixes reduces the overall dive duration.

Just curious as it’s good to learn from people who’ve actually done these dives.

If you think those CNS and OTU levels are enormous then I'd hate for you to take a look at those 20h+ dives done by the WKPP.

 

[Superlyte27]

@Superlyte27 — What set point do you plan with for a v.deep bounce dive? Also do you switch diluent to reduce helium loadings?

Planning with Bulhmann yields enormous CNS and OTU levels. Switching to lower helium mixes reduces the overall dive duration.

Just curious as it’s good to learn from people who’ve actually done these dives.

I struggle with giving info that a Darwin candidate might use. Not talking about you, but thousands of idiots read this board.

I wouldn’t put as much worry into CNS and OTU as many people do. I’ve worked 200’ water towers on air at close to 1.6 for hours at a time. Working dives. Sure it was surface supplied, but none of us tox’d

With that said, 600’- 700’+? I’d probably be at a .6 or .7, no way higher than .8

But where your math and mine differ is ascent and descent. For example: My descent to 500’ was under 2 minutes. My ascent from 500’ to about 250’ was under a minute. That shaves an absolute buttload off of deco.

 

[Superlyte27]

If you think those CNS and OTU levels are enormous then I'd hate for you to take a look at those 20h+ dives done by the WKPP.

Exactly.

 

[beester]

I once was part (guinea pig) of a scientific test in a controlled environment. The purpose of the study was checking real pulmonary damage when breathing high PPO2 levels for extended times.

We were 15 divers breathing nitrox levels at 1.6 PPO2 in a 15m pool for 3 hours plus. Before the dive they checked our blood, spirotest and enzyme check on lungs. Same after the 3 hour + dive, with tests every half hour after getting out of the water. They had a lot of security divers in the water because they were afraid that the elevated OTU and CNS levels would pose a risk for O2 hits.

The sample size is of course very limited but nobody in the test team got a hit, and we all had CNS% levels above 300% and OTU's above 400. I'm not saying you should now just exceed limits without any thought, and if am longer on pure O2 or a 1.6PPO2 I'll take O2 breaks or (if on ccr) I'll make sure my PPO2 stays lower (1.4 or 1.5).

 

[Vicko]

Out of my (compared to some people in this group limited) experience being a safety diver or a tank monkey on a number of deep dives, out of 10 divers who do a 3-8 hour dive 1 will have some sort of respiratory problems, and 0 of them even check their CNS because it's impossible to a dive like that and remain within the safe zone.

 

[Hiszpan]

I once was part (guinea pig) of a scientific test in a controlled environment. The purpose of the study was checking real pulmonary damage when breathing high PPO2 levels for extended times.

We were 15 divers breathing nitrox levels at 1.6 PPO2 in a 15m pool for 3 hours plus. Before the dive they checked our blood, spirotest and enzyme check on lungs. Same after the 3 hour + dive, with tests every half hour after getting out of the water. They had a lot of security divers in the water because they were afraid that the elevated OTU and CNS levels would pose a risk for O2 hits.

The sample size is of course very limited but nobody in the test team got a hit, and we all had CNS% levels above 300% and OTU's above 400. I'm not saying you should now just exceed limits without any thought, and if am longer on pure O2 or a 1.6PPO2 I'll take O2 breaks or (if on ccr) I'll make sure my PPO2 stays lower (1.4 or 1.5).

What about the results of the lung parameters after the test?

 

[beester]

What about the results of the lung parameters after the test?

The results were not conclusive. Probably because no lung damage occured in the test subjects. What the case wanted to test was if there are alternatives for testing lung damage. At that moment (and maybe still now I don't know) the industry standard was a spirometry test of the lungs before and after the dive. Calculating a difference in vital lung capacity before and after dive. However this method is not very accurate.

Dr. Melissa Vermeulen attempted to to test if measuring a specific VOC (volatile organic compound) in our breath would change dramatically after a long enough nitrox or O2 dive and would be a good idicator for O2 based lung damage. Measuring these VOCs are already done for diagnosing specific forms of lung cancer, lung inflamation, asthma, etc.

I only have the study in Dutch:
Vergelijking tussen de verandering in de Vitale capaciteit en de expiratoire “Volatile organic compound” concentratie ter detectie van oxidatieve longschade na hyperbare zuurstofblootstelling: een experimenteel onderzoek
Vermeulen Melissa
Universitaire Promotor: Prof. Dr. B. Nemery
Co-promotor: Dr. Pieter-Jan van Ooij*
*Hoofd Duikmedisch Centrum Koninklijke Nederlandse Marine

You probably will be able to find it as well in English.

 

[Nick_Radov]

It's interesting to me that it's okay to sanction world records for hot dog eating promoting death by cholesterol, but deep diving is forbidden.

Not sure if you're serious, but the vast majority of cholesterol in your body is the result of lipogenesis rather than consumption. Cholesterol you consume through hot dogs or any other food is broken down in your digestive system, and the amount you eat has little direct impact on blood levels. The latest research indicates that the hot dog buns are more likely to cause high cholesterol than the hot dogs themselves.

#224 ‒ Dietary protein: amount needed, ideal timing, quality, and more | Don Layman, Ph.D. - Peter Attia

“We want weight loss, but we don't want people to lose any lean mass. Especially if they're adults.” —Don Layman

peterattiamd.com

To be clear, I am not recommending eating a lot of hot dogs. Any highly processed food is usually not a great choice. But that's for reasons other than cholesterol content.

 

[Nick_Radov]

The results were not conclusive. Probably because no lung damage occured in the test subjects. What the case wanted to test was if there are alternatives for testing lung damage. At that moment (and maybe still now I don't know) the industry standard was a spirometry test of the lungs before and after the dive. Calculating a difference in vital lung capacity before and after dive. However this method is not very accurate.

Dr. Melissa Vermeulen attempted to to test if measuring a specific VOC (volatile organic compound) in our breath would change dramatically after a long enough nitrox or O2 dive and would be a good idicator for O2 based lung damage. Measuring these VOCs are already done for diagnosing specific forms of lung cancer, lung inflamation, asthma, etc.

I only have the study in Dutch:
Vergelijking tussen de verandering in de Vitale capaciteit en de expiratoire “Volatile organic compound” concentratie ter detectie van oxidatieve longschade na hyperbare zuurstofblootstelling: een experimenteel onderzoek
Vermeulen Melissa
Universitaire Promotor: Prof. Dr. B. Nemery
Co-promotor: Dr. Pieter-Jan van Ooij*
*Hoofd Duikmedisch Centrum Koninklijke Nederlandse Marine

You probably will be able to find it as well in English.

A VO2 Max test could also be useful for measuring lung damage, and is relatively cheap and easy to conduct using the equipment in any sports medicine lab. Of course there are potential confounding factors that could cause a reduction in VO2 Max independent of pulmonary oxygen toxicity, like overall stress/fatigue, poor nutrition, or simultaneous infection with a respiratory disease (i.e. COVID-19). But testing several divers after similar dive profiles would probably show if there was a significant reduction.

For individual divers you if you want to check whether your deco is burning out your lungs, you can do your own informal VO2 Max testing using any modern fitness tracker like a Garmin. Those aren't as accurate as a real lab test but close enough for our purposes. You just have to do a hard running or cycling workout that gets your heart rate up near maximum.