Woman dead, husband injured on 230 meter dive - Greece

[DandyDon]

How would ascending release bound CO at an accelerating rate? Or at any rate? I don't think the CO-hemoglobin bond in itself is affected by ambient pressure (not taking the effect of O2 pressure into consideration here), it's more of a chemical thing. From a total CO load perspective alone, the shallower the better. Or is it not?

Descending increases the partial pressure of the CO thereby causing more to bind to hemoglobin. Using an arbitrary figure for discussion, 10 ppm CO wouldn't hurt you at 1 atmosphere, as you descend - the effect is increased. Their dive to 23 atmospheres would increase the 10 ppm to an effect similar to 230 ppm. It's not that simple, but it's similar - like diving to depths increases Nitrogen loading as an example.

Ok, so after loading hemoglobin at such high levels, then ascending causes the CO to start being released, therefore the effect if magnified. But the nature of CO poisoning is so complex that it can't really be managed - just avoid it at all costs, even if you have to test tanks for recreational & deeper dives or use lab prepared gases for excessively deep dives.

My understanding is that the effect of the CO is masked by the higher ppo2 at greater depths and is revealed as the lower ppo2 at shallower depths doesn't provide the therapeutic effect that it did when higher. Do I have this wrong?

There is also some truth to that, but the bigger risk is what I described above here.

 

[fsardone]

Question to deep divers, inquiry mind wants to know, other than trying to break whatever records (personal, world, Guinness, etc.) and because it is there, what other compelling reasons to go to such cold, dark, unforgiving place? Rob Stewart was trying to film sawfish, but that's only to 70m (230 feet) deep.

Dan,
I deep dive wrecks, mainly. I also dive caves but those are maily shallow.
When I plan the dive sometimes (rarely I would now say) I realise that, IF I complete the dive I might exceed my previous maximum depth.
This is a reason to more accurately plan and maybe do a build up dive.

Depth not being the driver means that if conditions are not right you just abort the dive instead of life.

Cheers

 

[boulderjohn]

Descending increases the partial pressure of the CO thereby causing more to bind to hemoglobin.

...which prevents oxygen from binding and reducing the amount of oxygen being carried by the hemoglobin. It is the lack of oxygen being delivered to the tissues that causes the problem--the CO by itself does not cause tissue damage.

However, at those depths, the plasma in the blood often carries enough oxygen to overcome that. This allows more oxygen to get to the tissues. Additionally, the presence of the excess oxygen helps undo the chemical reaction of the CO binding to the hemoglobin. As the diver ascends, the PPO2 generally decreases, lessening that benefit. However, when a trimix diver ascends and switches gases, that switch usually creates a greater O2 partial pressure than the diver had during the working part of the dive, thus restoring the high oxygen environment.

treatment for CO poisoning is usually breathing pure oxygen. Hyperbaric oxygen treatment is also used, although the benefits of that over just breathing oxygen are inconclusive.

 

[oceancurrent]

Her statement was "the regular certification classes max out at 90m," which itself is wrong, but if she meant "regular trimix classes," then that makes sense.

Her exact words are: "[for people who want to increase their limits] there are master classes. Master classes include planning and executing dives deeper than 100m, whereas the certification in technical diving is to 90m. There is no certification for diving beyond 90m."

TDI's depth limit for Advanced Trimix divers is 100m (330ft), so she is almost correct. The 90m (300ft) depth limit is PADI's certification limit (TECHNICAL DIVING TEC TRIMIX), and she was a PADI Technical instructor (Scuba Diving in Greece with Atlantis Diving Center).

What I wonder is what "master classes" for diving deeper than 100m might she be referring to?

 

[boulderjohn]

What I wonder is what "master classes" for diving deeper than 100m might she be referring to

My guess is it is one of their own design.

 

[DiverLaura]

It's not unheard of that their profile (since both reported it) was such that they both suffered vestibular DCS with or without counter diffusion which could cause those symptoms and would seem far more likely than both suffering a reverse block at same depth.

 

[boulderjohn]

would seem far more likely than both suffering a reverse block at same depth

I agree. I don't see a reverse block as being highly likely after having successfully ascended to that level.

 

[ajduplessis]

He also claims that they did not have any symptoms of having cold before the dive. She started feeling dizzy during their 40m deco stop, kept getting herself entangled in the ascent line, then he became sick too. Essentially, his claim is that they experienced vertigo induced by a reverse block.

You description of vertigo at least to me indicate ICD. I have been told that ICD above 300 ft is a non-issue; but I was never in agreement. I would love to see the breathing gasses used and switch depths on this tragic dive.

 

[Kay Dee]

Question to deep divers, inquiry mind wants to know, other than trying to break whatever records (personal, world, Guinness, etc.) and because it is there, what other compelling reasons to go to such cold, dark, unforgiving place? Rob Stewart was trying to film sawfish, but that's only to 70m (230 feet) deep.

Re my now bolded above, while I have only been to 130m / 430ft, that was my reason, but by that I do not mean the depth itself (being there), but an undiscovered / undived wreck or cave was, especially in the case of a wreck, as thats where the undived / undiscovered ones were, i.e. at depths greater than what most / many divers could / would go. So to go there and photograph and survey them was the reason why I, and several of my colleagues, went there for.

But if I / we could have found 'em undived in 20m / 66ft, then I'da just as happily dived only there. (Well, the Japanese destroyer HIJMS Amagiri - yes, the very same on that cut JFK's PT-109 in half - was only in about 27m / 100ft, and one of the only virgin (well almost virgin i.e. dived only once before I got there) wrecks where one could spend way more time on the wreck than on deco.)

But hey, everyone has their own motivation / goals, so each to their own as to why one dives deep.

However, anyone diving below 200m / 660ft (and even shollower when I was actively exploring) better have a damn good reason for going there (IMO) than just to come back with a 'record' or high number on their dive computer to show their mates; but again that's just IMO.

 

[Kay Dee]

It's not unheard of that their profile (since both reported it) was such that they both suffered vestibular DCS with or without counter diffusion which could cause those symptoms and would seem far more likely than both suffering a reverse block at same depth.

I agree. I don't see a reverse block as being highly likely after having successfully ascended to that level.

Exactly, as Laura surmises, way more likely a so-called inner ear 'bend'. And VERY nasty business that from what I know from those that have experienced it / survived it.