Fiona Sharp death in Bonaire

[fsardone]

Buddy Dive typically removes stickers when they refill a tank. So those are probably new, not old stickers. Also, many folks do not analyze a tank after an air fill. As RB tanks, they were filled in the tech shop at BD, and I do not know whether the tech shop puts stickers on when they fill, or if those are stickers she put on.
Here is her 80% AL40, for comparison. I do not have a picture of her other 40.
View attachment 546302

I believe there is a chance that her on-board dil bottle was air and used for the BCD (no dry suit has been established) and her off board bailout (20/20) used for BOV and as offboard diluent for the loop (this was already proposed as a possibility a few posts above).

 

[happy-diver]

My tribute for the affronted

To people who put themselves on the line get published and contribute pertinently to diving for many decades

 

[John the Pom]

Lots of people use a "hot" dil instead of oxygen once you are past the point where a mCCR orifice cuts off. Like they might use 50% as an o2 source at 300ft. Its not really as dramatic a ppO2 pulse as you're suggesting here.

Narcosis and WOB would still be insane but ppo2 not necessarily

Reaction to high PPO2 is a personal thing that changes with age, health, etc. My former SCUBA mate was an ex-navy diver, and they were chosen for a high tolerance to O2 so that they could use old-fashioned O2 rebreathers. He suffered pneumonia following an episode of hypothermia, and after his recovery he couldn't tolerate elevated PPO2 any more.

 

[Rechno]

Since there are several threads, discussing whether she used air or 20/20 my question is, how relevant is this?
Concerning the ppO2, 20 vs 21 % in the mix should be rather irrelevant (especially if you consider the tolerance when measuring)
Concerning narcosis the 20 % He should make some difference but since the report says she made it back to 80ft this should also not have been an issue.
Concerning WOB there would have likely been a difference at depth. But again, reflecting that she was found at 80ft, would it have been relevant?

 

[rjack321]

Since there are several threads, discussing whether she used air or 20/20 my question is, how relevant is this?
Concerning the ppO2, 20 vs 21 % in the mix should be rather irrelevant (especially if you consider the tolerance when measuring)
Concerning narcosis the 20 % He should make some difference but since the report says she made it back to 80ft this should also not have been an issue.
Concerning WOB there would have likely been a difference at depth. But again, reflecting that she was found at 80ft, would it have been relevant?

If your WOB is crazy high at depth you could have IPE which got progressively worse until succumbing at 80ft.

Not saying that happened, but there are more than temporary impacts from using air, in a rebreather, at 300ft.

 

[Duke Dive Medicine]

Not sure. The one of those that I thought of was hypercapnea from overexertion with a functional scrubber, but I think that would be less likely to cause plain LOC than the other symptoms. The other recovery scenarios seem pretty remote, but there is a bell curve for everything...

I guess my concern about these arguments for gag straps or FFM is that they put more responsibility on these devices than they are really good for, and thus imply that solo CCR diving is fine as long as you have one of them. From the limited data out there, it seems that their main benefit is allowing for a buddy rescue, as in the Gempp paper. Not for these remote scenarios where a solo diver recovers from a significant neurological hit like LOC.

And, it depends on the type of gag strap. The Gempp paper specifically recommends a strap with a lip guard to minimize water ingress if the wearer becomes unconscious or has a grand mal seizure, which was the rationale used by Mitchell and Doolette (2018) in recommending either a full face mask or gag strap during in-water recompression. Straps that simply retain the mouthpiece in place do not meet this criteria.

Best regards,
DDM

 

[Dan]

This article, What Happens After A Lack of Oxygen to the Brain? mentions that it’ll take from 30 to 180 seconds for someone suffering from lack of oxygen to pass out. Let’s say conservatively it takes 3 minute delay response at the onset of hypoxia for someone to pass out. At ascent rate of 10m/min, one would ascent 30 m before passing out.

 

[FreeFlyFreak]

This article, What Happens After A Lack of Oxygen to the Brain? mentions that it’ll take from 30 to 180 seconds for someone suffering from lack of oxygen to pass out. Let’s say conservatively it takes 3 minute delay response at the onset of hypoxia for someone to pass out. At ascent rate of 10m/min, one would ascent 30 m before passing out.

If you can recognize you are hypoxic.
Breathing need is controlled by CO2 buildup.
The scrubber should prevent CO2 build up unless there is a problem.

 

[Dan]

If you can recognize you are hypoxic.
Breathing need is controlled by CO2 buildup.
The scrubber should prevent CO2 build up unless there is a problem.

What I’m trying to say is that there would be a time delay response from physiological stress that one needs to account. If she was found at 80’ depth, the physiological stress could start at deeper depth. Some people can cope with the stress better and at higher tolerance than others, which could imply the onset of the stress could happen even at greater depth.

 

[doctormike]

What I’m trying to say is that there would be a time delay response from physiological stress that one needs to account. If she was found at 80’ depth, the physiological stress could start at deeper depth. Some people can cope with the stress better and at higher tolerance than others, which could imply the onset of the stress could happen even at greater depth.

Similarly, time spent at high PO2 at depth lowers the threshold for ox tox later in the dive. So just because an event happened at 80 feet, that doesn't mean that what happened deeper than that was non-contributory.