Fatal dive accident - Lake Werbellin, Germany

[DandyDon]

As this was the standard mandatory procedure back in the eighties, I did assume that every filling station is routinely doing the same since then. I think it would be criminal not doing so.

Yes, well, I have toured a few fill stations over here, and only one tested daily.

It'd be great if divers toured the fill stations they use and ask what air tests they ran that day.

 

[hilljo88]

Not that anyone on SB would leap to a conclusion, but has it been confirmed that CO poisoning is to blame? Did the two victims use a unique fill station? It sounds like they were members of a group of 15 divers. Even if they were not diving as a group on that dive, are there other tanks that can be sampled? And what about physiological manifestations of CO poisoning like nail bed distal border irregularities?

 

[Mod63]

We will never know unless the family agrees to release the official findings. Autopsie reports are not entered into public record in Germany.

 

[JohnN]

At sufficient depth (which I forget but isn’t super deep) oxygen will be dissolved into your plasma as well as being carried by you RBCs. This works to get oxygen to your cells. But as you ascend that stops working and your cells can’t get enough oxygen.

It’s part of why hyperbaric oxygen treatment is used for CO poisoning, though apparently it doesn’t work as well as you might hope.

I had to look this up, my memory ain't what it used to be:

From Oxygen Transport - Regulation of Tissue Oxygenation - NCBI Bookshelf.

At physiological PO2 (40 < PO2 < 100 mm Hg), only a small amount of oxygen is dissolved in plasma since oxygen has such a low solubility. At elevated PO2 (breathing 100 % oxygen or during hyperbaric oxygenation), however, the physically dissolved form of oxygen can become significant. Henry's law states that the amount of oxygen dissolved in plasma is directly proportional to PO2: [O2] = α PO2, where α = 0.003 ml O2 (100 ml plasma)−1 mm Hg−1. Thus, at a PO2 of 100 mm Hg (typical value for arterial blood), 100 ml of plasma contains 0.3 ml O2 (or 0.3 vol%).

So increasing the PO2 with depth is not going to do much for you (at least if you are on air). You'd have to be at roughly 5 ATM (~40 meters) to get the equivalent of huffing 100% O2 at the surface

 

[DandyDon]

has it been confirmed that CO poisoning is to blame?

Nothing has been released I don't think. Often these cases are written off as drownings without exposing the cause, so we often never know.

Even if they were not diving as a group on that dive, are there other tanks that can be sampled?

That wouldn't mean much. One tank coming off a compressor can be tainted while others at the same time won't be. That's a false security.

And what about physiological manifestations of CO poisoning like nail bed distal border irregularities?

That's not dependable. The only way to know is to test the tank before or after death. Before is preferable.

 

[RedSix]

It looks like this accident is not related to CO poisoning. It has been written somewhere, that both had empty tanks.

 

[DandyDon]

It looks like this accident is not related to CO poisoning. It has been written somewhere, that both had empty tanks.

The empty tanks were mentioned earlier, but that fact does not prove either way with CO.

 

[dmaziuk]

You'd have to be at roughly 5 ATM (~40 meters) to get the equivalent of huffing 100% O2 at the surface

It doesn't necessarily have to be at 1, it just needs to be "easier" to get to than the hemoglobin-bound O2. We'd need a nucular life scientist to tell us at what PPO2 that becomes plausible. (Recall that exhaled air is about .16 O2 so we only really use ~.005.)

 

[JohnN]

The increased PO2 doesn't change the amount of CO that preferentially binds to the haemoglobin, but rather the amount of O2 disolved in the plasma

 

[dmaziuk]

Right, the theory is that at sufficient PP of dissolved O2 our metabolism will use it and leave hemogolobin with its CO alone, and the question is how little (or much) of dissolved O2 there needs to be for that to happen.