Filmmaker Rob Stewart dies off Alligator Reef

[St John the Diver]

Again, not a CCR diver, so forgive me if this is a stupid question: aren't CCR divers generally taught to "stay on the loop"? That is, if someone didn't know they had a problem, wouldn't they be expected to do so?

Well... "If they didn't know they had a problem" they have a bigger problem, and that's called lack of knowlage. And it's very possible that this is what happened. Passing out after a few moments on the surface would play out exactly like what appears to have occurred.


But as to staying on the loop "if you get what's happening to you":

Not if its killing you and a better gas is available elsewhere. Hypothetically if you have a hypoxic mix in your loop and you're on the surface...breathe the air, dammit!

Just get positive and close that DSV to avoid the dead-bug syndrome


Now... Getting to that spot takes some pretty seriously poor dive planning. And that's what's really bothering me.

 

[Cowfish Aesthetic]

Well... "If they didn't know they had a problem" they have a bigger problem, and that's called lack of knowlage.

How unlikely would it be for someone (especially someone who just finished trimix training and may not have dove hypoxic trimix before) to fail to notice if they have a hypoxic mix?

 

[LandonL]

How unlikely would it be for someone (especially someone who just finished trimix training and may not have dove hypoxic trimix before) to fail to notice if they have a hypoxic mix?

Depends on the quality of instruction they received....... as well as task-loading, stress, situational awareness, etc.

 

[St John the Diver]

How unlikely would it be for someone (especially someone who just finished trimix training and may not have dove hypoxic trimix before) to fail to notice if they have a hypoxic mix?

It's certainly possible. The splash-zone (sea-surface interface) isn't where divers belong and certainly not rebreather divers. Being task loaded is one thing. Adding to that is the fact that the so-called "HUD's" on these rigs are very hard to see in bright sunlight and that he likely wasn't staring at his wrist display... It's very possible that he "lost the bubble" (meaning lost situational awareness).

It happens.

 

[cerich]

Steve: even if hypoxic, if you surface concious, once you breathe surface air for a few breaths you're not going to get worse. Recovery is fast.

umm..not quite. If you have have been breathing 10/50 at say 20 fsw, you are gonna go unconscious when you come up, come up slowly and it will occur uw,come up fast and you will on the surface on the surface. Your respiration of the atmospheric oxygen still will take some time to get into the circ system and to your brain box. During your assent the PPO@ dropped and your body was still metabolizing.

if you had been breathing a slightly hypoxic mix on the surface at depth, say a 15, you would most likely stay conscious but have a "gotta stop and breath moment", a 10 and you are gonna most likely enjoy a blackout of a few seconds to say 30 seconds.

 

[cerich]

(especially someone who just finished trimix training and may not have dove hypoxic trimix before) t

that is an assumption that many of us have been making, it may be wrong

 

[Cowfish Aesthetic]

that is an assumption that many of us have been making, it may be wrong

It certainly is, and it very well may be. But given the limited information currently available, all we can do is discuss the hypotheticals.

 

[PfcAJ]

Hypoxia is serious stuff.

http://m.wimp.com/hypoxia-when-the-brain-is-deprived-of-adequate-oxygen-supply/

This is why you need robust procedures and adequate and easy to access bailout.

10/50, while popular, imo isn't a good gas unless you genuinely need it.

 

[St John the Diver]

umm..not quite. If you have have been breathing 10/50 at say 20 fsw, you are gonna go unconscious when you come up, come up slowly and it will occur uw,come up fast and you will on the surface on the surface. Your respiration of the atmospheric oxygen still will take some time to get into the circ system and to your brain box. During your assent the PPO@ dropped and your body was still metabolizing.

if you had been breathing a slightly hypoxic mix on the surface at depth, say a 15, you would most likely stay conscious but have a "gotta stop and breath moment", a 10 and you are gonna most likely enjoy a blackout of a few seconds to say 30 seconds.

My degree is in physiology. I'm familiar with the process.

The latency time is only a few seconds to increase 02 saturation in the blood and only a few more to get that to your brain. It's not immediate but its rapid.

 

[cerich]

My degree is in physiology. I'm familiar with the process.

The latency time is only a few seconds to increase 02 saturation in the blood and only a few more to get that to your brain. It's not immediate but its rapid.

considering you're hiding who you are, getting offended that we don't accept your unquestioned authority, experience and all around greatness is silly. Fess up or live with it.

Now.."The heart pumps about 2,000 gallons (7,571 liters) of blood a day through its chambers." 2,000 gallons per day works out to 83 gallons per hour, or nearly 6 quarts per minute. So it takes about one minute for blood to make the round trip to the heart"

the brain box is on a highway, not a byway and gets the oxygenated blood fairly quickly, however, you can keep asserting that hypoxic mix on the surface is only a few seconds..maybe you better define that "few". Be happy to join you in a chamber and test out our respective theory (again for me..but it has been a minute or so)

I would argue those "few" seconds can be the rest of your life in some circumstances