Panic and the Hypercapnic Alarm Response

[Dan]

It's covered all here in his good and often cited presentation below. . .

(Go to 2:20 mark for a quick two minute overview, otherwise the entire hour long lecture clearly explains the respiratory physiology of CO2 and Diving):

Thanks for the tip. I watched the whole hour video. It reminds me to limit myself to warm-water, open-circuit, single tank, NDL recreational diving with air or EAN32. Stay away from trimix, drysuit, rebreather, decompression diving, etc. I am not smart enough for all those complicated aspects of technical diving, have read enough diving accidents and believe in KISS principle.

 

[Kevrumbo]

It's covered all here in his good and often cited presentation below. . .

(Go to 2:20 mark for a quick two minute overview, otherwise the entire hour long lecture clearly explains the respiratory physiology of CO2 and Diving):

Thanks for the tip. I watched the whole hour video. It reminds me to limit myself to warm-water, open-circuit, single tank, NDL recreational diving with air or EAN32. Stay away from trimix, drysuit, rebreather, decompression diving, etc. I am not smart enough for all those complicated aspects of technical diving, have read enough diving accidents and believe in KISS principle.

Remember the Palau Nitrox Diver's Dilemma @Dan_T ?
You're drift diving breathing a 11L Alu tank of EAN32 at 18m on Peleliu Wall or the Express around 40min elapsed time, and get caught & swept over the south plateau in a down current to 40m with 60bar showing on the SPG: based on what you learned in the video, should you fight the downcurrent to escape it? How would the panic of a hypercapnic response make the situation worse??

 

[Dan]

Remember the Palau Nitrox Diver's Dilemma @Dan_T ?
You're drift diving breathing a 11L Alu tank of EAN32 at 18m on Peleliu Wall or the Express around 40min elapsed time, and get caught & swept over the south plateau in a down current to 40m with 60bar showing on the SPG: based on what you learned in the video, should you fight the downcurrent to escape it? How would the panic of a hypercapnic response make the situation worse??

Don’t remember reading it. Please post the link.

I’ve been on down current in Crystal Bay, Nusa Penida, Bali, Indonesia to see oceanic mola mola (see my avatar). However, I listened to the dive briefing closely beforehand and stay close to the sloppy wall. As soon as I see my air bubbles started to go down to the abyss, I finned like crazy to the wall & stared an underwater rock climbing.

Another trick that I was told about escaping from down current when you are away from the wall is to swim across (horizontally perpendicular from) the current & launch your DSMB.

I did a dip dive on my own at 44m on EAN32 to see zebra shark for the first time in Palau (see the picture, below), under the watch of some of my dive buddies & guides at 30m for 2 minutes, no nausea or drunken feeling. I ascent back to 30m without any problem. So, if I’m calmly handling such situation, I might still be able to think rationally & survive the ordeal. Hopefully I would not ever experience it (knock on wood).

I was lucky to not experiencing any down current in Peleliu Express in December last year. I made sure to hook myself on the rock as soon as we swam over the ledge.

 

[Dr Simon Mitchell]

Sounds like @Dr Simon Mitchell needs to referee this boxing match

Hello,

I think they are disputing the meaning of one or two words, but both have fundamentally correct and valuable messages.

The cave video is very interesting, and portrays an incredibly dangerous situation. She could easily have drowned.

Simon M

 

[Akimbo]

which is one of the major irrational cognitive signs of a distressed diver in Hypercapnic Alarm Response:

I have seen and experienced the panic-inducing effect of CO2 far too many times. Very experienced and rational divers may not go into full panic but are certainly compromised, myself included. The insidious part is that it is rarely clear at the time but videos leave no doubt. It is especially disconcerting when breathing gas is contaminated with Carbon Dioxide. You practice all your reflexive deep breathing and relaxation tricks and it keeps getting worse. Time to go on bailout and go home.

STOP. BREATHE. (THINK. ACT.). . .

I would modify this to: Stop, breathe very deeply and slowly, assess, think, act. The problem is that what you thought was true during the event may not be reality.

 

[Kevrumbo]

I did a dip dive on my own at 44m on EAN32 to see zebra shark for the first time in Palau . . .under the watch of some of my dive buddies & guides at 30m for 2 minutes, no nausea or drunken feeling. I ascent back to 30m without any problem. So, if I’m calmly handling such situation, I might still be able to think rationally & survive the ordeal. Hopefully I would not ever experience it (knock on wood).

44m on EANx32 gives a ppO2 ATA of 1.7

Don’t remember reading it. Please post the link.

Surviving currents - do nothing?
Escaping Down Drafts

Hello. . .
The cave video is very interesting, and portrays an incredibly dangerous situation. She could easily have drowned.

Simon M

It may be just the tint of the lighting color, but it looks like her face is already going cyanotic:

 

[guyharrisonphoto]

I am grateful for this thread. My wife had a pretty severe immersion pulmonary edema episode a couple of years ago, while ascending from a 70' dive. She kept motioning to me "no air" even tho her gauge showed plenty, and handed me her primary to breathe from (it was fine). It got to the point where she began rejecting her primary and breathing her secondary, but only to reject that and switch back. This happened fast as I was holding her to get to the surface. She might have rejected her reg entirely but I held the reg in her mouth while we surfaced. She was turning blue on the surface. She needed an overnight hospital stay on O2 for it to resolve.

Now that I have seen this thread, I understand that her reaction was exactly the same as the elevated CO2 divers. But, in her case, the "relax and breathe deeply" procedure would not have helped, as she was just not getting enough O2, and not expelling enough CO2, due to the water in her lungs. This will give both of us a clearer understanding of how she reacted.