Oxygen poisoning seizure > how to react ?

[nickbutcher]

The severity of the convulsion is dependent on the ppo2 and critically the time breathing the mix. The sooner the depth is reduced the quicker the diver will recover, as you can’t change the mix.

What evidence is there for this?

I suspect that it's one of the many myths surrounding oxygen toxicity - another being that they come on almost instantaneously. In my case there was at least five minutes between me becoming aware of the onset of symptoms and unconsciousness. I believe that was due to me actually being aware of what was happening and staying on top of the situation until I was safe. I'm not sure how much longer I could have done so.

The sensation of toxing was actually very pleasant and I can fully understand why anyone who was not realising what was happening would just go with it until they succumb. To anybody watching, they would appear to have just started fitting with no warning.

I have no idea what the survival rate is for divers toxing underwater but I imagine that it's not high. So there is limited first-hand evidence of what happened leading-up to the incident.

Anecdotal evidence from people witnessing such events should probably be taken with a large pinch of salt. My buddy had no idea what was happening when I suffered mine and would certainly not have been much use if he'd tried to deal with it underwater. That's no reflection on his ability as a diver or his rescue skills.

 

[Celt]

What evidence is there for this?

I suspect that it's one of the many myths surrounding oxygen toxicity - another being that they come on almost instantaneously. In my case there was at least five minutes between me becoming aware of the onset of symptoms and unconsciousness. I believe that was due to me actually being aware of what was happening and staying on top of the situation until I was safe. I'm not sure how much longer I could have done so.

The sensation of toxing was actually very pleasant and I can fully understand why anyone who was not realising what was happening would just go with it until they succumb. To anybody watching, they would appear to have just started fitting with no warning.

I have no idea what the survival rate is for divers toxing underwater but I imagine that it's not high. So there is limited first-hand evidence of what happened leading-up to the incident.

Anecdotal evidence from people witnessing such events should probably be taken with a large pinch of salt. My buddy had no idea what was happening when I suffered mine and would certainly not have been much use if he'd tried to deal with it underwater. That's no reflection on his ability as a diver or his rescue skills.

We did oxygen tolerance test in a chamber to ppo2 of 2.8 (60 feet on100%) for 30 minutes. at the first sign of twitching or tingling the attendant would take you off the BIBS and you would breath the chamber air at 60 feet and recover immediately from what I know. Haven’t seen a diver go into convulsions so don’t know how long it would take.

 

[nickbutcher]

We did oxygen tolerance test in a chamber to ppo2 of 2.8 (60 feet on100%) for 30 minutes. at the first sign of twitching or tingling the attendant would take you off the BIBS and you would breath the chamber air at 60 feet and recover immediately from what I know. Haven’t seen a diver go into convulsions so don’t know how long it would take.

These things are always a bit of fun and an interesting exercise but I'm not sure they're anywhere near realistic for simulating a tox underwater.

You'll have all been on heightened alert for any symptoms that are out of the ordinary.

I never felt any tingling or twitching with mine. The initial symptoms, that I noticed, were extraordinary confusion and the 'wah-wah', but that crept-up on me whilst I was concentrating on other stuff.

What made me finally realise I was toxing was a sudden onset of tunnel vision and a sort of electrical buzzing in my head. I'm pretty sure if I'd been just sat on my arse in a chamber doing nothing else but just waiting for something odd to happen, I'd have noticed well before it was too late to stop it.

 

[nickbutcher]

If the only thing people take from this is how beneficial a gag strap might be, my work is done

 

[doctormike]

I'm going to rethink, what to do in these scenarios, and also will check gag straps. I know they are standard on some models (revo I believe). But it's not really a GUE (jj) thing, so need to check on this and how it work with our current procedures (probably won't in gas sharing events).

I'm going to rethink it too.

I dive a non-GUE JJ, and have considered a BOV/gag strap over the years. Speaking with my instructor and Jan, they haven't encouraged that, and have pointed out some of the downsides of the BOV (plenty of threads about that here, not going to rehash). Overall, I have been very impressed with the design decisions made for the JJ, and I'm not going to just dismiss these opinions out of hand.

I guess the only downside of a gag strap would be if you didn't have a BOV and had to remove the loop to bail out, there is the possibility that it might interfere with that.

I would be interested in hearing what the gag strap proponents say about diving a DSV. Do you feel that it's just a bad idea all around and that there is no valid argument against the BOV? Interested in different perspectives. I could adapt the AP gagstrap to my loop and add a BOV, but I'm hesitant to interfere with the JJ design without good cause...

 

[Wibble]

If the only thing people take from this is how beneficial a gag strap might be, my work is done

They're standard on a Revo...

They'll make life hard for anyone with a trapped longhose under the loop. The gag strap is relatively easy for the loop and mouthpiece to pull downwards with the gag strap still on. It's much harder to lift it over your head as it becomes tighter.

 

[Celt]

These things are always a bit of fun and an interesting exercise but I'm not sure they're anywhere near realistic for simulating a tox underwater.

You'll have all been on heightened alert for any symptoms that are out of the ordinary.

I never felt any tingling or twitching with mine. The initial symptoms, that I noticed, were extraordinary confusion and the 'wah-wah', but that crept-up on me whilst I was concentrating on other stuff.

What made me finally realise I was toxing was a sudden onset of tunnel vision and a sort of electrical buzzing in my head. I'm pretty sure if I'd been just sat on my arse in a chamber doing nothing else but just waiting for something odd to happen, I'd have noticed well before it was too late to stop it.

My point is it’s not instant, the time spent breathing a high ppo2 is critical. And the sooner the diver is off the high dose the better. And since you can’t take the reg from a diver the only thing you can do is get shallow to reduce the partial pressure.

 

[nickbutcher]

I'm going to rethink it too.

I dive a non-GUE JJ, and have considered a BOV/gag strap over the years. Speaking with my instructor and Jan, they haven't encouraged that, and have pointed out some of the downsides of the BOV (plenty of threads about that here, not going to rehash). Overall, I have been very impressed with the design decisions made for the JJ, and I'm not going to just dismiss these opinions out of hand.

I guess the only downside of a gag strap would be if you didn't have a BOV and had to remove the loop to bail out, there is the possibility that it might interfere with that.

I would be interested in hearing what the gag strap proponents say about diving a DSV. Do you feel that it's just a bad idea all around and that there is no valid argument against the BOV? Interested in different perspectives. I could adapt the AP gagstrap to my loop and add a BOV, but I'm hesitant to interfere with the JJ design without good cause...

I ditched my BOV when I sold my old analog JJ. I often dive hypoxic diluent and the idea of bailing to that on the surface scares the **** out of me. Also, the work of breathing of just about every BOV is hopeless at depth. The JJ BOV was woeful, even after I did some serious mods to it.

The Drager strap is designed to make bailing out very easy. The strap is angled-up and sits on the crown of the head. Pulling the loop up over the head is effortless. I do wear my mask strap under my hood though to avoid pulling that off to should I need to bail out.

Once you dive with one of these, there's no going back IMHO. It's so comfortable to use and no need to get jaw ache whilst you're sitting on the boat waiting for slack water. The mouthpiece even keeps your lips warm and helps avoid jellyfish tentacles.

They're just awesome all around.

 

[nickbutcher]

They're standard on a Revo...

They'll make life hard for anyone with a trapped longhose under the loop. The gag strap is relatively easy for the loop and mouthpiece to pull downwards with the gag strap still on. It's much harder to lift it over your head as it becomes tighter.

Are you wearing it correctly? I thought the rEvo strap was a copy of the Drager which sits on the crown of the head.

 

[doctormike]

I ditched my BOV when I sold my old analog JJ. I often dive hypoxic diluent and the idea of bailing to that on the surface scares the **** out of me. Also, the work of breathing of just about every BOV is hopeless at depth. The JJ BOV was woeful, even after I did some serious mods to it.

The Drager strap is designed to make bailing out very easy. The strap is angled-up and sits on the crown of the head. Pulling the loop up over the head is effortless. I do wear my mask strap under my hood though to avoid pulling that off to should I need to bail out.

Once you dive with one of these, there's no going back IMHO. It's so comfortable to use and no need to get jaw ache whilst you're sitting on the boat waiting for slack water. The mouthpiece even keeps your lips warm and helps avoid jellyfish tentacles.

They're just awesome all around.

So get a Drager strap instead of the AP one? And OK to use with a DSV?