Oxygen poisoning seizure > how to react ?

[happy-diver]

I'll be the 1st to admit I don't know. Gas switches scare me after reading about all the fatalities because of them.

Yeah I'm not happy you feel this way either

It is all about sort of what's printed below

Do we train for what to do if we have a wrong gas switch? I didn’t. I trained for how to do a proper gas switch. I grab the regulator. I trace it back to the tank and verify the MOD. Then my buddy traces from the regulator to the tank and verifies the MOD. Then we both check our current depth again and then he gives me the OK to switch. Then and only then do I switch. Then we repeat for him. Does it seem like a lot? Yes. Would I do it that way every time? Yes. It’s important.

I don't think it's a lot at all
but I grab the bottle first check the mod then run my hand along the hose to the reg, I'm always solo

So basic detail is very important detail

and stay out of those stinking incident reports


good ideas bloke our Wibble

 

[rob.mwpropane]

Yeah I'm not happy you feel this way either

Fear might be the wrong term, it's not that I wouldn't do a gas switch, it's respect for the importance of and for the amount of people that have died doing it.

I get that as someone else posted, the issue might start on land not being vigilant in analysing before a dive.

 

[Wibble]

Fear might be the wrong term, it's not that I wouldn't do a gas switch, it's respect for the importance of and for the amount of people that have died doing it.

I get that as someone else posted, the issue might start on land not being vigilant in analysing before a dive.

Just to pursue this a little, it sounds like you've not been through Nitrox training? Part of this is to always analyse and label up the cylinders yourself. As you've only one cylinder, there's no switching protocols taught.

When you embark on the first level of technical training, Advanced Nitrox and Decompression Procedures (ANDP), a major part of this training is the switching protocols as explained by @happy-diver above.

It's trivially easy to do and MUST be done even if you've only one stage cylinder -- it's your last chance to verify that you're not sticking pure oxygen in your mouth on the bottom.

Personally I'll label up the cylinder with MY label just under the 1st stage on the neck of the cylinder. This has in large writing the MOD in metres with an M suffix: 10m. There's often one on the side of the cylinder for others to see.

It is mine and only my responsibility to make sure that this is checked. It is me who will die if I get it wrong. No one else gives a rat's testicle.


For the incident mentioned a way back, I suspect that a major contributory factor was narcosis. That and not doing the switch 'drill' on every switch.


Question and thought (and a bit OT): my rebreather bailout cylinder sits alone on my left-side (the deco cylinder is hung on the right). Having written all of the above, I don't check the label when switching. Bad Wibble. Must start doing that on the bailout drill on every dive...

 

[Searcaigh]

Question and thought (and a bit OT): my rebreather bailout cylinder sits alone on my left-side (the deco cylinder is hung on the right). Having written all of the above, I don't check the label when switching. Bad Wibble. Must start doing that on the bailout drill on every dive...

I was trained to have both deco cylinders on the LHS, and when doing a gas change to show the tank to one of the team members to confirm that I was changing to the correct gas for the deco process at the correct depth.

I also have specific labels on the second stage exhausts that distinctly show the the percentage of the gas that I'm about to breath as well as different hose colours and different regulator makes, which although doesn't make it foolproof, at least reduces the odds for a high O2 exposure at depth.

 

[rob.mwpropane]

Just to pursue this a little, it sounds like you've not been through Nitrox training? Part of this is to always analyse and label up the cylinders yourself. As you've only one cylinder, there's no switching protocols taught.

When you embark on the first level of technical training, Advanced Nitrox and Decompression Procedures (ANDP), a major part of this training is the switching protocols as explained by @happy-diver above.

It's trivially easy to do and MUST be done even if you've only one stage cylinder -- it's your last chance to verify that you're not sticking pure oxygen in your mouth on the bottom.

Personally I'll label up the cylinder with MY label just under the 1st stage on the neck of the cylinder. This has in large writing the MOD in metres with an M suffix: 10m. There's often one on the side of the cylinder for others to see.

It is mine and only my responsibility to make sure that this is checked. It is me who will die if I get it wrong. No one else gives a rat's testicle.


For the incident mentioned a way back, I suspect that a major contributory factor was narcosis. That and not doing the switch 'drill' on every switch.


Question and thought (and a bit OT): my rebreather bailout cylinder sits alone on my left-side (the deco cylinder is hung on the right). Having written all of the above, I don't check the label when switching. Bad Wibble. Must start doing that on the bailout drill on every dive...

Understood, yes cert for nitrox, not for AN/DP yet. Just tagging along and learning.

 

[Wibble]

I was trained to have both deco cylinders on the LHS, and when doing a gas change to show the tank to one of the team members to confirm that I was changing to the correct gas for the deco process at the correct depth.

I also have specific labels on the second stage exhausts that distinctly show the the percentage of the gas that I'm about to breath as well as different hose colours and different regulator makes, which although doesn't make it foolproof, at least reduces the odds for a high O2 exposure at depth.

On OC it was all cylinders left until there were 3 ali80s at which point common sense prevailed.

On CCR (rebreather) there's the critical bailout cylinder which must be switched on and immediately available for the whole of the dive**. With the absolute critical importance of this cylinder I like to have it on its own on the left and hang the deco cylinder(s) on the right (lean left, rich right). This means that I need to properly confirm it's the right cylinder before jumping in and it's turned on.

Also, the bottom bailout is turned on at all times. The deco cylinders are turned off (but pressurised). Thus sticking the wrong one in would provide one breath only (still enough to be a problem).

Another mitigation for this is that the two CCR cylinders (bailout + bailout deco) are both modular valves and "handed" for sidemounting, one left, one right. Thus a rich cylinder cannot be hung left as the valve handle would be on the wrong side. Of course this doesn't stop me from putting the wrong, shallower, bailout in the car....

As it happens, the rich bailout cylinder would also use a green nitrox hose.

TL;DR -- be careful with all switches.

** ignoring hypoxic mixes...

 

[doctormike]

I am surprised that no one has commented on the link I provided to a consensus report by a group of acknowledged experts after a review of research. I will summarize key points:

• If the regulator is not in the mouth, the diver's only hope of survival is to get to the surface ASAP.
• If a regulator is in the mouth during the initial phases of a seizure, it is not clear whether an ascent can safely begin immediately. There are indications that the glottis is not totally closed, and it is further possible that even if it is primarily closed for inhalation, exhalation may occur. Because of the lack of certainty, the group decided to stick with the advice to wait out the seizure before ascending, making certain that the regulator was well sealed by the lips.

I think that the discussion has moved pretty far from the OPs question. These are all good points, and thanks to @boulderjohn for providing that resource. However, the question wasn't about what to do with an actively seizing diver at depth, and the barotrauma implications of ascending with a forcefully adducted (closed) glottis.

Also, while all of the discussion about proper practices for analyzing and labeling bottles, and for safe gas switches is extremely important, it is also irrelevant to the OPs question.

The questions was about what to do if you are faced with rescuing a seizing diver after the seizure has stopped, the diver is breathing but unconscious, and there is a deco obligation.

John, when I try to download your PDF, it gets flagged as a security risk and my browser won't get it. But I have read similar things in the past. The point about getting a diver to the surface ASAP would be relevant if you find a diver with the regulator out after a seizure. In this case, the chance of survival is minimal (but not zero, I have seen a survival of that personally), so there would be little point in the rescuer ascending rapidly with the victim if there was a deco obligation (dual fatality). This might be the one case where making a diver buoyant and sending them to the surface would make sense. It's a hail Mary, but reasonable for a number of reasons - not the least of which is that you wouldn't have to risk a recovery dive later, especially if you used a reel as a tether.

 

[100days-a-year]

Assuming my buddy was not a horrible person who neglected to adequately marks their reg and stage, having been sufficiently trained and practiced and was not violating any of my arbitrary safety standards I would immediately ensure a seal on the correct reg and begin a safe ascent to see see if the seizure abated. If not I would continue the ascent, constantly looking for signs they were regaining consciousness. If I saw signs of breathing I would try to ensure as much deco as possible was carried out barring gas switches if they were still unresponsive but breathing. Place them in direct care with the surface crew and return to finish deco if possible.
If they hadn't met all my prerequisites I would do the same, if they were a complete stranger I would do the same as I am not a giant wank.

 

[Searcaigh]

A key point that I don't think anyone has pointed out yet is "what surface support do you have?"

I haven't dived off Jeddah in years, so I can't comment about doing technical diving there, but off the east coast of UAE it's next to zero with the exception of perhaps diving with XR Hub at Fujairah, but I'm not fully sure how they operate since they took over from Coastal Technical Divers about five years ago, who did have a protocol for dealing with "bent" divers etc., but probably not O2 poisoning with a convulsing diver.

My last serious technical dives were undertaken with a bunch of mates, who have all now sold their boats and some left the country. However, it was reassuring that they were all very well trained (BSAC/IANTD) and knew how to deal with most issues that could occur if SHTF until it did happen when surface support was not there at all.

Most boat drivers on dive boats over here (UAE) are just that, boat drivers (and some not very good at it either!), if anything goes wrong and you need assistance, you really need a surface crew to understand and manage the situation. I doubt any dive boat drivers here and in Saudi Arabia are trained for any emergencies at all.

 

[doctormike]

If they hadn't met all my prerequisites I would do the same, if they were a complete stranger I would do the same as I am not a giant wank.

This ^