Deep diving accident

[wedivebc]

SO far I have not heard of a case where a HEALTHY person diving within the normal limits has had a seizure.. All the cases I have heard either the person had a past history of seizures (manyin the distant past) or had an undiagnosed conditon that was discovered afterwards.. The elevated o2 triggered an existing condition.. As the use of Nitrox grows people that never had problems might have had problems due to other medical conditions..

O2 tolerance varies from day to day, but all the measureable changes are well outside the normal accepted ranges..

Would you include some OTC medications with the health issue group?

 

[z3r0c00l]

But what is the normal PPO2 level anyway? I expect that in a million people, you will see numbers below 1.2 of isolated cases. This is a very hard thing to define, but I honestly dont think you are 100% safe just because you are below 1.6 for short periods, or 1.4 for long periods.

 

[padiscubapro]

Would you include some OTC medications with the health issue group?

Many medication s have side effects even very common ones.. Just look at decongestants.. Most can have an impact on the central nervous system..

 

[BMCG]

DA - introducing Helium into the mix should enhance CO2 removal which should - at least viewed unidimensionally - reduce the risk of Oxtox...

Granted if there's another mechanism involving Nitrogen that reduces susceptibility to Oxtox, they may well be offsetting...

 

[padiscubapro]

DA - introducing Helium into the mix should enhance CO2 removal which should - at least viewed unidimensionally - reduce the risk of Oxtox...

Granted if there's another mechanism involving Nitrogen that reduces susceptibility to Oxtox, they may well be offsetting...

Nitrogen is a very strong CNS depressent..
Although He will make the gas easier to breathe, all modern regs perform quite well with regards to WOB.. Some of todays best regs can perform at depths of 200m (~660fsw) using AIR better than some of the best regs a decade ago using a rich He mix!..

 

[limeyx]

Nitrogen is a very strong CNS depressent..

I am very interested in any published research, word of mouth, or any reasonable evidence of this one ... I have heard it for the first time very recently, and definitely want to know more about this ...

 

[padiscubapro]

I am very interested in any published research, word of mouth, or any reasonable evidence of this one ... I have heard it for the first time very recently, and definitely want to know more about this ...

There are lots of papers on the subject of nitrogen narcosis.. I would start with the rubicon foundation... There are a few papers floating around with regards to otox..


The properties of nitrogen with regards to physiology SHOULD have been covered in a good nitrox class.. The CNS properiteis of nitrogen have been known for a long time... A common form of a nitrogen mixture is Nitrous Oxide... And we all know thats been used to put people out for many years..

 

[limeyx]

There are lots of papers on the subject of nitrogen narcosis.. I would start with the rubicon foundation... There are a few papers floating around with regards to otox..


The properties of nitrogen with regards to physiology SHOULD have been covered in a good nitrox class.. The CNS properiteis of nitrogen have been known for a long time... A common form of a nitrogen mixture is Nitrous Oxide... And we all know thats been used to put people out for many years..

I searched Rubicon and published my results here -- nothing conclusive either way.

if it's been "known for a long time" perhaps you could point me to some papers/websites or books that cover some studies? I dont seem to have anything like that in my PADI Nitrox materials.

I dont breathe Nitrous oxide underwater generally, so I dont really see how that's going to help me.

 

[Rick Inman]

Saturday, while diving in SD, I talked to someone who was there when it happened. He said that the diver was under-weighted and therefore unable to hold depth on his final 20' stop. To avoid surfacing without completing his deco stop (there was no line), he kicked down to a depth he could maintain - below 20' -and toxed at that depth, still breathing his 20' bottle. He missed 6 mins of deco and suffered no ill effect for the missed deco.

I was not there, and am retelling the story as I remember it told to me by someone who was there, so take it for what it's worth.

BTW, I was also under-weighted on a deco dive Saturday and had to hold the line to complete my final stop, which was why the story was told to me.

 

[Ayisha]

Good to know, Rick, thanks. It makes sense. That explains the struggle to maintain his buoyancy at the stop.

That has probably happened to a lot of us. It's best to do a weighting check at the end of the dive, when your tank is less full, BUT that's pretty hard to do when you're beginning a dive with a new kind of exposure protection or a new environment, ie. salt water or fresh water. Also, many of us try not to drain our tanks, so if one day we have to do the safety stop with a nearly empty tank, our weighting might be a little light. So I guess you weigh yourself to float a foot or so lower than eye level at the beginning and then re-check your weighting at the end of the dive.

So what could be done in a situation like this? I suspect holding onto a buddy might be futile - you wouldn't want to yank them up - or is it possible at that shallow depth? Or I guess if you're using a depth-sensitive gas, disregarding the last bit of deco time instead of going deeper? But then, I guess he didn't expect the oxtox issue at that depth. Don't know...