Where i have better chances to survive

[tyrell]

I have a theoretical scenario.
Diving on TriMix at 75 msw and after 10 minutes in the bottom I have a total malfunction in the bottom mix and the only gas I left with the deco gas.

I have two possible options, the first one is to jump up to 30 meters as fast as possible and start using the 50% o2 and take the risk of getting helium decompression. Or start using the 50% in the bottom, go up in 20 m/min and take the risk of getting o2 toxicity.
:wacko:
In this particular scenario, in which is the preferred action to take, and where I have better chances to survive with minimum damage.

Regards

Mark

 

[Diver0001]

tyrell once bubbled...
I have a theoretical scenario.
Diving on TriMix at 75 msw and after 10 minutes in the bottom I have a total malfunction in the bottom mix and the only gas I left with the deco gas.

I have two possible options, the first one is to jump up to 30 meters as fast as possible and start using the 50% o2 and take the risk of getting helium decompression. Or start using the 50% in the bottom, go up in 20 m/min and take the risk of getting o2 toxicity.
:wacko:
In this particular scenario, in which is the preferred action to take, and where I have better chances to survive with minimum damage.

Regards

Mark

I think you have a third option, which is to abort with your buddy on his bottom mix and ascend normally.

R..

 

[tyrell]

that is obvious, but this is not the issue.

the question is
about what is the best way in the physical, medical point of view to survive a situation like this ( if it is possible at all to survive it)

mark

 

[padiscubapro]

tyrell once bubbled...
I have a theoretical scenario.
Diving on TriMix at 75 msw and after 10 minutes in the bottom I have a total malfunction in the bottom mix and the only gas I left with the deco gas.

I have two possible options, the first one is to jump up to 30 meters as fast as possible and start using the 50% o2 and take the risk of getting helium decompression. Or start using the 50% in the bottom, go up in 20 m/min and take the risk of getting o2 toxicity.
:wacko:
In this particular scenario, in which is the preferred action to take, and where I have better chances to survive with minimum damage.

Regards

Mark

every table I ran (except programs enforcing deep stops) using a 50Tx17 mix (50% helium), with a 10 minute runtime, has the first stop at 18m, if you are stuck on you last breath you should still be able to do a reasonable ascent and switch to 50%...

 

[tyrell]

padiscubapro once bubbled...


every table I ran (except programs enforcing deep stops) using a 50Tx17 mix (50% helium), with a 10 minute runtime, has the first stop at 18m, if you are stuck on you last breath you should still be able to do a reasonable ascent and switch to 50%...

ok,
that means im in 75 meters, now, what is the fastest assent rate without getting the risk of helium decompression.

i can make an emergency accent from 75 mt to 20 mt that is 55 mt. lets say i can hold my breath for 1.5 min under these circumstances, this is still 30 meter/min ascent.

Again my question is, will I get helium decompression during the fast ascent?

When to switch to the 50% at 20mt ? or deeper.

 

[Dr Deco]

Hello tyrell:

I would probably take my chances with DCS. This is a good probability that you are resistant and would not get the bends.

If you live, then it is your lucky day; you might also want to purchase a lottery ticket when you reach shore.:mean:

Oxygen toxicity [CNS] is a more serious problem unless someone is there to assist you with breathing. You will probably not get any late treatment options with drowning.

Dr Deco :doctor:

 

[padiscubapro]

tyrell once bubbled...


ok,
that means im in 75 meters, now, what is the fastest assent rate without getting the risk of helium decompression.

i can make an emergency accent from 75 mt to 20 mt that is 55 mt. lets say i can hold my breath for 1.5 min under these circumstances, this is still 30 meter/min ascent.

Again my question is, will I get helium decompression during the fast ascent?

When to switch to the 50% at 20mt ? or deeper.

even if you did so what..

we can unbend you we can't undead you....

I would not risk oxygen toxicity... its much much more likely than a bend...

I hope you wouldn't be holding your breath otherwise you'll probably get some form of expansion injury.. assuming you has started with a po2 of 1.4, you can ascend for quite a while on this.. you can also "cheat" if you HAD to hit your 50% by not fully exhaling all the gas in you lungs, and "topping" it with some 50% to replenish some of the lost o2...
sure youll have some CO2 but at least your not breathing a really high po2 at depth..
By 30M I would take a fairly good breath, and breath normally while asecnding from this point, dont hang at depth... thats only 45 meters, it should be easily accomplished...

You should find out how far you can confortable go at a constant depth without taking a breath... you'll probably be surprised, ascending in my oprion is even easier....

 

[vicky]

When getting to the "relative safety" of 30m and switching to the deco mix, one can ask for assitance from the support team (a diver to watch and help in case one gets DCS symptoms, more breathing gas, 100% O2 to be used on the last stages and on boat, etc).
I think it sums up to better survival chances compared to an attempt to begin ascending from 75m breathing 50% O2.

 

[tyrell]

thnx Dr Deco,

i just wanted to know if someone has to face cns or getting bent underwater, where he gets better chances to survive.

padiscubapro, i know how long i can hold my breath, and upon that i made athe calculations of ascenting for 1.5 minutes (CESA as they call it in PADI) "topping" is also a good idea.

i have no intention at all to perform a stunt like that, it was a theoretical question

thanks
mark.

 

[Dr Deco]

Dear SCUBA SOURCE Readers:

Lesser of Two Evils

I believe that it was Mae West who said, “When faced with a choice between two evils, I take the one I haven’t tried yet.” When faced with the choice between DCS and whatever, one should always remember that DCS is not a sure thing. There are many commercial divers who have been hauled up by the tenders to shallow depths and have been OK. It is certainly not something you would choose to do. However, if I thought that I would very likely get an oxygen “hit” or a possible DCS “hit,” I would opt for DCS and pray that it was mild (or did not appear at all).

The same can be said for reentering the water to recover “missed decompression stops.” Usually waiting and watching on the boat is better. I am not talking The Last Dive here; they were in big trouble from the start. But, a matter of a missed few minutes is often fraught with more problems than it solves.

Dr Deco :doctor: