DCS incident analysis requested

[Snowbear]

i remember my gue instructor saying that repetetive dives wherein succeeding dives MUST be shallower than the previous was a misconception and that they have tested going deeper on rep dives safely.

But.... that's with proper gasses and proper decompression.

I actually gave you my "analysis" in the other thread.... I'll go find it and bring it here.

 

[Snowbear]

First of all ~ please don't take this post as criticism. That's not my intent... just a few observations from someone who used to push the envelope

talked to the local dan rep and he mentioned that i did have slight dcs symptoms. he mentioned that their was no real factor but a combo of factors which made me more prone to dcs than usual. factors such as lask of sleep the night before, lowered immune system, repetetive deep dives all contributed to the occurence of slight dcs...

Yep, day to day factors can make you more "prone" to DCS. Looking at the brief description of your dives, it sounds like you did a couple of fairly aggressive dives, especially the first one. My opinion is that the first dive is probably where you got "bent" with each subsequent dive adding to the damage done until the symptoms became too persistant to ignore.

Although you did long SI's, I've personally found offgassing via a slower ascent and more time spent shallow for time spent deep (sound familiar )makes me feel a whole lot better (less tired, more energy, no headache, no "niggles") than even doing "NDL" dives within agency established "safety" parameters including deeps stops, safety stops and 30fpm ascent rates and counting on the SI to finish the deco for me.

You didn't mention what back gas or deco gas you were using when you "...even did our obligatory deco stop for 5 mins becasue our computers registered deco." If you're gonna do these dives, there are better gasses than air, especially for more efficient deco.

Hope you learn from all of this and dive more safely...

 

[Spoon]

But this is with the proper gas. You were diving these profiles on air right? Which tables were you diving?

yup i was breathing air, and you are corect when you say breathing with the proper gas.

 

[Ben_ca]

Of course, the big problem in cases like this is that it's all a matter of statistics/luck or (un)luckiness. We can shift the balance of luck for us or against us, but one could repeat a profile a hundred times without problems,and then get DCS on the next one.

Spoon,

Don't take this harshly but I think you are still in denial. I think that this hit was more deserved than undeserved. I don't mean to put you down but I would throttle down a bit. And as far as a the profile being DIR I would say no... This should have been on 32%, and just because the computer says your okey doesn't make it so. Listen to your body... how do you feel? Not 100% maybe sit down and pass on the 2nd dive.

Like I said don't take this the wrong way... Next time I'm in town I'll buy you a beer and you can either drink it with me or hit me on the head with it.

Ben

 

[lamont]

First of all, i'd get check out for a PFO. I've read speculation that skin bends tends to correlate with PFOs and that would also explain why you got bent as well.

Second, recreational computers are poor for deco. Even "RGBM" computer do not do deep stops and will send you right up to 10 fsw to do your deco. So, the fact that you "did your mandatory stop" on the first dive doesn't really indicate that you did a clean deco.

Third, you were were on air. After that first dive where you hit deco you probably got a pretty massive free-phase bubble shower due to the agressiveness of the profile and the 21% you used. I find that I need to do 1-3-7 deco or so, even on totally weenie dives, on air in order to deco without getting fatigue after-effects. You were very unlikely to have completed that first dive with clean deco.

Fourth, what was your decompression like from your second dive? Since it was aborted early did you skip deep stops, safety stops, etc or skip them? What may have happened is that the free-phase bubbles from dive #1 got compressed and passed through the lungs and re-expanded giving you a home-made PFO. See http://www.wkpp.org/articles/Decompression/why_we_do_not_bounce_dive_after_diving.htm

Those are my thoughts: get checked for a PFO, EAN32, no deco diving on the 'puter.

 

[alibee]

Spoon,

Don't take this harshly but I think you are still in denial. I think that this hit was more deserved than undeserved. I don't mean to put you down but I would throttle down a bit. And as far as a the profile being DIR I would say no... This should have been on 32%, and just because the computer says your okey doesn't make it so. Listen to your body... how do you feel? Not 100% maybe sit down and pass on the 2nd dive.

Like I said don't take this the wrong way... Next time I'm in town I'll buy you a beer and you can either drink it with me or hit me on the head with it.

Ben

I agree with Ben. Spoon, you keep making these posts that sound like you think you did nothing wrong and that it was merely the fact that you exercised and were "unlucky". Did you read the plethora of replies that said you were out of most limits on any chart? Everyone who has checked your dives against a table has told you that you weren't just close to overdoing it, but that you PLAINLY and CLEARLY were out of non-deco bounds. I'm not trying to be harsh, but your current denial of the facts could very well lead to your death at a later dive.

 

[wedivebc]

Even "RGBM" computer do not do deep stops and will send you right up to 10 fsw to do your deco.

Maybe if your talking about suunto RGBM but this is not true for the true imlementations of RGBM such as HS explorer

 

[Charlie99]

Don't take this harshly but I think you are still in denial. I think that this hit was more deserved than undeserved. I don't mean to put you down but I would throttle down a bit. And as far as a the profile being DIR I would say no... This should have been on 32%, and just because the computer says your okey doesn't make it so.

The words you quoted were mine, not Spoons. In that post, Spoons comments are in italics.

I haven't seen enough info to know whether or not the profile was reasonable. Max depth and time; or even max depth, time and average depth still leave a lot unsaid.

My understanding is the the DIR position is that "air is only good for filling tires", and therefore any profile on air is not DIR.

 

[Charlie99]

Did you read the plethora of replies that said you were out of most limits on any chart? Everyone who has checked your dives against a table has told you that you weren't just close to overdoing it, but that you PLAINLY and CLEARLY were out of non-deco bounds. I'm not trying to be harsh, but your current denial of the facts could very well lead to your death at a later dive.

Many very reasonable multilevel profiles will be way off the charts of square profile tables.

 

[jonnythan]

Spoon, unless I missed it, you never let us know how you planned these dives?