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Type 1 DCS

3K views 18 replies 12 participants last post by  The Hurdy Gurdy Man 
#1 · (Edited)
An experienced friend of mine (of whom I have asked permission to post this) recently undertook a mundane, unchallenging dive. 25mfw for 42 mins on 32% (twin 12’s) in a puddle, sitting around taking pictures. I was with him on my rebreather using 18/45 and a ppo2 set-point of 1.2.
A painfully slow descent due to my ears saw us @ 25mfw after 4mins where we stayed until 42mins. We then slowly followed the bottom up when he decided that a more direct route to the surface was preferable and his conservative Suunto computer said ok, 1min @5mfw and 3min optional. However, my unit was telling me that 2mins @16mfw were required, so I obliged. Having cleared that obligation, I was presented with 2mins @4.5mfw but a slow crawl around the place saw that reduced to nothing by the time I got there. After a minute he signalled that he was clear to surface and we did.
From 3mfw I took about a minute and a half to surface, by which time he was de-kitting on the pontoon.
Why this post?
He’s heading for an RN62 in the pot for a type 1 DCS in his elbow.
Why?
Mr. Suunto was happy.
PADI 32% RDP would give you NDL of 40mins @26msw.
Z-Plan gives you only 1min@3mfw if you don’t ask it for deep stops.

We think a number of main reasons.
1, It was -1deg on the surface and 5deg at the bottom.
2, His suit leaked at the wrists and he was soaked to the upper arms.
3, He’s not a teenager anymore – sorry mate!
4, Lack of deep stop?

I put a question mark on the last one as the jury is apparently now out again on deep stops. I personally will always agree with them, there’s now way I’m going straight to 3/ 4.5/ 6msw from any serious depth and as long as you’re past the M value line your off gassing, so what’s the harm?
We reckon it’s mainly 1 and 2. You don’t off gas as efficiently when you’re freezing your nuts off. We’re taught in training to add extra conservatism in extreme conditions be they cold or otherwise challenging, but I know that I for one haven’t altered any of my settings from the dives I do in the summer, but it takes something to happen to you or someone nearby to drum it in.
Would a minute or so at mid depth have prevented this? God knows. A bit of 50/80/100%, again who knows? All we know is that decompression theory is not an exact science – according to the RDP, this was not a deco dive anyway!
Would it save a couple of days off work, a drive to the chamber, a five hour £9000 NHS treatment and a good spell away from our favourite hobby plus any subsequent treatments or inconveniences?
Who knows?
Well, speedy recovery mate and thanks for letting me share this. Still it could be worse.......










It could be me in the pot hahahaha!
Sorry! :embarassed:
 
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#2 ·
Hi - you didn't mention hydration - or more specifically dehydration?

Also while I'm thinking:
his max PPo2 was 1.12 (3.5 x .32) & you were running a perfect mix of 1.2 & yet you had an 'extra' stop at 16m. Shouldn't that have told you (or rather - him) to at least hang about for a few more minutes..!!!.

at least he's ok - something about pushing limits & or not 'planning' the dive correctly springs to mind.
 
#3 ·
Also while I'm thinking:
his max PPo2 was 1.12 (3.5 x .32) & you were running a perfect mix of 1.2 & yet you had an 'extra' stop at 16m. Shouldn't that have told you (or rather - him) to at least hang about for a few more minutes..!!!.
The 45% helium in the rebreather is likely to have contributed to the 16m stop. Stops with helium tend to start deeper.
Simon A
 
#4 ·
When did this dive take place? i.e. is this his first trip to the pot? or has it happened since his first?

Could the size of the camera equipment being dragged around exacerbate the problem?

Was he wearing marigolds? or is that a newer fetish?
 
#5 ·
Hobbsy your statement.................
"I personally will always agree with them, there’s now way I’m going straight to 3/ 4.5/ 6msw from any serious depth and as long as you’re past the M value line your off gassing, so what’s the harm?"

is not quite correct not "past it"......but "below it"
Above the pressure line, below the theoretical M value line

The leading prevention (apart from following conservative tables !) is correct hydration, allthough your right, it aint a fully understood science, as long as he's OK.
He was close the limit of the table he was on.
Any previous DCI that might predispose him to future problems ?
 
#9 ·
2, His suit leaked at the wrists and he was soaked to the upper arms.
I would suggest that in 5C water this would make quite a difference to blood flow and therefore gas exchange in the area, with ONgassing being faster than OFFgassing as he was warmer at dive start than finish.

As always, You'll never know and even if you did it's likely to be a combination of things, but I would think this to be a factor.

Juz
 
#10 ·
Thanks Mr H... :)

20/20 hindsight is a great luxury and I'd subscribe to Nos 1-4 as all being partially to blame for my hit.

I don't believe dehydration was an issue. I'm very careful about maintaining good hydration and need a pee valve because of it! Though of course its not the water consumed immediately before a dive but that consumed the day before. I habitually drink two pints of water though the night and also guzzle pints (of water!!!) during the evening.

The solution is simple. Recognise that at 51 years old, a stone and a half overweight and perhaps not being the fittest dude in the race a "mundane, unchallenging dive. 25mfw for 42 mins on 32%" may not be that mundane after all (even if Mr Suunto says yes) and sucking some 80% may not be such a bad idea...
 
#15 ·
Generally speaking the trouble with DCS is that it is totally unpredictable.Even taking all the so called factors into account doesnt explain a hit.At my age now ( er over 60 ) I get a skin bend and muscle pain after nearly every deep dive. Varying stop times, ascent rates and deep stops doesnt seem to make much difference.True by todays standards I am always dehydrated . With my bladder I need to be. Well last year it all went tits up and I had a rapid ascent from close to 60m at the end of the dive.. I missed 67 mins of stops and the water was cold. Was I bent to hell? No not a bit of it. A tiny niggle in the elbow and no skin bends.I had a precautionary 4 hours in the pot and was right as rain.Mind you the pot folk said it was a miracle. Some you win, some you dont.
 
#16 ·
Back from the Pot... Went to the London Chamber which, believe it or not, is easier to get to than DDRC from S. Wales...

Oliver Firth and his (largely antipodean) team are first class. I phoned ahead and they had the chamber primed for a RN 62 and extensions which did the trick nicely. A quick retreat the following day to aid the healing and I'm right as ninepence :).

I can't recommend the London Chamber enough (having experienced its facilities on more than one occasion...) A big thanks to those guys (especially to Gemma who did the big stint with me) who are very people orientated and very knowledgable divers too, most being ex Oz navy. Hey, even the food rocks too!

Take care guys. Over and out.
 
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