O2 convulsion

Drmike

I was on a trip last year and we had a diver do a slow ascent from 72m (after spending about 15-20 mins working down there, he spent no more than 30 secs on the surface shouting instructions to the crew then turned straight around and descended back to depth and did all his deco. He didnt get any DCI.

Not recommended - but it can be done in an emergency, afterall commercial divers used to do this quite regularly doing their deco in on-board chambers with a fairly good sucess rate. Of course only for emergency here.

I also use those patches (they are the only thing that stop me throwing up) The time I had my twitch I was using the patch but I think thats a coincidence because I always use them and have logged some horendously high CNS% with the patch on.

I guess seeing as toxing is effected by retained CO2 levels, which is increased by effort, there is good sense in lowering the ppo2 at the working depth as you have done and boosting it during the resting phase/deco. Especially on deeper dives where the bottom ppo2 has less impact to amount of deco you have. When I had my twitch it was after a hard-hard dive where Im sure my CO2 levels were quite high.

Was your dive a hard one?

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jhaaja

The dive itself was not so hard. We did swim and did some light work put there was no current at the site. The visibility was bad (around 1-2 meters with lights) so it was tough on the nerves.

I have also used scopolamin with success earlier. I have also heard that finnish navy divers use it sometimes. It is the only thing they are allowed to use. The difference is that they don`t dive that deep.

Would be nice to know if others also use scopolamin with deep diving. I have an idea that something (the medicines maybe) led to slower CNS% drop between the dives. I mean that the 90 minutes half-time was not correct at that time. I must have had some CNS% before the dive, because on the dive I accummulated only around 50% according to VR3 before the convulsion.

JH
Finland

scubagrunt

what a experience! pass, glad you are okay.Oxygen toxicity is a strange malady. I have had to rescue a OC buddy having a seizure from 15 fsw. The real weird thing here was his clock was at only 24% and the max PPO2 during the dive was 1.61 atm at 20 fsw on 100% for 2 minutes only!!! Then after 15 minutes at 15 fsw on 100% he goes into a seizure. This is all pretty scary, and is the reason I am starting to work with FFM on CCR. It would be interesting to get some real stats on CNS O2 hits relating to clock and PO2.

JonnyB

As a commercial diver myself, unfortunatelly we do surface decompresison more often that you think. Basically you will arrive do all you deco up to 9m and then you have 5 minutes to get from 9m in water and down to 12m in chamber. Most companies have stopped this and use a closed bell even for shallower dives than 50meter. But still there are people doing it regurlaly. Which is something that i totally disagree with.

just my ppO2
Jonny

dave t

do you always cal at 98%? only a small point I know but if you cal at 98% and you actually have 100% in the lid whilst calibration your actuall breathed po2 will be higer than the controller thinks so at 1.3 it will be 2%higher plus any error and ambient pressure (at calibration)

small point but one to consider

E-man

I believe its more the other way around erring on the side of lower PP02 inspired. You have 98% (.98 PPO2)(1ATA) but your telling it that thats 100% (1.00 PPO2)(1ATA)
21% 02 = .23 PPO2 (1ATA)


Good to hear you made it through the incident pretty well. I agree sounds to me like maybe your CNS% didnt drop as much as it should have?

caveseeker7

Glad to hear you came out of it allright.
Congratulations to you and the team, especially your buddy.

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Drmike

Er nope, you are telling your controller that 100% is in fact only 98%.

So it would in fact give you extra O2.

__________________
Cave diving is a sport
Wreck diving is a sport
Diving in general is a sport

'Rebreather diving' is not a sport
its the delusional obsession with a highly dangerous and often inappropriate piece of equipment

Sutty

Hi, Glad it worked out OK - good advert for having a (competent) buddy.
A few thoughts, you mentioned your symptom of diaphragm contractions - what did it feel like exactly, did it interfere with your breathing? If this wasn't diaphragm contraction but palpitations (can feel like fairly dramatic thuds in the chest too) then it could have been an abnormal heart rhythm, which could possibly be caused by the aerius (listed as a side effect), and may be made more likely by the scopolamine (also increases heart rate). The seizure would then be secondary to a lack of blood to the brain - we see this occasionally in hospital, when people lose their cardiac output they can have a secondary seizure.

dive2dive2000

Glad you okay!
Do you know what your OTU count was?

On the scolopine subject, I switched a long time ago to Phenergan, The patch is great, but once you start using it more than once a week it builds up in your body and there are some nasty side efects, and thats on land not sure what diving wiil do to the side effects. Phenergan is fantastic, there is a bit of drowssyness but nothing crazy, and it beats

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Safe Diving,
Martin