Decompression Accident in North Sulawesi

[uncfnp]

He is not in favor of Nitrox dives, using a Nitrox setting even put on a +1 or +2 conservatism. For this the divers have to realise that a dive computor does not know how a particular body behaves. They should therefore dive with wider margins than the computor indicates, especialy if risk factors are present. Moreover for dives with mandatory deco stops, the computor gives only ways and techniques in order to minimise a risk that is way bigger than dives within the NDL.

.........


2 or 3 dives per day is OK, as long as succesive dives do not put the diver too close to the Deco line AND to rest without diving for 24 hours every 4/5 days. The goal, surprisingly, is more to give a chance to the dive computor to "reset" rather to enable the diver to recover. After several days of multi dives, a lot of computors are quite a bit lost, he explained.

I am sorry but I simply can not follow the logic of these two statements. Would @rsingler or @Dr Simon Mitchell be willing to give their take on this?

 

[outofofficebrb]

Hi, @Freewillow. What a nice summary of your visit. It sounded really helpful and worthwhile. Please keep us updated on the PFO!

I wonder if there is a particular algorithm that you should be diving given this information. On top of those practices, a more conservative algorithm or preferred algorithm.

 

[Kevrumbo]

It is much better to do square profiles or a two-levels dive, e.g. 20/25 meters, then half depths and then immediately to the safety stop.

He admits that to make a safety stop with enriched nitrox over 70% 02 could be a plus, but not essential for the recommended profiles

I can understand Dr. Germonpré's recommendation to refrain from post-dive exercise, and dive profiles to minimize surfacing slow-tissue supersaturation and latent post-dive bubbling -Rule Out PFO.

But if you had to make several long slow "photographer's profile" ascents and similar to your original consecutive four-day multi-dive schedule, would 100% O2 safety stop(s) then become a mandatory contingency?

 

[Bubblesong]

So as not to steal the thunder of the researchers: A surprise lesson…

this is great information, and makes me think the only way to go from colder to hotter underwater is with a heated vest.
So would a heated vest, that was on a timer be the best option? I’d want a timer that would turn it on low, after the planned bottom time elapses, so that i don’t have one more thing to recall as i am wrapping up a dive.

 

[tursiops]

this is great information, and makes me think the only way to go from colder to hotter underwater is with a heated vest.
So would a heated vest, that was on a timer be the best option? I’d want a timer that would turn it on low, after the planned bottom time elapses, so that i don’t have one more thing to recall as i am wrapping up a dive.

My thermalution vest, for use with a wetsuit, has a controller on a coil-cable that comes out at your neck. You can turn it off, or lo, med, or hi. I usually run it off until I get chilled, and them put it on lo for a while, then off again. At the end of the dive, I can put it on lo or med until I exit.

 

[Freewillow]

I am reading your answers. Please be aware that the recommendations were done FOR MYSELF: age 69, confirmed ADD on pretty "normal" dive profile, high suspicion of a PFO.

So do not draw direct conclusions for your own practice.

 

[Centrals]

I am reding your answers. Please be aware that the recommendations were done FOR MYSELF: age 69, confirmed ADD on pretty "normal" dive profile, high suspicion of a PFO.

What would you do if you have PFO?
Would you close it or give up diving completely?

 

[Freewillow]

@ centrals, to close it is NOT an option, especially at my age. The risk/price/benefit ratio is too small IMHO. The recommandation do take into account the presence of a PFO. So a positive diagnosis would not make a difference in my case.

From what I have read in the litterature, the following steps are used in some places: ADD, diagnosis of PFO, recommendation of "safer dive profiles" and then eventually a PFO closure in case of ADD reoccurence.

Of course we are talking about recreative divers.

 

[Dr Simon Mitchell]

I am sorry but I simply can not follow the logic of these two statements. Would @rsingler or @Dr Simon Mitchell be willing to give their take on this?

Hello,

I think that these issues have been raised in the context of a conversation in which it is assumed that Freewillow probably has a right to left shunt (eg PFO) and they are exploring means of risk mitigation. One obvious way of mitigating the risk of a PFO would be to have it repaired. Freewillow is not particularly enthusiastic about this. Another means of mitigating the risk is to dive in a manner likely to produce less venous bubbles (which can cross the PFO and cause more trouble); I believe that is what the two statements are about.

In the first Peter is saying that diving nitrox whilst using air tables or computer settings will likely result in reduced venous bubbles, but in diving nitrox and using nitrox tables or computer settings you lose this opportunity to make your diving more conservative.

The second, I think, is simply part of a general recommendation to avoid diving right up to the no decompression limits (or computer ceiling), along with the observation that none of our predictive algorithms have been adequately tested over multiple consecutive days of multiple dives per day. Having a day off periodically in such a sequence is a common recommendation perceived to be likely to increase safety.

Simon M

 

[uncfnp]

Thank you Dr Mitchell. My confusion with the first statement is the preference for nitrox on air settings over a DC set very conservative but I am probably looking at this too much in my own prespective. When I think of conservative diving I think of the RGBM, already conservative, with option of increasing the SF. It was my assumption that since the algorithm is reputed to account for added factors, such as ascent rate, SI and repetitive dives, it would be safer than simply diving a computer set for air. (I dive a Cressi and a Petrel)

My confusion with the second statement was this...

“The goal, surprisingly, is more to give a chance to the dive computor to "reset" rather to enable the diver to recover.”