In Water Recompression

[100days-a-year]

Not gonna happen,not anywhere close to practical for all but a few charters.

Not in cost,not in space,not in weight,not in personnel.

It'd be nice, but I'd rather have a 02 membrane system on my boat than a chamber.Lugging Ts to be filled and stashing them on the boat is a real PITA.

 

[oldschoolto]

I think you'd be lucky to have a aluminium or light steel tube with a window and a pressure gauge that you could put a diver in and bring it up to 60-100 psi... At least you could stop it from getting worst and be able to get them to a real chamber..

Jim...

 

[KevinNM]

You'd have to be running a fairly big ship before it's practical, or go very exotic places with very well funded and paranoid divers.

 

[Akimbo]

A 90-100' liveaboard can easily accommodate 54" double-lock like this plus two large LP compressors. I've installed them on vessels of opportunity lots of times. Below deck would keep the CG low and use the least desirable passenger space.

 

[KevinNM]

Well sure. On the spree you’d lose 2/3 of the passenger space. And would require cutting a huge hole in two decks.

So hope you have some really wealthy paranoid passengers who really like to dive.

 

[Duke Dive Medicine]

If you're diving 45m and deeper with mandatory decompression profiles over two weeks (eg Bikini Atoll), with the next nearest chamber a 30 hour return back to port, then it would be prudent to have an onboard 6ata Recompression Chamber rather than solely relying on O2 IWR. . .

Not that it would increase the likelihood of this happening, but you could get away without the 6 ATA. A chamber that goes to 60 fsw and has O2 would handle 99.9% of DCS cases. That opens up the option of some lighter flexible recompression chambers.

Best regards,
DDM

 

[RayfromTX]

Would a 3ATA chamber also give you a bridge to get to the 6ATA chamber for the other .1% or at that point are we into the cases that don't resolve favorably anyway? When we are talking about the last 1% or less the individual variables would have a greater impact on the outcome than the treatment options, it would seem to me from my position of interested ignorance.

How much more reasonable is it to have a 3ATA chamber? Is it still way out of reach? Isn't staffing and training the bigger issue. I'm just trying to learn and I only see these issues touched on but not quantified in a nutshell I can retain easily.

 

[Duke Dive Medicine]

Is there any meaningful difference in patients' reaction to IWR and HBOT if we take away the fact that one takes place in the water? If not, it seems to me that we could learn a lot about the potential risks of IWR from HBOT treatment. That is, what percentage of HBOT patients suffer side-effects that would be problematic underwater (loss of consciousness, convulsions, etc.). And what percentage of patients initially suspected of DCI are later determined to be suffering from something else?

Hi Cowfish Aesthetic,

The risks are different. A US Navy Treatment Table 6 / Royal Navy TT 62 goes to 60 fsw / 18 msw and is a minimum of 4 hours and 48 minutes long lock to lock. It's not safe for an immersed diver to breathe oxygen at 60 feet due to the increased likelihood of O2 toxicity, and that length of time under water would increase the probability of hypothermia and dehydration. There are also operational considerations like availability of equipment, level of training of the dive team, emergency decompression plan, etc. The max 100% O2 treatment depth that the formal IWR tables recommend is 30 fsw / 9 msw.

Best regards,
DDM

 

[Duke Dive Medicine]

Would a 3ATA chamber also give you a bridge to get to the 6ATA chamber for the other .1% or at that point are we into the cases that don't resolve favorably anyway? When we are talking about the last 1% or less the individual variables would have a greater impact on the outcome than the treatment options, it would seem to me from my position of interested ignorance.

How much more reasonable is it to have a 3ATA chamber? Is it still way out of reach? Isn't staffing and training the bigger issue. I'm just trying to learn and I only see these issues touched on but not quantified in a nutshell I can retain easily.

Hi Ray,

I've personally never seen a DCS case go to 165 feet, though some facilities use deeper tables and swear by them. The one time it happened at Duke (before my time) is still legendary there. The old protocol for gas embolism used to involve a 165 foot spike and the option is still there if the diver can be placed in the chamber immediately or doesn't respond to initial treatment at 60 feet.

This isn't a product endorsement, but the Hyperlite 1 chamber is one example of a flexible recompression chamber that would take up a lot less space than the DDC in the picture that Akimbo posted (though the old hard hat diver in me loves it). It's still very pricey and so probably isn't a realistic option for any but the most well-funded (or well-connected) dive expeditions. It also does require additional training and experience.

Best regards,
DDM

 

[Akimbo]

Most DLCs (Double-Lock Chambers) used by the commercial diving industry are rated for 300-350' -- basically as deep as the particular pressure vessel code dictates for 3/8" or 10mm steel plate. We looked at making DLCs from thinner plate but the cost savings was marginal. There is a USN treatment table to 225', but I think most of the motivation is for structural integrity for handling. I have seen a chamber out of service in a bone yard because the hull was dented.

I suspect there is a non-trivial amount of divers who return for a reped (as Akimbo calls it) or IWR.

BTW, Reped is short for REPEtitive Dive... Repet sounds like replacing your dog. I think I picked it up from the Brits in the 1970s.