Decompression Tables

[wedivebc]

I have never met a diver that has had a DCS hit nor have I ever met a diver who knew a diver that was rumored to have had a hit.

I have been hit more than once. All 3 times using RGBM. One time it took 6 months to resolve.

 

[gcbryan]

I have been hit more than once. All 3 times using RGBM. One time it took 6 months to resolve.

Did you learn anything? (serious question by the way). I know the easy comment for someone to make is that you must be doing something wrong or shouldn't be diving but I'm serious when I ask was there anything for you to learn or was it just a random thing given the number or type of dives that you do?

 

[syntaxerrorsix]

You can probably give Richard a call at the Hyperbaric Center (919) 684-6726 or e-mail him at: moon002@mc.duke.edu

To break the ice, ask him if he's the famous guy who tested silicone breast implants?


I haven't been to Duke in years; since Pete Bennett ran the Atlantis Project there in the early 80's (chamber dives to 2300 ft). I was an Observer for one of the tests (visiting from DCIEM).

Can I hijack the thread and request results for the Atlantis project?

Please?

 

[kgault]

E-mailing contact at NEDU for confirmation one way or the other.

The post you reference is over a year old.

Current nitrox Tables/Dive Computers that have been authorized for use by the US Navy are based on either the VVAL-18 or VVAL-18M parameterizations of the Thalmann Algorithm. The Thalmann algorithm is a deterministic Exponential-Linear algorithm.

In the 11 years that I have been at NEDU we have not used VPM as a decompression tool for Navy diving. Current model development efforts are in probabilistic models for which Gene has given the references that started with Capt. Paul Weathersby & Capt. Ed Thalmann's group out of NMRI.

How does the post being a year old cause problems? it was made after Rev 6 was released, and the Navy has not released a newer set of tables even though the forward to Rev 6 indicated that the Supervisor of Diving was starting on Rev 7.

Keith

 

[kgault]

I was an Observer for one of the tests (visiting from DCIEM).

Where you still at DCIEM in the spring of 89?

Keith

 

[Gene_Hobbs]

Can I hijack the thread and request results for the Atlantis project?

Please?

They were published...

We have a few of Bennett's publications here and more from Salzano here. (mainly abstracts)

Other publications can be found through searching Bennett in PubMed as well as Salzano. Look at publications in the late 70's and early 80's for the Atlantis work. Stolp still owes me his PhD thesis so I don't have that one yet...

The profiles from 3 of the 4 dives along with a few photos can be found on the Duke HBO site.

Hope this gets you started. PM me if you need help finding anything.

 

[wedivebc]

Very good question actually and one I had to ask myself at one time. After my type 2 hit (most recent) I got a PFO test (neg). I no longer use RGBM.Not that I believe it was at fault I did plenty of deep dives without bends using same computer. I actually did 400ft a week after that hit using same algorithm with no issues. No algorithm can guarantee zero chance of DCS some just have better probability than others. I find I feel better after a VPM-B schedule padded with 25% above nominal critical radius and feel pretty confident in that. Will I get bent using that algorithm? Yeah probably if I dive it enough.

Did you learn anything? (serious question by the way). I know the easy comment for someone to make is that you must be doing something wrong or shouldn't be diving but I'm serious when I ask was there anything for you to learn or was it just a random thing given the number or type of dives that you do?

 

[kgault]

The tables were written with a 5% rate of bends. It's an acceptable risk for the Navy.

The USN56 air tables were not written to have a specific risk of DCS. They were evaluated with the probabilistic algorithms to assess the risk of the schedules. The probabilistic algorithms used to assess the risk assumed wet working divers (hard exercise on bottom; 60F in a wetsuit, so cold for bottom time and deco).

The schedules were found to have an estimated risk of DCS of approximately 2.2% (depending on the probabilistic model) at the no-stop limits (See Rev 5 of the USN Diving Manual). The general trend is for the risks to rise to approximately 5% at the dividing line between the allowed schedules and the Extreme Exposures. In the Extreme Exposures the risk could rise above a 10% estimated risk.

When dove without the stresses of Navy diving the observed outcomes of DCS are lower (i.e. in a drysuit, scootering, etc)

It was/is considered acceptable for the risk of DCS to rise as the total decompression time rose due to other factors in the risk analysis of Navy diving.

In Rev 6 the Navy puts an increased emphasis on switching from air decompression to in-water oxygen, and then onto surface decompression with oxygen when possible to lower the risks to the divers.

Keith

 

[DCBC]

Where you still at DCIEM in the spring of 89?

Keith

Hi Keith,

No, I was transferred to DCIEM from Fleet Diving Unit (Atlantic) in 73 and served as a Diving Officer there until 85.

 

[DCBC]

Can I hijack the thread and request results for the Atlantis project?

Please?

I'll send you a personal message.