Deep Stops Increases DCS

[ajduplessis]

Yes we dive VPM-B +2 OC.

 

[UWSojourner]

And the hit rate of the many divers completing 250-400ft dives on VPM-B+2? Do you know hits (numerator) vs. dives (denominator) of those executed right at the VPM-B+2 ceiling?

 

[ajduplessis]

0% hits with 100's of dives completed yearly. Profiles are dived to the number.

 

[victorzamora]

Are "niggles" appearing? Also, has someone honestly tried 40/70 on a deep dive and compared how they felt in terms of being tired? Niggles and exhaustion are why nearly all of my acquaintances doing these dives have moved to a "shallow-stop" model.

 

[UWSojourner]

0% hits with 100's of dives completed yearly. Profiles are dived to the number.

I attended the 2008 Deep Stop conference. During that event one of the training agencies stood up in support of deep stops and made a similar claim -- no hits, hundreds of technical dives, and "what works works" kind of thing. It was rather humorous that someone at the event had participated in treating (or was involved somehow) with a diver who actually had a very bad DCS event with that agency. The response of the agency was "Well, we don't know if they don't report it back to us."

Now all of my description is from memory (which can be faulty) so the quotes aren't quotes, but the basic lesson is there. How do you know there were no hits? Were you following up for hours after each of hundreds of dives? Who was evaluating claims of shoulder pain, or a rash, or the precaution of breathing O2 on the surface, or ..., to determine if a DCS event occurred? How do you know not one of these hundreds of divers had a serious hit 12 hours following a dive, but you never heard?

These types of claims are exceedingly difficult to accept if for no other reason than we've heard them before and they wither under scrutiny, if indeed you can get enough solid information to actually scrutinize it.

 

[boulderjohn]

I attended the 2008 Deep Stop conference. During that event one of the training agencies stood up in support of deep stops and made a similar claim -- no hits, hundreds of technical dives, and "what works works" kind of thing. It was rather humorous that someone at the event had participated in treating (or was involved somehow) with a diver who actually had a very bad DCS event with that agency. The response of the agency was "Well, we don't know if they don't report it back to us."

And even if they do report it....

I used to be with an agency that advocated very deep stops, and it still does. Their position on those stops also included a belief that no adjustments needed to be made to the plan for diving at high altitude. They, too, said the proof was that no one was getting bent doing that profile at altitude.

I pointed out that I knew of six cases myself, just in the small group of people with whom I was diving. One of them involved a helicopter evacuation. Several were handled through IWR (and they teach a course for that, BTW).

Ah, but those didn't count.

Why not?

Because there were reasons for the DCS other than the ascent profile and altitude.

What were the reasons?

Can't be sure. It could have been PFO's, for example.

So how do you know it was not the ascent profile and altitude?

Because we know those are not responsible for DCS, so it had to be something else.

(BTW, when I started a thread on altitude and decompression on ScubaBoard, I said that I was interested in this because a number of friends had gotten bent that way. I got an email from the instructor involved warning me that if I posted anything about that again, he would contact PADI and report me for violating member standards about saying bad things about other agencies, and I could possibly be expelled.)

 

[rongoodman]

I haven't been following this discussion as closely as I should have, I guess. Is all this discussion based on the results of the single NEDU study?

 

[LiteHedded]

Yes this thread is about the Nedu study. See post #1

 

[ajduplessis]

I attended the 2008 Deep Stop conference. During that event one of the training agencies stood up in support of deep stops and made a similar claim -- no hits, hundreds of technical dives, and "what works works" kind of thing. It was rather humorous that someone at the event had participated in treating (or was involved somehow) with a diver who actually had a very bad DCS event with that agency. The response of the agency was "Well, we don't know if they don't report it back to us."

Now all of my description is from memory (which can be faulty) so the quotes aren't quotes, but the basic lesson is there. How do you know there were no hits? Were you following up for hours after each of hundreds of dives? Who was evaluating claims of shoulder pain, or a rash, or the precaution of breathing O2 on the surface, or ..., to determine if a DCS event occurred? How do you know not one of these hundreds of divers had a serious hit 12 hours following a dive, but you never heard?

These types of claims are exceedingly difficult to accept if for no other reason than we've heard them before and they wither under scrutiny, if indeed you can get enough solid information to actually scrutinize it.

The divers in our group have done more combined deep dives than the NEDU study utilising VPM-B +2 without incident. We live and dive together for a week at a time, so yes we know when someone has an issue. They dont call it the bends for nothing, you know when someone takes a hit.

Let me ask you this. Those that wake up 12 hours later with a shoulder niggle, how do you know the niggle is not related to sleeping on that shoulder, or workload related while unloading the boat earlier in the day? I have woken up at night with knee pain, shoulder pain or any other pain you can think of, but I was not in the water for a week. Did I have DCS? Of course not. Would my pain reduce taking a chamber ride? Yes! Because chambers are medical devices used to threat and heal many different injuries, not just DCS.

If you report any form of pain/numbness to a chamber operator/doctor and stating you dived even if you have never been in the water, the outcome will be DCS. "Diver:I dived today and have a shoulder niggle. Doc:Take a ride! Do you feel better? Yes! Perfect you had a type 1 hit". Is this a 100% true reflection? No one will ever know for sure, but it becomes a statistical number.

Do I know of divers that have taken hits? Yes! Each and every one of them was due to user error (dehydrated, flu, obese, unfit, wrong gas switches, longer BT than planned, air deco) not the model.

 

[Dr. Lecter]

Let me ask you this. Those that wake up 12 hours later with a shoulder niggle, how do you know the niggle is not related to sleeping on that shoulder, or workload related while unloading the boat earlier in the day?

First, it won't take 12 hours for genuine niggles to show up. Second, the throbbing bone pain is a dead-giveaway IMO. Third, when you go to 20' with a bottle of O2 and your shoulder feels better, congratulations it's a genuine niggle.

It may, however, still be related to unloading the boat after diving...one of the reasons I scrapped VPM for dives below 200' was having to slap a 70% GF surfacing limit on it to feel halfway decent after hauling myself and my stuff back aboard, to say nothing of helping haul anchor.