Bends possible while flying 24 hrs after a dive?

[Albion]

SeaJay once bubbled...
...What was also fascinating was the unbelievable temperature change in a matter of about two minutes... Going to depth, we saw a temperature change of about 15*. That is, the room went from 75 to 90 in two minutes, without anything blowing... No heaters, no nothing. It was very weird.

...What was even weirder was feeling the temperature drop the same amount on decompression, again without anything blowing in cold air. Much to the delight of everyone involved, "fog" appeared before your very eyes, thick enough to obscure the person sitting next to you. It was truly amazing.

.

P1 x V1 / T1 = P2 x V2 / T2
in your case V1=V2 therefore a rise in pressure also gives a rise in Temp

Obviously physics not required in your DIR F training (j/k ok)

 

[SeaJay]

Albion once bubbled...
.
Obviously physics not required in your DIR F training (j/k ok)

Lol...

Hey, we all knew it was coming. I expected it to a degree simply because of my experience filling tanks.

...And as they shut the door to the chamber, we were warned - briefed - as to what to expect.

...But it was still the weirdest thing... 15* might actually be conservative. Care to calculate temperature increase in going from 1 to roughly 3 ATA's? Decrease?

Now... Think about this... Maybe this will help to explain why it was so weird...

All of the gas in our bodies did exactly the same thing. That is, it increased or decreased by 15* or more. So... It wasn't just a temp increase on our skin... It was like a temp increase EVERYWHERE. Many of us broke out in a sweat and got chilled going the other way.

That made the temperature difference super-weird. I thought about the practical applications of this... I mean, we have microwaves which can heat instantly... But we don't really have an invention that can cool instantly.

...Think about how impressive this would be to treat people who have heat stroke or other heat-related illness... Much more effective than the "cool bath" concept used today.

 

[BRW]

Guys,

Glad you enjoyed your chamber dives. Great way to cool
down on flight simulation.

A few years ago, DAN sponsored an Altitude Workshop
at Duke. Players from rec, tec, military, commercial, and
scientific sectors attended. We reached a consensus about FAD
(flying-after-diving), but DAN wanted to put it on hold pending
some additional testing.

Roughly one consensus then on data was 15 hrs
FAD after single (air) dives within the NDLs, and 18 hrs
for repets. Single deco required 20 hrs FAD.

New data is roughly saying same.

No surprise really when you consider the hoards of divers
using the 12 hr rule (and D-Grp rule which is even less
conservative). And few probs -- like 1/100,000 DCS hits
on airplanes.

Bruce Wienke
Program Manager Computational Physics
C & C Dive Team Ldr

 

[Karl_in_Calif]

BRW once bubbled...

Roughly one consensus then on data was 15 hrs
FAD after single (air) dives within the NDLs, and 18 hrs
for repets. Single deco required 20 hrs FAD.

Data is roughly confirming same.

Bruce Wienke
Program Manager Computational Physics
C & C Dive Team Ldr

Is 20 hours also the saturation / desaturation time threshhold for the majority of body tissues?

 

[BRW]

Karl,

The sat/desat times for DISSOLVED gases in tissues/blood
are roughly 6 times the tissue halftimes. So, 20 hrs is sat/desat
time for the 20/6 hr tissues and faster compartments. That is,
200 minutes and faster.

But BUBBLES are something else. If they are stabilized for
time spans of hours, slower tissues can pump gas into them
and cause probs. Gas must diffuse across the interfaces
to shrink them.

Back of the envelope calcs for biosubstances suggest
diffusion times for bubbles coupled to surrounding tissues
are roughly 1.5 - 2.0 times the tissue halftime. If we
could test bubbles in divers, we could pinpoint this number.
We can't yet, of course.

All of our data suggests the 15 hr FAD rule is cool.

EARLIER POST:

Glad you enjoyed your chamber dives. Great way to cool
down on flight simulation.

A few years ago, DAN sponsored an Altitude Workshop
at Duke. Players from rec, tec, military, commercial, and
scientific sectors attended. We reached a consensus about FAD
(flying-after-diving), but DAN wanted to put it on hold pending
some additional testing.

Roughly one consensus then on data was 15 hrs
FAD after single (air) dives within the NDLs, and 18 hrs
for repets. Single deco required 20 hrs FAD.

New data is roughly saying same.

No surprise really when you consider the hoards of divers
using the 12 hr rule (and D-Grp rule which is even less
conservative). And few probs -- like 1/100,000 DCS hits
on airplanes.

Bruce Wienke
Program Manager Computational Physics
C & C Dive Team Ldr

 

[pipedope]

Of DCI during flying after diving have the situation that the diver was symptomatic of DCI (but in denial) on the surface before the flight.

If you are bubbling and showing symptoms (even slightly) then it is going to get worse when you reduce pressure.

If you haven't read GI3s pages on deco on the WKPP site then read them now. He makes some very good points.
http://www.wkpp.org/decompression.htm

 

[Rick Murchison]

Let's see if we can put this in perspective... Is it possible to suffer DCS from flying after waiting 24 or more hours from your last dive? Absolutely! In fact, it is possible to suffer DCS on a flight if you have never made a dive in your entire life!
However - if you are truly symptom free after your recreational "no decompression" diving, and you then wait 24 hours before flying, I would characterize your chances of getting bent on a flight as statistically indistinguishable from the general non-diving population.
Rick

 

[SeaJay]

BRW once bubbled...
Guys,

Roughly one consensus then on data was 15 hrs
FAD after single (air) dives within the NDLs, and 18 hrs
for repets. Single deco required 20 hrs FAD.

New data is roughly saying same.

I am not prepared to talk deco... I'm simply not educated enough about it to have any sort of opinion whatsoever.

...But I would like to know what you're basing your claim, "New data is roughly saying the same" on. I've seen the data... Experienced it, in fact... And talked at great length with the very likable individuals responsible for collecting and interpreting that data. They don't at all say what you do... They say that "previous data was basically nonexistent," and that "what did exist was inconclusive." They also mention, "When hard-pressed for an answer years ago by the big dive agencies about flying after diving, we took an overly-conservative, untested viewpoint that we were confident was not incorrect information." In other words, they didn't know how long a body would have to wait after diving... But they knew that 24 hours was reasonable from a practical standpoint, veeeery conservative, and a good, safe bet for anyone.

Today, they're looking for a more scientific opinion, and so they're doing the testing. What little data they had before this study I have seen... It's right there at Duke. I tell you, it's inconclusive at best, which is exactly why the Navy has sponsored such a study... To get real information so that everyone can develop educated opinions.

To the Navy, the "interval before flying" is vitally important... Think about how many specialty divers they have who can perform a certain task... It's a relatively small group. Today they may be needed off the shores of California, and tomorrow they may need to be in the Red Sea. The Navy needs to know how long they have to wait before sending their boys (recovery divers, SEALS, rescue, etc.) on a plane, half a world away. In some cases, time may be of the essence... So "knowing" safe interval time before flying is truly crucial.

...Which is why they're doing this study. They wouldn't be doing it if ANY data supported "15 hours looks good."

...Which brings me to your post... I have a serious issue with your words. What you have just done is recommend something which is far more aggressive than what is being taught today. The common teaching is to wait 24 hours before diving. The bottom line is that there is research being done currently which appears to be supporting a much shorter interval... But evidence doesn't point to 15 hours... It's pointing to NO interval. THAT is why they're doing the research.

...But until there is an official report, you are out of line and possibly recommending a dangerous profile.

Furthermore, I believe that if Duke University's Hyperbaric Facility can publicly admit, "We need more testing, 'cause we don't know," then you claiming to "know" is simple arrogance at it's finest. No, you don't know. Unless you've done more testing than they have, then you don't know. And what's worse is that you don't know that you don't know.

Well, then I'm telling you. You don't know. Period. Nobody knows what the best time is to wait to fly after diving. If they did, then they wouldn't be spending a cool million to find out.

The best there is - the people who would know if anyone did - don't know.

...So until they know, I'd say to stick with the plan... Which is 24 hours between dive and flight. If you blow that, well... It's not recommended, but they're currently seeing much more aggressive profiles than what you did, with zero ramifications... So if you're exhibiting no DCS symptoms, then I wouldn't worry about it.

 

[CincyBengalsFan]

SeaJay once bubbled...



...So until they know, I'd say to stick with the plan... Which is 24 hours between dive and flight. If you blow that, well... It's not recommended, but they're currently seeing much more aggressive profiles than what you did, with zero ramifications... So if you're exhibiting no DCS symptoms, then I wouldn't worry about it.

If you dive for like 7+ days in a row doing more than 3 dives a day to depths of 100' or more.... I would wait at least 36-48 hrs. to off gas all the residual crap.

There is nothing wrong with telling people to wait 30+ hrs. The longer the better I say.

 

[SeaJay]

Rick Murchison once bubbled...
Let's see if we can put this in perspective... Is it possible to suffer DCS from flying after waiting 24 or more hours from your last dive? Absolutely! In fact, it is possible to suffer DCS on a flight if you have never made a dive in your entire life!
However - if you are truly symptom free after your recreational "no decompression" diving, and you then wait 24 hours before flying, I would characterize your chances of getting bent on a flight as statistically indistinguishable from the general non-diving population.
Rick

I think Rick's nailed it, and he's right... People can get DCS from altitude alone.

There is no profile that is going to reduce your chances of getting DCS to zero. If you want zero chance, then don't have a profile at all. That is... Stay at home on the couch.

I've seen examples where people dive to shallow depths for short times and do not fly at all, and get bent. I've seen examples where people don't dive at all, fly, and get bent. And then I've seen examples where people do repetitive dives for days, and two hours from their last dive board a plane and fly home, many hours away... And never experience one symptom. The funny thing is that NONE of these things are rare occurrences... Meaning that they're not "out of the norm." There IS no "norm."

I've heard and read at great length George Irvine's "diatribe" and "convoluted" idea on deco. Many of my friends and co-divers trust his ideas with their lives.

The bottom line is that he may be on to something with his ideas... They're certainly logical. However, they are untested. Sure, they worked for him and the WKPP. Sure, they work for many other divers. Sure, the WKPP has been "incident free" since 1992 or something... So what? That's a comparatively small number of divers doing a comparatively small number of dives.

When I brought GI3's information to Duke, they looked it over and said, "Looks pretty interesting. He's got some great ideas that would make sense to test and check out." THAT is an "open mind" for you. I love scientists.

...And while GI3 has done lots of his own testing, in no way is he prepared to make recommendations for your own dives. His methods are unconventional and not accepted by the mainstream dive community... Although there is no quesstion that the mainstream dive community has no sure idea of what to recommend.

Let me draw an analogy here... A patron walks into a restaurant and orders "Rahrah soup." Not knowing what that is, but not wanting to look stupid either, the waiter takes the order to the kitchen and places the order for something that nobody's ever heard of before. All the cooks look at each other ignorantly, but nobody wants to admit that they've never heard of "Rahrah soup" before.

What we have here is about 50 cooks all in the same kitchen, trying to make "Rahrah soup." There is no such thing as "Rahrah soup," but they've been instructed to try to make it.

Everyone sorta stands around, thinking about what they could put together that would be interesting, unique, and liked by everyone who tried it. They begin to discuss, and they begin to experiment. The bottom line is that five or six "groups" of cooks have each made what they think "Rahrah soup" should taste like. All of the soups are very different... And all are aimed to please. But none of them have any basis in fact as to what "Rahrah soup" looks or tastes like.

Enter a new cook... His name is GI3. He's had lots and lots of experience cooking for a small group of about a dozen specialty eaters... For many years. He's cooked many a meal, but has served only a few individuals. (None of which, by the way, have had gas since 1992.)

Immediately he bullies his way to the front of the kitchen and announces, "I know what Rahrah soup is, and you're all wrong." He immediately begins to put together his own concoction, and many other cooks look on, interested, but in many cases doubtful.

Now, the truth is that Mr. Patron, who waits patiently for his soup to be served, is fully aware that there is no such thing as Rahrah soup. He made it up. He thought he'd see what the restaurant came up with. He sometimes entertains himself in this way. He's a sick person.

The bottom line is this... Nobody knows what Rahrah soup is, and nobody knows what the heck is going on with DCS. There's some great theories, and certainly there's some great ideas. GI3's might be some, and they might not. Who knows? GI3 knows what he likes... He's going to make Rahrah soup the best he knows how... And that's great. It may be really good stuff... There seems to be a good deal of logical thought put into it.

...But that doesn't make it Rahrah soup until it's served to the customer, he agrees it's Rahrah soup, and we all call the new recipe Rahrah soup.

...So the bottom line is this: You don't have a clue. GI3 doesn't have a clue. Nobody does. If they did, they wouldn't be doing the research that they are. All we can truly say is that thus far, we've found out that ice cream and Tobasco sauce don't go together in soup... And waiting 24 hours after diving seems to be a good idea.

But that's where the knowlege stops.

But what really irritates those of us who know that they don't know, are those people who don't know that they don't know. Get my drift?