Bends possible while flying 24 hrs after a dive?

[CincyBengalsFan]

SeaJay once bubbled...

And waiting 24 hours after diving seems to be a good idea.

Even better to wait longer......

 

[SeaJay]

CincyBengalsFan once bubbled...


Even better to wait longer......

Possibly.

That's like saying that "it's even better to drive slower." While that certainly would be more conservative, there's a point at which the additional safety margin is counterproductive.

Take Grandma driving at 40 mph in the left lane of the interstate... She thinks she's safer driving slower. Is that reality? Well, perhaps... But she doesn't have many friends, does she? It irritates the other drivers and actually creates for them a hazard which they must avoid for their own safety.

If safety was the only name of the game, we wouldn't BE diving. That is the only way to ensure that you won't get bent... No diving, and no flying.

Sounds like fun, eh?

The key here is to find the right balance... And traditional thought - whether correct or not (they're not sure) - is 24 hours between wet and high.

 

[crispos]

I am going to Bogota Colombia in a few weeks, and have been prescribed Diamox for potential altitude sickness. So, I am going to have a dry dive soon. Thanks for the bubble info Bruce, I hope NAUI is paying for all that research out in the New Mexico desert.

 

[BRW]

Seajay,

It's a question of statistics, not gut feelings. And if
you care to check statistics in depth, I can direct you to the
sources.

FAD, deco, NDLs are "all on average". For rec diving, across
the board the average for DCS is on the order of 1/10,000
to 1/100,000 from meter manufacturers, training agencies,
and data bases. FAD probs are even less.

Check with Dick Vann at DAN who runs PDE at Duke/DAN.
(and the altitude study you are referencing). He has 36 cases of
DCS across his PDE data bank. Or check with Petar Denoble
who runs the PDE data acquisition program with Dick. Tell
them I told you to call.

The 24 hr FAD early recommendation by DAN was "recalled"
because data didn't support it (as being overly conservative).
Cumulative dive experiences of 10,000s do not support it either.
The DAN Altitude Wkshp was convened to address it -- you
weren't there for the "stats" nor the discussions.

At C & C, we have our own tec data bases. And our ops
(with mucho FAD) do not support 24 hrs either for no-deco, single
dives. And there are stats to back it up -- not that you would
care, I presume, from your comments.

BTW, if you are possibly familiar with the old D-Grp rule
for flying, a bit more liberal than even the old 12 hr FAD rule,
it was used for years and years (still is by diehards) without
noted spikes in DCS incidence rates for altitude excursions.

Of course, there's nothing wrong with using a 24 hr FAD,
for single no-deco air dives. It's your call.

Many prefer to dive "within the statistics". Even on air.

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

 

[Dr Deco]

Dear SCUBA SOURCE Readers:

Bends in Planes

I am not aware of anyone who got DCS while in the cabin of a commercial aircraft (8,000 feet) that had not gone diving previously. If there are instances, I would be very interested in them. I am suspecting that they might be related to “weather pains.”

Scientists and Research

I wrote a long piece (long for me anyway) about science and scientists; it was couple of threads ago and is probably lost in the mists of time. Too bad. One should read it and understand that there are many reasons why scientists do what they do. Some are reasonable and some are simply because scientists are people too with all of their foibles.

Flying After Diving Tests

I am not aware of the experimental protocol at DAN for the flying-after-diving study but I suspect that I would question it. Many groups do not send research proposals out for review and, if reviewed, do them if they really want to. Based on the results obtained, something sounds “spooky” to me. I would have a high index of suspicion. I suspect that the proper mix of exercise (musculoskeletal activity) has not been factored into the study. In other words, divers (as contrasted with laboratory test subjects) do not really sit around during the dive, after the dive, and during the trip to the airport. This activity makes a large difference.

Bubble Detection

In all studies of bubble detection, it requires finesse to get good signals when very few bubbles are present. I have seen good labs miss signals – and misinterpret others. Naturally in this case I cannot say without being there, but it is an old problem that must always be considered by working scientists.

Theoretical DCS

A lot is known about DCS and bubbles. Not every scientist knows it all, but some are acquainted with certain parts more than others. A great deal of very interesting aspects are lost because of the holdovers from the concepts of Haldane. Readers of this FORUM will know that from my commentaries over the past several years.

I will be interested in the FAD results but I will also be looking at the experimental protocol. The devil is in the details.

Dr Deco :doctor:

 

[CincyBengalsFan]

SeaJay once bubbled...


Possibly.

That's like saying that "it's even better to drive slower." While that certainly would be more conservative, there's a point at which the additional safety margin is counterproductive.

Take Grandma driving at 40 mph in the left lane of the interstate... She thinks she's safer driving slower. Is that reality? Well, perhaps... But she doesn't have many friends, does she? It irritates the other drivers and actually creates for them a hazard which they must avoid for their own safety.

Possibly? I beg to differ...

Driving in the fast lane slow has no comparison to Residual Nitrogen?

My story is the the 2nd post in this thread. My best friend "Hooked up" with this lady I'm talking about that got bent in Cozumel (She was hot). I was there and I know exactly what happened. The only rules she broke was doing more than two 100 ft. repetitive dives in a day...Over a week period for everyday in that week. While she stayed within her pressure groups she still got bent well after 24 hrs. waiting to fly..... (She had minor systems the day before if you read my first post in this thread).

I've taught 100% of my students since that day to NEVER dive like this and the general rule of thumb is 24 hrs. I highly recommend 36 hrs..

Waiting an additional few hours has no comparison to driving slow in the fast lane. In fact that's dangerous.

When in Grand Cayman I take the 5 Oclock p.m. flight out. That gives me roughly 30 hrs. from my last dive and I make sure my last day of diving is 60 ft. or shallower.

There is nothing wrong with waiting an addtional day or day and a half and I'm pretty sure it's not going to piss anyone off like driving slow in the the fast lane.

 

[BRW]

Well said, Dr D.

And let me also suggest some misinfo about "DAN said" in
a post -- Seajay, I believe.

Seajay,

We know much about FAD -- where do you think all those
"rules" started. Some closure of testing and model data fits
gave those rules. Somebody didn't just pull them out of
their butts. And so I doubt if anybody at DAN said "we know
nothing about FAD".

There have been many presentations on all that data,
plus some new stuff at DAN. The cast of players here is very
large.

This isn't "Rahrah Soup" either, because coarse grain
dynamics get matched to real data. And not gut feelings.
And professional do the chores.

There is much data accumulated about altitude
excursion, FAD, and such (Bell and Borgward at UC,
Bassett at the Air Force, Sahni in Turkey, Buhlmann,
plus dozens of others). DAN wants to tune data further,
which is their call because they pay the bills. But it's
hardly "first time" stuff, because "we don't know anything".

What I mentioned about FAD still stands a few posts ago.
Don't be too surprised to hear a 15 hr FAD rule from DAN.

And yes, I DO know about some DAN preliminary info,
what went on at the DAN Altitude Wkshp (was there),
and overall stats from the diving community.

In either case, we at C & C use our own tec data.

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

 

[SeaJay]

BRW once bubbled...
Seajay,

It's a question of statistics, not gut feelings.

I never said it was. Show me where I said the words "gut feelings." The only "gut feeling" I have is to stick to stats, which I've already told you I saw and studied in person. My findings - as any logical person's would be - is that more research needs to be done; which is precisely what's happening as we speak... I know because I'm a part of it.

And if you care to check statistics in depth, I can direct you to the
sources.

Great! You mean that the conclusive research has already been done? Better tell Duke that... And the US Navy. They're spending millions of dollars and thousands of hours...

FAD, deco, NDLs are "all on average".

"On average" implies a mean, which is only one aspect of the statisical information gathered.

Check with Dick Vann at DAN who runs PDE at Duke/DAN.
(and the altitude study you are referencing). He has 36 cases of
DCS across his PDE data bank. Or check with Petar Denoble
who runs the PDE data acquisition program with Dick. Tell
them I told you to call.

I know them... They were the ones that briefed my group before entering the chamber.

I talked to Dick for a while about this sort of stuff, and he told me that the data was inconclusive, and that more research was needed. Which isn't a surprise to me... Apparently it is to you?

The only point I made is that the data's not in yet... So NOBODY is truly qualified to make a recommendation regarding FAD times. Until further data can be assessed, it's prudent to stick with the agency recommendation of 24 hours.

By the way, I'm fairly confident that Dick's database on this has a few more than 36 cases in it.

The 24 hr FAD early recommendation by DAN was "recalled"
because data didn't support it (as being overly conservative).
Cumulative dive experiences of 10,000s do not support it either.
The DAN Altitude Wkshp was convened to address it -- you
weren't there for the "stats" nor the discussions.

I beg your pardon... I was. Of course, your "discussion" might have been different from the one that I participated in... I suggest that the topic has been discussed many times - even on internet forums.

Nonetheless, I agree with your point about the data not supporting the need for a 24 hour FAD time... That's exactly why they're doing a FAD study now.

But I don't see what difference that makes. Recommending a shorter FAD than the accepted norm is a dangerous practice - especially on an internet forum. the evidence is not yet in to be able to make that recommendation, and until it is, the prudent thing to do is to recommend what's currently accepted as "safe."

At C & C, we have our own tec data bases. And our ops
(with mucho FAD) do not support 24 hrs either for no-deco, single
dives. And there are stats to back it up -- not that you would
care, I presume, from your comments.

I don't know where you got that idea. Of course I care. Do you think that I drove twelve hours and took three days off from work so that I could sit in a metal box for $120? I have a great interest in the project, and was thrilled to be a part of the research.

I would be very interested in your statisics, and I can assure you that I will looking especially at their authenticity and validity. If they prove authentic and valid, then I will be weighing them against DAN's findings... And if they agree, then that really begins to lend validity to EVERYONE'S claims.

...Then and only then will a new "standard of safety" be accepted.

BTW, if you are possibly familiar with the old D-Grp rule
for flying, a bit more liberal than even the old 12 hr FAD rule,
it was used for years and years (still is by diehards) without
noted spikes in DCS incidence rates for altitude excursions.

Agreed... And you'll find that DAN's study is finding similar results even on much more aggressive FADs. That's interesting information, but wasn't my point. My point was in the danger of making recommendations before the data has even finished being collected.

Many prefer to dive "within the statistics". Even on air.

Agreed. And I suggest defining "statisics" as "that data which has been collected and verified," rather than "that data which we're seeing a trend for." If you make recommendations based solely on your experiences (or before the complete data is in), then... Well... You're no better off than GI3.

 

[SeaJay]

BRW once bubbled...

We know much about FAD -- where do you think all those
"rules" started. Some closure of testing and model data fits
gave those rules. Somebody didn't just pull them out of
their butts. And so I doubt if anybody at DAN said "we know
nothing about FAD".

That's another misquote. Please show me where I said "DAN knew nothing about FAD" or that they "just pulled [the recommendation] out of their butts."

What I said, specifically, was that the data they had was inconclusive, and that more research needed to be done.

...And you're giving recommendations to people based on the trend that you're seeing. That's all well and fine that you've observed a trend... I have observed it too.

...But the last thing that the resident experts on this subject said was, "No flying for 24 hours after diving." When I specifically questioned the people who were most likely to know more specific information on that, I was told that the 24 hour figure was based on their previous data collection, which supported a statistically significant occurrence of DCS within 24 hours of a dive. In other words, if you're not bent within 24 hours of diving, you're statistically much less likely to show symptoms. Notice that this has nothing to do with flying after diving.

...But when they were pressed to answer the question of, "when can I fly," they took a conservative route and said, "Wait 24 hours."

It's really that simple.

The research is being done now... More accurately, the research is being continued, and they should have a better, more statistically supported answer for us in the next couple of years.

Until then, I will continue to plan what the experts in the field recommend... Which is still to wait at least 24 hours before flying.

What I mentioned about FAD still stands a few posts ago.
Don't be too surprised to hear a 15 hr FAD rule from DAN.

Actually, I wouldn't be surprised at all.

In fact, it wouldn't surprise me to hear them say, "twelve" or even less.

That's not the point.

 

[CincyBengalsFan]

CincyBengalsFan once bubbled...


Possibly? I beg to differ...

Driving in the fast lane slow has no comparison to Residual Nitrogen?

My story is the the 2nd post in this thread. My best friend "Hooked up" with this lady I'm talking about that got bent in Cozumel (She was hot). I was there and I know exactly what happened. The only rules she broke was doing more than two 100 ft. repetitive dives in a day...Over a week period for everyday in that week. While she stayed within her pressure groups she still got bent well after 24 hrs. waiting to fly..... (She had minor symptoms the day before if you read my first post in this thread).

I've taught 100% of my students since that day to NEVER dive like this and the general rule of thumb is 24 hrs. I highly recommend 36 hrs..

Waiting an additional few hours has no comparison to driving slow in the fast lane. In fact that's dangerous.

When in Grand Cayman I take the 5 Oclock p.m. flight out. That gives me roughly 30 hrs. from my last dive and I make sure my last day of diving is 60 ft. or shallower.

There is nothing wrong with waiting an addtional day or day and a half and I'm pretty sure it's not going to piss anyone off like driving slow in the the fast lane.