DAN is putting a real "flying after diving" study together, since Bennett at the DAN conference last weekend admitted that everyone, including DAN, has simply been guessing to date.
Roak
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Flying and Diving, bring me up to speed
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John Reinertson
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This was covered in some detail in a couple of diving medicine conferences. I no longer remember the exact combination of math and statistics well enough to recount it completely, but the 24 hour rule came from study of data that showed no increase in DCS episodes (above the baseline 2 to 4 per 10,000 dives that we all face for each dive) when a 24 hour interval was studied.
There was no significant increase in events when 24 hours had elapsed, and some increase (with uncertain statistical significance) when 12 hours had elapsed. The consensus from multiple diving medical officers was that a 24 hour rule was safe, but we didn't know precisely how much less than that represented a hazard.
There was no question in their minds that there was increased risk immediately afterward. There was no question ( and pretty decent math and statistics) that less than twelve hours probably represented some risk, and that 24 hours was reasonable enough that all the docs teaching the conference were not worried about a 24 hour interval being adequate.
When we're left with imperfect data, it's always a good idea to copy the behavior of the experts, particularly when it matches math and physiology.
John
There was no significant increase in events when 24 hours had elapsed, and some increase (with uncertain statistical significance) when 12 hours had elapsed. The consensus from multiple diving medical officers was that a 24 hour rule was safe, but we didn't know precisely how much less than that represented a hazard.
There was no question in their minds that there was increased risk immediately afterward. There was no question ( and pretty decent math and statistics) that less than twelve hours probably represented some risk, and that 24 hours was reasonable enough that all the docs teaching the conference were not worried about a 24 hour interval being adequate.
When we're left with imperfect data, it's always a good idea to copy the behavior of the experts, particularly when it matches math and physiology.
John
OP
NAUI has changed theirs as well with the release of the rgbm-based tables.
annie
Contributor
Hi
I just started my cross over lectures from PADI to CFT which is the Irish underwater council, (affiliated to the French CMAS).
Last night we did tables, and I discovered that CFT use Buehlman tables. I read about them while doing my PADI DM theory over a year ago but don't remember much about them.
However I noticed last night they seem to have very different flying after diving recommendations . . . .. no such thing as waiting for 12 hours - more like 3 - 4 hours. I don't have the tables right in front of me to quote the details.
Why the difference? Is this safe for people to be flying 3 hours after a dive - I certainly wouldn't. Does any other certifying body recommend this?
>>There was no question ( and pretty decent math and statistics) that less than twelve hours probably represented some risk<<
I must ask the CFT guys about this.
I just started my cross over lectures from PADI to CFT which is the Irish underwater council, (affiliated to the French CMAS).
Last night we did tables, and I discovered that CFT use Buehlman tables. I read about them while doing my PADI DM theory over a year ago but don't remember much about them.
However I noticed last night they seem to have very different flying after diving recommendations . . . .. no such thing as waiting for 12 hours - more like 3 - 4 hours. I don't have the tables right in front of me to quote the details.
Why the difference? Is this safe for people to be flying 3 hours after a dive - I certainly wouldn't. Does any other certifying body recommend this?
>>There was no question ( and pretty decent math and statistics) that less than twelve hours probably represented some risk<<
I must ask the CFT guys about this.
I commend you for being both astute enough to pick up on this difference, and concerned enough to ask about it.
As you might suspect, judging by the handle I use, the subject of "flying after diving" is close to my heart.
There are two central points to this issue:
(1) Remember that ALL deco calculations are time-dose based, and that different researchers, (Haldane, Buhlmann, et al), make different assumptions about basic processes.
(2) The subject is in flux at the moment, due to on-going studies by DAN at Duke University. As an American radio commentator, Paul Harvey, would say: "Stand by for news!"=-)
Dr Deco
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Dear Readers:
Time Limit
I do not know the answer to your question, either. If Dr Buhlmann, then it propose such a limit certainly was tested to some degree with respect to use with his tables. All decompression strategies will have some restriction implicit in them. As I have mentioned on many occasions on the SCUBA BOARD, tables are tested on subjects at relative rest following the dive. Thus a diver who lifts equipment or plays volleyball is not acting according to the conditions under which the table was tested. Though not explicitly stated, this is a restriction. :nono:
I cannot imagine under what conditions a three-hour interval prior to flying is possible, but I will not argue that he said it. There are points on decompression theory with which I have argued with Professor Buhlmann, but I have never heard an explanation for this short duration.
Different Scenarios
Unfortunately, diving and flying have more scenarios than just diving. When you test a dive table, you can simply couple dives together for a day or so. Flay after diving should probably count several days of diving. This makes the test program very difficult. When the dive study involves multiple days, the cost rises and supervision increases. The PADI series with six dive days in a row was a logistical problem for our group at the Institute of Applied Physiology and Medicine in Seattle, Washington. It was costly and complex. It required breaking the group into five groups with six-day supervision and was a monster.
A fly-dive study might eventually come down to this.
Dr Deco :doctor:
Readers, please note the next class in Decompression Physiology :grad:
http://wrigley.usc.edu/hyperbaric/advdeco.htm
Time Limit
I do not know the answer to your question, either. If Dr Buhlmann, then it propose such a limit certainly was tested to some degree with respect to use with his tables. All decompression strategies will have some restriction implicit in them. As I have mentioned on many occasions on the SCUBA BOARD, tables are tested on subjects at relative rest following the dive. Thus a diver who lifts equipment or plays volleyball is not acting according to the conditions under which the table was tested. Though not explicitly stated, this is a restriction. :nono:
I cannot imagine under what conditions a three-hour interval prior to flying is possible, but I will not argue that he said it. There are points on decompression theory with which I have argued with Professor Buhlmann, but I have never heard an explanation for this short duration.
Different Scenarios
Unfortunately, diving and flying have more scenarios than just diving. When you test a dive table, you can simply couple dives together for a day or so. Flay after diving should probably count several days of diving. This makes the test program very difficult. When the dive study involves multiple days, the cost rises and supervision increases. The PADI series with six dive days in a row was a logistical problem for our group at the Institute of Applied Physiology and Medicine in Seattle, Washington. It was costly and complex. It required breaking the group into five groups with six-day supervision and was a monster.
A fly-dive study might eventually come down to this.
Dr Deco :doctor:
Readers, please note the next class in Decompression Physiology :grad:
http://wrigley.usc.edu/hyperbaric/advdeco.htm
annie
Contributor
Thanks for the input
>>I cannot imagine under what conditions a three-hour interval prior to flying is possible, but I will not argue that he said it. <<
It's in his tables. I'm pretty sure but will have another look just in case.
>>I cannot imagine under what conditions a three-hour interval prior to flying is possible, but I will not argue that he said it. <<
It's in his tables. I'm pretty sure but will have another look just in case.
Dr Deco once bubbled...
Dear Readers:I do not know the answer to your question, either. If Dr Buhlmann proposed such a limit, it certainly was tested to some degree with respect to use with his tables. All decompression strategies will have some restriction implicit in them. As I have mentioned on many occasions on the SCUBA BOARD, tables are tested on subjects at relative rest following the dive. Thus a diver who lifts equipment or plays volleyball is not acting according to the conditions under which the table was tested. Though not explicitly stated, this is a restriction. :nono:
I cannot imagine under what conditions a three-hour interval prior to flying is possible, but I will not argue that he said it. There are points on decompression theory which I used to argue with Professor Buhlmann, but I never heard an explanation from him for this short duration.
Unfortunately, diving and flying have more scenarios than just diving. When you test a dive table, you can simply couple dives together for a day or so. Flying after diving should probably count as several days of diving. This makes the test program very difficult. When the dive study involves multiple days, the cost rises and supervision increases. The PADI series with six dive days in a row was a logistical problem for our group at the Institute of Applied Physiology and Medicine in Seattle, Washington. It was costly and complex. It required breaking the group into five groups with six-day supervision and was a monster.---Dr Deco
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Dear Readers,
As you might imagine from my handle, the subject of "flying after diving" (FAD) is a subject near and dear to my heart.
One point that our good Doc makes that is NOT emphasized anywhere else, is his point about the testing regime utilized when the tables were constructed.
As he points out, ANY factor that varies from that strict set of conditions begins to skew YOUR particular situation AWAY from the conditions used to set up the table. Thus, the more the variables, or the the larger the factors, the LESS that table result will appy to you!
Example: You dive, shower, throw your gear in the bag, take the golf cart to the airstrip, and fly Tropic Air to Belize City Airport. The Cessna Caravan you are in has you at 1000+ feet for the trip. You check through the lines, carrying your bags, moving your gear, and a couple of hours later you are in a Fun Jet 727 going to Houston. Your body is now at 7600 to 8000 feet cabin altitude. (Please note: This is a hypothetical example. Do NOT do this at home, kids!)
Does ANY of this match the conditions which were extant when the testing was done for that particular table
Don"t make yourself into crash test dummies, please! Use some common sense, and adopt conservative guidelines. The DAN Research folks, under Dr. Richard Vann and others, have "volunteer crash test dummies" working on this study now. When all is said and done, we'll know more about this subject!
Until then, to paraphrase what Mr. Natural used to say: "Get the right TABLE for the job, kids!"
The Flying After Diving Study needs you! Subjects are still needed for the next USNFAD study on July 26, 2003. The profile being tested is 60/40 dive; 2 hr. SI; and 8000 ft/4 hr flight. If you have not done this profile yet, we invite you to participate this weekend. There is no Friday night session, just Saturday, and the brief medical check up on Sunday morning. To sign up you may contact me directly at jmoore@dan.duke.edu or 800-446-2671 ext. 260.
Thank you,
Jeanette Moore
Flying After Diving Research Study
Studies are being conducted in the hyper/hypobaric chambers of the Center for Hyperbaric Medicine and Environmental Physiology at Duke University Medical Center. Participants must be at least 18 years of age and certified divers or experienced in hyper/hypobaric chamber exposures. Diving students may participate if accompanied by their instructor. Each participant must complete a medical questionnaire prior to the study.
Compensation includes $120 plus one year of membership and preferred plan insurance from the Divers Alert Network if you are not currently covered ($100 value).
Please contact the Research Department at 919-684-2948, ext 260 (research@dan.duke.edu) for more information.
Available Study Dates are:
June 28-29, 2003
July 11-12, 2003
July 25-26, 2003
August 8-9, 2003
August 22-23, 2003
September 5-6. 2003
September 19-20, 2003
October 3-4, 2003
October 17-18, 2003
October 31-November 1, 2003
November 14-15, 2003
November 21-22, 2003
December 5-6, 2003
December 19-20, 2003
An introduction to our lab is available at http://hyperbaric.mc.duke.edu.
Thank you,
Jeanette Moore
Flying After Diving Research Study
Studies are being conducted in the hyper/hypobaric chambers of the Center for Hyperbaric Medicine and Environmental Physiology at Duke University Medical Center. Participants must be at least 18 years of age and certified divers or experienced in hyper/hypobaric chamber exposures. Diving students may participate if accompanied by their instructor. Each participant must complete a medical questionnaire prior to the study.
Compensation includes $120 plus one year of membership and preferred plan insurance from the Divers Alert Network if you are not currently covered ($100 value).
Please contact the Research Department at 919-684-2948, ext 260 (research@dan.duke.edu) for more information.
Available Study Dates are:
June 28-29, 2003
July 11-12, 2003
July 25-26, 2003
August 8-9, 2003
August 22-23, 2003
September 5-6. 2003
September 19-20, 2003
October 3-4, 2003
October 17-18, 2003
October 31-November 1, 2003
November 14-15, 2003
November 21-22, 2003
December 5-6, 2003
December 19-20, 2003
An introduction to our lab is available at http://hyperbaric.mc.duke.edu.
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