Are some divers more prone to bubble formation than others?+

[Diver0001]

It has long been suspected that some otherwise normal & healthy divers are more prone to bubble formation than others. Seems they may be.

"Aviat Space Environ Med. 2014 Oct;85(10):993-8. doi: 10.3357/ASEM.3805.2014.

Flying after diving: in-flight echocardiography after a scuba diving week.
Cialoni D, Pieri M, Balestra C, Marroni A.

INTRODUCTION:
Flying after diving may increase decompression sickness risk (DCS), but strong evidence indicating minimum preflight surface intervals (PFSI) is missing.

METHODS:
On return flights after a diving week on a live-aboard, 32 divers were examined by in-flight echocardiography with the following protocol: 1) outgoing flight, no previous dive; 2) during the diving week; 3) before the return flight after a 24-h PFSI; and 4) during the return flight.

RESULTS:
All divers completed similar multiple repetitive dives during the diving week. All dives were equivalent as to inert gas load and gradient factor upon surfacing. No bubbles in the right heart were found in any diver during the outgoing flight or at the preflight control after a 24-h PFSI following the diving week. A significant increase in the number and grade of bubbles was observed during the return flight. However, bubbles were only observed in 6 of the 32 divers. These six divers were the same ones who developed bubbles after every dive.

CONCLUSIONS:
Having observed a 24-h preflight interval, the majority of divers did not develop bubbles during altitude exposure; however, it is intriguing to note that the same subjects who developed significant amounts of bubbles after every dive showed equally significant bubble grades during in-flight echocardiography notwithstanding a correct PFSI. This indicates a possible higher susceptibility to bubble formation in certain individuals, who may need longer PFSI before altitude exposure after scuba diving."

Were the 6 tested for PFO's?

R..

 

[Akimbo]

Perhaps all three are correct, perhaps none. The "bubble paradigm" is not as clear cut as some used to have us believe…

The most compelling argument favoring the bubble, or microbubble, paradigm is that recompression frequently provides immediate relief of some or all symptoms. It “seems” plausible that biochemical changes might result from dissolved gas coming out of solution/tissues, but less probable that the variety of DCS symptoms would be reversed by compression so quickly. That argues that bubbles at least play a significant role.

It would sure be nice if unique biochemical markers for DCSs could be discovered, whether causal or resultant. I was one of many guinea pigs the Navy used to explore the efficacy of Doppler Sonograms to detect bends in the early 1970s. We had high hopes that it would be the magic bullet; but like many new sensory technologies it has also generated a lot more questions. I suspect it will be a long time before DCS is really understood.

 

[kelemvor]

Were the 6 tested for PFO's?

Already discussed in a previous post. Not mentioned in the abstract, and OP does not have the full documents. Further, he does not believe PFO would be likely to contribute.

 

[dreamdive]

The most compelling argument favoring the bubble, or microbubble, paradigm is that recompression frequently provides immediate relief of some or all symptoms. It “seems” plausible that biochemical changes might result from dissolved gas coming out of solution/tissues, but less probable that the variety of DCS symptoms would be reversed by compression so quickly. That argues that bubbles at least play a significant role.

It would sure be nice if unique biochemical markers for DCSs could be discovered, whether causal or resultant. I was one of many guinea pigs the Navy used to explore the efficacy of Doppler Sonograms to detect bends in the early 1970s. We had high hopes that it would be the magic bullet; but like many new sensory technologies it has also generated a lot more questions. I suspect it will be a long time before DCS is really understood.

I suspect the same - it will take some time.
I am not disagreeing with the bubble paradigm, however studies involving the role of nitric oxide NO are quite interesting don't you think? Groups of researchers are investigating how to prevent bubble formation in the first place, controlling/reducing micro-nuclei, researching the response to bubbles i.e. platelet aggregation, inflammatory cascade, overall endothelial disruption....

And .... a paradigm is just that.....until it gets replaced with another.

---------- Post added November 16th, 2014 at 04:11 PM ----------

Were the 6 tested for PFO's?

R..

Honestly R, a PFO should not have an effect on the initial bubble formation. The pathophysiology is such that it allows a bubble to bypass the filtration of the lungs and get into the left sided circulation where it can (but does not have to) cause symptoms.

 

[danvolker]

I suspect the same - it will take some time.
I am not disagreeing with the bubble paradigm, however studies involving the role of nitric oxide NO are quite interesting don't you think? Groups of researchers are investigating how to prevent bubble formation in the first place, controlling/reducing micro-nuclei, researching the response to bubbles i.e. platelet aggregation, inflammatory cascade, overall endothelial disruption....

And .... a paradigm is just that.....until it gets replaced with another.

And this may end up relating to the VO2 Max correlation George Irvine, Bill Mee and Dr Bill Hamilton used for the exploration teams of WKPP....It was hypothesized, that George could do much less deco that the vast majority of the others, due to his amazingly high VO2 Max scores.....VO2 max gets to be high from a combination of good genetics, and peripheral adaptation to intense interval training...or cardio training in general. The divers ends up with better perfusion, there is a definite issue with NO in athletes involved in high intensity training.....much of the biochemistry involved in recovering from these workouts, may tie in well with the high VO2 max diver's ability to inhibit inflamation, and counteract platelet aggregation.....Those of us that did intense cycling or Master swimming, tended to be near George in VO2 max, and could use his tables without issue....those that were 15 or 20 ml per KG below George, had to use significantly slower deco schedules....Much of this study was going on when they were first developing the RB 80, and planning some huge penetrations..... like the 6 hour runtime over 3 miles , at 280 feet....where George did only 12 hours of deco.

 

[Diver0001]

Dan, this is all made to sound very scientific but can you cite any actual scientific research to back it up?

I have no doubt that some people can do less deco than others and I'm sure there must be a reason for it, but as far as I'm aware there hasn't been any conclusive scientific research to determine (in contrast to your theory spinning) why this actually happens.

Cite the actual research please. I'd like to see a scientific article written by an expert that correlates VO2max to deco obligations. Who wrote that? Which article should we be reading?

R..

 

[Akimbo]

Dan, this is all made to sound very scientific but can you cite any actual scientific research to back it up?

I have no doubt that some people can do less deco than others and I'm sure there must be a reason for it, but as far as I'm aware there hasn't been any conclusive scientific research to determine (in contrast to your theory spinning) why this actually happens...

There have been a few individuals at EDU (the USN’s Experimental Diving Unit) over the last 80 years who have demonstrated the ability. One in particular was discussed in The Terrible Hours: The Man Behind the Greatest Submarine Rescue in History and was a well-known when I was a Navy Diver.

The first Helium-Oxygen decompression tables were being developed and Navy divers at EDU were the human subjects. The testing program consisted of verifying and adjusting calculated HeO2 tables and was fairly abbreviated due to budget constraints. As a result, one successful dive often meant progressing to another more aggressive table. It took a while for them to discover this one individual never got bent (can’t remember the name), but divers after him frequently did. He was taken out of the rotation.

It would be a difficult thing to study. First, it is hard to find people in that tiny category. What do you do, intentionally bend hundreds or thousands of divers until you find enough for a statistically meaningful analysis? DCS is just too rare and we are able to “adequately” manage it so nobody is motivated to spend that kind of money. Decompression research is a victim of its own success.

 

[danvolker]

I could ask Bill Mee to write something up on this....I don't believe George or Bill ever had any desire to publish their findings--and the tables they ended up with, were ONLY for WKPP use. At the time, they did not want to share this outside of WKPP, with the exception of the Navy's Spec Warfare guys.....Bill can elaborate on their interest in these tables,

 

[dreamdive]

Dan, this is all made to sound very scientific but can you cite any actual scientific research to back it up?

I have no doubt that some people can do less deco than others and I'm sure there must be a reason for it, but as far as I'm aware there hasn't been any conclusive scientific research to determine (in contrast to your theory spinning) why this actually happens.

Cite the actual research please. I'd like to see a scientific article written by an expert that correlates VO2max to deco obligations. Who wrote that? Which article should we be reading?

R..

In none of all the articles that I read and pulled for the AddHelium Reference Library did I come up with a mention correlating VO2 max and decreased deco. That being said, I have only been doing lit searches from the last 15 years. Perhaps there was something earlier, but the current studies are not looking at that.

 

[Diver0001]

I could ask Bill Mee to write something up on this....I don't believe George or Bill ever had any desire to publish their findings--and the tables they ended up with, were ONLY for WKPP use. At the time, they did not want to share this outside of WKPP, with the exception of the Navy's Spec Warfare guys.....Bill can elaborate on their interest in these tables,

So... Bill is a decompression scientist doing scientific research on the correlation between VO2max and offgassing mechanics?

R..