Heart Rate monitor for Precise Decompression
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Hoosier
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superstar
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Reading this thread got my heart rate up.
OP
1_T_Submariner
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I forgot about this thread should probably just let it Die. I got the answer for the question from DR. Deco long ago. Some of the other posts where interesting others just jousting etc...
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It's not a question of jousting or the length of one's intromittent organ or the distance of one's liquid waste stream, it's a question of standards of intellectual honesty. When something is posted as an accepted "fact" in an authoritative fashion, by a community leader, but the "fact" is that there is no data to support the concept, people need to be made aware of the discrepancy.
I've know Bill for over twenty years, we've worked together on any number of programs and I've yet to hear of (or read of) his "major role in the US Navy table." I know that the WKPP dives presented him (and the snake eater types) with a testing ground that they couldn't pass up and would never have been able to push through a Human Subjects Committee.
I agree
Push the concept all you want, divers in good shape are likely at lower risk for any number of reasons, but please be intellectually honest and point out that there is no data to support any relationship between high VO2 max and "better" offgassing. In point of fact, there is a good theoretical argument that divers with a high VO2 max may take up more nitrogen.For all practical purposes, you can figure about a quarter of all the people your preferred agencies take in each month, have PFO's...this far more irresponsible, than my discussing tables which were created in a population which was selected for no PFO and for reasonably high VO2 max...
Oh, and good job getting me interested in helping you in your continueing interest related to the topic you just highlighted.....I'll be in a huge rush to help
Dan
I would not rest easy on that withered and dried laurel. Regardless of your belief system, intellectual honesty, once again, requires that it be pointed out that there is no data to support the concept.
An excellent way for any us to spend our spare time.
Dr Deco
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Hello Readers:
I have finally returned to the US but have had a bad jet lag problem from a shift of ten time zones.
VO 2 max and DCS
The many responses from readers indicate differing opinions on this topic. One published study does indicate a relationship between fitness and reduced bubble formation. [Reference below].
At NASA, we looked at maximum oxygen uptake during the development of the prebreathe procedures and its relationship to Doppler [venous] bubble formation. There was a trend when more fit subjects [larger max oxygen uptake] produced fewer Doppler bubbles, but there was also considerable scatter in the data.
Bubble Formation Tendency
Other NASA studies have indicated that bubble formation is repeatable in a given subject and highly variable among individuals. I would propose that the combination of these factors composes the tendency toward bubble formation and by extension the development of DCS.
Why some individuals are bubble formation resistant and others are formation prone is unknown. It is my feeling that bubble formation tendency is the biggest factor in DCS [after gas loading] and unfortunately we know little about it.
Dr Deco :doctor:
References
Carturan D, Boussuges A, Vanuxem P, Bar-Hen A, Burnet H, Gardette B. Ascent rate, age, maximal oxygen uptake, adiposity, and circulating venous bubbles after diving. J Appl Physiol. 2002 Oct;93(4):1349-56.
Decompression sickness in diving is recognized as a multifactorial phenomenon, depending on several factors, such as decompression rate and individual susceptibility. The Doppler ultrasonic detection of circulating venous bubbles after diving is considered a useful index for the safety of decompression because of the relationship between bubbles and decompression sickness risk. The aim of this study was to assess the effects of ascent rate, age, maximal oxygen uptake (VO(2 max)), and percent body fat on the production of bubbles after diving.
Fifty male recreational divers performed two dives at 35 m during 25 min and then ascended in one case at 9 m/min and in the other case at 17 m/min. They performed the same decompression stops in the two cases. Twenty-eight divers were Doppler monitored at 10-min intervals, until 60 min after surfacing, and the data were analyzed by Wilcoxon signed-rank test to compare the effect of ascent rate on the kinetics of bubbles. Twenty-two divers were monitored 60 min after surfacing. The effect on bubble production 60 min after surfacing of the four variables was studied in 47 divers. The data were analyzed by multinomial log-linear model. The analysis showed that the 17 m/min ascent produced more elevated grades of bubbles than the 9 m/min ascent (P < 0.05), except at the 40-min interval, and showed relationships between grades of bubbles and ascent rate and age and interaction terms between VO(2 max) and age, as well as VO(2 max) and percent body fat. Younger, slimmer, or aerobically fitter divers produced fewer bubbles compared with older, fatter, or poorly physically fit divers. These findings and the conclusions of previous studies performed on animals and humans led us to support that ascent rate, age, aerobic fitness, and adiposity are factors of susceptibility for bubble formation after diving.
I have finally returned to the US but have had a bad jet lag problem from a shift of ten time zones.
VO 2 max and DCS
The many responses from readers indicate differing opinions on this topic. One published study does indicate a relationship between fitness and reduced bubble formation. [Reference below].
At NASA, we looked at maximum oxygen uptake during the development of the prebreathe procedures and its relationship to Doppler [venous] bubble formation. There was a trend when more fit subjects [larger max oxygen uptake] produced fewer Doppler bubbles, but there was also considerable scatter in the data.
Bubble Formation Tendency
Other NASA studies have indicated that bubble formation is repeatable in a given subject and highly variable among individuals. I would propose that the combination of these factors composes the tendency toward bubble formation and by extension the development of DCS.
Why some individuals are bubble formation resistant and others are formation prone is unknown. It is my feeling that bubble formation tendency is the biggest factor in DCS [after gas loading] and unfortunately we know little about it.
Dr Deco :doctor:
References
Carturan D, Boussuges A, Vanuxem P, Bar-Hen A, Burnet H, Gardette B. Ascent rate, age, maximal oxygen uptake, adiposity, and circulating venous bubbles after diving. J Appl Physiol. 2002 Oct;93(4):1349-56.
Decompression sickness in diving is recognized as a multifactorial phenomenon, depending on several factors, such as decompression rate and individual susceptibility. The Doppler ultrasonic detection of circulating venous bubbles after diving is considered a useful index for the safety of decompression because of the relationship between bubbles and decompression sickness risk. The aim of this study was to assess the effects of ascent rate, age, maximal oxygen uptake (VO(2 max)), and percent body fat on the production of bubbles after diving.
Fifty male recreational divers performed two dives at 35 m during 25 min and then ascended in one case at 9 m/min and in the other case at 17 m/min. They performed the same decompression stops in the two cases. Twenty-eight divers were Doppler monitored at 10-min intervals, until 60 min after surfacing, and the data were analyzed by Wilcoxon signed-rank test to compare the effect of ascent rate on the kinetics of bubbles. Twenty-two divers were monitored 60 min after surfacing. The effect on bubble production 60 min after surfacing of the four variables was studied in 47 divers. The data were analyzed by multinomial log-linear model. The analysis showed that the 17 m/min ascent produced more elevated grades of bubbles than the 9 m/min ascent (P < 0.05), except at the 40-min interval, and showed relationships between grades of bubbles and ascent rate and age and interaction terms between VO(2 max) and age, as well as VO(2 max) and percent body fat. Younger, slimmer, or aerobically fitter divers produced fewer bubbles compared with older, fatter, or poorly physically fit divers. These findings and the conclusions of previous studies performed on animals and humans led us to support that ascent rate, age, aerobic fitness, and adiposity are factors of susceptibility for bubble formation after diving.
Dr Deco
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Hello Readers:
I have finally returned to the US but have had a bad jet lag problem from a shift of ten time zones.
WKPP Decompression
I have mentioned several times over the years that I believe the effective decompression with WKPP is the result of buoyancy in the water for the whole of the decompression. This is similar to decompression on orbit and the lack of musculoskeletal stress decreases tissue microbubble formation and a drop in DCS incidence. In space, this is about a five-fold to ten-fold reduction [depending on the analysis method].
Dr Hamilton
He was once my chief and taught me much about laboratory diving procedures. He did not work on the US Navy tables [in the Dive Manual]; these were made in the 1950s. For the Navy, he did work on neon gas diving and saturation decompression procedures.
Dr Deco :doctor:
I have finally returned to the US but have had a bad jet lag problem from a shift of ten time zones.
WKPP Decompression
I have mentioned several times over the years that I believe the effective decompression with WKPP is the result of buoyancy in the water for the whole of the decompression. This is similar to decompression on orbit and the lack of musculoskeletal stress decreases tissue microbubble formation and a drop in DCS incidence. In space, this is about a five-fold to ten-fold reduction [depending on the analysis method].
Dr Hamilton
He was once my chief and taught me much about laboratory diving procedures. He did not work on the US Navy tables [in the Dive Manual]; these were made in the 1950s. For the Navy, he did work on neon gas diving and saturation decompression procedures.
Dr Deco :doctor:
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Welcome back.
I also question the statistic choices. Whilst non-parametics are fine, it is usually more powerful to normalize the data to a Z-score and then use a plain old ANOVA. This approach would permit the use of block effects and interactive terms to parse the contribution of each variable rather than coming up with what I can only describe as a squishy conclusion, "... support that ascent rate, age, aerobic fitness, and adiposity are factors of susceptibility for bubble formation after diving."
I suspect that each of thoe variables make a contribution, but the critical issue of the contribution of each taken independently and interactively appears, from the abstract, to be left unaddressed.
It makes theoretical sense that a high VO2max might be indicative of faster offgassing (and uptake to that matter). I'll have to read Carturan's paper to see what it actually says. Several items in the abstract give me pause (e.g., I'd have preferred to have had a non-diving control group and to be sure that the Doppler operator was blind with respect to the which of the then three groups were being looked at).
I also question the statistic choices. Whilst non-parametics are fine, it is usually more powerful to normalize the data to a Z-score and then use a plain old ANOVA. This approach would permit the use of block effects and interactive terms to parse the contribution of each variable rather than coming up with what I can only describe as a squishy conclusion, "... support that ascent rate, age, aerobic fitness, and adiposity are factors of susceptibility for bubble formation after diving."
I suspect that each of thoe variables make a contribution, but the critical issue of the contribution of each taken independently and interactively appears, from the abstract, to be left unaddressed.
That's the $64K question for me ... we've all know big, beer-belly types that were seemingly unbendable. Why?
This is fascinating, could you expand on it? Also what difference would the slight pressure head difference in the pulmonary cavity when rotated from vertical to horizontal make? Do you buy the alveolar collapse explanation?
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Hello Thalassamania:
This [in water suspension] is fascinating, could you expand on it?
[1] My interpretation of my NASA studies is that the larger tissue nuclei arise from hydrodynamic cavitation, a process wherein low-pressure regions are created in fluids that move. This fluid movement in tissues in divers results when the diver moves; this is greatest when on the surface and the movement involves fighting gravity (e.g., lifting tanks).
When astronauts are depressurizing in space, the experience a lower incidence of DCS on the same deco schedule as tested on the ground. This has been tested in the laboratory and might be attributed to the difference in activity level between 0-g and 1-g. The term is stress-assisted nucleation.
When divers are suspended in water, as the WKPP decompressions are, the musculoskeletal stress is much less than on divers in a dry chamber. The deco procedure could go faster and still have a low incidence of DCS. That is my interpretation anyway.
Also what difference would the slight pressure head difference in the pulmonary cavity when rotated from vertical to horizontal make? Do you buy the alveolar collapse explanation?
I do not believe that it is a very significant effect.
Dr Deco :doctor:
This [in water suspension] is fascinating, could you expand on it?
[1] My interpretation of my NASA studies is that the larger tissue nuclei arise from hydrodynamic cavitation, a process wherein low-pressure regions are created in fluids that move. This fluid movement in tissues in divers results when the diver moves; this is greatest when on the surface and the movement involves fighting gravity (e.g., lifting tanks).
When astronauts are depressurizing in space, the experience a lower incidence of DCS on the same deco schedule as tested on the ground. This has been tested in the laboratory and might be attributed to the difference in activity level between 0-g and 1-g. The term is stress-assisted nucleation.
When divers are suspended in water, as the WKPP decompressions are, the musculoskeletal stress is much less than on divers in a dry chamber. The deco procedure could go faster and still have a low incidence of DCS. That is my interpretation anyway.
Also what difference would the slight pressure head difference in the pulmonary cavity when rotated from vertical to horizontal make? Do you buy the alveolar collapse explanation?
I do not believe that it is a very significant effect.
Dr Deco :doctor:
Short comment, only reading parts of this thread:
The subject line is very missleading. The heart rate monitor has nothing to
do with the decompression calculation, it only affects the distribution
of blood in certain compartments(on/off-gassing).
Völlm and Bühlmann had diver's on ergometers in the pressure chamber, I had
a long tal with Völlm about this in 2001.
I don't know how much of that was ever published.
Probably not that much as it ws paid by Uwatec and went into ADT.
Alf B.+Christian G. are now continuing the work and
let's hope that they can answer the questions. My understanding
is that the system is complex but they are well on the way.
Using pigs makes it possible to do things you can't do with humans.
It is well know that the amount of fatty tissue has a
big effect on the bubble formation, large storages. When we know where
the bubbles are born we can also better make simulation of the physical situation.
Future dive computers will allow for personal tailoring of paramteters.
Still it is big challenge do modell deep/short dives
as oppposed to long shallow etc etc and having one good/simple simulation
for cases.
Previously heart rate was not available in dive computers
and thus the theory is in it's infancy. As somebody
said decompression is a multifactor problem. Whenever we add
one measurement we can take reduce the effect of one
unkown factor. The algorithms will mature with time.
It's already a big thing that we can reliably measure heart rate
online under water in a commercially available computer.
Niclas
Working for Polar, previously working for Uwatec
Not an official spokesperson for any of the companies
The subject line is very missleading. The heart rate monitor has nothing to
do with the decompression calculation, it only affects the distribution
of blood in certain compartments(on/off-gassing).
Völlm and Bühlmann had diver's on ergometers in the pressure chamber, I had
a long tal with Völlm about this in 2001.
I don't know how much of that was ever published.
Probably not that much as it ws paid by Uwatec and went into ADT.
Alf B.+Christian G. are now continuing the work and
let's hope that they can answer the questions. My understanding
is that the system is complex but they are well on the way.
Using pigs makes it possible to do things you can't do with humans.
It is well know that the amount of fatty tissue has a
big effect on the bubble formation, large storages. When we know where
the bubbles are born we can also better make simulation of the physical situation.
Future dive computers will allow for personal tailoring of paramteters.
Still it is big challenge do modell deep/short dives
as oppposed to long shallow etc etc and having one good/simple simulation
for cases.
Previously heart rate was not available in dive computers
and thus the theory is in it's infancy. As somebody
said decompression is a multifactor problem. Whenever we add
one measurement we can take reduce the effect of one
unkown factor. The algorithms will mature with time.
It's already a big thing that we can reliably measure heart rate
online under water in a commercially available computer.
Niclas
Working for Polar, previously working for Uwatec
Not an official spokesperson for any of the companies
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