Anyone use the heart rate monitor on their sol ?

[mathauck0814]

I'm no expert on decompression, but the cardiac output does effect nitrogen loading and that's why by default the Sol adapts the algorithm to the workload as determined by the heart rate. This is discussed in the manual (see section 2.9.5 page 37). Increased workload shortens the no-deco times and increases deco times. It has to do with the increased rate of nitrogen uptake with increased cardiac output and the redistribution of blood flow to the different tissues with increased cardiac output.

OK - so I'm no "expert" either, but I have some understanding of gas laws. What about cardiac output would have an impact on nitrogen loading? I can see how rapid body heating upon surfacing would cause bubbling, but that's not what this model would be accommodating for, no? Otherwise, if we're limited to just the potential swing in temperature that the body can undergo (for argument's sake, let's say that you could get internal tissues up to 105'F) it's not that dramatic of a swing. I don't *know* but I suspect that if you took the time to build a table for a normal body temperature based on exertion and another table based on elevated cardiac output and higher temperature you wouldn't see dramatic differences.

Besides, if the system heated up through exertion and your body pumped more blood wouldn't that mean you'd expire nitrogen faster on ascent(as the circulatory system brings loaded blood back into the lungs at a greater rate while the ambient pressure drops)?

Like I said, I see the risk of suddenly you surface to 100'F in a drysuit and your body goes sudden and dramatic temperature change. I just can't figure out how it would happen in the water (and how this particular mechanism would do anything to prevent that).

Happy to be wrong (fun discussion nonetheless)

 

[Hatul]

OK - so I'm no "expert" either, but I have some understanding of gas laws. What about cardiac output would have an impact on nitrogen loading? I can see how rapid body heating upon surfacing would cause bubbling, but that's not what this model would be accommodating for, no? Otherwise, if we're limited to just the potential swing in temperature that the body can undergo (for argument's sake, let's say that you could get internal tissues up to 105'F) it's not that dramatic of a swing. I don't *know* but I suspect that if you took the time to build a table for a normal body temperature based on exertion and another table based on elevated cardiac output and higher temperature you wouldn't see dramatic differences.

Besides, if the system heated up through exertion and your body pumped more blood wouldn't that mean you'd expire nitrogen faster (as the circulatory system brings loaded blood back into the lungs at a greater rate)?

Like I said, I see the risk of suddenly you surface to 100'F in a drysuit and your body goes sudden and dramatic temperature change. I just can't figure out how it would happen in the water (and how this particular mechanism would do anything to prevent that).

Happy to be wrong (fun discussion nonetheless)

OK I'll take a stab at it. As you descend the partial pressure of nitrogen increases and nitrogen passes from lungs into blood and into other tissue. There is a pressure gradient as long you're not saturation diving. With increased work your minute ventilation and cardiac output increases; more blood passes through the lungs and carries more nitrogen to the tissues. Also the blood is distributed differently to the tissues, as more blood goes to muscle, so that's going to effect how the algorithm handles the different tissues.

As I said I'm no expert on this but there is a brief discussion of this in the Sol manual. It also mentions that if you turn the workload calculation to OFF then the Sol behaves like the Uwatec Aladin Prime.

 

[mathauck0814]

OK I'll take a stab at it. As you descend the partial pressure of nitrogen increases and nitrogen passes from lungs into blood and into other tissue. There is a pressure gradient as long you're not saturation diving. With increased work your minute ventilation and cardiac output increases; more blood passes through the lungs and carries more nitrogen to the tissues. Also the blood is distributed differently to the tissues, as more blood goes to muscle, so that's going to effect how the algorithm handles the different tissues.

As I said I'm no expert on this but there is a brief discussion of this in the Sol manual. It also mentions that if you turn the workload calculation to OFF then the Sol behaves like the Uwatec Aladin Prime.

So you're increasing the mol concentration then by increasing the volume? Based on this idea if you were on your ascent when the heartrate changed would you off-gas faster as well? Seems counterintuitive to what we know about ascents, but could I get myself worked up a bit or kick into a current to shorten a stop?

(We're of course just passing time until someone who actually studied physics comes along and explains what the missing variable or complementary equation to Henry's law would be in this case...)

 

[Hatul]

So you're increasing the mol concentration then by increasing the volume? Based on this idea if you were on your ascent when the heartrate changed would you off-gas faster as well? Seems counterintuitive to what we know about ascents, but could I get myself worked up a bit or kick into a current to shorten a stop?

(We're of course just passing time until someone who actually studied physics comes along and explains what the missing variable or complementary equation to Henry's law would be in this case...)

On ascent the situation is different. On descent the partial pressure of nitrogen in the lungs is very high and there is a big nitrogen pressure gradient from the lungs to tissues. On ascent the partial pressure in the lungs is lower than tissues, but the gradient from tissues to lungs is small. In this case the increased cardiac output may not make much difference.

 

[joel smith]

Been looking at these about a year now cant wait to get mine. Im learning how to use it before I buy Dive Computer Training. I would love to get this as soon as possible , all donations will be greatly appreciated.

 

[mathauck0814]

The gradient in the lungs would be just as different, just inverted on the ascent. And yes, I know we want a slow release on ascent - I was merely making the point that if you stayed within your gradient factor (assuming it adjusted itself based on your exertion) you ought to be able to accelerate your off-gasing.

I still don't believe that this could possibly make enough of a difference as to actually change your dive in a meaningful way. Guess I need to see the math.

 

[GrumpyOldGuy]

Hijack: Doesn't somebody have the signature along the lines of "Scuba Diving: Measure with a micrometer, mark with a chalk and cut with an ax"?

Seriously, is there scientific basis (i.e. published in peer reviewed journals) that the magnitude of a realistic heart rate difference will affect your Ni load significantly and can be predicted in a simple dive computer?

 

[mathauck0814]

Hijack: Doesn't somebody have the signature along the lines of "Scuba Diving: Measure with a micrometer, mark with a chalk and cut with an ax"?

Seriously, is there scientific basis (i.e. published in peer reviewed journals) that the magnitude of a realistic heart rate difference will affect your Ni load significantly and can be predicted in a simple dive computer?

I think that's sort of what I'm getting at. I'm struggling to believe that there's even a theoretical possibility that such an effect could make a meaningful difference, much less one founded in scientific basis (though honestly, all of this is voodoo anyway - just a fun mental exercise).

 

[Hatul]

Hijack: Doesn't somebody have the signature along the lines of "Scuba Diving: Measure with a micrometer, mark with a chalk and cut with an ax"?

Seriously, is there scientific basis (i.e. published in peer reviewed journals) that the magnitude of a realistic heart rate difference will affect your Ni load significantly and can be predicted in a simple dive computer?

I found a DAN article with references relevant to this:

Divers Alert Network

"Timing of exercise during diving

Physical activity during the dive also has a direct impact on decompression safety.4,5,6,9 Exercise during the compression and bottom phase increases inert gas uptake, effectively increasing the subsequent decompression obligation of any exposure. It is important to remember that dive tables and computers estimate inert gas uptake, they never know reality. On the flipside, light exercise during the decompression phase (including safety or decompression stops) increases inert gas elimination and reduces risk. The caveat regarding exercise during decompression is that more is not always better. Too much or too intense exercise during the decompression phase can stimulate bubble formation, thus inhibiting inert gas elimination and increasing decompression risk."

 

[Dirty-Dog]

I think I remember hearing this same backward rhetoric about dive computers. and Nitrox.

Do you use a dive computer or Nitrox?

As a matter of fact, I do. With a good understanding of the physiology involved.

You've been asked repeatedly, by more than one poster, to produce support for your claims in the form of actual studies. You have repeatedly dodged these requests. I've seen other people dodge requests for support, over the years. It's generally turned out to be because they could not.

SO, when will you be providing some reason, supported by fact, to believe that workload affects gas diffusion.

Hint: Truth by Blatant Assertion doesn't really work...