Breathing rate, air integrated computers and DCI correlation

[redacted]

All nice and technical, but this is a Basic Area and lets face it the likelihood of DCI on an individual dive is pretty low while staying within the limits of any accepted model.

Uwatec added an optional automatic way to trigger added conservatism that you don't like - that doesn't make it VooDoo. The user selectable conservatism factors on the three brands of computers I own, including the Uwatec, seem pretty arbitrary, too.

Changing the assumed altitude will surely make the profile more conservative, but how did someone determine how much was necessary? I suspect that they conveniently selected 3000', the point where we start adjusting tables for altitude. It is just a convenient and easy way to accomplish getting a conservative profile.

Frankly, I bought this computer because I wanted AI and a digital compass. I still have analog guages as a backup to the magic, but I like having everything on one display. I am still exploring features if the computer. Most I will never use, some make sense, others are fluff. Probably true on most computers.

BTW the default setting for Workload Sensing is Off.

Not so. Altitude diving adjustments actually have some science as their basis. Actually, lots of science since it is basically an adjustment for a different pressure baseline. This "fluff" is lacking good science. But if you think it is neat, then enjoy.

 

[herbdb]

Not so. Altitude diving adjustments actually have some science as their basis. Actually, lots of science since it is basically an adjustment for a different pressure baseline. This "fluff" is lacking good science. But if you think it is neat, then enjoy.

I disagree, using a sensor to trigger an adjustment has nothing to do with how the adjustment is made. It is the same as pressing a button. Adjustment on/adjustment off.

Altitude adjustments are a method that makes for a more conservative profile. I have seen nothing that supports a specific level of adjustment. People wanted a way to get a more conservative profile, altitude adjustment was there and easy to apply. The fact that it works is immaterial, thumbing a dive would work better.

 

[beaverdivers]

fact that heavy exertion should be addressed with greater conservatism, or that heart and/or respiration rate(s) can serve as a proxy for when to apply such conservatism

Agreed! DCS is a function of workload.

I recently ran into an unexpected heavy current around 100-110' coming back from a long, deep air shore dive; I adjusted for the unexpected exertion of kicking all the way back against it by changing from 0 to +3 conservatism in VPM on the fly... the extra deco time was enjoyably cleared in the reefs of Hanauma Bay. Then again, I use computers that don't bar the diver from changing such settings on the fly...maybe Beaver Divers can tell us which Scubapro dinosaur offers that option instead of a chest strap heart monitor?

Isn't it better to have the algorithm adjusted by actual infomation than by an assupmtion of a diver in a stressful situation. The Galileo takes a sample every 4 seconds and adds real data into the algorithm. What if the diver guesses incorrectly?

It's very clear Beaver's claim is, "I modified a diver's behavior and I am taking credit for preventing future DCS."

Thank You!

Since this DCS event, we have been diving with air integrated computers that take into account workload resulting in extremely low incident of DCS.

We had one case of DCS due to a heart condition. It actually end up being a blessing in disguise.

We have had approximately 30,000 diver-hours over the past 15 years. The dives have taken place all over the world including Papua New Guinea, Solomon Islands, Indonesia, Micronesia, Fiji, Tahiti, Galapagos, Soccoro, the Caribbean, Utah & Colorado.

 

[nimoh]

DCS is a function of workload.

This would imply that other factors are insignificant in determining DCS. However I think depth and time are very significant.

 

[beaverdivers]

This would imply that other factors are insignificant in determining DCS.

Incorrect!

However I think depth and time are very significant.

Correct! DCS is also a function of depth and time.

 

[Dr. Lecter]

Isn't it better to have the algorithm adjusted by actual infomation than by an assupmtion of a diver in a stressful situation. The Galileo takes a sample every 4 seconds and adds real data into the algorithm. What if the diver guesses incorrectly?

No, for a few reasons. First, relying on a system of sensors, communications, data interpretation, and data application is inherently more failure-prone than the 6 or so button presses needed for me to manually select, alter, and confirm a new conservatism level. Too many links in the chain, not enough transparency as to the correct functioning of any of them while diving.

Second, trusting the computer to get it right based on its conversion of biometric readings into applied conservatism is both philosophically and realistically wrong-headed. Philosophically, because if I haven't the foggiest idea how or why the computer is making its conservatism choices, I'm sure as Hell not trusting my safety to it. You may as well tell divers they're ready for multi-gas deco dives as long as they follow their computer. Realistically, because you can't know if the biometric sensors are generating good readings, and because even if they are you can't know that the conservatism applied is enough for you. As others have already pointed out, I more or less know what the various adjustments will do given my dive profile and selected algorithm(s). Based on gases used, profile(s) dove, and what's left in the dive to complete,I use my training and judgment to select an appropriate level of conservatism before and during a dive, and I have a good idea what my choices will mean in terms of changes to my profile. Nobody flying their computer via biometrics applied to a proprietary algorithm can say the same thing.

Relatedly, you mention "real data" versus diver guessing. That's a nice, solid sounding phrase, and I have no doubt that the computer (if all its sensors and communications are working correctly) can accurately measure heart rate (respiration strikes me as a much trickier matter). But knowing that number and giving it a useful meaning in the context of a specific diver, dive, and conditions are two very different things -- and the latter is necessary for it to be "real data."

What if the diver guessed incorrectly when deciding what computer to buy and gets bent on a proprietary algorithm adjusted by "real data" in a manner they know not how?

 

[nimoh]

Incorrect!
Correct! DCS is also a function of depth and time.

perhaps we also disagree on what a function is

 

[herbdb]

What if the diver guessed incorrectly when deciding what computer to buy and gets bent on a proprietary algorithm adjusted by "real data" in a manner they know not how?

I don't agree with Beaverdiver that this is a terrific feature, but I don't think its harmful. At the worst it will kick in and make the dive more conservative. If you positively want a conservative factor on, you just activate it (a different function).

You can "what if" all day? What if a diver guessed incorrectly on the computer to buy and messes up settings for Nitox mix and dies? You can do something dangerous with just about any computer.

Now the deco planning and diving are the bells and whistles I will never use. FWIW those who are interested in the status of various tissue compartments, the Sol and Luna will display the current status of the eight compartments it uses and tell if the compartment is on or off gassing at that time. Give you something to do hanging on the line during a deco stop.

This data can also be downloaded to a computer for any and all points in the dive. I may go back and look at my last dive on the Spiegel Grove out of curiosity. Had not thought of it before and it might be interesting to see how they change and which are controlling at different parts of the dive.

 

[TSandM]

What really bothers me is that neither heart rate nor respiratory rate is a good measure of workload. Both can be elevated by many things other than exertion, and most of those things (nervousness, discomfort, cold) have little or nothing to do with nitrogen absorption.

The fact is that the incidence of DCS in divers who observe NDLs and have good ascent practices is EXTREMELY low, with or without heart rate monitors.

 

[redacted]

I disagree, using a sensor to trigger an adjustment has nothing to do with how the adjustment is made. It is the same as pressing a button. Adjustment on/adjustment off.

Altitude adjustments are a method that makes for a more conservative profile. I have seen nothing that supports a specific level of adjustment. People wanted a way to get a more conservative profile, altitude adjustment was there and easy to apply. The fact that it works is immaterial, thumbing a dive would work better.

The adjustment is straight forward calculations (arithmetic). The science involved is the same as is used at sea level. It is the same algorithms using a different measured ambient pressure value.

A little light reading: http://njscuba.net/zzz_gear/deco_m-values.pdf