Joe Dituri patent for device to detect deco stress with HRV

[Imla]

Garmin devices can get real-time heart rate data during the dive only if you wear the device directly on bare skin. They can also download heart rate data from certain chest straps post-dive. I don't know whether they are calculating HRV during dive activities.

I dont have a Garmin Dive computer, but I have had various forerunners. And paired with the HRM-Pro I have no issues getting pretty accurate readings while diving. I either strap it to my ankle or in the chest pocket of my drysuit. I do however prefer not to have it against bare skin, as there seems to be a tendency for the charging port to create vacuum against skin, and I end up with blisters.

I record the activity as "other" and manually change to diving when on land.

Personally I would not be interested for use of the data in realtime, but as a learningpoint for future dives.

 

[Nick_Radov]

HRV and Decompression Induced Physiological Stress - Alert Diver Magazine | DAN Europe

Editor’s note: We present here a contributor’s analysis on a recent and vastly debated topic, shedding light on a study in which DAN Europe researchers...

alertdiver.eu

 

[johndiver999]

I don't think that something like that would work for me. I would run out of air the first time 4 bullsharks start circling me on my deco stop. My heart rate would go through the roof, the computer would then tell me to descend, which would make me even more nervous and then the computer would figure I am undergoing decompression stress and keep telling me to descend until I run out of air or my heart explodes..

 

[lowwall]

Color me extremely skeptical. This study looks at the association of HRV with markers of inflammatory stress which in turn are believed to be associated with decompression stress.

It's hard for me to believe that you will be able to pull actionable information from something that is both two steps downstream from the thing you want to measure and that is known to be affected by multiple other factors, both internal and external.

Even if researchers believe they can sort the signal from the noise (and that there is sufficient signal to begin with), manufacturers aren't going to offer this unless they can be convinced it doesn't increase their liability exposure. Manufacturers have coalesced around ZHL-16 in large part because having an industry-wide standard, even if it's just a de facto standard, makes it much easier to defend tort claims.

Unless further research finds a significant and consistent advantage to some sort of HRV algorithm over ZHL-16, I can only see this being used as an adjunct to pressure and time-based algorithms. Basically, I expect if it gets used at all, it will only be as a conservatism feature to shorten the calculated NDL if certain stress signatures are encountered.

I don't see how it could be used in deco diving at all. You obviously can't use it for planning. Even using it as an aid during ascents risks throwing dive plans and teams into chaos as every diver ends up with a different ascent profile.

 

[dylanfromwinnipeg]

As a practical matter it's difficult to reliably get high fidelity heart rate data to a dive computer while underwater. In warm water with a shorty wetsuit the wrist optical sensor can work (provided the strap is tight enough). But that's useless in cold water with a full wetsuit or drysuit. I have a Garmin HRM-Pro chest strap that I can wear under my drysuit and it will record heart rate data during a dive but the dive computer can't pick up live transmissions. You can only download data after you return to the surface and end the dive activity. I guess they would need a different heart rate sensor that could transmit using low frequency radio or audio signals like an air integrated tank pressure transducer?

An apple watch worn underneath the wetsuit/drysuit should do it I imagine. With this guys app making the watch vibrate if it detects problems.