Joe Dituri patent for device to detect deco stress with HRV

[Nick_Radov]

The latest episode of The Adrenaline Zone podcast has a fascinating interview with Dr. Joseph Dituri, a retired naval officer from the Navy Experimental Diving Unit (NEDU) who is currently a biomedical researcher. The whole episode is worth listening to. But one topic of particular interest to this forum is that he has built and patented a wearable device which can supposedly use heart rate variability (HRV) to detect decompression stress before the onset of clinical symptoms. The idea is to alert the diver if they are ascending too fast based on a direct physical measurement rather than a model of dissolved gas.

Dr. Deep Sea’s Oceanic Adventures with Dr. Joe Dituri — The Adrenaline Zone

In this episode of the Adrenaline Zone, Dr. Joe Dituri, a former commander in the US Navy, shares his experience as a deep-sea diver, special operations officer, and engineering duty officer. His passion for diving started at a young age when his father gave him a double hose regulator that allowed

www.theadrenalinezone.com

Does this approach make sense? I tried to find the patent he mentioned but didn't come up with anything so it's not clear whether it has actually been issued yet.

 

[Imla]

Would be really nifty if someone made that into an app for Garmin...

 

[scubadada]

Not enough information for me to evaluate, maybe someone else knows more about this

Sandy Winnefeld: But at 22 ft, though, most people who are knowledgeable on scuba diving, you can go down to 22 ft for an hour and you don't have to do anything. You probably don't even have to do a safety stop on the way back up. But if you live down there for 100 days, you are now saturated with nitrogen. So if you had an appendectomy, there's a process you have to go through in order to come back to the surface, right?

Dr. Joe Dituri: And the sad part is, nobody knows that. So here I am doing their third-order partial differential equations, and you're basically calculating M values on bone tissue saturation. Because at this point, it's not the other tissues in your body, it's the bone. It's the ones that are poorly perfused tissues. So those bones and the cartilage, you're trying to figure out what their saturation rates are. The answer is nobody knows, and everybody's rolling dice, so we're making stuff up. I'm literally calculating this as we go along. But the good thing is, 14, 15 days ago, I just got issued my US patent, and that is on heart rate variability and how the autonomic nervous system is stressed. So I can detect decompressive stress prior to symptoms being shown. I can detect the heart. I can detect hypercapnic stress. I can detect oxidative stress. So when the autonomic nervous system is stressed, I can detect that prior to symptomology coming on, and I proved it so much.

Sandy Winnefeld: Is that something that a recreational diver would eventually, someday just strap off? Is it a small device like a Fitbit or something? Where it goes, “Hey, not only are we calculating that you're making a mistake here, your body is telling me that you're making a mistake here.”

Dr. Joe Dituri: Exactly. And what I've done– so it's a really teeny device at this point because it's all computer chip at this point. So my initial prototype was obviously the size of my hand. But this is like the size of a watch, for crying out loud. And what I did is I put a little cell phone vibrator in it. So now it goes every time you're messing up and you're going and decompressing too shallow. So it's not perfectly ready for primetime. It just got a patent two weeks ago.

 

[scubadada]

Association Between Heart Rate Variability and Decompression-Induced Physiological Stress

The purpose of this study was to analyze the correlation between decompression-related physiological stress markers, given by inflammatory processes and immune system activation and changes in Heart Rate Variability, evaluating whether Heart Rate Variability can be used to estimate the...

www.frontiersin.org

 

[Nick_Radov]

Would be really nifty if someone made that into an app for Garmin...

Only Garmin themselves could build such a feature. Descent dive computers can calculate HRV from either a wrist optical sensor or separate chest strap, but that's just for sports training on dry land. For safety reasons they don't allow using third-party ConnectIQ data fields during dive activities because defects in those can cause the device to crash.

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?

 

[VikingDives]

Over a decade ago, a friend and I were kicking around the idea of building an app to measure HRV in athletes. At the time there was quite a bit of data that supported using HRV to measure for things like overtraining. We never got past the investigational stage primarily because, at the time, you needed multiple leads to provide the necessary sensitivity. There was a commercially available device, but it wasn't popular with athletes.

I'd guess that the tech has changed enough that multiple leads wouldn't be as necessary, or the sensors have become smaller.

It wouldn't surprise me if HRV could be used as a marker for decompression stress, but IIRC you had to have baseline data (pre-excercise), data during exercise and then post-excercise data to make comparisons, so I wonder how the device would be used in the real world.

 

[VikingDives]

Only Garmin themselves could build such a feature. Descent dive computers can calculate HRV from either a wrist optical sensor or separate chest strap, but that's just for sports training on dry land. For safety reasons they don't allow using third-party ConnectIQ data fields during dive activities because defects in those can cause the device to crash.

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?

Scubapro's Galileo and G2 have something that is real-time during the dive... Are you getting HRV data from Garmin post-dive?

 

[Nick_Radov]

I'd guess that the tech has changed enough that multiple leads wouldn't be as necessary, or the sensors have become smaller.

It wouldn't surprise me if HRV could be used as a marker for decompression stress, but IIRC you had to have baseline data (pre-excercise), data during exercise and then post-excercise data to make comparisons, so I wonder how the device would be used in the real world.

Garmin and Apple dive computers do continuously record HRV using only a wrist optical sensor. You have to wear the device for a couple weeks to establish a reliable baseline. Garmin smart watches use that data to calculate various fitness metrics and to recommend daily workouts, but they don't use it for anything diving related.

 

[Nick_Radov]

Scubapro's Galileo and G2 have something that is real-time during the dive... Are you getting HRV data from Garmin post-dive?

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.

 

[scubadada]

Heart rate variability is more complex than heart rate, but modern technology has made accurately measuring it considerably easier. Exactly how this would be done while diving, in real time, remains to be determined. The prediction of decompression stress remains to be fully and accurately demonstrated. The advantages over currrent decompression algorithms need to be elucidated

I am not holding my breath.