Doppler sensor to measure bubble formation after dives

[LFMarm]

Has anybody tried this doppler sensor to measure bubble formation after dives? It looks interesting to find out appropriate GFs that take into account physiological variability and type of diving.

The O'Dive solution - O'Dive

Paragon is the US distributor and here are the prices: O'Dive Sensors
The version for hypoxic trimix is 1,179 USD.

 

[J-Vo]

I believe David Doolette said fairly clearly in RF4 that doppler bubble measurements are only useful across large test samples and not for the individual divers/dives.

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Rebreather Forum 4 Presentations RF4 addressed safety, physiology, technology, training, and knowledge gaps relevant to rebreather diving. The primary goals were to: 1) consolidate the knowledge base and enhance knowledge transfer, and 2) promote best practices within the community. The program...

rebreatherforum.tech

 

[Sevenrider860]

Has anybody tried this doppler sensor to measure bubble formation after dives? It looks interesting to find out appropriate GFs that take into account physiological variability and type of diving.

The O'Dive solution - O'Dive

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Paragon is the US distributor and here are the prices: O'Dive Sensors
The version for hypoxic trimix is 1,179 USD.

At the recent NSS-CDS conference Dr. Neal Pollock was asked about this. He did not give it high praise. I don't remember the exact details, but I think he mentioned that the measurement interval (30 minutes and 1 hour) did not capture accurate data. I am sorry I don't remember the exact details. I do know he did not mention this device as one of the methods to reduce decompression stress.

 

[Johnoly]

Bubble sizes & quantities are an extremely complicated subject with many different parameters. It would be great to see some independent, hands on, Peer Review from any of the active DAN research doctors who have published studies on this new product. The bubble reading sensor is the easy part, analysis is the problem. I give the company credit for wading into a very difficult problem with a new product and service.

 

[AdamJ]

I tried this during my CCR MOD 1 a month ago. Was very finicky to use but I was interested enough to purchase for myself. I then found out you have to buy different versions of “hardware” to adjust your max depth and need to pay for every analysis after so many free measurements. Turns into a very expensive paperweight very fast that I don’t see the need for unless I was running a dive shop.

Edit: I now see on their page the owner has unlimited analysis. They either changed this or I didn’t notice before. One less downside but I still don’t like needing to buy new hardware as you progress to only get software changes.

 

[justinthedeeps]

Some of the guides/instructors that I've dived with were using them, and encouraged me to give it a try for deco dives.

I think the statistical model for how "good" a dive outcome is from a deco standpoint involves some combination factors, including the dive profile.

I don't remember seeing whether its formulation was open to inspection, so it is unclear how to understand the reported 'scores' on any precise technical basis.

As a personal device, you could use it to develop a running assessment for what the thing thinks about the differences between your dives. If you're getting all 90's, and then a low 'score' for a dive, presumably it means there was something correctable about the dive that might correlate with a higher risk of DCS.

Obviously, for something like this to be truly predictive, at least thousands of dives would need to be made, wherein O Dive measurements were logged, and then linked to any DCS/DCI reported for any of the dives (if it ever occurs). Then you could do some stats that do unsupervised clustering, or correlate the measured parameters to actual incidence of decompression issues. The collection of that data in aggregate is probably one hope for the developers--I believe it uploads the data to its cloud.

 

[Learner Diver]

Are you or anyone you know prone to decompression sickness?

 

[Johnoly]

...Obviously, for something like this to be truly predictive, at least thousands of dives would need to be made, wherein O Dive measurements were logged,

Bubble life has so many changing variables that even a thousand data points is almost useless. Here's an example:
While at different and varying depths you just rhythmically flex each limb about 3 times in sequence lowest to highest of moving all joints in the limb. The movement will dislodged small bubbles sequestered in venous capillaries, and change the size, wall strength and the grade of VGE passing beneath a 5.0- or 2.5-mHz ultrasound wave sensor and will change the DCS outcome. In just this tiny scenario you have atleast 6 constantly changing data points that would be almost impossible to repeat again to retest & re-prove the outcome.

Bubbles are really really hard to predict if they will grow, shrink, split, absorb, change shape, squeeze and the very worst>>>>hide.

 

[justinthedeeps]

Complex stuff! Every tissue/capillary its own little fizzling coke bottle.

Perhaps this explains why very deep dives incur such a higher rate of DCS/DCI. Every tiny bubble anywhere can grow to ten times its original size.

99.9% efficient deco could still mean a dozen stuck bubbles. Now that automatic on-board chamber session, every time, makes sense for the deep commercial divers.

 

[LFMarm]

I believe David Doolette said fairly clearly in RF4 that doppler bubble measurements are only useful across large test samples and not for the individual divers/dives.

Programme - Rebreather Forum

Rebreather Forum 4 Presentations RF4 addressed safety, physiology, technology, training, and knowledge gaps relevant to rebreather diving. The primary goals were to: 1) consolidate the knowledge base and enhance knowledge transfer, and 2) promote best practices within the community. The program...

rebreatherforum.tech

Correct, here is another presentation where David Doolette makes this point:

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