Doppler Bubble Monitor -Do you own/use one?

lowviz · Jun 5, 2014

Attended an excellent dive club meeting yesterday:
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Keystone Divers Presents: Dr. Marvin Gozum
'Individual Resistance to Bubble Formation after Diving'
KDA Meeting: Wednesday, June 4, 2014
Barnaby's in West Chester
7 PM Meeting
8 PM Speaker

Individual Resistance to Bubble Formation after Diving A relationship between bubble formation observed via Doppler testing and decompression illness exists. Suggestion of individual resistance to hypobaric decompression illness was published since 1944. We'll review published decompression studies that reveal patterns suggesting inherent per person resistance to decompression illness. This phenomenon may account for extraordinary performance in decompression dives, suggesting it is actually more common than superhuman. We'll then examine a use of doppler testing in a live demonstration to assist assessment of decompression stress or provide concerned divers a rationale for adjusting conservatism in tables or computers. Marvin Gozum puts over 100 dives annually and is an avid full trimix and full cave diver. His perspective is as a physician "who does the dives," whether its drift decompression, cave or reef dives, mixing diving medicine theory, science and practical experience from over a thousand non-training problem free sport dives. Dives with 6 hours run times, 17,000 linear feet penetration, or depths 300' are routine and without issue. He directs a sport diving oriented diving medicine program at Thomas Jefferson University, is a referral physician for the Divers Alert Network, and can be found many weekends year round in a local quarry, New Jersey wrecks or Florida. A proponent of Hogarthian diving without an attitude, he is at home discussing all facets of diving, from decompression theory to batteries for a dive light.
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He brought this monitor with him: Mini Dopplex Vascular Doppler | Huntleigh Healthcare Doppler Really sweet, simple device. Pricey, though. About $600 USD.

He made an interesting point: We all know that divers, profiles, and bubble scores can get quite complex. However, one should sound the same before and after a dive. This simple metric allows one to 'adjust' generic profiles to individual divers. Most interesting concept as doing so is far more conservative than using physical cues as an endpoint, i.e. 'rashing' etc.

Dr. Gozum also mentioned that a very inexpensive ~$100 USD (Chinese) model exists. Anybody know of such? -can't seem to find it...

DaleC · Jun 5, 2014

I just did a chamber tour last weekend and don't think one would sound the same pre/post dive. We were shown some doppler video and it was amazing how much was going on in asymptomatic divers.
I see this as being akin to the PFO discussion: Whether divers should get tested to see if they have one. 1/3 of us have them, we do not see injuries in 1/3 the diving population, so is knowing that data going to reduce injury.

How many divers are getting bent following generic profiles while relying on physical effects as negative feedback to efficacy?

If you monitored yourself post dive and had a mild to moderate score; what would you do? Rush to the chamber or wait for physical symptoms to manifest.

lowviz · Jun 5, 2014

DaleC:
I just did a chamber tour last weekend and don't think one would sound the same pre/post dive. We were shown some doppler video and it was amazing how much was going on in asymptomatic divers.

No, not at all. It (your bubble score) seems to be a very 'gross' assessment. There are only four levels: from no bubbles, to 'should be dead'. Yes, indeed, asymptomatic divers have a lot going on. The whole idea is how YOU respond to a bubble category. Some people are extremely sensitive and others are stupidly insensitive to bubbling. The key point *seems to be* that no matter how subtle or excessive, a bubble score is a predictor that is more conservative than a physical manifestation, such as a rash or loss of sensation.

DaleC:
I see this as being akin to the PFO discussion: Whether divers should get tested to see if they have one. 1/3 of us have them, we do not see injuries in 1/3 the diving population, so is knowing that data going to reduce injury.

Look at it this way, assume a PFO and standard dive profiles will bend you. Now find a bubble score that YOU tolerate and you can appropriately add conservatism to the profiles via 'trial and error'.

DaleC:
If you monitored yourself post dive and had a mild to moderate score; what would you do? Rush to the chamber or wait for physical symptoms to manifest.

Nope. Just collect the data and record the physical manifestations. Again, I am beginning to believe that bubble scores do not directly predict physical effects, but they certainly precede them. Meaning that tracking bubble scores against dive profiles has merit.

kwinter · Jun 5, 2014

I carry one in my dive bag. Inexpensive baby Doppler monitor that works better than the really expensive one that Marv has. You can get alternate probes at different frequency for better results.

iPhone. iTypo. iApologize.

lowviz · Jun 5, 2014

kwinter:
I carry one in my dive bag. Inexpensive baby Doppler monitor that works better than the really expensive one that Marv has. You can get alternate probes at different frequency for better results.

iPhone. iTypo. iApologize.

Name?, Link? Something??? -you're killing me here...

---------- Post added June 5th, 2014 at 11:00 PM ----------

Don't go all "South Jersey" on me. I bet I could bribe Rusty into letting me onto the boat...

-just give up the goods and I'll stay north. :cool2:

---------- Post added June 6th, 2014 at 11:34 AM ----------

If standard profiles work for you then a doppler monitor is a waste of time and money. If you are symptomatic while using standard profiles, then this approach appears to be an informed way to add conservatism.

found two:

Bistro Hi-dop Vascular Doppler 8mhz , 5mhz or 4mhz probe at your choice , - Blood Pressure Monitor Depot

Edan Sonotrax Vascular Doppler 8mhz , 5mhz or 4mhz probe at your choice , + battery , FREE SHIPPING USA - Blood Pressure Monitor Depot

-any input on these is welcome...

kwinter · Jun 6, 2014

I have a Sonoline, but I don't remember which model. It has a removable probe, so I can use either the 3MHz that came with it or the 8MHz one I bought separately. There are tons of them on eBay, both new and used. If you want a new one with both probes, here is a listing. Hot Sale Fetal Doppler 3 MHz Waterproof and 8 MHz Vascular Probe Prenatal Baby | eBay
But you could get it cheaper buying a used one and just using that probe. I haven't found all that much more sensitivity with the 8MHz probe, but one of my dive buddies is an ultrasound tech and told me it would be better.

lowviz · Jun 7, 2014

-Just bought the Edan Sonotrax Vascular Doppler 8mhz. I'll report back when I have something to say about it...

$99 USD shipped. Sweet.

DaleC · Jun 7, 2014

I guess my point is whether the activity requires such attention to detail and are divers getting bent following current guidelines.
Yes, Doppler could be useful for developing a personal set of tables based on ones reactions (bubbling) to particular depths/durations but is that a needed precaution for most divers most of the time?
If divers were getting bent following computer or table recommendations I'd say a better tool were needed but they aren't.

To look at it another way: What if they created a tool that you wore on your wrist that warned you of a potential heart attack. The problem being that it only warned of a potential attack, in the same way that doppler warns you of potential DCS. Would you want to wear that tool or would it turn you into a neurotic mess? Do most people need a potential heart attack warning device most of the time?

lowviz · Jun 7, 2014

OK, I'm way over the line here. However, you aren't the "standard" diver, either. You deserve an honest answer.

Let's just say that there exists a population of very aggressive divers that use this monitor as a final *personal* warning that they have gone too far. "Too far" having nothing to do with tables or any other standard metric. I am fascinated by this and drawn to the flame...

we are solidly into 'unsafe diving practices' and this post/thread may very well not last...

---------- Post added June 7th, 2014 at 01:51 AM ----------

I am an engineer, I believe in closed loop control systems. The only bio-feedback I know of is rashing, headaches, and getting bent. Bubbling should preceed this. So if I'm following the tables and still bubbling, do I back off or continue to do what is 'generally approved behavior'?

Seriously, I am a conservative diver, and a scientist/engineer. I have problems discounting doppler scores as an 'early warning' device. Nothing more.

ajduplessis · Jun 7, 2014

Very nice. There is however a point (slightly of topic) around PFO's I would like to mention, as a large % of divers don't know/understand. The fact that a PFO is not present on the day of the test does not mean that this will stay as is!

a Simple cough can damage and open up a PFO, same for lifting heavy objects, cardio illness, age, muscle disorders to name a few. You PFO status is not given!!!!

Listen to you body and dive safe!

Doppler Bubble Monitor -Do you own/use one?

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