Bubbles? PFO? Decompression Q

[JTemple]

Hi Doc,

I have a question regarding the following statement in the Moon & Bove article, found on page 2 (or 272):

The majority of DCI cases in both recreational and commercial diving consist of pain or sensory abnormalities (16,17), and no one has yet shown that PFO is related to most of these cases. The exception is skin bends, but this is uncommon.

It seems to me this is saying that a PFO is related, or even is likely the cause, of skin bends?

It interests me as I suffered a severe case of skin bends last year, took 3 rides in the chamber, have since been diagnosed with a PFO, and am awaiting closure. I also had experienced a minor episode of skin bends a couple of years earlier. And after all of my research, I have come to realize (accept) that I have had other very mild symptoms after other dives which were probably indicative of very minor 'hits', such as migraines with aura, fatigue, etc.

I am a 'migraine with aura sufferer', and I am aware of the research being done in relation to migraines and PFOs. But right now, I am specifically looking for another interpretation of the above statement from the article with regards to skin bends.

TIA!

 

[Dr Deco]

Hello Readers:

Just a few comments to confirm what was written by Doc Vikingo.

PFO

Bubbles - not PFOs - cause DCS. It is possible for bubbles to pass though the lungs, even in the absence of a PFO. Straining while breath holding , e.g., climbing the ladder to the boat, can cause pressure building for a moment in the right atrium and cause PFO admittance of bubbles to the systemic arterial circulation.

The prevalence of PFOs is greater than 20% in the general population. There is also a variation in size of a PFO. Bigger is not better.

In general, testing is not necessary for a PFO. If you have an “undeserved” hit, it might be considered. My definition of "deserved" would be excessive gas loads, strenuous exercise underwater and/or on the surface, straining to reenter the boat, and Valsalva-like maneuvers are all bad practices. Many would consider DCS under these conditions as not being "undeserved.”

Migrane with aura has been associated with a PFO, as has been skin bends.

Origin of Bubble “Seeds”

It is not known with certainty where the "seeds" arise. My thinking on this is that small ones [nuclei] arise from thermal [molecular] activity and cling to surface of cells. With musculoskeletal activity, these form the seeds that can grow during decompression with an influx of dissolved nitrogen by diffusion.

Some degree of bubble formation is tolerated by the body. When these grow in pain-sensitive tissue, you will experience discomfort. This event is probably extravascular. Doppler bubbles are vascular [in the blood stream].

Stroke and Microbubbles

You need more than one tiny bubble to cause CNS damage. The arterial pressure will push a bubble through the capillaries [ small pore pressure]. If there are many small bubbles, this “pushing mechanism” will be overwhelmed.


Dr Deco :doctor: