Now, I'm sure there are holes in my understanding of decompression theory but I thought that once bubbles form, even micro bubbles, they don't dissolve and off gas the way normally dissolved gas in tissue does, hence the long chamber rides for bendy people. Also, can't the micro bubbles act as sort of a nucleus for larger bubbles to form up on?
I thought the current thinking was that bubbles form on all dives and are routinely filtered out in the lungs. Too many, or too large, and the process breaks down. The issue with PFOs is that those bubbles can gain access to the arterial circulation before being removed and be pushed into places where they don't belong.
There is no difference in the physics between tech and rec dives. Rec dives simply limit the inert gas load to that which can be handled safely with a normal ascent to the surface. Increase it beyond those limits and stops along the way become required to allow for safe off gassing.the tech stuff is another world and it's voodoo gets spooky down there.