OK, so people have figured out how to get O2 gas into people's bloodstreams by injection, in a form that doesn't cause embolism or bends.

It's actually ready for use in emergency medicine to save patients who have their breathing cut off, and who can't have it restored quickly enough to avoid oxygen starvation.

http://www.techwench.com/scientists-...out-breathing/

One would be tempted to think about using this to do amazing, 20-minute dives or mer swims.

More experience with the technique would have to be gained before anyone should try this in a non-emergency situation, though. In the case of lipid microsomes, while they will circulate, nobody knows yet what chronic use would do in the bloodstream, especially under elevated pressure.