How to Breathe Water...and Not Die?
sbms.blogspot.com
sbms.blogspot.com
* Liquid breathing solutions have to be really, really sterile. You're introducing a liquid past all your defensive mechanisms, and typical immune responses (coughing or sneezing) won't do anything. As a result, immune response/inflammation can be quite severe. This would be hard to maintain in a marine environment.
* Even with a liquid breathing solution, high pressure can still have health impacts. I don't think this has ever been tested (at least not in an unclassified setting), but HPNS (High Pressure Nervous Syndrome) would probably still be a major issue at depths beyond 800-1000 feet.
* It's my understanding that total liquid breathing (as opposed to partial liquid breathing, where only one lung is filled or both lungs are partially filled) will cause a lot of damage to the lung surfactant layer. I'm not sure if this is still the case--human tests with total liquid breathing are very rare.
There's lot more information about medical applications in this paper, written by Thomas Shaffer (mentioned in the article): http://pedsinreview.aappublications.org/cgi/content/full/20/...
COMEX (a French commercial diving company) has done successful working dives to beyond 1,700 feet on hydroheliox, a mixture of 49% hydrogen, 50% helium, and 1% oxygen. However, there are major practical issues with breathing a hydrogen mixture--namely, if you have hydrogen and oxygen together at high pressure with more than a tiny fraction of oxygen, it will explode. This makes it only practical to use a hydrogen mixture at a depth great enough where 1% oxygen is a high enough partial pressure to sustain consciousness.
Also, hydrogen at high partial pressures is said to have a narcotic effect similar to LSD, but permanent.
Water normally doesn't have enough dissolved oxygen
The new suit allows its wearer to breathe a specialized liquid chock-full of oxygen molecules; called a PFC or perfluorocarbon, the liquid can store large amounts of dissolved oxygen.
I imagine this will be an extremely unpleasant experience. Humans don't like having any kind of fluid in their lungs. Safer deep diving is exciting.