Breathing From Liquid: Is Diving’s Holy Grail Here?

No more decompression illness. And no more limits to depth or time of a dive, other than physical limitations unconnected with gas breathed. Diving using liquid breathing, formerly a wonder of science fiction like James Cameron's movie The Abyss, seems to have moved closer to reality with the design of a unit that allows a diver to breathe via a re-oxygenated liquid circulated through the lungs. Its inventor is Arnold Lande, a retired heart and lung surgeon who worked at University of Texas Medical School in Houston. He revealed his system in a presentation given late last year at the first International Conference on Applied Bionics and Biomechanics in Venice.

In Lande's design, the diver's lungs, nose and ear cavities are filled with the liquid perfluorocarbon (PFC), contained within a closed helmet. The gag reflex, Lande believes, should be controllable through a combination of training and, if needed, a drug to desensitize the diver to the feeling of liquid entering the body. PFC is moved in and out of the lungs by a ventilator unit that fits around the upper body and uses a pump to vary pressure on the ribcage. "This would provide the assistance to the diver's breathing that he needs while he is working hard, having to pull a liquid into his lungs and expel it again," Lande told the press.

Gaseous oxygen is bubbled into the PFC, which can absorb very high gas levels, to maintain supply. By absorbing liquidsuspended gas, the diver does not on-gas. "The beauty of doing it all from a liquid is that you don't have to use these highly compressed gases in the lungs that are going to dissolve into the blood," said Lande. ''You have a liquid that you can infuse with just as much oxygen as you need."

The oxygen supply is contained, along with a battery power-pack, in a propeller-driven unit managed by the diver, in a similar manner to an underwater scooter. The removal of carbon dioxide is managed by taking blood out of the body, via a catheter inserted into the groin's femoral vein, and circulating it through a gas-permeable-membrane gill fitted within the suit. Carbon dioxide is absorbed by a substance such as soda lime placed on the other side of the gill membranes, before blood is returned to the body.

The gas-exchange concept is based on that already used in hospital heart and lung machines, or membrane oxygenators. The use of re-oxygenated PFC has already been applied successfully in the hospital environment; a small number of U.S. hospitals have used liquid ventilation successfully on highly premature babies since the mid-'90s. It has not been reported how close Lande's design is to a working prototype for humans - - and whether or not any human guinea pigs have signed up to try one.

- - previously published in the January 2011 issue of DIVER