Liquid Breathing

Is it possible for a human to sustain himself while breathing liquid? The surprising answer is yes, not only is it possible but it has been done for quite a few years. In 1920 Winternitz and Smith demonstrated that human lungs can tolerate large amounts of a saline solution without damaging them. The major breakthrough came in 1966 when Clark and Gollan starting using perfluorocabons(PFC). They submerged mice in the liquid and the mice breathed in the liquid. After keeping them in the liquid for some time they returned them to normal breathing and the mice were fine.

Perfluorochemical (perfluorocarbon) molecules have very different structures that impart different physical properties such as respiratory gas solubility, density, viscosity, vapor pressure and lipid solubility. PFC liquids have 1/4 the surface tension, 16 times the oxygen solubility and 3 times the carbon dioxide solubility of water. Since oxygen and carbon dioxide dissolve so easily in this liquid it is excellent for carrying oxygen. The liquid spreads the oxygen much more quickly than gas.

Liquid breathing could assist in the treatment of patients with severe pulmonary or cardiac trauma, especially in pediatric cases. Liquid breathing has also been proposed for use in deep diving and space travel.

The primary application of liquid breathing is the medical treatment of certain lung problems. For example, babies born prematurely often have underdeveloped lungs. Because perflubron can carry more oxygen than air, it can help relieve respiratory distress until the lungs are able to function with regular air. But it has also been used for adults with acute respiratory failure, whether due to disease, trauma, burns, or the inhalation of smoke, water, or other toxins.

The other potential use for liquid breathing is in diving. Ordinarily, divers must breathe heavily pressurized gases to prevent their lungs from collapsing deep underwater, but this requires decompression on the way up and carries the risk of nitrogen narcosis and numerous other problems. If the lungs were filled with a liquid instead, most of those problems would simply disappear. This would, in theory, enable divers to reach greater depths, ascend more quickly, and experience somewhat lower risks.

Liquid immersion provides a way to reduce the physical stress of G forces. Forces applied to fluids are distributed as omnidirectional pressures. Because liquids cannot be practically compressed, they do not change density under high acceleration such as performed in aerial maneuvers or space travel. A person immersed in liquid of the same density as tissue has acceleration forces distributed around the body, rather than applied at a single point such as a seat or harness straps. This principle is used in a new type of G-suit called the Libelle G-suit, which allows aircraft pilots to remain conscious and functioning at more than 10 G acceleration by surrounding them with water in a rigid suit.

The major difficulty involved in the use of liquid breathing is that it is much harder for human lungs to move liquid in and out than it is to breathe air. Even though perflubron is so much better than air at carrying oxygen and carbon dioxide, that advantage can be lost if you don’t circulate it rapidly enough.