Chapter 29: RespirationBizarre Facts in Biology |
The 1989 movie The Abyss (20th Century Fox) popularized the idea that animals could breathe liquid as long as it had oxygen carrying properties similar to the air we breathe. In the movie, a mouse is shown submersed in a mysterious pink liquid. After recovering from the initial shock of inhaling a fluid, the mouse begins to breathe as it normally would in standard room air. Although water does contain dissolved oxygen, it does not have enough carrying capacity to be able to deliver a sufficient amount of oxygen to support our tissues. The human lung evolved to exchange gases with the air we breathe. When filled with water, the gas exchange surface is unable to meet the demands of the body and our tissues begin to starve for oxygen. At the same time, our ability to expel carbon dioxide as a waste product becomes compromised. The mystery behind the pink liquid is that it contains a molecule called perfluorooctyl bromide.
The concept of liquid breathing was first explored by Dr. J. Kylstra at the State University of New York at Buffalo. By "forcing" oxygen into a simple saline solution, Dr. Kylstra was able to significantly increase the amount of oxygen carried by this liquid. The mice in Dr. Kylstra's lab were able to breathe the liquid and receive adequate amounts of oxygen. Problems arose when it was discovered that the saline was unable to effectively remove carbon dioxide from the mice. Carbon dioxide levels quickly rose to lethal levels in his test subjects. Many different formulations have been tested, but the current use of liquid breathing mediums involves the employment of the perfluorocarbons. In addition to being able to carry 20 times more oxygen than Dr. Kylstra's saline, these compounds also have excellent carbon dioxide carrying capacities. The oxygen and carbon dioxide carrying capacities of these compounds are only a couple of the many unique characteristics that make perfluorocarbons useful in liquid ventilation and oxygenation of tissues.
When most divers drop below the surface, they rely on a tank that has been filled with compressed air. Sometimes this air has been modified to reduce the amount of nitrogen which has been shown to be the source of a wide variety of diving injuries and sicknesses. While it may be many years before SCUBA tanks are routinely filled with a liquid breathing medium, the medical applications of this technology are becoming realized.