HYPERBARIC CHAMBER

also called Decompression Chamber, or Recompression Chamber, sealed chamber in which a high-pressure environment is used to relieve symptoms of pressure-related diseases and other medical afflictions. Experimental recompression chambers first came into use in about 1860. In its simplest form, the hyperbaric unit is a cylindrical metal tube large enough to accommodate one or more persons. The outer door has rubber gaskets that permit high-pressure seals. The air or breathing mixture is pumped into the chamber by compressors; the pressure increases proportionally to the amount of air forced into the hyperbaric unit. Most chambers operate at air pressures three to six times greater than the atmospheric pressures ordinarily encountered. As the air becomes more compressed, it increases in density and concentration. A person breathing air at six atmospheres (six times atmospheric pressure) is taking into his body six times the amount of oxygen with each breath that he would normally consume outside of the chamber. It is because of this increase in oxygen level that the chamber is valuable for certain medical problems. Some bacteria, such as those that cause tetanus (lockjaw) and gas gangrene, cannot grow in environments containing oxygen. Persons afflicted with these diseases have been successfully treated in hyperbaric chambers because of the increased amount of oxygen forced into the bodily tissues. Babies born with certain heart defects (blue babies) have increased chances of survival during the delicate heart operation if they receive more oxygen by means of the hyperbaric chamber. Another valuable function of the chamber is treatment of pressure-related diseases such as air embolism and decompression sickness. When an underwater diver or airplane pilot goes from an environment of high pressure to one of lower pressure, the air and gases inside the body begin to expand. If the transition is slow enough, the expanding gas is passed out of the lungs with no tissue damage. In rapid pressure changes, however, the trapped air expands in the tissue, causing bubbles to form. Bubbles may lodge in the joints, muscles, nervous system, lungs, or heart. The symptoms can range from pain, dizziness, joint stiffness, nausea, vomiting, and extreme fatigue to convulsions, visual and hearing abnormalities, speech difficulties, unconsciousness, and paralysis. The hyperbaric chamber returns the affected person to a high-pressure environment in which the bubbles are recompressed and allowed to be slowly assimilated back into the tissues. The gas then leaves the body through the respiratory tract as the pressure is slowly and gradually returned to normal.