Unequal Pressures

Barotrauma (or 'squeeze') is the inability to equalize pressures within body cavities as a result of unequal pressures due to diving and increased eternal pressure. The most common example of barotraumas is not being able to equalize ear pressure, and is experienced on airplanes as well as while diving. Other areas, which experience barotraumas, are the sinuses, lungs, gut, and any other cavities susceptible to compression. Descent must be stopped if any pain is felt as further descent could lead to rupture of the eardrums, or other compressible cavity.

Air embolisms are also a problem resulting from unequal pressures, and are considered the most serious of diving accidents. Air embolisms occur when a diver holds his breath while ascending to the surface. Boyle's law states that a gas will expand during the lungs as the pressure decreases when a diver returns to the surface. If a diver doesn?t expel air from his lungs while ascending or fails to breath regularly through the regulator the volume of the lungs can expand to more the twice their volume and ultimately explode. The air from the lungs can do one of three things:
1.Air may push through the lung tissues and enter the skin about the neck
2.Air may push through the lung tissues and into the spaces between the lungs and cause a pneaumothorax
3.Air embolism may also result when air from the lung is forced into the blood vessels