injuries and poisoning
Barotrauma
Introduction
Barotrauma is tissue injury caused by a change in pressure, which compresses or expands gas contained in various body structures. The lungs, gastrointestinal tract, part of the face covered by a face mask, eyes, ears, or sinuses can be affected. Symptoms vary and may include breathing problems or chest pain ( Pulmonary (lung) barotrauma ), bloodshot eyes ( Risk of barotrauma is greatest from the surface to 33 feet (10 meters). Measures that can help prevent barotrauma include ascending slowly and breathing during ascent (pulmonary barotrauma), blowing out air from the nose into the face mask (mask barotrauma), and yawning or swallowing with the nostrils pinched and taking a nasal decongestant before diving (sinus and ear barotrauma). (See also Overview of Diving Injuries .) Increased pressure outside the body is transmitted equally throughout the blood and body tissues, which do not compress because they are composed mainly of liquid. Thus, the legs, for example, do not feel squeezed as water pressure increases. However, gases (such as the air inside the lungs, sinuses, or middle ears or inside a face mask or goggles) compress or expand as outside pressure increases or decreases. This compression and expansion can cause pain and damage to tissue. Barotrauma most often affects the ears. However, barotrauma affecting the lungs (pulmonary barotrauma) is the most serious. Risk of barotrauma is increased by conditions that can keep air from freely flowing between spaces, such as sinus congestion or blockage of an eustachian tube (a small passageway that connects the middle ear with the back of the nose). 