Information on Barotrauma
Barotrauma is physical damage to body tissues caused by a difference in pressure between an air space inside or beside the body and the surrounding gas or liquid. Barotrauma typically occurs to air spaces within a body when that body moves to or from a higher pressure environment, such as when a SCUBA diver, a free-diving diver or an airplane passenger ascends or descends. Boyle’s law defines the relationship between the volume of the air space and the ambient pressure. Damage occurs in the tissues around the body’s air spaces because gases are compressible and the tissues are not. During increases in ambient pressure, the internal air space provides the surrounding tissues with little support to resist the higher external pressure.
Barotrauma can manifest as a pneumothorax, with a tension pneumothorax being the most feared complication in mechanically ventilated patients. The continuous application of positive-pressure ventilation serves to perpetuate the passage of air into the extra-alveolar space, eventually causing a tension pneumothorax if untreated. In these patients, bedside detection of a pneumothorax can be difficult because of the noise from the equipment usually needed for mechanical ventilation. Decreased breath sounds on the side of the pneumothorax is an initial finding. After tension develops, accumulating air displaces the mediastinum and associated structures away from the pneumothorax (contralateral). This process includes contralateral displacement of the trachea.
Symptoms of barotrauma include “clogging” of the ear, ear pain, hearing loss, dizziness, ringing of the ear (tinnitus), and hemorrhage from the ear. Dizziness (or vertigo) may also occur during diving from a phenomenon known as alternobaric vertigo. It is caused by a difference in pressure between the two middle ear spaces, which stimulates the vestibular (balance) end organs asymmetrically, thus resulting in vertigo. The alternobaric response can also be elicited by forcefully equalizing the middle ear pressure Politzer maneuver, which can cause an unequal inflation of the middle ear space.
The air pressure in the middle ear is usually the same as the air pressure outside of the body. The eustachian tube is a connection between the middle ear and the back of the nose and upper throat. If the eustachian tube is blocked, the air pressure in the middle ear is different than the pressure on the outside of the eardrum, causing barotrauma. Many people experience barotrauma at some time. Barotrauma commonly occurs with altitude changes, such as with flying, scuba diving, or driving in the mountains. If you have a congested nose from allergies, colds, or upper respiratory infection, barotrauma is more likely. Blockage of the eustachian tube could also be congenital (present before birth), or may occur because of swelling in the throat.
The most common example of barotrauma occurs to some air travellers. As a plane descends to land, the air pressure becomes higher nearer the ground. This pushes the eardrum inwards. If the pressure inside the middle ear is not equalised quickly, then you can get ear pain. Other situations where air pressure may quickly rise outside the ear is during scuba diving, diving to the bottom of a swimming pool, or rapidly descending in a lift (elevator).
Ear barotrauma is caused when the eustachian tube gets blocked and your body is not able to equalize the air pressure inside and outside the eardrum. Ear barotrauma is usually not severe or dangerous and is easily treatable, but occasionally there are complications such as loss of hearing, ear infection, dizziness, or a perforated (punctured) eardrum.
