Otic Barotrauma

To maintain equal pressure on both sides of the tympanic membrane, gas must move freely between the nasopharynx and middle ear. When an upper respiratory infection, allergy, or other mechanism interferes with eustachian tube function during changes in environmental pressure, the pressure in the middle ear either falls below ambient pressure, causing retraction of the tympanic membrane, or rises above it, causing bulging. With negative middle ear pressure, a transudate of fluid may form in the middle ear. As the pressure differential increases, ecchymosis and subepithelial hematoma may develop in the mucous membrane of the middle ear and the tympanic membrane. A very large pressure differential may cause bleeding into the middle ear, tympanic membrane rupture, and the development of a perilymph fistula through the oval or round window of the inner ear.

Symptoms of otic barotrauma are severe pain, conductive hearing loss, and, if there is a perilymph fistula, sensorineural hearing loss and/or vertigo. Symptoms usually worsen during a rapid increase in external environmental pressure, such as a rapid ascent (eg, during scuba diving) or descent (eg, during air travel or sky diving). Sensorineural hearing loss or vertigo during descent suggests the development of a perilymph fistula; the same symptoms during ascent from a deep-sea dive can suggest an air bubble formation in the inner ear.

If patients have eustachian tube dysfunction are treated with hyperbaric oxygen and experience similar symptoms during their first hyperbaric treatment, they require placement of tympanostomy tubes. Tube placement is also reasonable for patients with ear pressure after their first hyperbaric dive; such patients may have occult eustachian tube dysfunction or dysfunction only in certain situations (eg, only during hyperbaric treatment but not during an airplane flight). Tubes should be placed prophylactically for patients who have known eustachian tube dysfunction.