Barotrauma

Barotrauma is damage to the middle ear caused by unequal air pressure on the two sides of the eardrum.

The eardrum separates the ear canal and the middle ear. If air pressure in the ear canal from outside air and air pressure in the middle ear are unequal, the eardrum can be damaged. Normally, the eustachian tube, which connects the middle ear and the back of the nose, helps maintain equal pressure on both sides of the eardrum by allowing outside air to enter the middle ear. When outside air pressure changes suddenly--for example, during the ascent or descent of an airplane or a deep-sea dive (see Section 24, Chapter 295)--air must move through the eustachian tube to equalize the pressure in the middle ear.

See the figure The Eustachian Tube: Keeping Air Pressure Equal.

If the eustachian tube is partly or completely blocked because of scarring, a tumor, an infection, the common cold, or an allergy, air cannot move in and out of the middle ear. The resulting pressure difference may bruise the eardrum or even cause it to rupture and bleed. If the pressure difference is very great, the oval window (the entrance into the inner ear from the middle ear) may rupture, allowing fluid from the inner ear to leak into the middle ear. Hearing loss or vertigo occurring during descent in a deep-sea dive suggests that such leakage is taking place. The same symptoms occurring during ascent suggest that an air bubble has formed in the inner ear.

When sudden changes in pressure cause a sense of fullness or pain in the ear, often the pressure in the middle ear can be equalized and the discomfort relieved by several maneuvers. If outside pressure is decreasing, as in a plane climbing upward, the person should try breathing with the mouth open, chewing gum, or swallowing. Any of these measures may open the eustachian tube and allow air out of the middle ear. If outside pressure is increasing, as in a plane descending or a diver going deeper underwater, the person should pinch his nose shut, hold the mouth closed, and try to blow gently out through the nose. This will force air through the blocked eustachian tube. People who have an infection or an allergy affecting the nose and throat may experience discomfort when they fly in a plane or dive. However, if flying is necessary, a decongestant, such as phenylephrine nose drops or nasal spray, relieves congestion and helps open the eustachian tubes, equalizing pressure on the eardrums. Diving should be avoided until the infection or allergy is controlled.