Chapter 128 - Tympanotomy tubes

Summary

The placement of tympanotomy or pressure equalization tubes is the most common minor ambulatory procedure performed in the USA. Most often done in children, it is also needed in some adults. In appropriately selected patients the procedure can be straightforward and extremely beneficial, but these patients should be monitored to identify complications.

The normal middle ear is an air-filled space which functions to transmit sound from the outside world to the inner ear (Figure 128.1). Basic functions of its mucosal lining are the production of a small amount of mucus and the absorption of air from the middle ear space. In a physiologically normal state, the Eustachian tube functions to open with swallowing and yawning to allow for adequate ventilation and mucociliary clearance of the middle air space. About 1 mL per 24 hours is the usual amount of air which must be transported through each Eustachian tube to maintain near-atmospheric pressure in the middle ear.

It follows then that any disruption of the normal function of the Eustachian tube can offset the pressure balance within the middle ear and create problems. Abnormal sub-atmospheric middle ear pressure occurs if there is failure of the Eustachian tube to transmit sufficient air; if there is undue loss of air from the middle ear through the Eustachian tube during sniffing; or if there is a special circumstantial need (e.g., descent portion of aircraft travel, descent in a submarine, diving, or during hyperbaric therapy) for greatly increased gas transport through the Eustachian tube. Such abnormal sub-atmospheric middle ear pressure may lead to otitis media, and can create scarring or negatively affect hearing. When the Eustachian tube is dysfunctional, placement of a trans-tympanic tube serves to restore adequate drainage and ventilation of themiddle ear space.