VENTILATION TUBE PERMITTING TWO-WAY GASEOUS COMMUNICATION WITH ONE-WAY LIQUID VALVE

摘要

A myringotomy tube allowing two-way gaseous communication between an external ear canal and a middle ear cavity and only one-way liquid communication from the middle ear cavity to the external ear canal includes a ball mounted within the tube to move freely into and out of contact with a valve seat for preventing liquid from flowing into the middle ear cavity. When fluid is present in the external ear canal, fluid pressure operates to move the ball into contact with the valve seat to provide a positive seal against ingress of fluid. In the absence of fluid within the external ear canal, the ball is free to move away from the seat to permit pressure equalization and liquid drainage from the middle ear to the outer ear. Longitudinal openings are provided in the portion of the tube within the external ear canal to facilitate free passage of fluid past the ball.