Tympanostomy tube 
(重定向自T tube)
      
 
A tympanostomy tube (also known as a grommet, T-tube, ear tube, pressure equalization tube, vent, PE tube or myringotomy tube) is a small tube inserted into the eardrum in order to keep the middle ear aerated for a prolonged period of time, and to prevent the accumulation of fluid in the middle ear.  The operation to insert the tube involves a myringotomy and is performed under local or general anesthesia. The tube itself is made in a variety of designs.  The most commonly used type is shaped like a grommet.  When it is necessary to keep the middle ear ventilated for a very long period, a "T"-shaped tube may be used, as these "T-tubes" can stay in place for 2-4 years.  Materials used to construct the tube are most often plastics such as silicone or Teflon.  Stainless steel tubes exist, but are no longer in frequent use.