Appendix A
A-33
Patent Tympanostomy Tube or Perforated Tympanic Membrane
In the case of a tympanic membrane perforation or a patent tympanostomy
tube, the air pressure produced by the MicroTymp2 Handle escapes through
the perforation or tube so that a pressure differential across the eardrum
does not occur. Because the air pressure changes have no effect on the
tension of the eardrum, the tympanogram is flat with an unusually high
equivalent ear canal volume. If the volume exceeds 2.5 cc, the MicroTymp2
Handle will not record a tympanogram at all, and the OPEN message will
appear. See Figure 28.
Flat Tympanogram Persistent OPEN
with too High Volume Message (can’t seal ear)
Figure 28
The Normal Ear
An example of a tympanogram from a normal ear is depicted in Figure 29.
Figure 29
-400 -200 0 200
2
0.5
0
1.0
1
GR
A
GR
C
PRESSURE - daPa
Ya - mmho
+200 Vea - cc
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