Welch Allyn MicroTymp User Manual

Conditions that artificial/y flatten the tympanogram.
In order to measure the mechanical properties of the middle ear,
the MicroTymp must be capable of changing the pressure differential
across the eardrum. Two conditions can prevent this from happening
and artificially flatten the tympanogram:
1. Ear canal occlusion: If the ear canal is occluded by impacted
cerumen, foreign body, tumor, stenosis, or atresia, the volume of
air in front of the probe will be very small. This small volume may
be manifest in two ways with the Welch
Allyn MicroTymp:
l The BLOCK ( zlz) symbol may be displayed, indicating that the
equivalent volume in front of the probe is less than 0.2 cc
l A flat tympanogram may occur with a small equivalent volume
( < .4cc for children or < .6cc for adults)
2. Tympanic membrane perforation or patent tympanostomy
tube:
In these cases the air pressure produced by the MicroTymp
escapes through the perforation or tube so that a pressure dif-
ference across the eardrum does not occur. Because the air
pressure changes have no effect on the tension of the eardrum, the
tympanogram is flat. In cases in which the middle ear mucosa is
relatively normal, the flat tympanogram will be accompanied by a
large equivalent volume ( > 1.5 cc for adults and 1.0 cc for
preschool-aged children). Many patients with tympanic membrane
perforations have a flat tympanogram but do not show a large
equivalent volume due to inflammation of the middle ear.
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Welch Allyn MicroTymp Specifications

General

Measurement Method	Infrared
Battery Life	Approximately 1000 measurements
Type	Tympanic (ear) thermometer
Display	LCD
Measurement	Body temperature
Memory	Last reading memory
Battery Type	2 AAA batteries