Section 4-Test Results; Ear Canal Volume; Compliance Peak - Welch Allyn TM262 Auto Tymp Service Manual

Section 4—Test Results

4.1 EAR CANAL VOLUME

NORMAL
As a general rule, values for ear canal volume should be between 0.2
3
and 2.0 cm . However, the normal values will vary with age and bone
structure. With use, you will develop a feel for the appropriate values.
ABNORMAL
An ear canal value of less than 0.2 cm
If the probe is partially plugged with cerumen or if the probe is position-
ed against the ear canal wall, a smaller-than-expected value will be
measured. If an individual has a relatively large bone structure for his/
her age, and a smaller-than-expected value is measured, the probe
could be partially occluded or up against the canal wall. It is also pos-
sible to collapse the canal if the probe is held too firmly against it. Exam-
ine the tympanogram and the reflex results to confirm your suspicions.
If they are abnormal, it is good practice to repeat the test.
An ear canal volume greater than 2.0 cm
mal condition. An important application of the ear canal volume mea-
surement is to determine if there is a perforation of the tympanic mem-
brane. If there is a perforation due to trauma or due to the presence of a
pressure-equalization (P-E) tube, the measured ear canal volume will be
much larger than normal since the TM 262
the combined volume of the ear canal and the middle-ear space.

4.2 COMPLIANCE PEAK

NORMAL
The range of normal compliance (admittance) is 0.2 cm
3
mately 1.4 cm
3
1.8 cm . A measured compliance peak within this range indicates
normal mobility within the middle ear system.
ABNORMAL
A compliance (admittance) value of less than 0.2 cm
pathological condition as the middle ear system is stiffer than normal.
To distinguish the probable cause of the stiffening, the pressure value
where this stiffened compliance peak occurs needs to be considered.
For example, normal pressure along with a stiff middle-ear system is
indicative of a "glue-ear", otosclerosis, a severely scarred tympanic
membrane or a layer of plaque across the tympanic membrane. On
the other hand, abnormal pressure along with a stiffened middle-ear
system is consistent with a poorly functioning eustachian tube with
possible effusion (serous otitis media).
. Some groups site a larger range of normal, up to
3
indicates an abnormal condition.
3
also may indicate an abnor-
TM Auto Tymp
3
TM is measuring
3
to approxi-
indicates a
39