Welch Allyn TM286 Auto Tymp - User Manual - Manual (Page 57)

Directions for Use Test Results 53
gradient values may also be found in the absence of abnormal parameters. This could
indicate a transient OME, so a retest after several weeks may be recommended.
When the middle ear's mobility is reduced to near 0 cm3, due to viscous effusion or a
"glue-ear" condition, no gradient value can be measured. In this case, dashes (- - -) will be
displayed next to the letters GR.
Very low gradient values are associated with a flaccid middle ear system. These low
values should be taken into consideration with the ear canal volume and compliance peak
values to determine the probable use of the flaccid condition.
Acoustic reflex
Normal
For screening purposes, an ipsilateral reflex measured at any one of the levels available
per frequency can be considered normal. Obviously, the lowest values are desired.
However, without knowing the hearing threshold level of the individual per frequency, it is
difficult to make a more definite statement. Generally speaking, the reflex is reported to
occur at between 70 and 90 dB HL above the hearing threshold in patients with normal
hearing. Remember that these values apply to reflex threshold measurements and that
this instrument does not permit reflex threshold measurements due to the use of a hand-
held probe. The presence of a reflex in the absence of a compliance peak suggests that
the tympanometric results should be considered invalid and the test repeated. This is true
because if there is no compliance measured during tympanometry, it is not possible to
measure any stiffening affect during the reflex stimulus presentation.
Abnormal
If a pressure leak occurs during the reflex testing and the pressure system is unable to
correct for this leak, the reflex test sequence is aborted. When this occurs, the test
results are assigned the letters NT (Not Tested).
If no response is obtained at the third and final stimulus level, the instrument will indicate
this with the letters NR or No. More detailed testing at the frequency where this occurred
is required to determine the reason for the no response.
Audiometry
Normal
A normal response from a child should be at or below 20 dB HL. A normal response from
an adult is at or below 25 dB HL. Remember that these normal values assume a quiet
environment during testing.
Abnormal
In children, a failure to respond to a 20 dB HL (or lower) stimulus presentation during a
retest performed four to six weeks after the initial test would indicate the need for more
extensive diagnostic testing to determine the cause.
In adults, a failure to respond at or below 25 dB HL when the room noise levels are low
indicates the need for more evaluation. However, the age and employment history of the
individual must also be considered.