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Hearing Screening Systems (Technical Manual)
40
5.8. Patient Preparation for ABR Test
To start operation on
Neuro-Audio-Screen
screening system one should study and
master ABR technique. It is especially important for the testing of newborns and
babies.
The quality of ABR test performing depends on many factors. Apart the device
functioning, the main factors to get the reliable and correct test results are the
preparation quality and patient’s condition. It is better to test a patient when she/he
sleeps. The newborn is recommended to be tested in between the feedings, when a
baby unlikely wants to suck or perform other artifacts connected with the muscle
activity. It is better to place the electrodes in a way described in this section below
before a newborn falls asleep. Though the testing by ABR technique is not so much
sensitive to the acoustic noise in comparison with OAE, however, it is desirable to
make no noise during the test performing. It is strongly recommended to perform the
testing at the disconnected external power supply of the device and away from the
electromagnetic noise sources such as the electric wiring and the electrical
appliances.
The places for the electrodes setting should be degreased and treated by the
electrode abrasive paste for skin preparation to decrease the skin impedance. The
paste remnants can be washed by the alcohol, and the skin should be dried. In case
the reusable cup electrodes are used, the cups should be filled with adhesive paste
before the placement. The electrodes can be fastened by the adhesive plaster to
provide the better fixation.
The electrodes should be placed in a following way: the red one (noninverting) is on
the forehead, the black one (inverting) is on the mastoid near the ipsilateral ear
(where the stimulus is delivered), green one (ground) is on the mastoid near the con-
tralateral ear. It is admissible to place the ear electrodes not only on the mastoid but
other places such as earlobe or ear canal. The example for the left ear is given of the
Fig. 20.
Fig. 20. The schematic of the electrodes placement at ABR registration (electrodes arrangement for the
left ear testing).