Limiting Noise - Equipment Setup - Interacoustics Eclipse Additional Information

Eclipse Additional Information
5. Always disconnect any powering of the patient bed during ABR test. It will cause more noise. We
have several cases where the noise was more than halved after the patient bed was disconnected to
power. A bed with a battery can cause noise even when the bed is not plugged into the wall, and
should be replaced with a bed without a battery.
6. Try to move the test site within the room; patient might be close to a power cord etc. perhaps hidden
in the wall close to patient and electrodes.
7. Position patient/child with head towards center of the room, not the wall, especially if there is a power
source at the head of the bed.
8. Request a quiet room, preferably away from roads, rooms containing power supplies/fuse boards.
9. Do not position equipment near mains sockets.
10. The test room should be placed away from devices causing electrical interference (e.g. autoclaves,
microwave ovens, mobile phones, hospital pager systems, lifts, escalators, air conditioning systems,
etc.).
11. Light and other electrical equipment not being used should be turned off as the patient will work as
an antenna and pick up electrical interferences.
12. Remember to turn off all other electrical equipment not used in the room, especially sources with
neon lights.
13. Do not use light dimming switches (a notorious source of interference).
14. Electrical interference may also appear through the ground lead if this is interconnected to many
computers, autoclaves, instruments using high power etc.
15. Unplug any non-essential networked computers in the room, remembering to remove the network
cable from the data socket located on the wall. Make the patient lay down to reduce interference
from neck muscle contractions.
16. For babies be prepared to suggest alternative positions, e.g. for the baby to be placed in a car seat,
rather than being held by a parent.
17. In some cases, it may be necessary to find another test location if there is too much ambient acousti-
cal or electrical noise.
Operating rooms
1. Operating rooms are usually acoustically noisy. Insert earphones help attenuate ambient acoustic
noise and are safer in post-myringotomy cases where blood could make an electrical connection be-
tween the patient and the transducer, but the transducer should be held (with a drip stand) at a
higher level than the tip to avoid blood entering the transducer under gravity.
2. Pulse oximeters are sometimes the source of electrical interference. Try turning it off to see if this
eliminates the interference (if so, then negotiate with the anaesthetist to do without if possible). If an
oximeter is used, position as far away from patient and equipment as possible (at patient's feet end).
Even if the oximeter is run on battery it may create interference.
3. Sedation pumps (mostly running on batteries) should at any time be positioned as far as possible
away from the patient electrodes.
4. If many types of equipment are connected to the patient, use the same power outlet to minimize the
small current leakage through patient.

2.2.3 Limiting noise - Equipment setup

1. Always check the wall outlet for a proper ground when establishing an ABR test room. Sometimes
the ground lead is found inside the wall outlet, but is not connected to ground.
2. Carry out listening check if no responses are seen or unusual waveforms are recorded.
3. Odd-looking responses can be recorded if the electrode leads are incorrectly connected (response
may be inverted) and a flat-line is likely if we inadvertently record across the mastoids.
4. If interference occurs try running the laptop on battery, disconnected from its power supply and with
the power supply unplugged (check battery charge is adequate to complete the test).
5. Do not cross over any leads or cabling, especially electrode, transducer, and power supply leads.
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