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CSM FAQ - CSM Unit

3.1 Q: Is it possible to place the sensors on either side of the head?
A: Yes, both left and right-sided set up can be used with the same good results. Use the side farthest from the surgical area in order to minimize artefacts.

3.2 Q: Shall the sensors be placed in exactly the same position every time?
A: The 2 sensors on the forehead shall be placed close to the normal hair-limit. The third sensor shall be placed on the mastoid bone behind the ear. The sensors should be positioned on bony surfaces in order to avoid movement artefacts. A deviation in the position of the sensors up to 2 cm has no significant influence on the index.

3.3 Q: Why do we place the neuro sensors on the frontal lobe and mastoid bone and not the temporal?
A: The CSM is based on Danmeter technology (Fuzzy Logic) originally implemented in the AEP/2 monitor, based on the extraction of mid-latency auditory evoked potentials. The AEP/2 monitor uses the frontal lobe and mastoid bone in order to capture auditory evoked potentials from the EEG.

3.4 Q: Is it necessary to prepare the skin before attaching the sensors?
A: Yes. It is important to clean the skin using a skin prep  product (i.e. 3M Skin Prep) before the sensors are positioned to remove dead skin cells and grease. This ensures better electrode impedance values.
Alcohol is not recommended as a skin cleanser; as it leaves a film layer that may cause high sensor impedance. If alcohol is used, allow 30 seconds drying time before using the skin prep product.

3.5 Q: Which type of sensor does the CSM use?
A: The CSM uses the Danmeter Neuro Sensor. These are high-quality self-adhesive wet-gelled Ag/AgCl sensors.

3.6 Q: Are the Danmeter Neuro Sensors LATEX free?
A: Yes.

3.7 Q: Is the CSM patient cable LATEX free?
A: Yes. The Cable is made of PVC.

3.8 Q: How should the sensor be attached to the skin?
A: Press the edges of the sensor, NEVER press centre of sensor.  


3.9 Q: What is a CSM Procedure Pack?
A: The CSM Procedure pack contains all you need to make your patient ready for CSM monitoring. It includes 3 Danmeter neuro sensors and a piece of skin prep.

3.10 Q: How many times can I use the sensors?
A: The Danmeter Neuro Sensors are single-use only.

3.11 Q: How long can the sensors be attached to the skin?
A: The Danmeter Neuro Sensor uses a gel, which is specially designed for long-term use, without causing skin irritations. Change sensors every 24 hours to check skin integrity.

3.12 Q: What is sensor impedance, and how does a “sensor impedance check system” work?
A: The sensor impedance is the resistance that the amplifier “sees” when it is connected to the sensors. If the skin is not cleaned properly the impedance will be high and in that case it will be more difficult for the EEG signal to be measured without distortion from external noise sources.
The impedance is measured automatically by the CSM every 60 seconds by applying a 110 Hz frequency, low intensity (0,01uA) current that facilitates the calculation of the impedance. If the impedance is above 5 kOhm, the display will show the impedances and flash to let the user know that a better connection is needed. CSI, BS and EMG readouts will be blanked (- - displayed).

3.13 Q: Can the CSM make impedance measurements on demand?
A: Yes, please see user manual.

3.14 Q:  Can the CSM sensor impedance measurements be turned off?
A: No, the sensor impedance measurement functionality is always on.

3.15 Q: Does the sensor impedance influence the SQI?
A: Yes, if the impedance of the white or black sensor exceeds 1kΩ, the SQI will fall gradually. Poor impedance conditions may cause the SQI to fall to 50%.
Low and equal sensor impedances are best for reducing the incoming noise.
Increasing electrode-to-skin impedance, and especially the different dimensions, results in proportionally higher sensitivity to noise and reduces the SQI, see table below for details.

The Green sensor is not critical due to being the reference.
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