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Datex-Ohmeda S/5 monitors
Document No. 800 1018-1
4
2.1.2
Response
Before each stimulation, the sequence offset, noise and threshold for the response detection is
measured. Offset is a baseline of the noise measurement. Noise is calculated by the same
algorithm as the response signal itself. The response detection threshold is calculated based on
the noise, and if the response is not greater than the threshold then it is interpreted as no response.
EMG
Mechano
Sensor
Measurement
EMG leads off
Timing control
A/D & P
µ
Figure 2
Principle of response measurement
EMG measurement
The EMG response is measured as integrated muscle activity. The EMG measurement starts 3 ms
after the stimulation and lasts 15 ms. The 3 ms delay helps to prevent the effect of stimulation
artifact.
Mechano sensor measurement
Response is measured as movement of the thumb, which is the area of positive signal.
2.1.3
Regional block
A regional block cable can be used as a nerve locator in local anesthesia. A maximum current of
5.0 mA is given every, every other or every 3rd second. The response measurement is ocular.
2.2
Main components
2.2.1
NMT board
The NMT Circuit Board consists of the following functional sections:
•
constant current stimulator
•
measuring electronics for the EMG signals
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