24
Incorrect system hookup.
Loss of system power.
Corruption/loss of data over network due to unplugging the network cable or data interruption during data
transfer/hardware failure/ corrupt software.
Corruption of data due to external stimulus applied to the patient (e.g., magnetic s
timulation, electrical
stimulation or defibrillation, etc.)
System damaged from being dropped, aging or other mechanical damage.
Improper application of electrodes may prevent or interfere with data acquisition.
Always use the largest surface electrodes possible for the patient ground electrode to reduce environmental
noise.
Additional Information - Electrical Stimulator
The stimulator probe can deliver electrical output of up to 400 V or 100 mA. This device is intended for use only by or on the order
of a licensed medical practitioner.
For initial electrical stimulation, set the electrical intensity (current or voltage) at a low level. Slowly increase the intensity to the
desired level of stimulation to prevent patient discomfort.
The output waveform of the Natus Electrical stimulator is AC coupled through a transformer. Therefore, there is no DC component.
The pulse durations can range from 10uS to 1000uS, the repetition frequencies range from 0.1Hz to 200Hz.
The maximum amplitude of the Natus electrical stimulator, in the constant voltage mode, is 400V (not supported by all Natus
equipment). The maximum amplitude, in the constant current mode, is 100mA. Both maxi mums are with respect to a 4K ohm load.
As the load impedance is increased, the current will drop off according to the equation I = 400V/R. As the load impedance is
decreased below 3.2K ohm, the voltage will drop off according to the equation V = 125mA x R.
The maximum energy output of the electrical stimulator into a 1Kohm load is (180mA)2 x 1Kohm x 1mS = 32.4mJ.
Stimulation Pulse Terminology
The term “pulse duration” or “pulse width” refers to the length of time from point A to point B. The “pulse amplitude” refers to
the output level reference from points C and D with the rated load. See Figure 1.
Figure 1
Maximum constant current, as listed in the product specifications, will not be achievable with load impedances greater than
the 4k ohm rated load.
