Enraf Nonius 1498.901, Инструкция по эксплуатации

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Page 43 of 72 EN109-1498751-47 IFU
Dipole vector manual
With the dipole vector technique, the currents from the two electrode pairs are vectorially summed in
the tissue. The effect is that stimulation only occurs into the direction of the resulting vector, which
can be adjusted over a range of 360º. Amplitude modulation occurs in the equipment and the
modulation depth is 100%.
F
IGURE
4
Stimulation with 100% modulation depth only occurs into the direction of
the vector.
The advantage of this method is that the direction of the stimulation can be adjusted electronically
after positioning the electrodes.
Dipole vector automatic
With the automatic dipole technique, the dipole vector described above is rotated at an adjustable
speed. If the current amplitude is increased exceeding the motorial threshold, the tissue will contract
and relax rhythmically. The automatic dipole vector current is ideally suited for areas where
mechanical pressure (massage) is not desirable.
Parameters:
•
Carrier frequency , expressed in kHz, is the base frequency of the alternating current.
•
Beat frequency , expressed in Hz, defines the channel frequency difference in classical
interferential mode and the rate at which the amplitude is internally modulated in the vector
modes.
•
Frequency modulation , expressed in Hz, defines a variable frequency range that is summed to
the Beat frequency i.e. when the Beat frequency is set to 80 Hz and the Frequency modulation is
set to 40 Hz, the final frequency will vary from 80
– 120 Hz.
Frequency modulation is often used to prevent accommodation to stimulation or to improve
patient tolerance.
• Modulation program defines the time and sequence in which the frequency will sweep through
the Frequency modulation range (figure 26-28).
• Balance defines the difference in current amplitude between the two channels. Only available in
classical interferential mode.
• Vector position adjustment defines the angle of the dipole vector with respect to the position of
the electrodes.
•
Rotation speed , expressed in seconds, defines the time elapsed during one revolution of the
vector in automatic dipole vector mode.
Biphasic pulsed currents (TENS)
Asymmetrical and alternating asymmetrical
The asymmetrical biphasic pulsed current waveform is often used in TENS (Transcutaneous Electrical
Nerve Stimulation) applications. This waveform is characterized by variable phase duration and
variable pulse frequency. Its typical amplitude, duration, and rate of rise and decay are unequal for
each phase with respect to the baseline. The waveform is fully balanced, i.e. the phase charges of each
phase are equal. See figure 6 for a graphical representation.