EMS COMBINATION 850 Manual page 8

In addition, the penetration depth of these currents is poor and in part is limited
by the discomfort to the patient.
Interferential therapy overcomes the problem of skin impedance. At 50 Hz
(faradic current) the impedance for a 100 cm
ohms. At 4000 Hz (medium frequency) the skin impedance of the same area is
around 50 ohms. This means that a much lower voltage signal can be used to
produce the desired current, resulting in less skin sensation and a more
comfortable treatment. This medium frequency is, however, well outside of the
normal biological frequency range (0.1 to 250 Hz). In order to produce the
required stimulation, two medium frequencies are used. A constant frequency
of, say, 4000 Hz is applied to one pair of electrodes and a slightly different
frequency of say 3900 Hz is applied to the other pair. These two frequencies
'interfere'to produce an amplitude modulated medium frequency (beat
frequency) in the tissue. The tissue responds to the cyclic rise and fall in the
current intensity. It is the amplitude modulation frequency (AMF) that is within
the normal biological frequency range and not the medium frequency (carrier).
Combination Therapy
In general terms, combination therapy involves the simultaneous application of
ultrasound with an electrical stimulation therapy. In Europe, diadynamic
currents are frequently used, but in the UK, ultrasound is most often combined
with two-pole interferential therapy.
By combining ultrasound with interferential therapy, the advantages and effects
of each treatment modality can be realised - but lower intensities are used to
achieve the effect. The accommodation effects that normally accompany
interferential therapy are reduced (or even eliminated).
The main advantages of such a combination are said to be:-
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COMBINATION 850
in localising lesions (especially chronic) ie. diagnostic use.
in ensuring accurate localisation of ultrasound treatment to provide
increased accuracy / effectiveness in treating deeper lesions.
in treating trigger points.
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of skin is approximately 3000
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