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EN109-1498740-40 IFU
One of the first to investigate the combined application of acupuncture and electrical stimulation was
professor Han. He investigated the best settings to use for maximum production of the two central
opioid peptides that are associated with pain relief. His method is called
Han stimulation
.
Low Frequency stimulation at 2 Hz accelerates the release of enkephalin, whereas High Frequency
stimulation at 100 Hz selectively accelerates the release of dynorphin. The combination of these two
frequencies produces a simultaneous activation of the enkephalin and dynorphin systems, resulting
in a more effective therapy than stimulation at either one or the other frequency. The alternating
stimulation of the two systems induces a much more analgesic effect than that induced by a constant
frequency stimulation.
NMES
The main objective of NMES is to improve muscle strength in patients suffering from disuse atrophy
and in healthy individuals. The mechanism of NMES relates primarily to muscle fiber type and
stimulation frequency, though there are almost certainly other parameters that have an influence (e.g.
waveform, stimulation pattern, electrodes). Therefore, practitioners need to set the electrical
stimulation parameters prior to therapy.
The stimulation parameters, affecting muscle and nerve response, include:
•
current waveform
•
amplitude (stimulation intensity)
•
current output CC
•
pulse duration
•
pulse frequency
•
duty cycle (ON:OFF ratio)
•
ramp times (up / down)
•
electrical stimulation mode
•
duration and frequency of treatment
•
electrodes (type, size, and electrode placement)
Current waveforms
Biphasic current wave forms seem to be the most effective.
Some researchers have published evidence which supports the asymmetric over the symmetric
waveform because the asymmetric current produced more force output. However, force of
contraction is not only depending on the shape of the stimulating waveform: it is also determined by
the amplitude, frequency and duration of the pulse. To produce a contraction of a designated
intensity, it should be remembered that
the shorter the pulse duration, the greater the pulse amplitude
needed
(this is demonstrated in so-called Strength-Duration curve).
The therapist should adjust the waveform to produce a satisfactory contraction in as comfortable a
fashion as possible. Although it is not clear from the literature which waveforms are most acceptable,
patient preference must also be kept in mind when selecting an NMES current wave form.
Amplitude (stimulation intensity)
This is best used on a subjective rather than an objective basis. The most commonly used method to
achieve this is to gradually increase the stimulation intensity (with the patient making no contribution)
until a significant contraction is achieved with the machine alone. Once this level is established, the
patient is instructed to 'join in' with the stimulation patterns, which is straightforward if a patterned /
ramped stimulation is employed.
Setting current amplitude in NMES is critical because of
the physiologic correlation between the current
amplitude and spatial motor unit (MU) activation
, The higher the current amplitude used, the greater
