OMNISTIM
®
500A USER MANUAL
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CONFIDENTIAL AND PROPRIETARY
STIMULATION THERAPY MODES
Interferential Current Therapy (IFC)
The new Webster Encyclopedia Dictionary of the English Language defines interference as “the mutual action of
waves of any kind (water, sound, heat or light) upon each other, by which the vibrations and their effects are
increased, diminished or neutralized.”
As such, interferential current (IFC) therapy requires at least two signal sources, which “interfere” within the tissue
to be treated. The resulting interference of the generators generates therapeutically useful stimulation of the area
undergoing treatment. Interferential current therapy technique relies on amplitude differences between two or more
isolated independent signals to produce fields of higher or lower intensity within the tissue.
The purpose of interferential current therapy is to provide deep tissue treatment, which is not generally obtainable
with conventional electrotherapy approaches. Its primary application is in the reduction of pain and in the
stimulation of increased blood flow in the deeper tissues and muscles.
1. Frequency Difference (FD) Technique
Dr. Hans Nemec, an Austrian physician, first introduced the concept of frequency difference interferential current
therapy to the medical community in the late forties. The original U.S. patent (2,622,601) for the technique was filed
on October 27, 1948 and granted on December 23, 1952. It has since expired and many manufacturers worldwide
produce interferential current therapy devices according to Dr. Nemec’s original method.
Simply stated, electric currents with frequencies in the range of 1000-10,000 Hz, known as medium frequency
currents, are run through the tissue to be treated. These frequencies inhibit nerve conduction based on the fact that
they cause temporary nerve membrane depolarization while present. This effect is known as Wedensky Inhibition.
Medium frequency currents have an inhibitory effect on pain transmission and sensation within the field of
treatment. This effect is responsible for the decreased sensation under the stimulation electrodes. Medium
frequencies are also selected due to their excellent tissue penetration. This occurs as a result of the decreased tissue
resistance at higher frequencies.
If the frequencies of the two generators are not the same, then a beat frequency (which is the difference between the
two signal frequencies) is produced at right angles to the plane of the four stimulation electrodes. This beat
frequency modulates the medium frequency current to produce a burst medium frequency within the tissues.
The effects of frequency difference interferential current therapy may be described as follows:
a. Stimulation of deep tissue only with two fields.
b. Produces surface Nerve Block via Wedensky Inhibition (helpful in acute pain treatment).
2. Vector Technique
In order to move the position of the deep interferential fields, researchers developed systems to alter the relative
amplitudes between stimulation channels in interferential stimulators. This alteration of relative amplitude changes
the phase relationships and the position of the summated field in the tissue.
Advantages of Dynamic Vector:
1.
When the patient expresses a poor pain location
and cannot indicate whether or not the therapy
feels the strongest at the subjectively perceived
location of the problem.
2.
When the target tissue area is extremely large.
3.
When you wish to increase the amount of current
density in the tissues to obtain a higher
therapeutic dosage.
4.
When your electrode placement sites are less than
optimal.
