As a durable medical equipment (DME) provider you no doubt already know about the therapeutic benefits and the market demands for electrical therapy devices. You may even be aware of the various devices on the market and what purpose each serves. But do you know how each device works and why?

Understanding the science behind the specific functions of each type of electro therapy device will help you to choose the best solution for your patients, which will improve the end user’s experience, which will in turn lead to customer satisfaction, referrals and more sales.

So here we go, one by one:

TENS

T.E.N.S.  is an abbreviation for Transcutaneous Electrical Nerve Stimulation. Transcutaneous (trans-kyoo-tey-nee-uhs) means “through, or by way of the skin.” TENS sends electrical impulses via electrodes or conductive garments to occupy the nerve pathways with a more comfortable sensation which overrides the pain. More specifically, according to Wikipedia, the high and low frequencies of TENS activate receptors in the spinal cord and the medulla. Further, high frequency TENS reduces excitation of central neurons that transmit nociceptive (pain) information, reduces the release of excitatory neurotransmitters and increases the release of inhibitory neurotransmitters (GABA) in the spinal cord, and activates the main “end” receptors centrally resulting in the blockage of pain. Low frequency TENS also releases serotonin and activates serotonin receptors in the spinal cord, releases GABA, and activates the main end receptors to reduce excitability of nociceptive neurons in the spinal cord.

EMS

E.M.S. is an abbreviation for Electrical Muscle Stimulation. Whereas TENS targets the nerves and is primarily for pain relief, EMS is more for aid in healing via direct muscle stimulation. It sends electric impulses to elicit muscle contraction and relaxation by mimicking signals normally coming from the central nervous system. Studies have shown EMS to be beneficial for the prevention of muscle edema and atrophy by increasing blood circulation. Positive results have also been shown for the adaptation (training) of skeletal muscle fibers, help in relaxing muscle spasms, maintaining or increasing range of motion or joint mobility, prevention of venous thrombosis (blood clots due to inactivity) immediately following surgery and for general muscle strengthening and toning.

IF

I.F. stands for Interferential. It crosses two slightly different, medium-frequency alternating currents to create a third, much stronger and deeper sub frequency current ideal for deep tissue stimulation. It has both healing and pain relief benefits. Its unique current is able to pass through skin, fat and bone—which are poor conductors of current flow—to target the fluid inside the cells of the damaged area. It changes the fluid in such a way that excess sodium ions are able to cross the cell’s plasma membrane and be actively transported out of the cell by activating the Na/K+ pump which then controls the concentration of sodium and potassium ion within the fluid that surrounds the cells. This occurrence forces displaced fluid to exit the swollen cell which eliminates edema. Inflammation is also reduced as the blood proteins that were trapped in the extra-cellular fluid are removed when the sodium imbalance is corrected and oxygen flow increases to the cell. Oxygen removes bradykin (a blood flow restrictor) and histamines (a chemical substance involved in edema and inflammation) thus speeding the cell’s recovery. Oxygen also removes prostaglandin—a natural pain substance of the body. To obtain IF frequency, electrode placement should be in an “X” pattern, with the point of intersection located directly over the affected tissue area.

HVPG

H.V.P.G. is an abbreviation for High-Voltage Pulsed Galvanic Current. Galvanic is another word for direct current (DC). Unlike low-voltage, alternating current (AC) that is found in TENS, EMS and IF, galvanic is best suited for major tissue trauma including bleeding and swelling. It quickly increases blood circulation while reducing edema. Like TENS, it stimulates the nerves, which aids pain relief. It also helps relax muscle spasms and is ideal for diabetic-induced neuropathy. It is unique in its application using a large dispersive pad which is placed in a neutral area on the body to ground the current while smaller “active” pads are placed over treatment area.