Physical Therapy Equipment: Interferential Current (IFC)
Interferential current (IFC) therapy is a therapeutic modality that is used often in an orthopedic physical therapy setting. The following article serves as a brief introduction to the modality and it's uses.
A piece of equipment commonly used by physical therapists is the interferential current machine. This machine produces electrical currents (~4000HZ) that pass through the affected area of the patient. The current tends to penetrate deeper than other electrical modalities and has a number of physiological effects that have therapeutic value.
The physiological effects of IFC
The physiological effects include:
1. an increase in localized blood flow which can improve healing by reducing swelling (the additional blood flowing through the area takes edematous fluid away with it) and as a result helps remove damaged tissue and bring nutrients necessary for healing to the injured area
2. the stimulation of local nerve cells that can have a pain reducing/anaesthetic effect due to potentially blocking the transmission of the pain signals (pain gate mechanism) or by stimulating the release of pain reducing endorphins (opiod mechanism)
3. some degree of muscle stimulation as muscle contraction can be achieved through external application of an electrical current, overcoming some of the muscle inhibition often caused by local injury and swelling
The electrical current is applied to the affected area using four electrodes. The four electrodes are placed in such a way that the two currents produced cross each other in the affected area. For example, if it is a knee injury that is being treated, the two currents can be applied so that they cross deep within the actual knee joint itself. Where the two currents meet, they actually 'interfere' with each other; hence the name 'interferential.'
Should the Patient Feel Interferential Current?
The patient should not feel any discomfort from the application of the interferential current. The electrodes will usually be used with a damp sponge placed between the electrode and the patient's skin. If discomfort is felt it is usually because an electrode sponge is not damp enough or because the sponge is not entirely covering the electrode and therefore is allowing some direct contact between a portion of the electrode and the skin.
During treatment patient will feel a tingling or 'pins and needles' sensation at the contact area of the sponges and may also feel the tingling sensation throughout the area being treated. This sensation may continue for a brief period following treatment as well. The intensity of the current should be increased within the patient's comfort level. A stronger current will usually have a more beneficial effect but the intensity should not be turned up so high as to cause pain.
Interferential Current (IFC) Equipment on Shoulder
Safety and Contraindications
IFC has been used in physical therapy treatment for many years and has been proven to be very safe. However, use should be avoided on individuals with pacemakers and near the low back or abdomen of pregnant women. You should also avoid the use of this modality in a body part where there is any possible risk of metastasis.
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