BASICS ON SHORTWAVE THERAPY

Shortwave therapy is the therapeutic application of high frequency electrical energy in either the electromagnetic or electrical field, commonly referred to as "diathermy".

It is known for its heating effects. Vasodilation, increased circulation, increased out-flow of lymph, increased removal of waste products, relaxation of spastic muscles and an overall reduction of pain are attributed to therapeutic heat.

Shortwave therapy facilitates exactly dosed and localized heating of tissue areas both close to the surface and at depth.

METHOD OF APPLICATION

Two distinctly different methods of application of shortwave energy are available and the equipment should provide for both alternatives:

A. The Induction of the Electromagnetic Field. The patient circuit consists of a coil such as an induction cable (pancake), hinged drum DIPLODE assembly or applicators such as MONODE, MINODE, etc.

B. Condenser or Electrical Field. The patient circuit consists of two electrodes (air-spaced or rubber pad) and the patient is between these electrodes as a dielectric constant. The high frequency electrical energy oscillates (passes through) between these two electrodes and the patient absorbs the energy by means of resistance.

If the condenser field is of low impedance (close contact to the skin), mostly superficial heating takes place and thus, has limited value.

When the condenser electrodes are applied with a relatively large distance (one inch from the skin), a high impedance circuit is established permitting depth heating. The tissue with high impedance such as fat and bones absorb more energy. (Refer to outline "Deep-Field Efficiency in Shortwave Therapy", Kebbel, Paetzold, Schwan, and "Choice of Modality for Therapy with High Frequency Energy".)

RESONANCE TUNING

Since the patient circuit represents the receiving circuit, which is not directly connected to the generator circuit, resonance tuning similar to radio and television tuning is necessary. It is particularly important for high impedance and floating application circuits. Thus, modern equipment incorporates automatic tuners. (See: "SERV-O-MATIC" - Siemens and ELMED equipment).

CONTINUOUS VERSUS PULSED ENERGY APPLICATION

There seems to be no dispute that the continuous application is the method of choice when thermal therapy (tissue heating) is indicated.

Since the shortwave therapy is high frequency electrotherapy, the hypothesis has been formulated that a stimulation effect is the primary objective. This theory is still disputed, but in indications which call for shortwave therapy without significant temperature rise, the pulsed application may have an advantage. This is similar to the reasoning with ultrasonics.

In all instances, a shortwave therapy unit should provide the continuous mode and the pulsed mode might be an adjunct.