This chapter describes the general procedures used to set up and apply shortwave diathermy. Because of the variability between units, the instruction manual for your particular brand and model must be your clinical guide for the setup and application of shortwave diathermy. The setup and application information presented here is intended to serve only as a guide.
• Shortwave diathermy (SWD) application involves placing the patient in the unit's electromagnetic field for the induction method or directly in the electrical path for the capacitive method. This energy is then converted to heat in the body's tissues.
Shortwave diathermy units are capable of producing up to 1000 watts of output energy. However, the output intensity does not reflect the amount of energy that is actually absorbed by the tissues. Unlike superficial heating agents or therapeutic ultrasound, SWD is capable of penetrating through all tissue layers. The tissues affected depend on the type of shortwave diathermy being applied (inductive or capacitive field method), the location of the tissues relative to the source of the energy, and the composition of the tissues (see Fig. 9.1).
Medical diathermy, including shortwave diathermy, is regulated under Chapter V, Subchapter C—Electronic Product Radiation Control (Sections 531 to 542) of the Federal Food, Drug, and Cosmetic Act. The Center for Devices and Radiological Health is the U.S. Food and Drug Administration (FDA) center responsible for the oversight of these devices. The exact regulations are located in Title 21, Code of Federal Regulations, Parts 1000 to 1050.
The nuances of shortwave diathermy application are manufacturer and generator specific. The information presented in this chapter only describes the basic parameters and principles of SWD setup and application. The actual clinical delivery of this modality must adhere to the unit's user's manual.
The general output parameters for pulsed SWD treatment doses are presented in Table 10-1, but dosage techniques and protocol are generator specific. The amount of heating is also based on the method of application (capacitive or inductive), the size of the electrodes or drum(s), and the distance of the source of the energy to the tissue. The output intensity for thermal treatments is based on the patient's report of heat. Parameters for vigorous heating using pulsed SWD are presented in Table 10-2.
TABLE 10-1Dosage Parameters Used With Pulsed Shortwave Diathermy |Favorite Table|Download (.pdf) TABLE 10-1 Dosage Parameters Used With Pulsed Shortwave Diathermy
|DOSE ||TEMPERATURE SENSATION ||INDICATIONS ||PULSE WIDTH ||PULSE RATE |
|NT ||No detectable warmth ||Acute trauma ||65 μsec ||100–200 pps |
|Acute inflammation || || |
|Edema reduction || || |
|1 ||Mild warmth ||Subacute inflammation ||100 μsec- ||800 pps |
| ||200 μsec || |
|2 ||Moderate warmth ||Pain syndromes ||200 μsec- ||800 pps |
|Muscle spasm ||400 μsec || |