1. Shortwave Diathermy
Chapter 9

2. Description High-frequency electrical currents
Radio waves
Pass through the tissues
Cause molecular vibration
Results in deep heating
Capable of heating large volumes of tissues
Causes both thermal and nonthermal effects

3. Uses Thermal Effects Deep heat Increased blood flow
Increased cell metabolism
Increased tissue extensibility
Muscular relaxation
Possible changes in enzyme reactions
Nonthermal Effects
Edema reduction
Lymphedema reduction
Superficial wound healing
Treatment of venous stasis ulcers

4. Types of Shortwave Diathermy
Induction Field
Capacitive Field

5. Induction Field Diathermy
Places the patient in the electromagnetic field
Selectively heats muscle
Also referred to as:
Condenser field diathermy
Magnetic field diathermy

6. Induction Field Diathermy (Cont.)
A coil is housed within a drum
Current flowing within the coil produces a rotating magnetic field
Magnetic field produces eddy currents in the tissues
Eddy currents cause friction that produce heat
Although rare, cables are sometimes used in place of drums

7. Capacitive Field Diathermy
Uses the patient’s tissues as a part of the circuit
The tissues’ electrical resistance produces heat
Selectively heats skin
Muscle is heated via conduction from the adipose
Also referred to as “condenser field diathermy”

8. Capacitive Field Diathermy (Cont.)
Heat is produced by the dipole effect
Charge particles within membrane align with the field
The movement produces heat + - + - + - + + - + -

9. Modes of Application Continuous Increases tissue temperature
Increased risk of burns
Pulsed
May or may not increase temperature
Pulses allow for increased treatment intensity and duration
Not the same as “nonthermal”

10. Ultrasound & SWD Comparison
Ultrasound Shortwave Diathermy
Energy type Acoustical Electromagnetic
Tissue heated Collage-rich C: Skin, adipose tissue
I: Muscle, vessels
Tissue volume Small (20 cm2) Large (200 cm2)
Temp increase 1 MHz: > 6.3°F C: > 7°F
3 MHz: > 14.9°F I: > 18°F
Heat retention 3 min > 9 min
C = Capacitive method
I = Induction method

11. Biophysical Effects Inflammation
Assists in removal of cellular debris and toxins
Nonthermal:
Alters diffusion rate across the cell membrane
Thermal
Increases intramuscular metabolism

12. Biophysical Effects Blood and Fluid Dynamics Vasodilation increases:
Blood flow
Capillary filtration
Capillary pressure
Oxygen perfusion
Increased fibroblastic activity and capillary growth
Effects occur deeper than other forms of heat

13. Biophysical Effects Tissue Elasticity
SWD can vigorously heat deep tissues
Alters collagen properties, allowing it to elongate
Requires stretching during and/or immediately following the treatment
Multiple treatments are required

14. Biophysical Effects Wound Healing
Nonthermal SWD increases rate of phagocytosis
Number of mature collage bundles increase
ATP activity increases (assisting wound regeneration)
Necrosed muscle fibers decrease

15. Contraindications Metal implants or metal jewelry Cardiac pacemakers
Ischemic areas
Peripheral vascular disease
Perspiration and moist dressings: The water collects and concentrates the heat.
Tendency to hemorrhage, including menstruation.
Pregnancy
Fever
Sensory loss
Cancer
Areas of particular sensitivity:
Epiphyseal plates in children
The genitals
Sites of infection
The abdomen with an implanted intrauterine device (IUD)
The eyes and face
Application through the skull