What is Diathermy?
the application of shortwave or microwave electromagnetic energy to produce heat and other physiological changes within tissues
What is the frequency and wavelength of Shortwave energy?
Frequency of 10 - 100 MHz
Wavelength of 30 - 3 meters
What do shortwave and microwave radiation have in common?
They are both non-ionizing (we are not killing the cells).
What is PSWD?
Pulsed Shortwave Diathermy
What determines how much energy will be absorbed by the tissue and how warm it will become?
Electromagnetic field intensity and tissue type
What are the advantages of Diathermy?
*Diathermy can heat deeper than hot packs
*Diathermy heats a larger area than unltrasound
*SWD is not reflected by by bones so no risk of periosteal burns
*Rx's are generally short
*Rx's do not require clinician to be in direct contact with pt
Diathermy is what type of heat transfer?
Conversion: causes rotation of polar molecules which results in friction between the molecules and an increase in tissue temperature
What are the typical Diathermy Rx times?
Thermal: 20 Minutes
Non Thermal: 30 Minutes
What are the 2 types of SWD applicators?
Inductive Coil and Capacitive Plate
Why is heating with an inductive coil diathermy applicator known as heating by the magnetic field method?
Because the electric current that generates the heat is induced in the tissues by a magnetic field
Where do inductive coil diathermy applicators produce the most heat?
In tissues that have high electrical conductivity and that are closest to the applicator; deeper tissue
What does the electrical conductivity of tissue depend on?
on the tissue type and the frequency of the signal being applied
What has high electrical conductivity?
Metal and tissues with high water and electrolyte content
examples: muscle and synovial fluid
What has low electrical conductivity?
Tissues with a low water content
example: fat, bone, collagen
Why is heating with capacitive plates known as heating by the electrical field method?
because the electric current that generates the heat is produced directly by an electric field
Where do Capacitive plates produce more heat?
in skin and superficial tissues
What are the thermal effects of Diathermy?
*Vasodilation (hemodynamic effects)
*Increased metabolic rate
*Increased collagen extensibility
*Pain Control
What are the non-thermal effects of Diathermy?
*Increased microvascular perfusion: increases local circulation which can increase local tissue oxygenation, nutrient availability, and phagocytosis
*Altered cell membrane function & cellular activity
*Promotes wound, nerve, or fracture healing
What are the clinical indications for Thermal-Level Diathermy? (cont./pulsed at higher intensity)
*Rx goal is to increase temp in larger area
*Pain Control
*Acclerated tissue healing
*Increased ROM
*Decreases Joint Stiffness (w/stretching)
What are the clinical indications for Non-Thermal Pulsed SWD?
*Control of pain & edema
*Acute or chronic infections
*Soft tissue healing
*Osteoarthritis
*Promotes wound, nerve, or fracture healing
Contraindications for the use of all forms of diathermy
*Any implanted electric device (pacemaker)
*Pregnancy
Contraindications for the use of Thermal level Diathermy
*Metal Implants
*Malignancy
*Eyes
*Testes
*Growing Epiphyses
Contrindications for the use of Nonthermal Pulsed Shortwave Diathermy
*Deep tissues such as internal organs
*Pacemakers, elecronic devices, metal implants
Precautions for the use of all forms of Diathermy
*near electronic or magnetic equipment
*obesity
*copper-bearing intrauterine contraceptiive devices
Therapist Precautions
*Stay at least 1 - 2 meters away from continuous SWD applicators
*Stay 30 - 50cm away from PSWD applicators
*Stay out of direct beam of MVD device
*Pregnant therapists should not operate and avoid SWD
What tissue type is at the greatest risk of burning?
Adipose: less vascularized so it cannot cool effectively and pt will not feel thermal effects
How do you avoid burns during application of DIathermy?
Pt skin must be kept dry and use a towel as a barrier
Using Diathermy for Pain Relief
*Mode: Continuous
*Intensity: based on pt's sensation; mild to mod. warmth (20 - 70 watts)
*Time: 20 -30 minutes
How is pain relief achieved using Diathermy?
Gate Control Mechanism: Diathermy stimulates A-Beta fibers which will counteract and close pain gates
Using Diathermy for Muscle Spasm
*Mode: Continuous
*Intensity: based on pt's sensation; mild to mod. warmth (20 - 70 watts)
* Time 20 - 30 minutes
How is Muscle Spasm alleviated using Diathermy?
*Breaks Pain-Spasm-Pain cycle
*Increases Blood flow
*Increases delivery of O2 and other nutrients
*Accelerates removal of waste
Using Diathermy for ROM
*Mode: Continuous
*Intenisty: based on pt's sensation; mild to mod. warmth (20 - 70 watts)
*Time: 20 - 30 minutes
*Must be combined with stretching (tissue temp shoudl be 99.5 - 110 degrees)
Nonthermal SWD Applications
*Mode: Pulsed
*Intensity: adjusted according to the specific finds or recommendations of studies demonstarating clinical efficacy for your application (Pt will generally not feel any heat)
*Time: 30 - 60 minutes
Pulsed Parameters: Acute
*Width: 65
*Frequency: 10 Hz
*Time: 30 minutes
*Intensity: 50 - 100 Watts
Pulsed Parameters: Subactute
*Width: 200
*Frequency: 50 Hz
*Time: 30 minutes
*Intensity: 100 - 150 Watts
Pulsed Parameters: Chronic
Width: 400
Frequency: 400Hz
TIme: 30 minutes
Intensity: 150 - 200 Watts