Shortwave and microwave diathermy Flashcards
What is diathermy?
application of high frequency electrical energy that is used to generate heat in the body tissues as a result of the resistance of the tissue to the passage of energy
Do diathermies create muscle or nerve depolarization?
no, their wavelengths are too short
What are the responses to diathermy?
increased blood flow, metabolic rate dilation of blood vessels muscle relaxation heightened pain threshold enzymatic activity is stimulated decrease tissue/joint stiffness
How much temperature can reduce mild inflammation and increase metabolism?
1 degree C
How much temperature can decrease pain and muscle spasm?
2-3 degrees C
How much temperature can cause tissue extensibility?
3-4 degrees C
What will greater heating effect?
greater collagen elongation
Heating occurs in proportion to what?
in proportion to the square of the current density and in direct proportion to the resistance of the tissue
Heating=?
current density^2 x resistance
How is non thermal diathermy useful?
Sodium tends to accumulate in cells due to the inhibition of the sodium/potassium pump during the inflammatory process creating a negative environment. Diathermy can create a magnetic field that can reactivate the pump to regain normal balance.
What are the advantages of diathermy?
provides heating area larger than ultrasound
hands free treatment that doesn’t need constant monitoring
provides deeper heat than moist hot packs
What is specific absorption rate (SAR)?
determines the amount of energy absorbed per unit of area of tissue mass
What does a shortwave generator have?
radio frequency oscillator, amplifier, output resonance tank, electrodes, power supply, monitors, and controls
What is dose I?
no sensation of heat
What is doe II?
mild heating sensation
what is dose III?
moderate heating sensation, comfortable heating
What is dose IV?
vigorous heating that is tolerable below the pain threshold
What kind of field does a shortwave with 13.56 MHz produce?
magnetic field
What kind of field does a shortwave with 27.12 MHz produce?
electric field
What type of electrodes produce the strongest magnetic fields?
drum type (induction electrode)
What type of electrodes produce the strongest electrical field?
air space plates (capacitor electrode)
How should the pads be placed to get the strongest electrical field?
close together (center of field is strongest current density)
What is the difference between capacitor and induction electrodes?
The patient is not part of the electrical circuit with induction electrodes
What are the parameters for shortwave pulsed diathermy?
pulse duration=20-400 microseconds
intensity=up to 1000W per pulse
15-20 minutes
if longer off time than on time is used-allows heat to dissipate and thus not achieving heating effects
What are the contraindications of diathermy?
acute and inflammatory injuries ischemic areas reduced or absent sensation fluid filled areas head and face malignancies infection near reproductive organs growth plates in bone metal implants
How does microwave diathermy work?
generates strong electrical field
vibrates molecules that are high in polarity
What’s the difference between shortwave and microwave?
shortwave units have a greater depth of penetration due to it’s ability to penetrate the fat layer of the body
shortwave is safer
What are the indications of diathermy?
post acute injuries increased blood flow, metabolism, enzyme activity, collagen extensibility, pain threshold, nerve growth and regeneration enhanced injury recovery absoption of hematoma vasodilation muscle relaxation
The shorter the wave the stronger the ______ field. Longer the wave the stronger the ________ field.
Electrical/magnetic
