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Flashcards in Diathermy Deck (26)
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What is diathermy?

Use of shortwave and microwave electromagnetic energy to heat deep soft tissue and large surface areas while minimally heating superficial tissues


How does diathermy induce heat in deep soft tissues?

Interaction between an electric and magnetic field at right angles to each other

Greatest current flow through the tissues with least resistance (fat) and allows or heating in tissues with high water and electrolyte content (muscle)


How does it differ than other thermal agents?

Large deep tissue healing (US is small surface area)
Can be used over limbs in casts
Heats deeper tissue than hot packs
heat does not concentrate at the periosteum
Increases circulation in muscles vs. cutaneous tissue
Moderate heat retention


How does diathermy work?

Alternating current is converted to radio frequency of 27.12 MHz
Frequency passes into the drum
A fluctuating magnetic field is generated around the coil
As the radio frequency exits the drum, an oscillating magnetic field is produced in the body perpendicular to the coil and induces electrical eddying currents within the tissue


What are the benefits of diathermy?

Maintains tissue temperature- nice window of opportunity for stretching
Tendons and ligaments maintain therapeutic heating levels for up to 10-15 minutes post treatment
Heats surfaces up to 25x the size of the average US transducer
Heat is applied uniformly with static stationary application
Rate of tissue cooling is significantly slower than with US
Clinician does not have to be in contact with the patient during treatment


How does diathermy differ from US?

Diathermy- electromagnetic, heats 3-5 cm deep, heats muscle skin and fat, constant tissue heating, area affected is 200cm, moderate heat retention, longer treatment time, no attendance required

US- mechanical energy, heats 2-3cm deep, heats high collagen tissues (tendons, joints), tissue heating is variable due to sound head movement, area affected 12-15 cm, minimal heat retention, shorter treatment time, attendance required


What types of applicators are used for diathermy?

Continuous SWD- heating deep tissues
Pulsed SWD- pulsing for a thermal physiological effects

Inductive coils, drum, garments
Capacitive plates
Magnetron- MWD (Europe)


How do they produce heat in the tissues?

Increase random motion and kinetic energy amount atoms, ions and molecules
Eddying currents created in the tissues


Are there different types of diathermy?

Inductive coil method
Capacitive method


What are the Thermal and Non-Thermal effects of diathermy?

Thermal- large deep tissue healing; goal is to elevate deeper tissue temperature to 104-113 deg F

Non-thermal - increased micro vascular perfusion (increase circulation, nutrient circulation, phagocytosis); altered cell membrane function and cellular activity (growth factor activation and ATP synthesis)


What are the indications for diathermy?

Heating joint capsules before stretching or mobilizations
Enhancement of soft tissue healing
Musculoskeletal disorders- joint stiffness, muscle guarding, pain
Areas of treatment that are uneven or irregular (shoulders, hips, ankles)
Degenerative joint disease
Decreased collagen extensibility
Peripheral nerve regeneration


What are the precautions for diathermy?

All types/ units- keep at least 3 meters away from other electrical equipment (preferably 5 meters); obesity and copper bearing IUD

Non thermal PSWD- skeletal immaturity; pregnancy

Do not operate when pregnant


What are contraindications for diathermy?

Recent or potential hemorrhage
Impaired sensation
Impaired mental ion
Malignant tumor

Implanted or transcutaneous stimulators (including pacemakers)

CSWD- metal implants, malignancy, eyes, testes, growing epiphyses

PSWD- directly over deep tissue/ internal organs; as a substitute for conventional therapy for edema and pain; metal implants( confirm with x-ray


What are the physical properties for diathermy?

Three shortwave frequency bands
We use 27.12 MHz

Broadest band
Easiest and least expansive to generate


What is the temperature determined by?

Field intensity (electrical/ magnetic)
Tissue type (muscle, fat, bone)
Duty cycle- continuous vs pulsed
Distance from patient (temperature change decreases with distance)


Physiological effects of deep heating

Increased rate of nerve conduction
Elevation of pain threshold
Alteration of muscle activation
Acceleration of enzymatic activity
Increased soft tissue extensibility


Clinical applications for thermal CSWD

Pain control
Accelerated tissue healing
Decreased joint stiffness
Increased joint ROM


Clinical applications for non-thermal PSWD

Control of pain and edema
Soft tissue, nerve and bone healing
Improvements of OA symptoms


Mechanical effects

Dipole rotation occurs in the water molecules and collide with other molecules increasing heat generation

No polar molecules oscillate back and forth and create a small amount of friction


How much energy will be absorbed by the tissue and how warm it will become depends on?

Strength of the magnetic field (determined by distance of tissue from applicator)
Type of tissue ( high/low conductive tissue)
Tissue content ( high vs. low water content)


Inductive coil method

Electrical current that generates heat in the tissues produced by a magnetic field, allows for deeper penetration

Majority of energy absorbed within the deeper structures

Produce the most heat in tissues that have high electrical conductivity and tissues that are closest to the applicator


Capacitive plate method

High frequency AC flows from one plate to another through the patient

Electrical field and flow of current in the body tissue so the patient becomes part of the electrical circuit

Increases the tissue temp

Generally over areas of low fat content- ankles, shoulders, knees, hands

Be aware of the alignment of the two plates to make sure everything is evenly distributed

Produce more heat in the skin and superficial tissues


Dose 1

Non thermal response

Acute injuries, edema reduction, cell repair


Dose 2

Mild heating sensation

Subacute injuries, inflammation

12 Watts


Dose 3

Moderate heat sensation

Pain, muscle spasm, chronic inflammation

24 Watts


Dose 4

vigorous heating

Increase circulation, heat collagen tissues for stretching of soft tissues

48 Watts