Diathermy Flashcards
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)
Bursitis
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 Thrombophlebitis Impaired sensation Impaired mental ion Malignant tumor
Implanted or transcutaneous stimulators (including pacemakers)
Pregnancy
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
Vasodilation 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
