Diathermy-MWD-SWD - NOTES ABOUT THE USE OF DIATHERMY PDF

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NOTES ABOUT THE USE OF DIATHERMY...

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DIATHERMY 

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Application of electromagnetic waves in the radio frequency range of the electromagnetic spectrum to the tissues of the body Both SWD and MWD can be delivered in a continuous or pulsed mode and when delivered at a sufficient average intensity

TWO TYPES OF DIATHERMY 1. SHORT WAVE DIATHERMY  1.8 to 30 MHz  The most common form of diathermy in use today uses 27.12 MHz frequency waves from the short wavelength range of radio frequency waves  Less likely to create hotspots  Can heat greater volume area 2. MICROWAVE DIATHERMY  The frequency most commonly used for microwave diathermy is 2,450 MHz  300 MHz to 300 GHz frequency  Can create hotspots more frequently compare to SWD

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For patient with some acute and subacute conditions and preventing tissue temperatures from increasing too fast or too high. 2. CONTINOUS SHORTWAVE DIATHERMY - Increases subcutaneous tissue temperature, but its use is generally limited to chronic conditions

PHYSICAL PROPERTIES OF DIATHERMY  

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SHORTWAVE RADIATION 

Within the radiofrequency range (3 kHz to 300 MHz frequency and 1 m to 100 km wavelength), and radiofrequency is between extremely low frequency (ELF) and microwave radiation

MICROWAVE RADIATION 

Frequency between that of radiofrequency and Infrared

MODES OF DIATHERMY 1. PULSED SHORTWAVE DIATHERMY  When delivered in a pulsed mode at low average intensities, heat is dissipated before it can accumulate; however, pulsed low-intensity electromagnetic energy in the shortwave or microwave frequency range may produce physiological effects through nonthermal mechanisms

A pulsed signal can allow heat to dissipate during the off cycle of pulse. Electromagnetic field intensity and tissue type determine how much energy will be absorbed by the tissue and how warm it will become. Diathermy heats deeper than hot packs and heats a larger area than ultrasound. SWD is not reflected by bones and therefore does not concentrate at periosteum or pose a risk of periosteal burning as does ultrasound MWD is reflected at tissue interfaces including those between air and skin, between skin and subcutaneous fat and between soft tissue and superficial bones and therefore does produces more hear in the areas close to the interfaces. Reflection of Microwaves can lead to formation of standing waves, resulting in hotspots in other areas. Both SWD and MWD treatment generally need little time for application and do not require the clinician to be in direct contact with the patient throughout the treatment period.

TYPES OF DIATHERMY 1. INDUCTIVE COIL  Made up of a coil through which an alternating electrical current flows  Alternating current produces a magnetic field perpendicular to the coil, which induces electrical eddy currents in tissues.  These electrical currents cause charge particles → Tissue Oscillation → Friction produced by oscillation → Elevation in tissue temperature  Heating with an inductive coil diathermy applicator is known as heating by the magnetic field method because the electrical current that generates the heat is induced in the tissues by a magnetic field.  Inductive coils can heat both deep and superficial tissues, but they produce the most heat in tissues closest to the

applicator and in tissues with the highest electrical conductivity. a. THE AMOUNT OF HEAT GENERATED IN AN AREA OF TISSUE - It is affected by the strength of the magnetic field that reaches the tissue, and by the strength and density of the induced eddy currents b. THE STRENGTH OF THE INDUCED EDDY CURRENTS - Determined by the strength of the magnetic field in the area and by the electrical conductivity of the tissue in the area. c. INVERSE SQUARE LAW

currents within the tissues directly in front of it 2. CAPACITIVE PLATES

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The strength of the magnetic field is determined by the distance of the tissue from the applicator and decreases in proportion to the square of the distance of the tissue from the applicator d. Electrical Conductivity

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Depends primarily on the tissue with high water and electrical content. High Water and Electrical Content = High Electrical Conductivity Low Water and Electrical Content = Low Electrical Conductivity

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When an alternating electrical current flows through these wires, eddy currents are induced inside the limb

DRUM APPLICATOR

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Made of a flat spiral coil contained within plastic housing The drum is placed directly over the area being treated, and the flow of alternating electrical current in the coil produces a magnetic field, which in turn induces eddy

Heating with capacitive plate diathermy applicators is known as heating by the electrical field method, because the electrical current that generates the heat is produced directly by an electrical field Current will always take the path of least resistance, when a capacitive plate type of applicator is used, the current will generally concentrate in the superficial tissues and

Capacitive plates produce more heat in the skin and superficial tissues, whereas inductive applicators produce more heat in deeper structures. 3. MAGNETRON (CONDENSER)

Bundles of plastic-coated wires are applied by wrapping them around the patient’s limb

As current flows through the tissue, it causes oscillation of charged particles anf thus an increase in tissue temperature

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2 BASIC FORM OF INDUCTIVE COIL APPLICATOR CABLES

Made of metal encased in plastic housing, or transmissive carbon rubber electrodes that are placed between felt pads

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Produces a high-frequency alternating current in an antenna, is used to deliver MWD The alternating current in the antenna produces an electromagnetic field that is directed toward the tissue by a curved reflecting director surrounding the antenna Can be useful during rehabilitation when only small areas of tissue are involved; they are also popular for the medical treatment of malignant tumors by hyperthermia The microwaves produced by a magnetron generate the most heat in tissues with high electrical conductivity; however, this highfrequency, short-wavelength radiation penetrates less deeply than SWD The shallow depth of microwave penetration, the reflection at tissue interfaces, and the potential for standing waves all contribute to increased risk of uneven heating and burning of the

superficial skin or fat with this type of diathermy device. EFFECTS OF DIATHERMY 1. THERMAL EFFECTS

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NERVE HEALING BONE HEALING OSTEOARTHRITIS SYMPTOMS OTHER APPLICATIONS

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↑ Tissue Temperature ↑ Vasodilation ↑ Rate of Nerve Conduction ↑ Pain Threshold Alteration of Muscle Strength Acceleration of Enzymatic Activity ↑ Soft Tissue Extensibility ↑ Circulation of Muscles

Sweating 2. NON-THERMAL EFFECTS a. ↑ Microvascular Perfusion

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3. 4. 5. 6.

Application of PSWD for 40 to 45 minutes at settings that the device manufacturer states do not increase tissue temperature has been found to increase local microvascular perfusion Increasing microvascular perfusion, and thus local circulation, can increase local tissue oxygenation, nutrient availability, and phagocytosis. b. ALTER CELL MEMBRANE FUNCTION AND CELLULAR ACTIVITY It can trigger a cascade of biological processes, including growth factor activation in fibroblasts, chondrocytes, and nerve cells; macrophage activation and changes in myosin phosphorylation.

It can affect the regulation of the cell cycle by altering calcium ion binding, and it has been shown that exposure to electrical fields can accelerate cell growth and division when it is too slow and inhibit it when it is too fast. CLINICAL INDICATION I. THERMAL LEVEL DIATHERMY 1. Indicated when one is trying to achieve the clinical benefits of heat in deep structure II. NON-THERMAL PULSED SHORTWAVE 1. CONTROL OF PAIN AND EDEMA 2. SOFT TISSUE HEALING

Non-thermal PSWD may provide OF therapeutic benefit when applied in the treatment of various forms of neuropathy, ischemic skin flaps, cerebral disease, and myocardial disease and management of head injury

CONTRAINDICATION FOR THE USE OF ALL FORMS OF DIATHERMY 1. IMPLANTED OR TRANSCUTANEOUS NEURAL STIMULATORS, INCLUDING CARDIAC PACEMAKERS

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Electromagnetic energy of the diathermy may interfere with functioning of the device 2. PREGNANCY CONTRAINDICATION FOR THE USE OF THERMAL LEVEL DIATHERMY 1. 2. 3. 4. 5.

METAL IMPLANTS MALIGNANCY OVER THE EYES OVER THE TESTES OVER GROWING EPIPHYSES

CONTRAINDICATION FOR THE USE OF NONTHERMAL PULSED SHORTWAVEE DIATHERMY 1. DEEP TISSUES SUCH AS INTERNAL ORGANS 2. SUBSTITUTE FOR CONVENTIONAL THERAPHY FOR EDEMA AND PAIN 3. PACEMAKERS, ELECTRONIC DEVICES, OR METAL IMPLANTS (WARNING) PRECAUTIONS FOR THE USE OF ALL FORMS OF DIATHERMY 1. NEAR ELECTRONIC OR MAGNETIC EQUIPMENT 2. OBESITY 3. COPPER-BEARING INTRAUTERINE CONTRACEPTIVE DEVICES PRECAUTIONS FOR THE USE OF NONTHERMAL PULSED SHORTWAVE DIATHERMY 1. PREGNANCY 2. SKELETAL IMMATURITY

PRECAUTION FOR PT APPLYING DIATHERMY A. CONTINUOUS DIATHERMY

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Stay at least 1 to 2 m away from all continuous diathermy applicators B. PSWD

• Time of irradiation • Type of applicator • Treatment duration • Patient positioning • Distance of the applicator from the patient • Patient’s response to the treatment

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At least 30 to 50 cm away from all PSWD applicators, C. MWD

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Out of the direct beam during patient treatment

ADVERSE EFFECTS 1. BURNS

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To avoid burns during the application of diathermy, the patient’s skin must be kept dry by wrapping with towels

POSITIONING

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CAPACITIVE PLATES

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Directly over tissues to be treated, almost touching towel on skin

Magnetron

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Both must be placed an equal distance from the skin surface, about 1 to 3 inches (2 to 10 cm) from the skin, parallel to skin surface

Inductive drum:

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Position applicator appropriately in relation to patient’s skin:

Should be placed a few inches from the area to be treated and directed toward the area, with the beam perpendicular to the patient’s skin

MICROWAVE DRUM

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Parallel to patient’s skin, about 1 to 3 inches (2 to 10 cm) away

DOCUMENTATION The following should be documented: • Area of the body treated • Frequency range • Average power or power setting • Pulse rate

DURATION AND FREQUENCY OF TREATMENTS  Thermal level diathermy is usually applied for 20 minutes.  PSWD is usually applied for 30 to 60 minutes, once or twice daily  SWD APPLICATION: Usually 20 minutes but Starkey recommends 20 to 30 minutes of SWD for moderate intensities and about 15 minutes for vigorous heating....