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diathermy Greek word means
through heat
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3 types of SWD
- longwave (300-30m)
- shortwave (30-3m)
- microwave (3-.03m)
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diathermy is
- elctromagnetic or electric energy converted into heat energy in the body tissue.
- heat energy is produced by resistance of the body tissue to the passage of the energy
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SWD can be delivered by
continuous or pulsed electromagnetic waves
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SWD frequency
- is nonionizing radiation and is 27.12 MHz with a wavelength of 11m
- the high frequency will not allow depolarization of motor nerves or elicit a contraction from innervated or denervated skeletal muscle
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SWD has two circuits
- primary circuit
- secondary circuit
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primary circuit
connected to the power supply is also called a machine or power circuit
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secondary circuit
is connected to the patient and it is called the patient circuit
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power supply
AC current to power machine
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power amplifier
is used to increase the power output to a level that is appropriate for treatment
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patient tuning circuit
- must be done to bring the oscillating frequency of the patient circuit in resonance (in tune) with that of the machine
- can be automatic or manual
- output can be adjusted once this is done
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patient output circuit
2 types
- applicators that produce heat energy that is delivered to patient
- electic field (capacitive or condensor)
- electromagnetic (inductive field)
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electric field
- air spaced condensor electrodes, rubber pad electodes
- energy oscillates between the two condensor plates and thermal effect is produced due to tissue resistance
- patient is part of the circuit
- one pad is positive and one negative
- single layer towel to prevent contact with skin
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coplanar arrangement
pads are parallel. seperated by a distance of at least one pad. greater distance greater depth. high conductivity tissue like muscle are more heated
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contraplanar arrangement
pads can be in series. plates facing each other across jt. heats tissue with high resistance (fat) treatment of deep internal organs, large jts and big muscle groups
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electromagnetic field
one attachment must have a coil (may be inside drum). penetration is limited. pt is not part of the circuit. the circuit is a magnetic field produced by the patient circuit. current is induced within the body part of the pt
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in electromagnetic field energy is absorbed mostly in
muscle and blood and produces deeper heating
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eddy current
electric currents induced in the body part produce small or circular shaped currents responsible for the heating
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single drum
- monode or minode
- coil inside teh drum
- used to treat a single body surface
- require one towel between pt and drum
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multiple unit drum
- diplode
- coil inside drum that is hinged so that more than one surface can be treated
- require one towel between pt and drum
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cable or coil wrap
- wrap around extremity
- pancake like wrap out of the cable
- spacers are used to prevent the cable from touching each other
- requires 2-4 layers of towels
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dosage
- dose 1 (lowest) no sensation of heat (acute)
- dose 2 (low) mild heating sensation, barely felt (sub acute)
- dose 3 (medium) moderate, but pleasant heat sensation (sub acute)
- dose 4 (heavy) vigorous heating below pain threshold
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duration of treatment
- acute- 2 to 3 times daily with dose 1 or 2 for 15 minutes
- chronic- 3 or 4 15 to 30 minutes
- 20-30 min treatments are therapeutically beneficial (takes 3-8 min for tissue to reach temp)
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indications for SWD
bursitis, DJD, fracture healing (after closed methods) indirect healing of perivascular disease, joint contractures, muscle spasms, PID, pleurisy sacroiliac strains,
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contraindications for SWD
acute inflammatory, active bleeding, cardiac insufficiency, decreased sensitivity, epiphyses of growing bone, fever, infections, malignancis, metal, older or younger pt's pacemaker, PVD, pregnant
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precautions for SWD
- metallic objects
- electro-medical devices
- high fluid volume tissues
- casts
- moist clothing
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