Short wave diathermy srs

1. Sreeraj S R
SHORT WAVE DIATHERMY
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Dia means through
Thermo means temperature /heat.
Frequency of 27.12 MHz
Wavelength greater than 11meter
Description
High-frequency electrical currents
›Radio waves
Pass through the tissues
Cause molecular vibration
Results in deep heating
Capable of heating large volumes of tissues
Causes both thermal and non thermal effects

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Production

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Production

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Production

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Production

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Production

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Effects on Tissues
•Ionic motion
•Dipole rotation
•Molecular distortion

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Physiological effect
Effects on
1.Metabolism
2.Circulation
3.Nervous tissue
4.Muscle tissue

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Therapeutic Effect
Effects on
1.Inflammation
2.Bacterial Infection
3.Relief of pain
4.Traumatic conditions
5.Reduce healing time

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Types of Shortwave Diathermy
Induction Field
Capacitive Field

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Induction Field Diathermy
•Places the patient in the
electromagnetic field
•Current flowing within the
coil produces a rotating
magnetic field
•Magnetic field produces
eddy currents in the tissues
•Eddy currents cause friction
that produce heat
•Selectively heats muscle
•Also referred to as:
–Magnetic field diathermy

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Capacitive Field Diathermy
•Uses the patient’s tissues as
a part of the circuit
•The tissues’ electrical
resistance produces heat
•Selectively heats skin
–Muscle is heated via
conduction from the
adipose
•Also referred to as
“condenser field diathermy”

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TYPES OF ELECTRODES
Flexible pads:
consist of metal
electrode
encased in rubber
and produce an
electrostatic field.

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TYPES OF ELECTRODES
•Space plates: consist
of a rigid metal
electrode encased in
a Perspex cover 
electrostatic field.

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TYPES OF ELECTRODES
•Coil or cable
electrode consists of
a wire with plugs at
either end creates
electromagnetic
field.

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TYPES OF ELECTRODES
•The monode :
flat, rigid coil
encased in plastic
cover
 electromagnetic
field.

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TYPES OF ELECTRODES
•The diplode : or
drum electrode,
consists of a flat coil
electrode encased in
a Perspex cover with
two wings
• electromagnetic
field

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FACTORS INFLUENCE FIELD DISTRIBUTION IN S.W.D
Spacing :
allows the lines of force in the electrostatic field to diverge
before entering the tissues. This prevents concentration of
heat in the superficial tissues and ensures more heating
through the part.
•Spacing provided by:
1.wrapping flexible pads in towel.
2.flat felt spacing pads
between pad electrode and
skin
3.air when using space plates.

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FACTORS INFLUENCE FIELD DISTRIBUTION IN S.W.D
•Normal spacing 
even field distribution.
•Increased spacing  deep field
concentration.
•Decreased spacing
superficial concentration.

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FACTORS INFLUENCE FIELD DISTRIBUTION IN S.W.D
Electrode size:
if the electrodes are too small
than the diameter of treated
part line of force will be
concentrated superficially.
If the electrodes are markedly
larger the line of force will
be lost in the air.
Ideally, the electrodes should
be slightly larger than the
area treated.

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FACTORS INFLUENCE FIELD DISTRIBUTION IN S.W.D
•To concentrate heat
on one aspect of the
part the electrode
should be unequal in
size (smaller one
placed over the area
where concentration
of heat is required).

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FACTORS INFLUENCE FIELD DISTRIBUTION IN S.W.D
•You can produce concentration of heat by
using equal size electrodes but with unequal
spacing (25 mm over concentrated area and
more than 30 mm on other electrode).

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FACTORS INFLUENCE FIELD DISTRIBUTION IN S.W.D
•Metal: metal causes the lines of force to
concentrate on the metal

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THERAPEUTIC VARIATION IN THE FIELD DISTRIBUTION
•Coplanar application to treat
structures on one aspect of the
body. If the spacing is less than
25 mm more concentration in
the superficial tissue. If spacing
increases more depth
achieved.
•The distance between
adjacent ends must be
greater than the sum of skin
electrode distance (A+B)
otherwise the line of force
will pass directly between
electrodes rather than
tissues.

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THERAPEUTIC VARIATION IN THE FIELD DISTRIBUTION
•Contra planar
applications
Two flexible pads, two
space plates or
flexible pad with a
space plate are used.
It is essential to put a
cotton towel between
the two limbs to
absorb any
perspiration.

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THERAPEUTIC VARIATION IN THE FIELD DISTRIBUTION
•Cross-fire application:
•For the treatment of
sinuses, space plates
positioned diagonally,
after half of treatment
time the positions are
alternate. This ensures
that all aspects of the
sinus membrane are
heated.
•Care must be taken to
avoid direct placement
over the eye, uterine
disorders such as
dysmenorrhoea.

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THERAPEUTIC VARIATION IN THE FIELD DISTRIBUTION
•Application using a
coil electrode:
1.The coil wound evenly
firmly
2.Pancake application

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THERAPEUTIC VARIATION IN THE FIELD DISTRIBUTION
•Application using
diplode:
•Adjust wings of
diplode parallel
to the skin of the
treated area,
electromagnetic
field will
produce.

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Dangers
1.Burns
•Concentration of electric field
•Excess current
•Impaired blood flow
•Hypersensitive skin
•Leads touching skin
2.Scalds
3.Electric shock
4.Overdose
5.Precipitation of gangrene
6.Faintness
7.Giddiness

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Contraindications
•Metal implants or metal jewelry
(be aware of body piercings)
•Cardiac pacemakers
•Ischemic areas
•Peripheral vascular disease
•Perspiration and moist dressings:
The water collects and
concentrates the heat.
•Tendency to hemorrhage,
including menstruation.
•Pregnancy
•Fever
•Sensory loss
•Cancer
•Deep X ray
•Tumours
•Unreliable patients
•Areas of particular sensitivity:
–Epiphyseal plates in children
–The genitals
–Sites of infection
–The abdomen with an implanted
intrauterine device (IUD)
–The eyes and face
–Application through the skull