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Dr. Mumux Mirani
BPT, MPT Sports, PhD Scholar,
Asst. Professor
SPB Physiotherapy College,
Surat.
Whenever I ask something, like…
What is SWD???
Le ME*
Le
SYBPT*
SWD
What patients tell us when we give
electrotherapy
EMF:
• it is the force producing the flow of electrons
from the more negative to the less negative
body if similar bodies are charged with
different qualities of electricity.
• If a path way is provided the EMF produces a
flow of electrons but if there is no pathway no
current can pass, but force still exist.
• The greater the potential difference the
greater is the EMF and both are measured in
the same unit volt.
• A volt is that EMF which when applied to
conductor with a resistance of one ohm
produces a current of one ampere.
• 1 volt = 1 joule/coulomb
• It is a electrical energy produced per unit
charge inside the source.
• Electron moves only so long as a potential
difference exists between the ends of the
pathway so long as the EMF is maintained.
• a potential difference can be produced by
friction but when a pathway is completed the
charges quickly neutralize each other and
current causes to flow.
• Other methods of producing potential
difference and EMF are
• by the chemical action in cells
• by electromagnetic induction in dynamo,
• by heat in a thermocouple and
• from radiant energy in a photoelectric cell.
• With all these methods the potential
difference is maintained in spite of the
electron flow.
• As fast as electron moves away from the
negative end of the conductor they are
replaced by other from the generator while
those reach the positive end are drawn away
by the generator.
• Thus the potential difference is maintained
and current continue to flow.
• Resistance: it is the obstruction to the flow of
electrons in a conductor.
• Unit is ohm. Resistance is directly proportional
to length and inversely proportional to area of
cross section, temperature and numbers of
free electrons in a unit volume.
• Ohm’s law: the current flowing through a
metallic conductor is proportional to the
potential difference across its ends provided
that all physical conditions remain constant.
• The magnitude of an electric current varies
directly with the EMF and inversely with the
resistance.
• I=E/R
• I= current in ampere
• R = resistance in ohms
• E = EMF in volts
• So 1 ohm is the resistance of a body in such
that 1 volt potential difference across the
body results in a current of 1 ampere through
it.)
• Displacement current:
• Ordinary electric current called conductive
current whether steady or varying produce
magnetic field in the vicinity of the current.
• A displacement of electrical energy occurs as
the result of polarization of the tissues and its
magnitude depends upon the capacitance of
the tissue and the frequency of the alternating
current.
• The use of inductive applicator relies on the
tissue being placed within a rapidly alternating
magnetic field which is generated by passing
the high frequency current through a coil
these results in the creation of eddy currents
within the tissues induced by the oscillating
electromagnetic field
SHORT WAVE DIATHERMY
• means the application of high
frequency electrical energy to the
body tissues in order to bring
physiological and therapeutic
effects, these effects can be
achieved by thermal or non
thermal effect.
• Radio waves are a type of electromagnetic
radiation with wavelengths in the
electromagnetic spectrum longer than infrared
light.
• Radio waves have frequencies from 300 GHz to
as low as 3 kHz, and corresponding wavelengths
ranging from 1 millimeter to 100 kilometers.
Characteristics of radio wave
• RF current does not penetrate deeply into
electrical conductors but tends to flow along
their surfaces; this is known as the skin effect.
For this reason, when the human body comes in
contact with high power RF currents it can cause
superficial but serious burns called RF burns.
• RF currents applied to the body often do not
cause the painful sensation of electric shock
as do lower frequency currents. This is
because the current changes direction too
quickly to trigger depolarization of nerve
membranes.
• RF current can easily ionize air, creating a
conductive path through it.
• Ability to appear to flow through paths that
contain insulating material, like the
dielectric insulator of a capacitor.
• When conducted by an ordinary electric cable,
RF current has a tendency to reflect from
discontinuities in the cable such as connectors
and travel back down the cable toward the
source, causing a condition called standing
waves, so RF current must be carried by
specialized types of cable called transmission
line.
Uses of radiowave
• For invasive surgeries, using radiofrequency
ablation and cryoablation, sleep apnea.
• Magnetic resonance imaging (MRI) uses radio
frequency waves to generate images of the
human body.
• Radio frequencies at non-ablation energy levels
are sometimes used as a form of cosmetic
treatment that can tighten skin, reduce fat, or
promote healing.
• It is also a method of heating tissue
electromagnetically for therapeutic purposes
in medicine.
• Surgically, the extreme heat that can be
produced by diathermy may be used to
destroyneoplasms, warts, and infected tissues,
and to cauterize blood vessels to prevent
excessive bleeding.
• The technique is particularly valuable
in neurosurgery and surgery of the eye.
Diathermy equipment typically operates in the
short-wave radio frequency (range 1–
100 MHz) or microwave energy (range 434–
915 MHz).
• Pulsed electromagnetic field therapy (PEMF) is
a medical treatment that helps to heal bone
tissue reported in a recent NASA study.
• This method usually employs electromagnetic
radiation of different frequencies - ranging
from static magnetic fields, through extremely
low frequencies (ELF) to higher radio
frequencies (RF) administered in pulses.
Types of Diathermy
Long wave
- longest wavelength 300 – 30 m
- most penetrating
- no longer utilized due to high potential of
causing burns and interference with radio
transmissions
Shortwave 30 – 3 m
Microwave
• Dia means through and Thermo
means temperature heat.
• so ‘diathermy’ is coined from a
GREEK word meaning ‘through
heating.
• SWD refers to deep heating
produced by electric or magnetic
fields which alternate at high
(shortwave radio) frequencies.
SWD - INTRODUCTION
• A deep-heating modality
• Application of High-Frequency Electromagnetic Energy
• Non ionizing radiation of radiofrequency portion of
EMS
• wavelength lies between medium radio waves and
microwaves on the EMS
• All radio frequencies in the range of 10 MHz to 100 MHz
are called shortwave & because the device for producing
therapeutic heating is in this range, it is called “shortwave
diathermy”.
• wave length of 3 to 30 m
• Does Not stimulate MOTOR & SENSORY NERVES.
• No contraction of muscle is produced
• No Danger of CHEMICAL BURNS 29
• Therapeutic diathermy uses
radiofrequency of 27.12 MHz at
wavelength of 11 M
• widest band which prevents
interference with other frequency
bands used in communications
• other less common frequencies and
wavelengths are
40 .68 MHz with 7 . 5 m
13 .56 MHz with 22 m
Electromagnetic Phenomena
• Electromagnetic phenomena can be considered
from three different aspects:
• 1- Electrostatic
• concerns the electric force between the electric
charges.
• These forces act between any charges and their
strength and direction can be described by
drawing lines called lines of electric force.
• The area in which this force acts is called an
electric field.
Electromagnetic Phenomena
• 2- When charges move
it is referred to as an
electric current. An
inevitable consequence
of constantly moving
charges is the formation
of magnetic force at
right angles to the
direction of the charge
motion. The area in
which the magnetic
force is evident, called
the magnetic field.
Electromagnetic Phenomena
• 3. If an electric charge is
accelerated it causes the
production of an
electromagnetic radiations
which radiates away from
the moving charge and
once generated is
independent of the charge.
These radiations include
radio waves (SWD), visible
light and X-rays.
There Are Two Circuits Here:
Machine circuit : composed of a high frequency
generator, amplifier, oscillator coil.
Patient circuit: composed of a resonator coil, variable
capacitor, electrodes and the treated tissue.
1. (oscillator circuit) which produce high frequency
current coupled with
2. The patient circuit ( resonator circuit) through
inductors to transfer the electrical energy to the
patient.
Possible Shortwave Diathermy Unit
37
A=Power Switch
B=Timer
C=Milliameter (monitors current
from power supply not current
entering patient-volume control)
D= Intensity(%max power to patient)
E=Tuning Control(tunes output from
RFO)
• Generates Both an Electrical and a Magnetic
Field at 27.12 MHz = Stronger Electrical Field
• The amount of electric field to magnetic field
is dependent on:
1) The characteristic of the machine itself
(dependent on the manufacturer).
2) The type of electrodes that we use.
Machine circuit
1. Main supply:
it connected with AC mains that gives 220 to 240
V and frequency of 50 cycles /second
2. Transformer:
a) step down transformer whose secondary coil is
connected to the triode valve filament produces
potential of 20 V causes emission of electrons
from the cathode through thermo ionic emission
• b) step up transformer secondary coil is connected
to triode valve via oscillator circuit
3. Triode valve: Thermoionic valve which allows
electrons to move in one direction when electric
current flows through the filament from cathode
towards anode provided the grid is connected with
the grid leak resistance.
The grid acts as a regulator to the flow of current-
when positive allows flow of current and when
negative stops the current.
• 4.Grid leak resistance: consists of a resistance
coil connected to the grid of triode valve at
one end and the filament of cathode at other
end.
• 5. Oscillator: a stable condensor and oscillator
coil gives high magnitude, high frequency
oscillating currents to the resonator circuit.
6. Ammeter/ Neon lamp: when oscillator
and resonator circuit are tuned it shows
maximum reading / maximum glow. some
machines are auto tuned.
7. part of the body: between two electrodes act
as a dielectric of a condenser.
mechanism of production of SWD
Principle of Production
44
•This type of high frequency current is
obtained by DISCHARGING a
CONDENSER through an INDUCTANCE
of LOW OHMIC RESISTANCE.
production of SWD
• current is produced by rapidly discharging
condenser through an inductance of low
ohmic resistance.
• To charge and discharge condenser
repeatedly oscillator is incorporated in a
valve circuit.
• To produce high frequency current
capacitance and inductance should be
small.
• dimension of capacitor
and inductance should be
such that it will allow
electrons to oscillate at a
frequency of 27 . 12 MHz
• the frequency of
oscillator circuit depends
on its electrical size
which is a product of
capacitance (c) and
inductance (L)
• To maintain regular oscillation an electric switch
either a thermoionic valve or a transistor is
introduced in the circuit so that current is added in
time with the oscillations.
• this will give low power so a separate amplifier
circuit is needed to increase power to produced
therapeutic frequency.
• power from the mains drawn with the voltage
stepped up around 1000 to 2000 v to operate the
circuit.
• Resonator circuit:
it is parallel to the oscillator circuit consists of variable
condenser and inductance coil.
1) Resonator coil: high magnitude current from
oscillator flows in the resonator coil by
electromagnetic induction.
2)variable condenser: helps to bring the two circuits in
resonance
3) Outside the machine we have two electrodes + the
part being treated
4)electrodes: the output of machine is connected to
the electrodes via cable.
• The part to be treated included in resonator or
patient circuit coupled inductively to the
oscillator circuit.
• coil in each circuit is placed closed together
forming a transformer.
• the magnetic field generated by oscillator
circuit induces a current in the resonator coil.
• energy will be effectively transfered if the two
circuits are in resonance.
• for that the product of capacitance and
inductance in one circuit is same as product of
capacitance and inductance in other.
• the capacity of resonator circuit will changed
because of tissues contributes to the capacity.
• Use of variable capacitor is to match the parameters
of each circuit and must be adjusted to bring the
circuits into resonance.
• tunning can be done manually using the ammeter
maximum reading or brightness of light.
• automatically where ammeter drives the tunning
capacitor which itself regulated by the output from
the resonator circuit.
• once tunned the heating of tissues is regulated by
output of the machine.
• Depending on the form of SWD you can elicit an
thermal treatment or a non-thermal treatment.
• Heat is generated by the resistance of the passage of
energy through tissues.
• Non-thermal effects are elicited through
repolorization of damaged cells and the
• correction of their dysfunction.
• The depth of penetration of SWD is equal to or
greater than ultrasound and greater than any
infrared modalities
Types of units
1) Capacitance (the electric field is more than
the magnetic field) :
Can be achieved by using two space plates
together, or one space plate and a flexible
pad or diplodes.
2) Inductance (the magnetic field is more than
the electric field) :
Can be achieved by using the coil or the drums.
Relation of tissue with SWD
• In capacitor or condensor field method the
tissues are influenced by the oscillating
electric field where it act as part of dielectric
of a capacitor for SWD
• in cable or inductothermy method the tissues
are subjected to an oscillating magnetic field
which will induced oscillating current in the
tissues where it act as a part of load of an
inductance.
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”
Induction Field Diathermy cable method
• Places the patient in the electromagnetic field
• Current flowing within the coil produces a
rotating magnetic field which produces eddy
currents in the tissues
• •Eddy currents cause friction that produce
heat
• •Although rare, cables are sometimes used in
place
• Selectively heats muscle
• the interaction between the field and the tissues is
affected by a macroscopic property of the tissues
called the complex permittivity.
• it is related with dielectric constant.
• the dielectric constant represents the depolarization
characteristics of a tissue and primarily depends
upon the water content.
• complex permittivity is also a function of the field
frequency and therefore the propagation and
attenuation of the electromagnetic waves are
dependent upon the frequency.
Effects of Shortwave on The Molecules
and Ions of Tissues:
 If it is charged  there will be vibration.
 If it is dipole  it will rotate.
 If it is not charged  it won’t be affected.
distortion
EFFECTS OF HIGH-FREQUENCY CURRENTS
ON THE TISSUE :-
• The major effect of induced currents of
sufficient intensity at frequencies above 1MHz is
to cause heating.
• High-frequency currents induced in tissue
increases the kinetic energy of molecules of
body & produces heating.
HEAT PRODUCTION
• Dependent on:
SPECIFIC ABSORPTION RATE
Tissue conductivity
charged molecules
dipolar molecules
non-polar molecules
Electrical field magnitude
• The rise in tissue temperature during the
application of SWD depends on a factor
known as the specific absorption rate, (SAR).
• The SAR is the rate at which energy is
absorbed by a known mass of tissue and is
calculated in units of watts/kilogram.
• SAR and heat produced by SWD depends on
the electric properties of the tissue within the
electromagnetic field.
• The concentration of electric field will be
highest in the tissues with the high
conductivity.
• Different tissues contain varying proportion of
molecules influencing the conductivity and
hence the SAR.
Any living tissue consists of three types of
molecules:
• Charged molecules
• Dipolar molecules
• Non polar molecules
All of three types will influence the
conductivity and hence the heating produced
by SWD
SWD produces heat through tissue by:
- Vibration of charged molecules (ions and
certain proteins)
- Rotation of dipolar molecules (water and
some proteins)
- Distortion of non-polar molecules (fat cells)
VIBRATION OF IONS :-
• Tissues contain a large amount of ions, which are
charge carriers which move, producing a flow of
current.
• If an electric field is applied first in one direction &
then in other, the ions will be accelerated first one
way then the opposite, colliding with adjacent
molecules to give up some energy to them & so
increasing the total random motions, that is heating.
Charged Molecules
Ions and certain
proteins
Molecules are
accelerated along
lines of electric force
Most efficient way of
heat production
+
+
+
+
-
-
-
-
DIPOLE ROTATION :-
– Tissues are, of course, largely water. Water
molecules although electrically neutral, they
are polar; i.e. ends of molecule carry small
opposite charges. (because of this they are
sometimes called as dipoles)
– When rapidly reversing fields are applied to
polar molecules they will rotate to and fro.
– This rotational energy disrupts the motion of
adjacent molecules causing more total random
motion & hence heat.
Dipolar Molecules
Water and some
proteins
Positive pole of the
molecule aligns itself
to the negative pole
of the electric field
(vice versa)
Moderately efficient
heat production
MOLECULAR DISTORTION :-
• Atoms & molecules which are not charged can also be affected
by a rapidly oscillating electric field in that the paths of their
orbiting electrons are distorted.
• As electric field changes direction one side becomes more
positive & the other more negative, so the position of ‘electron
cloud’ shifts, being attracted to positive & repelled from the
negative side.
• This does not cause motion of molecules but the interaction
with neighbouring molecules lead to more random motion &
some heating.
• little heat is produced by this mechanism explains why plastic
cover of electrodes and leads do not become hot.
SWD - Methods
73
1. Capacitor field Method /
condenser Method
2. Inducothermy / Cable Method
Selection of Appropriate methods
Can Influence The Treatment
Capacitor (Condenser) Electrodes
The electrodes acts as CAPACITOR
The patient tissues & Insulating material acts as
DIELECTRIC MEDIUM.
Heat production by conversion of ELECTROMAGNETIC
ENERGY
MECHANICAL ENERGY(HEAT)
74
Capacitor (Condenser) Electrodes
If the goal of treatment is to
increase tissue extensibility & the
limitation is primarily to capsular
tightness, then capacitor field
method of SWD is the more
appropriate choice.
75
Capacitor (Condenser) Electrodes
Create Stronger Electrical Field Than Magnetic
Field
Ions Will Be Attracted Or Repelled Depending
on the Charge of the Pole
76
Capacitor (Condenser) Electrodes
Center Has Higher
Current Density
Than Periphery
77
Capacitor (Condenser) Electrodes
Patient Is Between
Electrodes and
Becomes Part of
Circuit
78
• The Tissue That Offers The Greatest Resistance
To Current Flow Develops The Most Heat
• –Fat Tissue Resists Current Flow
• –Thus Fat Is Heated In An Electrical Field
• –Precaution: electrical field may overheat area
with large fat content
Types of Electrodes:
1) Flexible pads
2) Space electrode
3) Monode
4) Minode
5) Diplode
6) Coil
Minode and monode are called “drums”
Types of Electrodes in SWD
Flexible pads : consist of metal electrode encased in
rubber and produce an electrostatic field.
81
When using them you should insure it is in full
contact.
 We have to wrap it in towel that is 2 cm thick,
less than that could cause a burn, more than
that will affect the amount of heating created
in the body.
 Distance between the electrodes should be
equal the diameter of the electrode, if it is less
than that there will be a shock.
Capacitor Electrodes (Pad Electrodes)
Greater Electrical Field
Patient Part of Circuit
Must Have Uniform Contact
(toweling)
Spacing Equal To Cross-
sectional Diameter of Pads
Part To Be Treated Should Be
Centered
83
Types of Electrodes in SWD
Air space electrodes or Space plates :
consist of a rigid metal electrode encased
in a Plastic cover  electrostatic field.
84
• Two Metal Plates
Surrounded By
Plastic Guard
• Can Be Moved 3cm
Within Guard
Air Space Electrodes
 They come in different sizes.
 Can be used in almost every part of the body, but
because they are rigid they will not fit every contour.
 It can be put on either side of the limb, or can be
used in the same side.
 If the electrodes are placed on the same side there
should be a distance between the electrodes,
because if there is no distance there would be a
shock, so we need to put a distance equal the
diameter of the electrode.
 Skin-electrode distance: is the distance
between the electrode and the skin.
 If we place two electrodes at the same
distance there will be even heating.
 If we placed one electrode closer to the skin
than the other, the heating won’t be even, it
will be more near the closer electrode.
 If we used a large electrode and a small one
the heating will be more near the small.
Sensation Of Heat In
Direct Proportion To
Distance Of Electrode
From Skin
Closer Plate
Generates More
Surface / superficial
Heat
89
Types of Electrodes in SWD
The monode: flat, rigid coil encased in
Perspex cover electromagnetic field.
90
• One Or More Monopolar Coils Rigidly Fixed In
A Housing Unit
• •May Use More Than One Drum Depending
On Area Treated
• •Penetration
• –Deeper Soft Tissues
• •Toweling Important
Types of Electrodes in SWD
• The minode
• The conical rigid coil encased in Perspex cover
Types of Electrodes in SWD
The diplode: or drum electrode , consists
of a flat coil electrode encased in a
Perspex cover with two wings
electromagnetic field
94
Drum Electrodes
 It is known to heat the deeper tissue without
heating the superficial tissue.
 Penetration to 3cm.
 Make sure that the fat layer of the patient is not
more than 2cm, because the penetration will be
limited and the absorption of heat will accumulate in
the fat layer which might cause a burn.
 The tissues that are heated are blood vessels,
muscles and sweat.
Types of Electrodes in SWD
Coil: or cable electrode consists of
a wire with plugs at either end
electromagnetic field.
97
Coil or cable
 Usually used for limbs
 Used in two ways:
1) wrapped around the part being treated.
2) Pancake (usually used on the back).
 When wrapping, the space between one turn and
the other should be 5 to 10cm and it is insure by
felt spacers (comes from the manufacturer).
 It is known to heat the deeper tissue without
heating the superficial tissue.
continuous SWD
• Capacitance technique- creates a stronger electrical
field rather than a magnetic field.
• The part is placed in-between the electrodes and
becomes part of the circuit.
• Thus, the tissues that provide the most resistance
inhibit the amount of heat transfer to the body. So
areas of the body that have lower amounts of body fat
tend to receive better electrical transmission.
• Capacitance uses air space plates and pad electrodes
to administer treatment.
METHODS OF PLACEMENT OF ELECTRODES –
CAPACITOR METHOD
1. COPLANAR METHOD
In this electrodes can
be placed side by side
on the same aspect of
the part, provided that
there is adequate
distance between them.
101
Increasing The
Spacing Will Increase
The Depth Of
Penetration. But Will
Decrease The Current
Density
Capacitive Method
Good for Treating
Superficial Soft
Tissues
102
• 2. CONTRAPLANAR
METHOD
• In this electrodes
are placed on
opposite sides of
the treatment part.
Most satisfactory
method for deeply
placed structures.
E.g. - Joints
3. CROSSFIRE METHOD
• In this first half of
the treatment is
given with the
electrodes in one
contra planar
position & for the
second half the
electrodes are
repositioned at right
angles to it.
4. MONOPOLAR
METHOD
The active electrode is
placed over the site of
the lesion & the
indifferent electrode is
applied to some
distant part of the
body.
105
continuous SWD
• Induction technique- creates a stronger magnetic
field and a lesser electrical field.
• Induction methods create a eddy currents, small
circular fields, within the tissues that cause heat
generation.
• In this method the patient is not part of the circuit
but part of a parallel circuit where the current will
flow through the tissues that provide the least
amount of resistance.
• Induction uses cable and drum electrodes to
distribute treatment.
• when the cable is wound like a spring over the
part treated there occur small capacitive
effect between each turn of the coil and large
effect at the ends.
• the center of turn have inductive effect due to
oscillating magnetic field generated by large
current at the center of the cable.
• electromagnetic induction of electric current
at right angle to the direction of magnetic
field.
• Two Arrangements:
Pancake Coils
Wraparound Coils
• Toweling Is Essential.
• Pancake Coil Must Have 6” in
Center and 5-10cm Spacing Between
Turns
110
• insulated drum contains the coil of the cable .
• flat helix called magnaplode and grid arrangement -
the ends of the cable are connected to the machine.
center part is used to treat large and flat areas.
• double helix where eddy currents produced in the
tissues lying between the two helices. Heating effect
in superficial area with low impedance.
• cable used with one condenser electrode in case of
deformed joints.
FACTORS INFLUENCE FIELD DISTRIBUTION IN
S.W.D
• 1- Spacing:
• It allows the lines of force in the electrostatic
field to diverge before entering the tissues.
• This prevents concentration of heat in the
super-facial 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.
• a- Normal spacing
 even field
distribution.
• b- Increased
spacing  deep
field
concentration.
• c- Decreased
spacing 
superficial
concentration
• About 4 cm distance will give heating of
the deep tissues.
• Conversely the minimum skin electrode
distance is about 2 cm, will give
superficial heating.
• Note: the spacing refers to the distance of the
metal electrode, not the plastic cover, from
the skin.
Position of electrode relative to the tissue
- Electrode parallel to skin surface
Uniform field
- The distance between electrodes less than
the combined skin electrode distances
Most of field passes through air space
- Electrode isn't parallel to skin surface
Superficial heat under closest part of
electrode
• 2.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 slight larger
than the area treated.
When Choosing The Size of Electrode
We Should Consider:
1) The size of the area treated.
2) Location of the area to be treated.
3) The depth of the targeting tissue.
4) Treatment goals.
5) The contraindications.
119
• 3. Metal
• metal causes the lines of force to
concentrate on the metal
• 4. Air in cavities:
• As sinuses or uterus, the lines of force deviate
to avoid air as it offers a high resistance.
• As a result only the sides of air cavity will be
heated.
Important Rule
 Chronic cases  you can treat it with thermal
or non thermal shortwave.
 Acute  only use non thermal shortwave
Advantages of Shortwave
 The deep penetration, it goes deep to 5cm.
 You can use it while attending to another
patient, which allows you to manage your time
in the clinic.
 It covers large areas.
 It can heat the deeper tissue without heating
the superficial tissue
 It can be used with sensitive tissues because it
doesn’t need to be in contact with the treated
tissue.
Uses
Thermal Effects
Deep heat
Increased blood flow
Increased cell metabolism
Increased tissue extensibility
Muscular relaxation
Possible changes in enzyme
reactions
125
Non-thermal Effects
•Edema reduction
•Lymphedema
reduction
•Superficial wound
healing
•Treatment of
venous stasis ulcers
Physiologic Responses To SWD
Tissue Temperature Increase
Increased Blood Flow (Vasodilatation)
Increased Venous and Lymphatic Flow
Increased Metabolism
Changes In Physical Properties of Tissues
Muscle Relaxation -
Analgesia -
126
Indications of SWD - A condition that
could benefit from a specific modality.
• Disorders of Musculoskeletal System:
Low back pain, O.A., R.A., Sprain, Strain,
Muscle & Tendon tear, Capsule lesion, Joint
stiffness, Hematomas, frozen shoulder,
myelegia, traumatic arthritis, ankylosing
spondylitis, Chronic Inflammatory
Conditions;
• Tenosynovitis, Bursitis, Synovitis, Sinusitis,
Fibrositis, Myositis)
2. Sports injury:
muscular strain of rectus femoris,
harmstrings, tensor facia lata etc.., contusion
of thorax.
3. Surgical conditins:
infected surgical incisions, stiched abcess
• 4. ENT:
chronic sinusitis, chronic otitis media
5. non specific pelvic inflammatory diseases.
6. Chest disorders:
To relieve muscle spasm in some forms of
bronchial asthma.
Sub-acute and chronic bronchitis.
7 - Neurological disorders:
Neuritis, Sciatica.
Contraindications - A condition that could be
adversely affected if a particular modality is used.
Metal implants or metal jewelry (be aware of body
piercings) – Concentration of the field.
Cardiac pacemakers – Interference with function
Ischemic areas – The inability of the circulation to
disperse heat could result in high temperature – Burns.
130
• Perspiration and moist dressings :
The water collects and concentrates the
heat.
• Tendency to hemorrhage, including
menstruation – Increase vasodilatation,
prolong hemorrhage.
• Pregnancy – Miscarriage
• Hyperpyrexia
• Sensory loss / Impaired thermal sensation
• Cancer / Malignant tissues – Accelerate the
rate of growth & Metastasis
• Active TUBERCULOSIS – Increase the rate of
development of the infection.
• Recent Radiotherapy – Skin sensation &
Circulation may be decreased.
• Dermatological Conditions – Will exacerbate
• Severe Cardiac conditions – Greater demand
of Cardiac output.
• DVT
Areas of particular sensitivity:
Epiphysis plates in children
The genitals
Sites of infection
The abdomen with an implanted
intrauterine device (IUD)
The eyes and face
Application through the skull
134
Therapeutic Effects of SWD
135
1- Pain relief:
Stimulation of Sensory heat receptors – Pain Gate
Mechanism.
2-Muscle spasm
Heating Secondary Afferent muscle spindle –
Inhibitory influence to motor pool.
3- Inflammation : Assists in removal of cellular debris
and toxins.
Nonthermal: Alters diffusion rate across the cell membrane
Thermal: Increases intramuscular metabolism
Therapeutic Effects of SWD
136
4- Accelerate wound healing : by increase cutaneous
circulation, Vasodilatation increases:
Blood flow
Capillary filtration
Capillary pressure
Oxygen perfusion
5- Infection : increase circulation and increase white
blood cells and antibodies – Reinforcing body’s
normal defense mechanism.
6- Fibrosis : increase extensibility of fibrous tissues
such as tendons, joint capsule and scars. Alters
collagen properties, allowing it to elongate.
Dangers and Precautions in SWD
1- Burn -
 Heat burn caused by SWD so word 'burn' use to warn
the patient for this possible danger.
 burn occur if the patient is unaware of the heat
mild case tissues are not destroyed but a bright red
patch is seen and blister will occur.
in severe case coagulation occur followed by destruction
of tissues results in white patch surrounded by a reddened
area of inflammation.
damage should be visible on removal of electrodes after
complition of the treatment.
137
• burns may occur due to
1) concentration of electric field
2) leads touching the skin
3) use of exess current
4) hypersensitivity of the skin
5) impaired blood flow
1) concentration of electric field:
this causes overheating of the tissues in the
affected area. if in the field a material of high
dielectric constant is present like metal or
moisture which will concentrate the electric
field and burn occur.
it depends on the size, shape and orientation
of the metal with respect to the field.
• all metals are relatively low resistance conductors
and even enclosed in plastic will provide a low
impedence pathway.
• e.g. armpiece of spectacles, metal in clothing-
hooks, zip fastners, buckles, earings, ornaments,
keys, embroidary, etc.
• a long slender pointed piece of metal like a key lies
parallel to the line of force of the field touching the
skin at its point provide a good conductor
concentrating the current at contact point results in
burn due to maximum heating.
• if a person is in an electromagnetic field
touches any conductor connected to the earth
provide a route to ground for a charge to
induced in the tissues. (earth shock)
• Metal implants: metal embedded in the
tissues in case of fixation of fracture, metal
arthroplasty or accidently embedded in the
tissues can cause burn at the junction of the
metal with the tissues depending upon the
position with electric field.
• burn occurs due to concentration of field rather than heating
of the metal.
• if metal implant lies parallel to the line of field it provides
pathway of low impedence for a considerable distance and it
liable to cause serious concentration of field.
• if it lies across the field the easier pathway is provided for a
short distance and concentration of field is less so there is less
effect.
• large wired dental splints, contact lences,
spects, hearing aids may be a risk when SWD
is given for sinus.
• IUCD considered as hazard during treatment
of the pelvis and lower lumber region in
female.
• Moisture: if the area being treated is damp
from prespiration or damp towels are used
with the cable a scald is caused by moist heat.
• if moisture is not localised it will not
concentrate the field but may be overheated
and skin damage occur.
• 2) Leads touching the skin:
if a lead approaches close to the patient's
body heat is produced in the area can cause
burn.
if spacing between two electrodes is
inedequate concentration of field occurs at
the electrode nearer to the skin results in
burn.
• 3). exess current: the patient's sensation is the
only indicator of the intensity of the
application and burn occur due to
• patient does not understand the high
intensity of current
• defective thermal cutaneous sensation
• fall asleep during treatment session
• unconcious patient
• if the intensity of machine increase quickly in
the begining of the treatment it will reach at
dangerous level and failure to reduce the
current immidiately when heat becomes
intense results in burn.
• Overdose: causes increase in symptoms
especially pain and mostely occur in acute
inflammation within a confined area. it is a
indicator to reduce intensity of application.
• 4). Hyper sensitive skin:
due to x-ray therapy or recent use of liniment
skin become hypersensitive where SWD dose
which is normally be safe may cause damage
to the tissues.
• 5) Impaired blood flow:
 the blood circulating through the tissues
normally dissipates the heat and prevent
exessive rise of temperature. due to impaired
blood flow this is not possible result in heat at
the area to be treated.
Heat accelerates chemical changes including
metabolic process in the tissues which
increases the demand for oxygen.
 due to impaired arterial supply to the tissues
the demand for oxygen is not met and
gangrene is liable to occur.
Burns can be avoided by
 Test of thermal skin sensation.
 Aware patient about mild comfortable warmth effect of
SWD
 Taking care during application over a bony prominence.
 Never apply SWD over clothing.
 Do not apply SWD directly to an area of impaired arterial
blood supply.
 Making sure that the skin is dry.
 If you apply over two skin surfaces in contact, they must be
separated by absorbent material towel.
• Making sure that the leads from the machine are
not touching or within 25 mm electromagnetic
field around the lead.
• Making sure that there is adequate spacing
between the electrodes and the skin.
• Remove metal, hearing aids, contact lences,
orthoses .
• Allowing 2 or 3 minutes on each intensity setting
maximum heat.
Dangers and Precautions in SWD
2- Electric shock -
it can occur if
 contact is made with the appratus circuit while switch is
on.
if any metal lies in the electromagnetic field is touched.
if corner of machine or electrodes is touched when
machine is on sparking may occur.
153
Electric shock can be avoided by:
• -Not increasing intensity unless the leads and electrodes are
connected to machine.
• -Making sure that the machine is earthed.
• -Not touching the machine, electrodes and leads when
machine is on.
• -Making sure that there is no metal within the range of
300mm.
• patient should be treated on wooden treatment table
without metal inside.
• -If the patient is wearing a hearing aid or electrophysiologic
orthoses  switch it off.
Dangers and Precautions in SWD
3.Synthetic Material
These do not absorb moisture as readily as normal
materials
They ignite more easily
The material may alter the field either by
absorbtion of energy or concentrating the field.
can be avoided by
ask patient to wear cotton clothes or remove the
clothes during the treatment
155
Dangers and Precautions in SWD
4. Giddiness
electric current applied to the head may cause giddiness due to its
effect on semicircular canals
can be avoided by
proper positioning of the patient with the head in a horizontal or erect
position.
5. Obese Patients
Fat layers more readily heated than the muscles
Fat absorbing power 8 times that absorbed in muscle.
156
• 6. Pregnancy:
• exposure in early pregnancy especially in 1st
trimester theremay be malformation in foetus
occur.
• can be avoided by
• restrict exposure to patient and therapist keep
the distance from the SWD machine about 1m
for contineous SWD, 0.5 for pulsed SWD.
• 6. Damage to the equipment
• the action of cardiac pacemakers, hearing aids and
other electronic devices( mobile, watch, calculator)
may be affected by disturbances set up by SWD.
• Leads may be damaged by overheating if they are
allowed to make contact with the conductor or a
break in the continuety of the wire.
• crack in the electrode within the rubber insulation
results in sparking and overheating.
can be avoided by
• remove all electronic equipment from the
vicinity of SWD field.
• leas should not touch or cross eachother.
• cable wire of main supply and output circuit
must be checked frequently.
• malleable electrodes should be checked for
any damage.
Continuous short wave diathermy
Increases tissue temperature
Increased risk of burns
Pulsed short wave diathermy
May or may not increase temperature
Pulses allow for increased treatment intensity and duration
Not the same as “non-thermal”
160
• Continuous SWD is of benefit in treatment of many
conditions such as osteoarthritis where reduction of
pain & increase in circulation are desirable.
• But one major limitation in use of SWD is that its
thermal effect is greatest in fatty tissues & this limits
the amount of energy which can be applied before
thermal damage occurs.
• Beneficial effects can be produced when sub-thermal
dose of shortwave is applied.
Continuous vs Pulsed SWD
Pulsed SWD (PSWD)
 A number of machine now exists which produce
electromagnetic energy with the aim of stimulating
tissue repair in a non-thermal way.
 Most operate at the radio frequency of 27.12 MHz,
which is same as CSWD & named
• PULSED SWD
• PULSED ELECTROMAGNETIC ENERGY (PEME)
• PULSED ELECTROMAGNETIC FIELD (PEMF)
• PULSED ELECTROMAGNETIC ENERGY TREATMENT
(PEMET).
When using the pulsed shortwave, there are
certain parameters that we need to know:
• Pulse width: measured by micro seconds.
• Pulse frequency: how many pulses we have
per second measured by Hz or pulses per
second (PPS)
• Peak power output: in watts, usually is a set
value that is determined by the manufacturer.
• Mean power output: is variable and is
determined by factors such as the pulse width
and the pulse frequency.
Pulsed SWD
By incorporating a timing circuit , the output can be
turned on & off allowing bursts of Oscillations.
Off-Time Longer Than On-Time
Low Mean Power Output
Uses Drum Electrode
Some machines give fixed – length pulses (65 or
400µsec)
165
Pulsed SWD
-The pulse frequency range is from 15 to 800 Hz.
-The maximum intensity is 1000 watts.
-The pulse duration is constant at 0.4 ms in square
pulse.
-The advantage of pulsed S.W.D. is that a very high
intensity of power can be administered with minimal
effect.
166
Pulsed SWD
167
PSWD - Physiological Effects
• effect is by thermal and non thermal mechanism.
• Total average power is high due to high peak power
and frequency - heat is produced.(effect of heat)
• 1-Increases the growth & activity of cells in the
injured region and there by repair
• 2-Reabsorption of hematoma .
• 3-Reduces swelling & Inflammation
• 4-Increases rate of fibrin deposition & orientation
• 5-Increases collagen deposition & organization
• 6-Increase nerve growth & repair.
• 7- pain control
Indications
• 1- Acute Sprains.
• 2- Contusions.
• 3- Acute Haematoma.
• 4- Bursitis.
• 5- Sinusitis.
• 6-Synovitis
• 7-Sports Injuries
• 8-Superficial Ulcers, incisional wound, burn related
injuries
• 9- Neurogenic Pain (Phantom Pain , Causalgia )
nerve injuries
Contraindications
• low average power -little danger of burn due to
concentration of field by metal or moisture
• otherwise all the contraindication of SWD is applicable.
• 1- Cardiac Pacemakers.
• 2- High fever.
• 3- Precancerous Tissues and malignant lesions
• 4- Metal in the area , including implants if thermal effect is
required.
• 5-Pregnant Women
• 6-Impaired sensation
• 7-Uncooperative / Unconscious patients
• 8-Tuberculosis
• 9-Hearing aids and other electronic equipments
PSWD - Therapeutic Effects
• 1- Decrease of pain & Swelling – Tissue
trauma.
• 2- Acceleration of Inflammatory & Healing
Process
• 3- Relaxation of Muscle Spasm
• 4- Decreases the rate of hematoma formation
• 5- Superficial ulcers are treated successfully –
Bed sores
• 6- Acceleration of bone growth
PSWD - Advantages
1-Effective in treatment of post
traumatic & Infective conditions
2-Often used in conditions where
continuous SWD is contraindicated.
172
Dosage of PSWD
• Based on principle of lower dose for acute
conditions and higer dose for chronic
conditions.
• can be applied for longer duration, high
frequency and mean power output.
• 25 min of treatment is effective
Dosage of Continuous SWD
• Patient Sensation Provides Basis For
Recommendations Of Continuous SWD
depends on perception of the patient
clinical experience of the therapist
15 - 20 min require for vascular adjustments
to occur so treatment duration is of 20 - 30
mins.
• Dose I (Lowest) - No Sensation of Heat
• Dose II (Low) - Mild Heating Sensation
• Dose III (Medium) - Moderate or
Pleasant Heating Sensation
• Dose IV (Heavy) -Vigorous Heating
Within Pain Threshold
• When increasing the intensity wait 2-3
minutes to allow the temperature to build in
the tissue before moving to the next stage.
How To Set The Parameters When
Using Pulsed Shortwave
If we want to set the pulsed shortwave:
 In acute conditions, the mean power output should
be 3 and the treatment time is 10 minutes.
 In sub acute, the mean power output should be 2-5
and the treatment time 10 to 15 minutes.
 In chronic conditions, the mean power output is
from 5-7 and the treatment can go up to 30
minutes.
Mean power output = peak pulse power /
percentage of on time
On time = pulse duration / pulse period
Pulse period = peak pulse power / pulse repetition
rate
When Using Thermal Shortwave
1) Adjust the machine.
2) Ask the patient.
3) If the temperature is too hot decrease it.
4) The patient is not feeling heat increase it.
• Dosage with the continuous shortwave depending
on the thermal sensation reported from the
patient.
• Use your clinical judgment in administering the
dosage .
Frequency of The treatment
 Daily or every other day.
 Depends on the patient’s response.
 If the condition is very acute, daily treatment will
give better results.
 Chronic condition, every other day treatment.
 If it didn’t improve  do it everyday.
TECHNIQUE OF APPLICATION
• Determine the case & side/site.
• Receiving the patient
• HISTORY
- name
- father’s & mother’s name
- age & occupation
- address
- chief complains & duration
- present, past, family, social & occupational history
- contraindications
- treatment history & investigations
PREPARATION OF TRAY
• Two test tubes for skin test
- one with hot water
- one with cold water
• Neon tube to ensure the machine is working.
• Cotton towels or felt pads for spacing.
• Pillows
• Sand bags
• Straps
• Positioning of patient
Put the patient in a comfortable position and well
support, allow the area to be treated to be
completely uncovered.
• Checking for general & local contraindications
• Inspection & palpation of part
• Checking skin sensation
• Ensure there is no metal (jewellery or hairpin) within
300mm of treatment area. Remove mobile, coins,
belt, metal instruments, etc.
PREPARATION OF PATIENT
• Instruction to patient
 Explain the procedure and feeling to the
patient, tell immediately on uncomfortable
heat feeling.
 Not to move, sleep or touch cable or any
other thing
 If the machine has a patient safety switch
instruct the patient to switch the machine
off if he feel more heat.
PREPARATION OF APPARATUS
• Shortwave machine with chosen electrodes
and its test tube to ensure the machine is
working.
• Check insulation of wires & cable
• Check plugs, socket, fuse & all knobs to be
placed at zero
• Testing of apparatus
• Positioning of electrodes & adequate spacing
• If using space electrodes adjust the distance
according to the concentration needed.
• If using flexible pad electrodes, wrap them
in several layers of toweling or place them
between felt pads to ensure the required
amount of spacing.
• switch the power on.
–Switch the intensity on and wait 2-3
minutes on the minimum intensity and ask
the patient about her/his feeling of heat.
–Adjust the timer to the required treatment
time.
–Intensity to be increased & do tuning
TERMINATION
• After treatment time has finished, turn the
intensity switch to zero and remove the
electrodes.
• Switch off machine
• Inspect part for erythema or any other adverse
effects
• Palpate for any pain
• ask the patient to stay few minutes for rest and
to regain to normal temperature.
• Record patient’s name, condition, dosage, type
of pad, spacing & duration.
PRACTICAL POINT OF VIEW
• If duration of condition is up to 10th day then it is
acute condition.
• If duration of condition is between 2 weeks to 6
months, then it is subacute condition & if it is above
6 months then it is a chronic condition.
• Spacing disc electrodes pad electrodes
narrow (for acute case) 1 inch 2 to 4 folds
medium (for subacute) 2 inch 4 to 6 folds
wide (for chronic case) 3 inch 6 to 8 folds
• Duration & Dosage
acute case - 10 to 15 minutes mild thermal
subacute case - 15 to 20 minutes subthermal
chronic case - 20 to 30 minutes thermal
Technique of Application
1-Application using two flexible pads or space
plates:
A- The electrodes should be slightly larger than the
area treated and spaced from the skin by
approximately 25 mm.
B- 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).
190
Technique of Application
C- Coplanar application to treat structures on one aspect of
the body.
The distance between adjacent ends (x) 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.
192
Technique of Application
D- Application using a coil electrode:
1- The coil wound evenly firmly
2- Pancake application
193
Technique of Application
E- Application using diplode:
Adjust wings of diplode parallel to the skin of the treated
area, electromagnetic field will produce.
194
Technique of Application
F- Applications to two limbs:
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.
195
Technique of Application
G- 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.
196
Treatment Time
Most Typically SWD Treatments Last For 10-20-
30 Minutes
Remember As Skin Temperature Rises
Resistance Falls
197
Define diathermy
Identify the parts of the SWD/MWD machine
Describe how heat is produced in SWD/MWD
Enumerate the therapeutic effects of
diathermy
Differentiate the types of SWD
Enumerate the indications, contraindications,
and precautions/guidelines for the use of the
modality
References
Kitchen, S. and Bazin, S. (1996). Clayton’s
electrotherapy (10th ed). Philadelphia: W.B.
Saunders Company.
Low, R. Reed, A. (1995). Electrotherapy
explained: Principles and practice (2nd Ed).
Oxford: Butterworth-Heinemann Ltd.
Michlovitz, S. L. (1996). Thermal agents in
rehabilitation (3rd Ed). Philadelphia: F. A. Davis
Company.

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SWD (Short wave diathermy)- Physiotherapy.ppt

  • 1. Dr. Mumux Mirani BPT, MPT Sports, PhD Scholar, Asst. Professor SPB Physiotherapy College, Surat.
  • 2. Whenever I ask something, like… What is SWD??? Le ME* Le SYBPT* SWD
  • 3. What patients tell us when we give electrotherapy
  • 4.
  • 5.
  • 6. EMF: • it is the force producing the flow of electrons from the more negative to the less negative body if similar bodies are charged with different qualities of electricity. • If a path way is provided the EMF produces a flow of electrons but if there is no pathway no current can pass, but force still exist. • The greater the potential difference the greater is the EMF and both are measured in the same unit volt.
  • 7. • A volt is that EMF which when applied to conductor with a resistance of one ohm produces a current of one ampere. • 1 volt = 1 joule/coulomb • It is a electrical energy produced per unit charge inside the source.
  • 8. • Electron moves only so long as a potential difference exists between the ends of the pathway so long as the EMF is maintained. • a potential difference can be produced by friction but when a pathway is completed the charges quickly neutralize each other and current causes to flow.
  • 9. • Other methods of producing potential difference and EMF are • by the chemical action in cells • by electromagnetic induction in dynamo, • by heat in a thermocouple and • from radiant energy in a photoelectric cell.
  • 10. • With all these methods the potential difference is maintained in spite of the electron flow. • As fast as electron moves away from the negative end of the conductor they are replaced by other from the generator while those reach the positive end are drawn away by the generator. • Thus the potential difference is maintained and current continue to flow.
  • 11. • Resistance: it is the obstruction to the flow of electrons in a conductor. • Unit is ohm. Resistance is directly proportional to length and inversely proportional to area of cross section, temperature and numbers of free electrons in a unit volume.
  • 12. • Ohm’s law: the current flowing through a metallic conductor is proportional to the potential difference across its ends provided that all physical conditions remain constant. • The magnitude of an electric current varies directly with the EMF and inversely with the resistance.
  • 13. • I=E/R • I= current in ampere • R = resistance in ohms • E = EMF in volts • So 1 ohm is the resistance of a body in such that 1 volt potential difference across the body results in a current of 1 ampere through it.)
  • 14. • Displacement current: • Ordinary electric current called conductive current whether steady or varying produce magnetic field in the vicinity of the current. • A displacement of electrical energy occurs as the result of polarization of the tissues and its magnitude depends upon the capacitance of the tissue and the frequency of the alternating current.
  • 15. • The use of inductive applicator relies on the tissue being placed within a rapidly alternating magnetic field which is generated by passing the high frequency current through a coil these results in the creation of eddy currents within the tissues induced by the oscillating electromagnetic field
  • 16.
  • 17. SHORT WAVE DIATHERMY • means the application of high frequency electrical energy to the body tissues in order to bring physiological and therapeutic effects, these effects can be achieved by thermal or non thermal effect.
  • 18.
  • 19. • Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. • Radio waves have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths ranging from 1 millimeter to 100 kilometers.
  • 20. Characteristics of radio wave • RF current does not penetrate deeply into electrical conductors but tends to flow along their surfaces; this is known as the skin effect. For this reason, when the human body comes in contact with high power RF currents it can cause superficial but serious burns called RF burns.
  • 21. • RF currents applied to the body often do not cause the painful sensation of electric shock as do lower frequency currents. This is because the current changes direction too quickly to trigger depolarization of nerve membranes. • RF current can easily ionize air, creating a conductive path through it.
  • 22. • Ability to appear to flow through paths that contain insulating material, like the dielectric insulator of a capacitor. • When conducted by an ordinary electric cable, RF current has a tendency to reflect from discontinuities in the cable such as connectors and travel back down the cable toward the source, causing a condition called standing waves, so RF current must be carried by specialized types of cable called transmission line.
  • 23. Uses of radiowave • For invasive surgeries, using radiofrequency ablation and cryoablation, sleep apnea. • Magnetic resonance imaging (MRI) uses radio frequency waves to generate images of the human body. • Radio frequencies at non-ablation energy levels are sometimes used as a form of cosmetic treatment that can tighten skin, reduce fat, or promote healing.
  • 24. • It is also a method of heating tissue electromagnetically for therapeutic purposes in medicine. • Surgically, the extreme heat that can be produced by diathermy may be used to destroyneoplasms, warts, and infected tissues, and to cauterize blood vessels to prevent excessive bleeding.
  • 25. • The technique is particularly valuable in neurosurgery and surgery of the eye. Diathermy equipment typically operates in the short-wave radio frequency (range 1– 100 MHz) or microwave energy (range 434– 915 MHz).
  • 26. • Pulsed electromagnetic field therapy (PEMF) is a medical treatment that helps to heal bone tissue reported in a recent NASA study. • This method usually employs electromagnetic radiation of different frequencies - ranging from static magnetic fields, through extremely low frequencies (ELF) to higher radio frequencies (RF) administered in pulses.
  • 27. Types of Diathermy Long wave - longest wavelength 300 – 30 m - most penetrating - no longer utilized due to high potential of causing burns and interference with radio transmissions Shortwave 30 – 3 m Microwave
  • 28. • Dia means through and Thermo means temperature heat. • so ‘diathermy’ is coined from a GREEK word meaning ‘through heating. • SWD refers to deep heating produced by electric or magnetic fields which alternate at high (shortwave radio) frequencies.
  • 29. SWD - INTRODUCTION • A deep-heating modality • Application of High-Frequency Electromagnetic Energy • Non ionizing radiation of radiofrequency portion of EMS • wavelength lies between medium radio waves and microwaves on the EMS • All radio frequencies in the range of 10 MHz to 100 MHz are called shortwave & because the device for producing therapeutic heating is in this range, it is called “shortwave diathermy”. • wave length of 3 to 30 m • Does Not stimulate MOTOR & SENSORY NERVES. • No contraction of muscle is produced • No Danger of CHEMICAL BURNS 29
  • 30. • Therapeutic diathermy uses radiofrequency of 27.12 MHz at wavelength of 11 M • widest band which prevents interference with other frequency bands used in communications
  • 31. • other less common frequencies and wavelengths are 40 .68 MHz with 7 . 5 m 13 .56 MHz with 22 m
  • 32. Electromagnetic Phenomena • Electromagnetic phenomena can be considered from three different aspects: • 1- Electrostatic • concerns the electric force between the electric charges. • These forces act between any charges and their strength and direction can be described by drawing lines called lines of electric force. • The area in which this force acts is called an electric field.
  • 33.
  • 34. Electromagnetic Phenomena • 2- When charges move it is referred to as an electric current. An inevitable consequence of constantly moving charges is the formation of magnetic force at right angles to the direction of the charge motion. The area in which the magnetic force is evident, called the magnetic field.
  • 35. Electromagnetic Phenomena • 3. If an electric charge is accelerated it causes the production of an electromagnetic radiations which radiates away from the moving charge and once generated is independent of the charge. These radiations include radio waves (SWD), visible light and X-rays.
  • 36. There Are Two Circuits Here: Machine circuit : composed of a high frequency generator, amplifier, oscillator coil. Patient circuit: composed of a resonator coil, variable capacitor, electrodes and the treated tissue. 1. (oscillator circuit) which produce high frequency current coupled with 2. The patient circuit ( resonator circuit) through inductors to transfer the electrical energy to the patient.
  • 37. Possible Shortwave Diathermy Unit 37 A=Power Switch B=Timer C=Milliameter (monitors current from power supply not current entering patient-volume control) D= Intensity(%max power to patient) E=Tuning Control(tunes output from RFO)
  • 38. • Generates Both an Electrical and a Magnetic Field at 27.12 MHz = Stronger Electrical Field • The amount of electric field to magnetic field is dependent on: 1) The characteristic of the machine itself (dependent on the manufacturer). 2) The type of electrodes that we use.
  • 39. Machine circuit 1. Main supply: it connected with AC mains that gives 220 to 240 V and frequency of 50 cycles /second 2. Transformer: a) step down transformer whose secondary coil is connected to the triode valve filament produces potential of 20 V causes emission of electrons from the cathode through thermo ionic emission
  • 40. • b) step up transformer secondary coil is connected to triode valve via oscillator circuit 3. Triode valve: Thermoionic valve which allows electrons to move in one direction when electric current flows through the filament from cathode towards anode provided the grid is connected with the grid leak resistance. The grid acts as a regulator to the flow of current- when positive allows flow of current and when negative stops the current.
  • 41. • 4.Grid leak resistance: consists of a resistance coil connected to the grid of triode valve at one end and the filament of cathode at other end. • 5. Oscillator: a stable condensor and oscillator coil gives high magnitude, high frequency oscillating currents to the resonator circuit.
  • 42. 6. Ammeter/ Neon lamp: when oscillator and resonator circuit are tuned it shows maximum reading / maximum glow. some machines are auto tuned. 7. part of the body: between two electrodes act as a dielectric of a condenser.
  • 44. Principle of Production 44 •This type of high frequency current is obtained by DISCHARGING a CONDENSER through an INDUCTANCE of LOW OHMIC RESISTANCE.
  • 45. production of SWD • current is produced by rapidly discharging condenser through an inductance of low ohmic resistance. • To charge and discharge condenser repeatedly oscillator is incorporated in a valve circuit. • To produce high frequency current capacitance and inductance should be small.
  • 46. • dimension of capacitor and inductance should be such that it will allow electrons to oscillate at a frequency of 27 . 12 MHz • the frequency of oscillator circuit depends on its electrical size which is a product of capacitance (c) and inductance (L)
  • 47. • To maintain regular oscillation an electric switch either a thermoionic valve or a transistor is introduced in the circuit so that current is added in time with the oscillations. • this will give low power so a separate amplifier circuit is needed to increase power to produced therapeutic frequency. • power from the mains drawn with the voltage stepped up around 1000 to 2000 v to operate the circuit.
  • 48. • Resonator circuit: it is parallel to the oscillator circuit consists of variable condenser and inductance coil. 1) Resonator coil: high magnitude current from oscillator flows in the resonator coil by electromagnetic induction. 2)variable condenser: helps to bring the two circuits in resonance 3) Outside the machine we have two electrodes + the part being treated 4)electrodes: the output of machine is connected to the electrodes via cable.
  • 49. • The part to be treated included in resonator or patient circuit coupled inductively to the oscillator circuit. • coil in each circuit is placed closed together forming a transformer. • the magnetic field generated by oscillator circuit induces a current in the resonator coil.
  • 50. • energy will be effectively transfered if the two circuits are in resonance. • for that the product of capacitance and inductance in one circuit is same as product of capacitance and inductance in other. • the capacity of resonator circuit will changed because of tissues contributes to the capacity.
  • 51. • Use of variable capacitor is to match the parameters of each circuit and must be adjusted to bring the circuits into resonance. • tunning can be done manually using the ammeter maximum reading or brightness of light. • automatically where ammeter drives the tunning capacitor which itself regulated by the output from the resonator circuit. • once tunned the heating of tissues is regulated by output of the machine.
  • 52. • Depending on the form of SWD you can elicit an thermal treatment or a non-thermal treatment. • Heat is generated by the resistance of the passage of energy through tissues. • Non-thermal effects are elicited through repolorization of damaged cells and the • correction of their dysfunction. • The depth of penetration of SWD is equal to or greater than ultrasound and greater than any infrared modalities
  • 53. Types of units 1) Capacitance (the electric field is more than the magnetic field) : Can be achieved by using two space plates together, or one space plate and a flexible pad or diplodes. 2) Inductance (the magnetic field is more than the electric field) : Can be achieved by using the coil or the drums.
  • 54. Relation of tissue with SWD • In capacitor or condensor field method the tissues are influenced by the oscillating electric field where it act as part of dielectric of a capacitor for SWD • in cable or inductothermy method the tissues are subjected to an oscillating magnetic field which will induced oscillating current in the tissues where it act as a part of load of an inductance.
  • 55. 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”
  • 56.
  • 57. Induction Field Diathermy cable method • Places the patient in the electromagnetic field • Current flowing within the coil produces a rotating magnetic field which produces eddy currents in the tissues • •Eddy currents cause friction that produce heat • •Although rare, cables are sometimes used in place • Selectively heats muscle
  • 58.
  • 59.
  • 60. • the interaction between the field and the tissues is affected by a macroscopic property of the tissues called the complex permittivity. • it is related with dielectric constant. • the dielectric constant represents the depolarization characteristics of a tissue and primarily depends upon the water content. • complex permittivity is also a function of the field frequency and therefore the propagation and attenuation of the electromagnetic waves are dependent upon the frequency.
  • 61. Effects of Shortwave on The Molecules and Ions of Tissues:  If it is charged  there will be vibration.  If it is dipole  it will rotate.  If it is not charged  it won’t be affected. distortion
  • 62. EFFECTS OF HIGH-FREQUENCY CURRENTS ON THE TISSUE :- • The major effect of induced currents of sufficient intensity at frequencies above 1MHz is to cause heating. • High-frequency currents induced in tissue increases the kinetic energy of molecules of body & produces heating.
  • 63. HEAT PRODUCTION • Dependent on: SPECIFIC ABSORPTION RATE Tissue conductivity charged molecules dipolar molecules non-polar molecules Electrical field magnitude
  • 64. • The rise in tissue temperature during the application of SWD depends on a factor known as the specific absorption rate, (SAR). • The SAR is the rate at which energy is absorbed by a known mass of tissue and is calculated in units of watts/kilogram. • SAR and heat produced by SWD depends on the electric properties of the tissue within the electromagnetic field.
  • 65. • The concentration of electric field will be highest in the tissues with the high conductivity. • Different tissues contain varying proportion of molecules influencing the conductivity and hence the SAR.
  • 66. Any living tissue consists of three types of molecules: • Charged molecules • Dipolar molecules • Non polar molecules All of three types will influence the conductivity and hence the heating produced by SWD
  • 67. SWD produces heat through tissue by: - Vibration of charged molecules (ions and certain proteins) - Rotation of dipolar molecules (water and some proteins) - Distortion of non-polar molecules (fat cells)
  • 68. VIBRATION OF IONS :- • Tissues contain a large amount of ions, which are charge carriers which move, producing a flow of current. • If an electric field is applied first in one direction & then in other, the ions will be accelerated first one way then the opposite, colliding with adjacent molecules to give up some energy to them & so increasing the total random motions, that is heating.
  • 69. Charged Molecules Ions and certain proteins Molecules are accelerated along lines of electric force Most efficient way of heat production + + + + - - - -
  • 70. DIPOLE ROTATION :- – Tissues are, of course, largely water. Water molecules although electrically neutral, they are polar; i.e. ends of molecule carry small opposite charges. (because of this they are sometimes called as dipoles) – When rapidly reversing fields are applied to polar molecules they will rotate to and fro. – This rotational energy disrupts the motion of adjacent molecules causing more total random motion & hence heat.
  • 71. Dipolar Molecules Water and some proteins Positive pole of the molecule aligns itself to the negative pole of the electric field (vice versa) Moderately efficient heat production
  • 72. MOLECULAR DISTORTION :- • Atoms & molecules which are not charged can also be affected by a rapidly oscillating electric field in that the paths of their orbiting electrons are distorted. • As electric field changes direction one side becomes more positive & the other more negative, so the position of ‘electron cloud’ shifts, being attracted to positive & repelled from the negative side. • This does not cause motion of molecules but the interaction with neighbouring molecules lead to more random motion & some heating. • little heat is produced by this mechanism explains why plastic cover of electrodes and leads do not become hot.
  • 73. SWD - Methods 73 1. Capacitor field Method / condenser Method 2. Inducothermy / Cable Method Selection of Appropriate methods Can Influence The Treatment
  • 74. Capacitor (Condenser) Electrodes The electrodes acts as CAPACITOR The patient tissues & Insulating material acts as DIELECTRIC MEDIUM. Heat production by conversion of ELECTROMAGNETIC ENERGY MECHANICAL ENERGY(HEAT) 74
  • 75. Capacitor (Condenser) Electrodes If the goal of treatment is to increase tissue extensibility & the limitation is primarily to capsular tightness, then capacitor field method of SWD is the more appropriate choice. 75
  • 76. Capacitor (Condenser) Electrodes Create Stronger Electrical Field Than Magnetic Field Ions Will Be Attracted Or Repelled Depending on the Charge of the Pole 76
  • 77. Capacitor (Condenser) Electrodes Center Has Higher Current Density Than Periphery 77
  • 78. Capacitor (Condenser) Electrodes Patient Is Between Electrodes and Becomes Part of Circuit 78
  • 79. • The Tissue That Offers The Greatest Resistance To Current Flow Develops The Most Heat • –Fat Tissue Resists Current Flow • –Thus Fat Is Heated In An Electrical Field • –Precaution: electrical field may overheat area with large fat content
  • 80. Types of Electrodes: 1) Flexible pads 2) Space electrode 3) Monode 4) Minode 5) Diplode 6) Coil Minode and monode are called “drums”
  • 81. Types of Electrodes in SWD Flexible pads : consist of metal electrode encased in rubber and produce an electrostatic field. 81
  • 82. When using them you should insure it is in full contact.  We have to wrap it in towel that is 2 cm thick, less than that could cause a burn, more than that will affect the amount of heating created in the body.  Distance between the electrodes should be equal the diameter of the electrode, if it is less than that there will be a shock.
  • 83. Capacitor Electrodes (Pad Electrodes) Greater Electrical Field Patient Part of Circuit Must Have Uniform Contact (toweling) Spacing Equal To Cross- sectional Diameter of Pads Part To Be Treated Should Be Centered 83
  • 84. Types of Electrodes in SWD Air space electrodes or Space plates : consist of a rigid metal electrode encased in a Plastic cover  electrostatic field. 84
  • 85. • Two Metal Plates Surrounded By Plastic Guard • Can Be Moved 3cm Within Guard
  • 86. Air Space Electrodes  They come in different sizes.  Can be used in almost every part of the body, but because they are rigid they will not fit every contour.  It can be put on either side of the limb, or can be used in the same side.  If the electrodes are placed on the same side there should be a distance between the electrodes, because if there is no distance there would be a shock, so we need to put a distance equal the diameter of the electrode.
  • 87.  Skin-electrode distance: is the distance between the electrode and the skin.  If we place two electrodes at the same distance there will be even heating.  If we placed one electrode closer to the skin than the other, the heating won’t be even, it will be more near the closer electrode.  If we used a large electrode and a small one the heating will be more near the small.
  • 88.
  • 89. Sensation Of Heat In Direct Proportion To Distance Of Electrode From Skin Closer Plate Generates More Surface / superficial Heat 89
  • 90. Types of Electrodes in SWD The monode: flat, rigid coil encased in Perspex cover electromagnetic field. 90
  • 91. • One Or More Monopolar Coils Rigidly Fixed In A Housing Unit • •May Use More Than One Drum Depending On Area Treated • •Penetration • –Deeper Soft Tissues • •Toweling Important
  • 92.
  • 93. Types of Electrodes in SWD • The minode • The conical rigid coil encased in Perspex cover
  • 94. Types of Electrodes in SWD The diplode: or drum electrode , consists of a flat coil electrode encased in a Perspex cover with two wings electromagnetic field 94
  • 95. Drum Electrodes  It is known to heat the deeper tissue without heating the superficial tissue.  Penetration to 3cm.  Make sure that the fat layer of the patient is not more than 2cm, because the penetration will be limited and the absorption of heat will accumulate in the fat layer which might cause a burn.  The tissues that are heated are blood vessels, muscles and sweat.
  • 96.
  • 97. Types of Electrodes in SWD Coil: or cable electrode consists of a wire with plugs at either end electromagnetic field. 97
  • 98. Coil or cable  Usually used for limbs  Used in two ways: 1) wrapped around the part being treated. 2) Pancake (usually used on the back).  When wrapping, the space between one turn and the other should be 5 to 10cm and it is insure by felt spacers (comes from the manufacturer).  It is known to heat the deeper tissue without heating the superficial tissue.
  • 99.
  • 100. continuous SWD • Capacitance technique- creates a stronger electrical field rather than a magnetic field. • The part is placed in-between the electrodes and becomes part of the circuit. • Thus, the tissues that provide the most resistance inhibit the amount of heat transfer to the body. So areas of the body that have lower amounts of body fat tend to receive better electrical transmission. • Capacitance uses air space plates and pad electrodes to administer treatment.
  • 101. METHODS OF PLACEMENT OF ELECTRODES – CAPACITOR METHOD 1. COPLANAR METHOD In this electrodes can be placed side by side on the same aspect of the part, provided that there is adequate distance between them. 101
  • 102. Increasing The Spacing Will Increase The Depth Of Penetration. But Will Decrease The Current Density Capacitive Method Good for Treating Superficial Soft Tissues 102
  • 103. • 2. CONTRAPLANAR METHOD • In this electrodes are placed on opposite sides of the treatment part. Most satisfactory method for deeply placed structures. E.g. - Joints
  • 104. 3. CROSSFIRE METHOD • In this first half of the treatment is given with the electrodes in one contra planar position & for the second half the electrodes are repositioned at right angles to it.
  • 105. 4. MONOPOLAR METHOD The active electrode is placed over the site of the lesion & the indifferent electrode is applied to some distant part of the body. 105
  • 106. continuous SWD • Induction technique- creates a stronger magnetic field and a lesser electrical field. • Induction methods create a eddy currents, small circular fields, within the tissues that cause heat generation. • In this method the patient is not part of the circuit but part of a parallel circuit where the current will flow through the tissues that provide the least amount of resistance. • Induction uses cable and drum electrodes to distribute treatment.
  • 107.
  • 108. • when the cable is wound like a spring over the part treated there occur small capacitive effect between each turn of the coil and large effect at the ends. • the center of turn have inductive effect due to oscillating magnetic field generated by large current at the center of the cable. • electromagnetic induction of electric current at right angle to the direction of magnetic field.
  • 109. • Two Arrangements: Pancake Coils Wraparound Coils • Toweling Is Essential. • Pancake Coil Must Have 6” in Center and 5-10cm Spacing Between Turns
  • 110. 110
  • 111. • insulated drum contains the coil of the cable . • flat helix called magnaplode and grid arrangement - the ends of the cable are connected to the machine. center part is used to treat large and flat areas. • double helix where eddy currents produced in the tissues lying between the two helices. Heating effect in superficial area with low impedance. • cable used with one condenser electrode in case of deformed joints.
  • 112. FACTORS INFLUENCE FIELD DISTRIBUTION IN S.W.D • 1- Spacing: • It allows the lines of force in the electrostatic field to diverge before entering the tissues. • This prevents concentration of heat in the super-facial tissues and ensures more heating through the part.
  • 113. • 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.
  • 114. • a- Normal spacing  even field distribution. • b- Increased spacing  deep field concentration. • c- Decreased spacing  superficial concentration
  • 115. • About 4 cm distance will give heating of the deep tissues. • Conversely the minimum skin electrode distance is about 2 cm, will give superficial heating. • Note: the spacing refers to the distance of the metal electrode, not the plastic cover, from the skin.
  • 116. Position of electrode relative to the tissue - Electrode parallel to skin surface Uniform field - The distance between electrodes less than the combined skin electrode distances Most of field passes through air space - Electrode isn't parallel to skin surface Superficial heat under closest part of electrode
  • 117. • 2.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 slight larger than the area treated.
  • 118. When Choosing The Size of Electrode We Should Consider: 1) The size of the area treated. 2) Location of the area to be treated. 3) The depth of the targeting tissue. 4) Treatment goals. 5) The contraindications.
  • 119. 119
  • 120. • 3. Metal • metal causes the lines of force to concentrate on the metal
  • 121. • 4. Air in cavities: • As sinuses or uterus, the lines of force deviate to avoid air as it offers a high resistance. • As a result only the sides of air cavity will be heated.
  • 122.
  • 123. Important Rule  Chronic cases  you can treat it with thermal or non thermal shortwave.  Acute  only use non thermal shortwave
  • 124. Advantages of Shortwave  The deep penetration, it goes deep to 5cm.  You can use it while attending to another patient, which allows you to manage your time in the clinic.  It covers large areas.  It can heat the deeper tissue without heating the superficial tissue  It can be used with sensitive tissues because it doesn’t need to be in contact with the treated tissue.
  • 125. Uses Thermal Effects Deep heat Increased blood flow Increased cell metabolism Increased tissue extensibility Muscular relaxation Possible changes in enzyme reactions 125 Non-thermal Effects •Edema reduction •Lymphedema reduction •Superficial wound healing •Treatment of venous stasis ulcers
  • 126. Physiologic Responses To SWD Tissue Temperature Increase Increased Blood Flow (Vasodilatation) Increased Venous and Lymphatic Flow Increased Metabolism Changes In Physical Properties of Tissues Muscle Relaxation - Analgesia - 126
  • 127. Indications of SWD - A condition that could benefit from a specific modality. • Disorders of Musculoskeletal System: Low back pain, O.A., R.A., Sprain, Strain, Muscle & Tendon tear, Capsule lesion, Joint stiffness, Hematomas, frozen shoulder, myelegia, traumatic arthritis, ankylosing spondylitis, Chronic Inflammatory Conditions; • Tenosynovitis, Bursitis, Synovitis, Sinusitis, Fibrositis, Myositis)
  • 128. 2. Sports injury: muscular strain of rectus femoris, harmstrings, tensor facia lata etc.., contusion of thorax. 3. Surgical conditins: infected surgical incisions, stiched abcess
  • 129. • 4. ENT: chronic sinusitis, chronic otitis media 5. non specific pelvic inflammatory diseases. 6. Chest disorders: To relieve muscle spasm in some forms of bronchial asthma. Sub-acute and chronic bronchitis. 7 - Neurological disorders: Neuritis, Sciatica.
  • 130. Contraindications - A condition that could be adversely affected if a particular modality is used. Metal implants or metal jewelry (be aware of body piercings) – Concentration of the field. Cardiac pacemakers – Interference with function Ischemic areas – The inability of the circulation to disperse heat could result in high temperature – Burns. 130
  • 131. • Perspiration and moist dressings : The water collects and concentrates the heat. • Tendency to hemorrhage, including menstruation – Increase vasodilatation, prolong hemorrhage. • Pregnancy – Miscarriage • Hyperpyrexia
  • 132. • Sensory loss / Impaired thermal sensation • Cancer / Malignant tissues – Accelerate the rate of growth & Metastasis • Active TUBERCULOSIS – Increase the rate of development of the infection. • Recent Radiotherapy – Skin sensation & Circulation may be decreased.
  • 133. • Dermatological Conditions – Will exacerbate • Severe Cardiac conditions – Greater demand of Cardiac output. • DVT
  • 134. Areas of particular sensitivity: Epiphysis plates in children The genitals Sites of infection The abdomen with an implanted intrauterine device (IUD) The eyes and face Application through the skull 134
  • 135. Therapeutic Effects of SWD 135 1- Pain relief: Stimulation of Sensory heat receptors – Pain Gate Mechanism. 2-Muscle spasm Heating Secondary Afferent muscle spindle – Inhibitory influence to motor pool. 3- Inflammation : Assists in removal of cellular debris and toxins. Nonthermal: Alters diffusion rate across the cell membrane Thermal: Increases intramuscular metabolism
  • 136. Therapeutic Effects of SWD 136 4- Accelerate wound healing : by increase cutaneous circulation, Vasodilatation increases: Blood flow Capillary filtration Capillary pressure Oxygen perfusion 5- Infection : increase circulation and increase white blood cells and antibodies – Reinforcing body’s normal defense mechanism. 6- Fibrosis : increase extensibility of fibrous tissues such as tendons, joint capsule and scars. Alters collagen properties, allowing it to elongate.
  • 137. Dangers and Precautions in SWD 1- Burn -  Heat burn caused by SWD so word 'burn' use to warn the patient for this possible danger.  burn occur if the patient is unaware of the heat mild case tissues are not destroyed but a bright red patch is seen and blister will occur. in severe case coagulation occur followed by destruction of tissues results in white patch surrounded by a reddened area of inflammation. damage should be visible on removal of electrodes after complition of the treatment. 137
  • 138. • burns may occur due to 1) concentration of electric field 2) leads touching the skin 3) use of exess current 4) hypersensitivity of the skin 5) impaired blood flow
  • 139. 1) concentration of electric field: this causes overheating of the tissues in the affected area. if in the field a material of high dielectric constant is present like metal or moisture which will concentrate the electric field and burn occur. it depends on the size, shape and orientation of the metal with respect to the field.
  • 140. • all metals are relatively low resistance conductors and even enclosed in plastic will provide a low impedence pathway. • e.g. armpiece of spectacles, metal in clothing- hooks, zip fastners, buckles, earings, ornaments, keys, embroidary, etc. • a long slender pointed piece of metal like a key lies parallel to the line of force of the field touching the skin at its point provide a good conductor concentrating the current at contact point results in burn due to maximum heating.
  • 141. • if a person is in an electromagnetic field touches any conductor connected to the earth provide a route to ground for a charge to induced in the tissues. (earth shock) • Metal implants: metal embedded in the tissues in case of fixation of fracture, metal arthroplasty or accidently embedded in the tissues can cause burn at the junction of the metal with the tissues depending upon the position with electric field.
  • 142. • burn occurs due to concentration of field rather than heating of the metal. • if metal implant lies parallel to the line of field it provides pathway of low impedence for a considerable distance and it liable to cause serious concentration of field. • if it lies across the field the easier pathway is provided for a short distance and concentration of field is less so there is less effect.
  • 143. • large wired dental splints, contact lences, spects, hearing aids may be a risk when SWD is given for sinus. • IUCD considered as hazard during treatment of the pelvis and lower lumber region in female.
  • 144. • Moisture: if the area being treated is damp from prespiration or damp towels are used with the cable a scald is caused by moist heat. • if moisture is not localised it will not concentrate the field but may be overheated and skin damage occur.
  • 145. • 2) Leads touching the skin: if a lead approaches close to the patient's body heat is produced in the area can cause burn. if spacing between two electrodes is inedequate concentration of field occurs at the electrode nearer to the skin results in burn.
  • 146. • 3). exess current: the patient's sensation is the only indicator of the intensity of the application and burn occur due to • patient does not understand the high intensity of current • defective thermal cutaneous sensation • fall asleep during treatment session • unconcious patient
  • 147. • if the intensity of machine increase quickly in the begining of the treatment it will reach at dangerous level and failure to reduce the current immidiately when heat becomes intense results in burn. • Overdose: causes increase in symptoms especially pain and mostely occur in acute inflammation within a confined area. it is a indicator to reduce intensity of application.
  • 148. • 4). Hyper sensitive skin: due to x-ray therapy or recent use of liniment skin become hypersensitive where SWD dose which is normally be safe may cause damage to the tissues.
  • 149. • 5) Impaired blood flow:  the blood circulating through the tissues normally dissipates the heat and prevent exessive rise of temperature. due to impaired blood flow this is not possible result in heat at the area to be treated. Heat accelerates chemical changes including metabolic process in the tissues which increases the demand for oxygen.
  • 150.  due to impaired arterial supply to the tissues the demand for oxygen is not met and gangrene is liable to occur.
  • 151. Burns can be avoided by  Test of thermal skin sensation.  Aware patient about mild comfortable warmth effect of SWD  Taking care during application over a bony prominence.  Never apply SWD over clothing.  Do not apply SWD directly to an area of impaired arterial blood supply.  Making sure that the skin is dry.  If you apply over two skin surfaces in contact, they must be separated by absorbent material towel.
  • 152. • Making sure that the leads from the machine are not touching or within 25 mm electromagnetic field around the lead. • Making sure that there is adequate spacing between the electrodes and the skin. • Remove metal, hearing aids, contact lences, orthoses . • Allowing 2 or 3 minutes on each intensity setting maximum heat.
  • 153. Dangers and Precautions in SWD 2- Electric shock - it can occur if  contact is made with the appratus circuit while switch is on. if any metal lies in the electromagnetic field is touched. if corner of machine or electrodes is touched when machine is on sparking may occur. 153
  • 154. Electric shock can be avoided by: • -Not increasing intensity unless the leads and electrodes are connected to machine. • -Making sure that the machine is earthed. • -Not touching the machine, electrodes and leads when machine is on. • -Making sure that there is no metal within the range of 300mm. • patient should be treated on wooden treatment table without metal inside. • -If the patient is wearing a hearing aid or electrophysiologic orthoses  switch it off.
  • 155. Dangers and Precautions in SWD 3.Synthetic Material These do not absorb moisture as readily as normal materials They ignite more easily The material may alter the field either by absorbtion of energy or concentrating the field. can be avoided by ask patient to wear cotton clothes or remove the clothes during the treatment 155
  • 156. Dangers and Precautions in SWD 4. Giddiness electric current applied to the head may cause giddiness due to its effect on semicircular canals can be avoided by proper positioning of the patient with the head in a horizontal or erect position. 5. Obese Patients Fat layers more readily heated than the muscles Fat absorbing power 8 times that absorbed in muscle. 156
  • 157. • 6. Pregnancy: • exposure in early pregnancy especially in 1st trimester theremay be malformation in foetus occur. • can be avoided by • restrict exposure to patient and therapist keep the distance from the SWD machine about 1m for contineous SWD, 0.5 for pulsed SWD.
  • 158. • 6. Damage to the equipment • the action of cardiac pacemakers, hearing aids and other electronic devices( mobile, watch, calculator) may be affected by disturbances set up by SWD. • Leads may be damaged by overheating if they are allowed to make contact with the conductor or a break in the continuety of the wire. • crack in the electrode within the rubber insulation results in sparking and overheating.
  • 159. can be avoided by • remove all electronic equipment from the vicinity of SWD field. • leas should not touch or cross eachother. • cable wire of main supply and output circuit must be checked frequently. • malleable electrodes should be checked for any damage.
  • 160. Continuous short wave diathermy Increases tissue temperature Increased risk of burns Pulsed short wave diathermy May or may not increase temperature Pulses allow for increased treatment intensity and duration Not the same as “non-thermal” 160
  • 161. • Continuous SWD is of benefit in treatment of many conditions such as osteoarthritis where reduction of pain & increase in circulation are desirable. • But one major limitation in use of SWD is that its thermal effect is greatest in fatty tissues & this limits the amount of energy which can be applied before thermal damage occurs. • Beneficial effects can be produced when sub-thermal dose of shortwave is applied.
  • 163. Pulsed SWD (PSWD)  A number of machine now exists which produce electromagnetic energy with the aim of stimulating tissue repair in a non-thermal way.  Most operate at the radio frequency of 27.12 MHz, which is same as CSWD & named • PULSED SWD • PULSED ELECTROMAGNETIC ENERGY (PEME) • PULSED ELECTROMAGNETIC FIELD (PEMF) • PULSED ELECTROMAGNETIC ENERGY TREATMENT (PEMET).
  • 164. When using the pulsed shortwave, there are certain parameters that we need to know: • Pulse width: measured by micro seconds. • Pulse frequency: how many pulses we have per second measured by Hz or pulses per second (PPS) • Peak power output: in watts, usually is a set value that is determined by the manufacturer. • Mean power output: is variable and is determined by factors such as the pulse width and the pulse frequency.
  • 165. Pulsed SWD By incorporating a timing circuit , the output can be turned on & off allowing bursts of Oscillations. Off-Time Longer Than On-Time Low Mean Power Output Uses Drum Electrode Some machines give fixed – length pulses (65 or 400µsec) 165
  • 166. Pulsed SWD -The pulse frequency range is from 15 to 800 Hz. -The maximum intensity is 1000 watts. -The pulse duration is constant at 0.4 ms in square pulse. -The advantage of pulsed S.W.D. is that a very high intensity of power can be administered with minimal effect. 166
  • 168. PSWD - Physiological Effects • effect is by thermal and non thermal mechanism. • Total average power is high due to high peak power and frequency - heat is produced.(effect of heat) • 1-Increases the growth & activity of cells in the injured region and there by repair • 2-Reabsorption of hematoma . • 3-Reduces swelling & Inflammation • 4-Increases rate of fibrin deposition & orientation • 5-Increases collagen deposition & organization • 6-Increase nerve growth & repair. • 7- pain control
  • 169. Indications • 1- Acute Sprains. • 2- Contusions. • 3- Acute Haematoma. • 4- Bursitis. • 5- Sinusitis. • 6-Synovitis • 7-Sports Injuries • 8-Superficial Ulcers, incisional wound, burn related injuries • 9- Neurogenic Pain (Phantom Pain , Causalgia ) nerve injuries
  • 170. Contraindications • low average power -little danger of burn due to concentration of field by metal or moisture • otherwise all the contraindication of SWD is applicable. • 1- Cardiac Pacemakers. • 2- High fever. • 3- Precancerous Tissues and malignant lesions • 4- Metal in the area , including implants if thermal effect is required. • 5-Pregnant Women • 6-Impaired sensation • 7-Uncooperative / Unconscious patients • 8-Tuberculosis • 9-Hearing aids and other electronic equipments
  • 171. PSWD - Therapeutic Effects • 1- Decrease of pain & Swelling – Tissue trauma. • 2- Acceleration of Inflammatory & Healing Process • 3- Relaxation of Muscle Spasm • 4- Decreases the rate of hematoma formation • 5- Superficial ulcers are treated successfully – Bed sores • 6- Acceleration of bone growth
  • 172. PSWD - Advantages 1-Effective in treatment of post traumatic & Infective conditions 2-Often used in conditions where continuous SWD is contraindicated. 172
  • 173. Dosage of PSWD • Based on principle of lower dose for acute conditions and higer dose for chronic conditions. • can be applied for longer duration, high frequency and mean power output. • 25 min of treatment is effective
  • 174. Dosage of Continuous SWD • Patient Sensation Provides Basis For Recommendations Of Continuous SWD depends on perception of the patient clinical experience of the therapist 15 - 20 min require for vascular adjustments to occur so treatment duration is of 20 - 30 mins.
  • 175. • Dose I (Lowest) - No Sensation of Heat • Dose II (Low) - Mild Heating Sensation • Dose III (Medium) - Moderate or Pleasant Heating Sensation • Dose IV (Heavy) -Vigorous Heating Within Pain Threshold • When increasing the intensity wait 2-3 minutes to allow the temperature to build in the tissue before moving to the next stage.
  • 176. How To Set The Parameters When Using Pulsed Shortwave If we want to set the pulsed shortwave:  In acute conditions, the mean power output should be 3 and the treatment time is 10 minutes.  In sub acute, the mean power output should be 2-5 and the treatment time 10 to 15 minutes.  In chronic conditions, the mean power output is from 5-7 and the treatment can go up to 30 minutes.
  • 177. Mean power output = peak pulse power / percentage of on time On time = pulse duration / pulse period Pulse period = peak pulse power / pulse repetition rate
  • 178. When Using Thermal Shortwave 1) Adjust the machine. 2) Ask the patient. 3) If the temperature is too hot decrease it. 4) The patient is not feeling heat increase it. • Dosage with the continuous shortwave depending on the thermal sensation reported from the patient. • Use your clinical judgment in administering the dosage .
  • 179. Frequency of The treatment  Daily or every other day.  Depends on the patient’s response.  If the condition is very acute, daily treatment will give better results.  Chronic condition, every other day treatment.  If it didn’t improve  do it everyday.
  • 180. TECHNIQUE OF APPLICATION • Determine the case & side/site. • Receiving the patient • HISTORY - name - father’s & mother’s name - age & occupation - address - chief complains & duration - present, past, family, social & occupational history - contraindications - treatment history & investigations
  • 181. PREPARATION OF TRAY • Two test tubes for skin test - one with hot water - one with cold water • Neon tube to ensure the machine is working. • Cotton towels or felt pads for spacing. • Pillows • Sand bags • Straps
  • 182. • Positioning of patient Put the patient in a comfortable position and well support, allow the area to be treated to be completely uncovered. • Checking for general & local contraindications • Inspection & palpation of part • Checking skin sensation • Ensure there is no metal (jewellery or hairpin) within 300mm of treatment area. Remove mobile, coins, belt, metal instruments, etc. PREPARATION OF PATIENT
  • 183. • Instruction to patient  Explain the procedure and feeling to the patient, tell immediately on uncomfortable heat feeling.  Not to move, sleep or touch cable or any other thing  If the machine has a patient safety switch instruct the patient to switch the machine off if he feel more heat.
  • 184. PREPARATION OF APPARATUS • Shortwave machine with chosen electrodes and its test tube to ensure the machine is working.
  • 185. • Check insulation of wires & cable • Check plugs, socket, fuse & all knobs to be placed at zero • Testing of apparatus • Positioning of electrodes & adequate spacing
  • 186. • If using space electrodes adjust the distance according to the concentration needed. • If using flexible pad electrodes, wrap them in several layers of toweling or place them between felt pads to ensure the required amount of spacing.
  • 187. • switch the power on. –Switch the intensity on and wait 2-3 minutes on the minimum intensity and ask the patient about her/his feeling of heat. –Adjust the timer to the required treatment time. –Intensity to be increased & do tuning
  • 188. TERMINATION • After treatment time has finished, turn the intensity switch to zero and remove the electrodes. • Switch off machine • Inspect part for erythema or any other adverse effects • Palpate for any pain • ask the patient to stay few minutes for rest and to regain to normal temperature. • Record patient’s name, condition, dosage, type of pad, spacing & duration.
  • 189. PRACTICAL POINT OF VIEW • If duration of condition is up to 10th day then it is acute condition. • If duration of condition is between 2 weeks to 6 months, then it is subacute condition & if it is above 6 months then it is a chronic condition. • Spacing disc electrodes pad electrodes narrow (for acute case) 1 inch 2 to 4 folds medium (for subacute) 2 inch 4 to 6 folds wide (for chronic case) 3 inch 6 to 8 folds • Duration & Dosage acute case - 10 to 15 minutes mild thermal subacute case - 15 to 20 minutes subthermal chronic case - 20 to 30 minutes thermal
  • 190. Technique of Application 1-Application using two flexible pads or space plates: A- The electrodes should be slightly larger than the area treated and spaced from the skin by approximately 25 mm. B- 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). 190
  • 191.
  • 192. Technique of Application C- Coplanar application to treat structures on one aspect of the body. The distance between adjacent ends (x) 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. 192
  • 193. Technique of Application D- Application using a coil electrode: 1- The coil wound evenly firmly 2- Pancake application 193
  • 194. Technique of Application E- Application using diplode: Adjust wings of diplode parallel to the skin of the treated area, electromagnetic field will produce. 194
  • 195. Technique of Application F- Applications to two limbs: 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. 195
  • 196. Technique of Application G- 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. 196
  • 197. Treatment Time Most Typically SWD Treatments Last For 10-20- 30 Minutes Remember As Skin Temperature Rises Resistance Falls 197
  • 198.
  • 199. Define diathermy Identify the parts of the SWD/MWD machine Describe how heat is produced in SWD/MWD Enumerate the therapeutic effects of diathermy Differentiate the types of SWD Enumerate the indications, contraindications, and precautions/guidelines for the use of the modality
  • 200. References Kitchen, S. and Bazin, S. (1996). Clayton’s electrotherapy (10th ed). Philadelphia: W.B. Saunders Company. Low, R. Reed, A. (1995). Electrotherapy explained: Principles and practice (2nd Ed). Oxford: Butterworth-Heinemann Ltd. Michlovitz, S. L. (1996). Thermal agents in rehabilitation (3rd Ed). Philadelphia: F. A. Davis Company.