Transcript Light Modalities

Shortwave Diathermy
Chapter 9
Description
• High-frequency electrical currents
– Radio waves
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Pass through the tissues
Cause molecular vibration
Results in deep heating
Capable of heating large volumes of tissues
Causes both thermal and nonthermal effects
Uses
Thermal Effects
• Deep heat
• Increased blood flow
• Increased cell metabolism
• Increased tissue
extensibility
• Muscular relaxation
• Possible changes in
enzyme reactions
Nonthermal Effects
• Edema reduction
• Lymphedema reduction
• Superficial wound healing
• Treatment of venous stasis
ulcers
Types of Shortwave Diathermy
Induction Field
Capacitive Field
Induction Field Diathermy
• Places the patient in the electromagnetic field
• Selectively heats muscle
• Also referred to as:
– Condenser field diathermy
– Magnetic field diathermy
Induction Field Diathermy (Cont.)
• A coil is housed within a
drum
• Current flowing within the
coil produces a rotating
magnetic field
• Magnetic field produces eddy
currents in the tissues
• Eddy currents cause friction
that produce heat
• Although rare, cables are
sometimes used in place of
drums
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”
Capacitive Field Diathermy (Cont.)
• Heat is produced by
the dipole effect
• Charge particles
within membrane
align with the field
• The movement
produces heat
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Modes of Application
Continuous
• Increases tissue temperature
• Increased risk of burns
Pulsed
• May or may not increase temperature
• Pulses allow for increased treatment
intensity and duration
• Not the same as “nonthermal”
Ultrasound & SWD Comparison
Energy type
Tissue heated
Tissue volume
Temp increase
Heat retention
C = Capacitive method
I = Induction method
Ultrasound
Acoustical
Collage-rich
Small (20 cm2)
1 MHz: > 6.3°F
3 MHz: > 14.9°F
3 min
Shortwave Diathermy
Electromagnetic
C: Skin, adipose tissue
I: Muscle, vessels
Large (200 cm2)
C: > 7°F
I: > 18°F
> 9 min
Biophysical Effects
Inflammation
• Assists in removal of cellular debris and
toxins
• Nonthermal:
– Alters diffusion rate across the cell membrane
• Thermal
– Increases intramuscular metabolism
Biophysical Effects
Blood and Fluid Dynamics
• Vasodilation increases:
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Blood flow
Capillary filtration
Capillary pressure
Oxygen perfusion
• Increased fibroblastic activity and capillary
growth
• Effects occur deeper than other forms of heat
Biophysical Effects
Tissue Elasticity
• SWD can vigorously heat deep tissues
• Alters collagen properties, allowing it to
elongate
• Requires stretching during and/or
immediately following the treatment
• Multiple treatments are required
Biophysical Effects
Wound Healing
• Nonthermal SWD increases rate of
phagocytosis
• Number of mature collage bundles increase
• ATP activity increases (assisting wound
regeneration)
• Necrosed muscle fibers decrease
Contraindications
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Metal implants or metal jewelry
Cardiac pacemakers
Ischemic areas
Peripheral vascular disease
Perspiration and moist
dressings: The water collects
and concentrates the heat.
• Tendency to hemorrhage,
including menstruation.
• Pregnancy
• Fever
• Sensory loss
• Cancer
• Areas of particular sensitivity:
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Epiphyseal plates in children
The genitals
Sites of infection
The abdomen with an
implanted intrauterine device
(IUD)
– The eyes and face
– Application through the skull