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Shortwave Diathermy

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					Shortwave Diathermy
       Chapter 9
               Description
   High-frequency electrical currents
    – Radio waves
 Pass through the tissues
 Cause molecular vibration
 Results in deep heating
 Capable of heating large volumes of
  tissues
 Causes both thermal and nonthermal
  effects
                    Uses
Thermal Effects          Nonthermal Effects
 Deep heat               Edema reduction
 Increased blood flow    Lymphedema
 Increased cell           reduction
  metabolism              Superficial wound
 Increased tissue         healing
  extensibility           Treatment of venous
 Muscular relaxation      stasis ulcers
 Possible changes in
  enzyme reactions
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
      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

                        Ultrasound        Shortwave Diathermy
Energy type             Acoustical        Electromagnetic
Tissue heated           Collage-rich      C: Skin, adipose tissue
                                          I: Muscle, vessels
Tissue volume           Small (20 cm2)    Large (200 cm2)
Temp increase           1 MHz: > 6.3°F    C: > 7°F
                        3 MHz: > 14.9°F   I: > 18°F
Heat retention          3 min             > 9 min
C = Capacitive method
I = Induction method
            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:
    –   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
   Metal implants or metal            Sensory loss
    jewelry (be aware of body          Cancer
    piercings)                         Areas of particular sensitivity:
   Cardiac pacemakers                   – Epiphyseal plates in children
   Ischemic areas                       – The genitals
   Peripheral vascular disease          – Sites of infection
   Perspiration and moist               – The abdomen with an
    dressings: The water collects          implanted intrauterine device
    and concentrates the heat.             (IUD)
   Tendency to hemorrhage,              – The eyes and face
    including menstruation.              – Application through the skull
   Pregnancy
   Fever