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Physical Agents > Diathermy > Flashcards

Diathermy Flashcards

1
Q

Diathermy

A

-Through heat
- high frequency modality emitting electromagnetic energy
-

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2
Q

Diathermy types

A 
Long wave ( 1 MHz, 300 m)
-no longer in use
Shortwave (27.12 MHz; 11m)
-within shortwave radio spectrum
-regulated by FCC
- Forms mainly magnetic fields in tissue
Microwave ( 2450 MHz; 0.12m)
-forms mainly electric fields in tissue
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3
Q

Microwave diathermy

A

Rarely used in US anymore due to:

  • metal in vicinity
  • skin burning
  • overheating of superficial tissue
  • increase reflection at tissue interfaces
  • loss of energy to surrounding environment
  • hot spots
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4
Q

Short wave diathermy

A

Uses high frequency (10-100 MHz) EMW to heat tissues

  • basically radio transmitter
  • available frequencies and wavelengths (FCC)
    • 27.12 MHz—11m
    • 13.56 MHz– 22m
    • 40.68 MHz– 7.5 rarely used
  • pt acts as radio receiver and is tuned in as part of circuit allowing for transfer of energy to the pt
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5
Q

Short wave diathermy how it works

A
  • converts AC current into radio frequency
  • passed into flat coil inside a drum
  • produces fluctuating magnetic field
  • in tissue magnetic field produces:
  • increase in kinetic motion along molecules
  • Eddy currents
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6
Q

Short wave diathermy current flow greatest in:

A

tissues with least resistance (fat)

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7
Q

Short wave diathermy current absorption greatest in:

A

tissues with low impedance (muscle, blood)

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8
Q

Continuous shortwave diathermy used to treat:

A
  • 1930s: treat infections

- today: used with caution due to rapid and vigorous heating of tissue

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9
Q

Pulsed short wave diathermy (PSWD)

A
  • Used to create both thermal and non thermal effects
  • pulse width
  • wider pulse generates more energy to tissue
  • measured in usec (20-400)
  • Pulse rate
    • the greater the pps, the greater the amount of energy produced and transmitted into tissue
    • measured in Hz
  • Power (intensity) measured in watts
  • on time is shorter than off time
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10
Q

PSWD: for acute trauma, no noticeable inflammation, edema reduction, cell repolarization and repair

A
  • nonthermal
  • pulse width: 65usec
  • pulse rate: 100-200 pps
  • Avg watts: N/A
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11
Q

PSWD: for subacute inflammation

A
  • mild warmth
  • pulse width: 100usec-200usec
  • pulse rate: 800 or 400 pps
  • Avg watts:24
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12
Q

PSWD: pain reduction, muscle spasm, chronic inflammation

A
  • moderate warmth
  • pulse width: 200-400usec
  • pulse rate: 800 or 400 pps
  • Avg watts: 24
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13
Q

PSWD: stretching collagen-rich tissues

A
  • vigorous heating
  • pulse width: 400usec
  • pulse rate: 800 pps
  • avg watts:48
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14
Q

Proposed theory for thermal effects of diathermy

A 
Ionic Oscillation
- charged particles oscillate producing kinetic energy
- NA+, K+, Cl-
Dipole rotation
-dipolar or water molecules
- H+, O-
-rotate and produce kinetic energy
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15
Q

Diathermy thermal effects

A
  • increase local metabolism
  • local vasodilation
  • muscle relaxation
  • sedation of sensory nerve endings
    • if heat is mild
    • leads to increased pain threshold
  • increased local perspiration
  • increased collagen extensibility
  • increased nerve growth and repair
  • increased body temp, pulse rate, & decreased blood pressure (possible)
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16
Q

Diathermy non thermal effects

A
  • reploarization of damaged cells
  • regularization of cell growth
  • reestablishment of NA+ pump
  • increased microvascular perfusion
  • increased locally in healthy pts and pts with diabetic ulcers
  • improved cell function
  • increased white cells in wound
  • altered cell membrane function and cellular activity
    • affect ion binding on cell membrane which triggers growth factor activation in fibroblasts and nerve cells, macrophage activation, and changes in myosin phosphorylation
    • affect regulation of cell cycle by altering calcium ion binding
17
Q

Clinical indications for use of PSWD

A
  • Control pain and edema
  • pain control
  • wound healing
  • nerve healing
  • bone healing
18
Q

Diathermy indications

A

Same as other thermal modalities

19
Q

Diathermy contraindications

A
  • acute traumatic Musculoskeletal injuries
  • acute inflammatory conditions
  • pts who have tendency to hemorrhage ( including menses)
  • cancer may spread due to increased blood flow
  • already existing fever will be elevated
    -over eyes or with contact lens
    over ischemic tissue ( may burn due to inadequate blood flow)
  • pts with cardiac disease (cannot tolerate increased demand on heart that is produced by heat)
  • over pregnant uterus
  • over epiphyseal plates in adolescents
  • metal in Tx area that cannot be removed
  • metal implants that form a loop
  • transcutaneous nerve simulators (pacemakers)
  • surface metal in area ( jewelry, snaps on clothes)
20
Q

Diathermy advantages

A
  • when tissues cannot tolerate the weight of external heating modalities
  • has ability to reach deeper tissue
  • can cause mild rise in tissue temp deep to subcutaneous fat
  • can treat a larger area than US
  • is not reflected by bone therefore will not cause periosteal burning
21
Q

diathermy disadvantages

A
  • Equipment is costly and difficult to set up effectively

- depending upon the set up tissue being treated may not be visible

22
Q

Capacitor electrodes

A
  • creates stronger electric field than magnetic field
  • positively charged electrode (repels + ions, repels - ions)
  • center of electric field has higher current density
  • pt placed between two electrodes or plates and becomes part of electric circuit
  • tissues that offer greatest resistance to current flow develop greatest heat
  • fat has highest resistance to current flow of biologic tissues
  • caution using capacitor electrodes due to heating of subcutaneous fat
23
Q

Capacitor electrode types: air spaced plates

A
  • seldom used anymore
  • two metal plates 7.5-17.5 cm in diameter
  • surrounded by glass or plastic guard
  • sensation of heat directly proportional to distance of plate to skin (inverse square law)
  • greatest surface heat will be under the electrodes
  • body areas low in subcutaneous fat (hands, feet, wrists, ankles, spine, ribs) suitable for this tx
24
Q

Capacitor electrode types: pad electrodes

A
  • must have uniform contact with skin
  • several layers of toweling necessary between pads and the skin
  • pads should be separated at least as far apart as they are wide
  • increasing distance between pads increases depth of penetration
  • tissue to be treated should be centered between pads
25
Q

Induction Electrodes

A
  • Stronger magnetic field than electric field
  • induces localized secondary “eddy currents”
  • pt is in magnetic field
  • greatest current flow is in tissue with least resistance
  • tissues high in electrolyte content increase in temp
    • muscle and blood
  • heating may not be as noticeable to pt
26
Q

Induction electrode types: Cable

A
  • Pancake-coil wound flat
  • center coil should be greater than 6 cm in diameter
  • 1 cm of toweling between coil and skin
  • spacers used to keep coils 5-10 cm between turns
27
Q

Induction electrode types: Drum

A
  • one or more monoplanar coils fixed inside a housing
  • one drum set up for small areas
  • hinged for larger or contoured areas
  • depth of penetration> 2-3 cm if drum is no more than 1-2 cm from skin
  • a towel must be placed between skin and drum to absorb moisture and prevent “hot spots”
  • housing should be in contact with toweling for best penetration
28
Q

Dosometry qualitative scale

A

Based upon pt’s perception of heat during tx

  • dose I: no perception of heat
  • dose II: mild perception of heat
  • does III: comfortable perception of heat
  • dose IV: max tolerable perception of heat
29
Q

Dosometry quantitative scale

A

Based upon the amount of energy delivered to pt during tx

  • Parameters
    • power: watts
    • frequency: pulses per second (PPS)
    • mode: continuous/pulsed
    • Duration: time
30
Q

Dosometry quantitative scale: pulsed mode power

A
  • In pulsed mode, mean power is equal to:
    mean power=peak power (W) x pulse duration (s) x frequency (f) (pm=PpxPDxF)
  • Dose= Pm(mean power, W) x Time (s)
31
Q

Dosometry quantitative scale: continuous mode power

A
  • power in continuous mode may be up to 800 watts

- Dose= Peak power x time

32
Q

Pulsed shortwave diathermy

A
  • AKA pulsed electromagnetic energy (PEME), Pulsed Electromagnetic Field (PEMF), or Pulsed Electromagnetic Energy treatment (PEMET)
    • energy delivered in series of high frequency bursts or pulse trains
    • pulse duration- 20 to 400 microsec
    • pulse intensity- 1000 W/pulse
    • pulse repetition rate- 1-7000 Hz
    • off cycle allows heat to dissipate thus reducing likelihood of perception of heat by pt
33
Q

Pulsed shortwave diathermy

A
  • delivered by drum or pad electrode
  • capable of treating larger areas than US
  • stationary set-up allows for more constant heating of tissue
  • decay of heating in target tissue slower than for US thus allowing more time for manual techniques
34
Q

Continuous shortwave diathermy

A
  • Part of EMS
  • creates electric and magnetic fields in tissue
  • produces thermal and non-thermal effects
  • capable of heating deep tissue
  • advantages over TUS
    • treat larger area
    • stationary technique
    • tissue temp degradation slower

Physical Agents (21 decks)

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