Diathermy

Question 1

Diathermy

Answer 1

-Through heat
- high frequency modality emitting electromagnetic energy
-

Question 2

Diathermy types

Answer 2

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

Question 3

Microwave diathermy

Answer 3

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

Question 4

Short wave diathermy

Answer 4

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

Question 5

Short wave diathermy how it works

Answer 5

• 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

Question 6

Short wave diathermy current flow greatest in:

Answer 6

tissues with least resistance (fat)

Question 7

Short wave diathermy current absorption greatest in:

Answer 7

tissues with low impedance (muscle, blood)

Question 8

Continuous shortwave diathermy used to treat:

Answer 8

• 1930s: treat infections

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

Question 9

Pulsed short wave diathermy (PSWD)

Answer 9

• 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

Question 10

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

Answer 10

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

Question 11

PSWD: for subacute inflammation

Answer 11

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

Question 12

PSWD: pain reduction, muscle spasm, chronic inflammation

Answer 12

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

Question 13

PSWD: stretching collagen-rich tissues

Answer 13

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

Question 14

Proposed theory for thermal effects of diathermy

Answer 14

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

Question 15

Diathermy thermal effects

Answer 15

• 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)

Question 16

Diathermy non thermal effects

Answer 16

• 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

Question 17

Clinical indications for use of PSWD

Answer 17

• Control pain and edema
• pain control
• wound healing
• nerve healing
• bone healing

Question 18

Diathermy indications

Answer 18

Same as other thermal modalities

Question 19

Diathermy contraindications

Answer 19

• 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)

Question 20

Diathermy advantages

Answer 20

• 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

Question 21

diathermy disadvantages

Answer 21

• Equipment is costly and difficult to set up effectively

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

Question 22

Capacitor electrodes

Answer 22

• 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

Question 23

Capacitor electrode types: air spaced plates

Answer 23

• 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

Question 24

Capacitor electrode types: pad electrodes

Answer 24

• 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

Question 25

Induction Electrodes

Answer 25

- 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

Question 26

Induction electrode types: Cable

Answer 26

- 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

Question 27

Induction electrode types: Drum

Answer 27

- 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

Question 28

Dosometry qualitative scale

Answer 28

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

Question 29

Dosometry quantitative scale

Answer 29

Based upon the amount of energy delivered to pt during tx - Parameters * power: watts * frequency: pulses per second (PPS) * mode: continuous/pulsed * Duration: time

Question 30

Dosometry quantitative scale: pulsed mode power

Answer 30

- 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)

Question 31

Dosometry quantitative scale: continuous mode power

Answer 31

- power in continuous mode may be up to 800 watts | - Dose= Peak power x time

Question 32

Pulsed shortwave diathermy

Answer 32

- 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

Question 33

Pulsed shortwave diathermy

Answer 33

- 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

Question 34

Continuous shortwave diathermy

Answer 34

- 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