Diathermy Flashcards
1
Q
Diathermy
A
-Through heat
- high frequency modality emitting electromagnetic energy
-
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
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
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
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
6
Q
Short wave diathermy current flow greatest in:
A
tissues with least resistance (fat)
7
Q
Short wave diathermy current absorption greatest in:
A
tissues with low impedance (muscle, blood)
8
Q
Continuous shortwave diathermy used to treat:
A
- 1930s: treat infections
- today: used with caution due to rapid and vigorous heating of tissue
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
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
11
Q
PSWD: for subacute inflammation
A
- mild warmth
- pulse width: 100usec-200usec
- pulse rate: 800 or 400 pps
- Avg watts:24
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
13
Q
PSWD: stretching collagen-rich tissues
A
- vigorous heating
- pulse width: 400usec
- pulse rate: 800 pps
- avg watts:48
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
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)
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
Induction Electrodes
- 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
Induction electrode types: Cable
- 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
Induction electrode types: Drum
- 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
Dosometry qualitative scale
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
Dosometry quantitative scale
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
Dosometry quantitative scale: pulsed mode power
- 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
Dosometry quantitative scale: continuous mode power
- power in continuous mode may be up to 800 watts
| - Dose= Peak power x time
32
Pulsed shortwave diathermy
- 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
Pulsed shortwave diathermy
- 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
Continuous shortwave diathermy
- 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
