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Modalities > Deep Heating Agents: Therapeutic Ultrasound and Diathermy > Flashcards

Deep Heating Agents: Therapeutic Ultrasound and Diathermy Flashcards

1
Q

human ear can hear sound waves

A

16- 20,000 Hz

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2
Q

ultrasound

A

any sound wave ABOVE 20,000Hz

THERAPEUTIC US : range 750,000 - 3,000,000 Hz
most frequently used: 1 MHz and 3 MHz

imaging us: 3.5 MHZ - 10 MHZ

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3
Q

acoustic energy

A
  • different than electromagnetic energy
  • must travel through a medium
  • like electromagnetic energy: can be reflected, refracted, and absorbed
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4
Q

therapeutic ultrasound

A
  • deep heating agent
  • thermal and non-thermal effects
  • converts electrical energy into acoustical energy
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5
Q

transducer

A

converts one form of energy into another

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6
Q

Piezoelectric crystal

A

crystal capable of contracting and expanding –> creates “piezoelectric effect”

  • -> electric current
  • —-> mechanical vibration of crystal
  • ——–> wave of acoustic energy results
  • if damaged, can cause “hot spots” irregular sound waves, burn athletes
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7
Q

Reverse piezoelectric effect

A

as the AC reversed polarity, the crystal expands and contracts, producing US energy

  • –> high frequency sound waves (acoustical energy) delivered to the body
  • —> travels through tissues and is absorbed
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8
Q

Effective Radiating Area (ERA)

A

the area of the sound head that produces ultrasonic waves (expressed in cm squared)

  • energy output is greater at the center of ERA
  • temp is greater at the center of the ERA
  • always less than actual sound head
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9
Q

Beam profile

A

beam of energy emitted from crystal is NOT uniform

  • multiple waves emerge from head (areas of high and low intensity)
  • energy is more uniform closer to head
  • energy diverges as it moves away from source
  • becomes less consistent farther from head
  • –> spatial peak intensity: most energy in far field

2 TYPES:

  • divergent: goes out at angles
  • collimating: lines up, parallel, straight down
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10
Q

Beam Nonuniformity Ratio (BNR)

A
  • the consistency (uniformity) of the US output
  • ratio between the highest intensity in and ultrasound beam and the output reported on the meter
    • lower ratio = more uniform beam = 1:1 perfect
    • 8:1 ratio = unsafe
      lower ratio =
  • more comfortable
  • less hot spots
  • less risk of periosteal pain
  • cost more
  • safer, more effective
    because of hot spots, keep head moving
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11
Q

Sound Energy Absorption

A
  • higher protein density = more absorption
    ex: tendon, ligaments, muscles
  • high water and low protein content = less absorption
    ex: blood, fat

*although cartilage and bone have lots of protein, the majority of US energy striking the surface of either of these tissues is likely to REFLECT

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12
Q

Parameters: Frequency

A

determined DEPTH of treatment
depth inversely related to frequency
higher frequency = less depth of penetration

of waves per second
Hertz: cycles per second
Megahertz: 1 million cycles per second

1 MHz 
= low frequency 
= greater depth of penetration
= deep tissue ~4cm (5 or more cm)
= .2 deg C per minute per w/cm2 SLOW
= heating effects last 2x longer
= relatively divergent beam profile
3 MHZ 
= high frequency 
= less depth of penetration
= superficial tissue 2 cm (0.8 - 3cm)
= heats tissue 3 x faster than 1 MHz
   - .6 deg C per minute per w/cm2 FAST
= absorption occurs faster --> danger of burn
= relatively collimating beam profile
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13
Q

Parameters: Dosage

A

Watts/ surface area (cm2)
higher dose = more sound energy delivered to tissues in less time
—> longer tx time for lower intensities
common dose: 1.5 w/cm2
doses greater than 2.5-3 may cause tissue damage
- depends on type of tissue, condition, duration

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14
Q

Rate of Ultrasound Heating

A

Temperature Increase per Minute
INTENSITY 1 MHz 3 MHz
(TISSUE DEPTH) (5cm) (1.2 cm)
0.5 0.04 deg C 0.3 deg C
1.0 0.2 deg C 0.6 deg C
1.5 0.3 deg C 0.9 deg C
2.0 0.4 deg C 1.4 deg C

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15
Q

treatment area

A

no greater than 2-3 times the ERA

  • keep sound head moving, slowly
  • maintain good contact with skin
  • larger area = less energy reaching tissue = less temp increase
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16
Q

coupling methods

A

US requires medium for energy to be transmitted from sound head to body tissue

1) direct coupling - transducer and gel in direct contact with skin
2) pad/bladder method - conforms to irregular shaped areas and limits treatment area size to allow more energy to be transmitted
3) immersion (water) - for treating irregularly shaped areas, sound head ~1” away in ceramic/plastic/rubber tub

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17
Q

If patient complains of pain or excessive heat

A

DECREASE intensity

INCREASE time

18
Q

Parameters: Duration

A

5-10 min (not <3min)
time based on treatment area
larger = longer
daily, decrease with improvement

19
Q

Parameters: Duty Cycle

A

continuous vs pulsed
continuous (100%) = thermal effects
pulsed (50%, etc.) = non thermal effects at cellular level, maybe some thermal effects but not as much as continuous

20
Q

Thermal Effects

A

MILD heating of 1 deg C

  • -> increased metabolic activity, initiation of inflammatory process
  • subacute phase (instead of pulsed)

MODERATE heating of 2-3 deg C

  • -> increased blood flow
  • -> decreased pain
  • -> decreased muscle spasm
  • -> decreased chronic inflammation
  • used most often (ex: tendonitis)

VIGOROUS heating of 3-4 deg C

  • -> improved viscoelastic properties of collagen
  • used post surgical, when trying to break up scar tissue
21
Q

Non Thermal Effects

A
  • primarily occur with pulsed US
  • little heat is produced due to dissipation that occurs during off time
    CAVITATION
  • stable = Good
  • unstable = bad
    ACOUSTIC MICROSTREAMING
22
Q

Cavitation

A

formation of gas filled bubbles that expand and compress –> pressure changes in tissue fluids

(1) stable cavitation: rhythmic contaction and expansion of gas bubbles
- facilitate fluid movement and membrane transport
- -> GOOD

(2) unstable cavitation: formation of bubbles at the low pressure part of the US cycle
- results in bubble collapse and tissue damage
- -> BAD

23
Q

Acoustical Microstreaming

A

unidirectional movement of fluids along the boundaries of cell membranes

  • us causes interstitial fluids to flow
  • fluids strike cell membranes
  • -> altering cell membrane permeability to Na and Ca ions important in the healing process
  • –> altering cell function

CELLULAR RESPONSE:

  • increases cell membrane permeability
  • alters cell membrane diffusion rate
  • increased histamine release
  • mast cell degranulation
  • increased rate of protein synthesis
24
Q

Indications

A
  • maybe prior to stretching and manual therapy when pt has restricted ROM
  • calcific tendonitis of the shoulder
  • scar tissue and joint contracture
  • -> inc tissue temp = inc elasticity
  • nontherapeutic use: identifying stress fx
    • continuous at 1 MHz, move slow, gradually increase intensity to 2.0 w/cm2
25
Q

Precautions

A
  • always use the lowest intensity to produce a therapeutic response
  • keep sound head moving
  • educate pt on what to feeel
  • caution with pacemaker or implanted electronic device
  • –> continuous not advised over metal implants
  • NEVER go over spine or face
26
Q

Contraindications

A
  • acute conditions
  • ischemic areas
  • impaired circulation
  • anesthetic areas
  • DVT
  • over active infection
  • over spinal cord
  • around hear, eyes, skull, or genitalia
  • over thorax in patient with pacemaker
  • over abdomen during pregnancy
  • over fx sites
  • over pelvic or lumbar area during menstruation
  • cancer
  • joint replacement (not continuous over metal)
27
Q

Combo: US and Stim

A
  • used to tx trigger points and muscle spasms

- thermal US and motor level estim

28
Q

phonophoresis

A

US used to deliver a medication via safe, painless, noninvasive technique

  • opens pathways to drive molecules into tissues
  • not likely to damage or burn skin like ionto
  • ex: dexamethasone (analgesic) and hydrocortisone (anti-inflammatory), script required
  • little evidence to support tx
28
Q

Short wave diathermy

A

therapeutic generation of local heating by high frequency electromagnetic waves
- shortwave or microwave diathermy
- continuous or pulses
primary benefit: increase local blood flow (delivery of nutrients and oxygen) from tissue heating
–> facilitating tissue repair

29
Q

continuous diathermy

A
  • used mainly with CHRONIC injuries
  • increases tissue temp
  • increases risk of burns
30
Q

pulsed diathermy

A
  • may or may not increase temp
  • –> higher pulse frequency = more tissue heating
  • –> heats to depth of 3-5cm
  • –> tissue temp controlled by duration (max 4-6 deg C increase)
  • transfers energy via high frequency current
  • pulse allows for increased tx intensity and duration
  • not the same as “non thermal”
31
Q

Advantages of Diathermy

A
  • thermal effects similar to US, but effect DEEPER tissue
  • heats larger area of tissue
  • doesn’t reflect from bone so less likely to create “hot spots”
  • pulsed can create thermal effects as week
  • heat retained 3 x longer
32
Q

Disadvantages of Diathermy

A
  • expensive
  • can only treat one pt at a time
  • potential for burns
32
Q

Disadvantages of Diathermy

A
  • expensive
  • can only treat one pt at a time
  • potential for burns
33
Q

Types of Shortwave Diathermy

A

(1) Induction field generators
- places pt IN the electromagnetic field
- magnetic waves generated as electric current is conducted through coiled wire
- produces greatest heat within the muscle directly beneath the coil
- induction cable or induction drum (most common)
- greatest heating in tissues with good electrical conductance (muscles, blood vessels, nerves)
- safer than capacitive fg

(2) capacitive field generators
- body is actually place IN the electric field as part of the circuit: pt place between 2 electrodes of opposite charge
- affects tissue under each plate
- electrical signals sent through body, acts as resistor
- tissues with greatest resistance create most heat as current flows through path of least resistance
- -> not recommended for pts with thick layer of adipose

34
Q

Types of Shortwave Diathermy

A

(1) Induction field generators
- places pt IN the electromagnetic field
- magnetic waves generated as electric current is conducted through coiled wire
- produces greatest heat within the muscle directly beneath the coil
- induction cable or induction drum (most common)
- greatest heating in tissues with good electrical conductance (muscles, blood vessels, nerves)
- safer than capacitive fg

(2) capacitive field generators
- body is actually place IN the electric field as part of the circuit: pt place between 2 electrodes of opposite charge
- affects tissue under each plate
- electrical signals sent through body, acts as resistor
- tissues with greatest resistance create most heat as current flows through path of least resistance
- -> not recommended for pts with thick layer of adipose

35
Q

US vs Diathermy

A
  • acoustical vs electromag energy
  • collagen rich vs good conductors tissue heated
  • small vs. large tx area
  • diathermy has greater temp increase
  • diathermy has deeper heat retention
36
Q

indications of diathermy

A
  • skin or underlying soft tissue is tender
  • areas where subcutaneous fat is thick and deep heating is required (induction)
  • when tx goal is to increase tissue temp over LARGE area
37
Q

indications of diathermy

A
  • skin or underlying soft tissue is tender
  • areas where subcutaneous fat is thick and deep heating is required (induction)
  • when tx goal is to increase tissue temp over LARGE area
38
Q

biophysical effects of diathermy

A

TISSUE ELASTICITY

  • can vigorously heat tissue
  • alters collagen properties –> elongate
  • requires stretching during and/or immediately after tx
  • multiple tx required
39
Q

Contraindications of Diathermy

A
  • metal implants or metal jewelry
  • cardiac pacemakers
  • ischemic areas
  • peripheral vascular disease
  • perspiration and moist dressings (water concentrated heat)
  • tendency to hemorrhage (menstruation)
  • pregnancy
  • fever
  • sensory loss
  • cancer
  • areas of sensitivity (epiphyseal plates in kids, genitals, sites of infection, abdomen with an implanted intrauterine device, eyes and face, application through skull)

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