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Passive Care > 9 - Ultrasound > Flashcards

9 - Ultrasound Flashcards

1
Q

US background

A
  • High frequency sound waves
  • Deep heating modality
  • mechanical effects
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2
Q

UC mechanism

A
  • electrical current passes through a crystal –> vibration
  • soundwaves are generated by vibrating crystal
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3
Q

UC duty cycle

A
  • continuous = 100%
  • pulsed = 50%
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4
Q

Piezoelectric effect

A

mechanical deformation of a crystal causes an electrical current to form

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5
Q

Reverse Piezoelectric effect

A
  • alternating current is passed through a crystal
  • results in very fast contractions and expansion of the crystal
  • this vibration proudces high frequency sound waves
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6
Q

Near field

A

treatment area

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7
Q

Far field

A

indirect effect

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8
Q

What determines the quality of US?

A
  • Effective Radiating Area (ERA)
  • Beam Nonuniformity Ratio (BMR)
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9
Q

Effective Radiating Area (ERA)

A

Area of the sound head that produces energy

  • Will always be smaller than the size of the US head
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10
Q

Beam Nonuniformity Ratio (BNR)

A

amount of variability of the US beam

  • BNR = (spatial peak)/(spatial average)
    • Ideal ratio = 1:1
    • Lower BNR = more uniform intensity,
  • US beams are not uniform across the US head
  • Ratio btwn Peak Intensity of the US beam, divided by Average Intensity of US beam
  • Used to compare quality of different machines
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11
Q

Peak Area of Maximum Beam Nonuniformity Ratio (PAMBNR)

A

describes the area of the sound head covered by the peak insitensity

  • Large PAMBNR = peak intensity covers a small area, thus LESS UNIFORM heating
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12
Q

Conducting media

A

used to help prevent reflection of sound waves by air

  • keep sound head flat against can, 90°
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13
Q

Gel Pad for indirect ultrasound

A

pad will decrease intensity of US current

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14
Q

Underwater ultrasound

A
  • indirect US
  • use plastic basin/bucket
  • wipe bubbles from skin and sound head occasionally
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15
Q

Amplitude for US

A
  • dosage = amount of energy per square centimeter (W/cm2)
  • more watts = more heat (NOT greater penetration)
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16
Q

frequency for US

A

affects depth of tissue, and time

  • high-frequency (3 MHz) = superficial tissue
  • low-frequency (1 MHz) = deep tissue
17
Q

Duty cycle for US

A
  • interrupted (pulsed)
  • Continuous = more energy delivered and absorbed. Greater tissue healing
18
Q

Absorption of US

A
  • Skin and fat absorb the least
  • [higher] of tissue = more absorption
19
Q

US Scatter

A

occurs when US wave entoucters a boundary btwn tissues

  • Reflection = occurs at soft tissue(muscle)/bone interface
  • Refraction = occurs at fascia/muscle interface (ie where tendons join bone)
20
Q

US tissue heating

A
  • causes increase metabolic activity
  • Good for REPAIR PHASE
  • Increase temp => decrease muscle spasm
21
Q

US Tx time

A
  • Deep tissue = 10 minutes
  • Superficial tissue = 5 minutes
22
Q

US Therapeutic effects

A
  • Increase: collagen fiber of tendons, blood flow, metabolism,
  • Decrease: joint stiffness, spasms
  • Healing = tendon, ligament, muscle
23
Q

Pulsed US

A
  • Little/no tissue heating
  • Affects tissue healing at cellular level
  • Works via acoustical streaming and stable cavitation
24
Q

Acoustical streaming

A

movement of fluids along cell membranes due to mechanical pressures exerted by soundwaves

25
Q

Cavitation

A

formation of gas filled bubbles from pressure changes in tissue fluids

26
Q

stable cavitation

A

arithmetic expansion and contraction of bubbles during repeated pressure changes over many acoustic cycles

27
Q

Unstable cavitation

A

collapse of gas bubble which may cause tissue damage

  • associated with low-frequency, high intensity US
28
Q

US risks

A
  • bony prominences
  • epiphyseal plate
29
Q

US intensity

A

0.5 – 2.5 W/cm2

  • higher intensity is NOT necessarily more effective
  • do not exceed peak intensity of 8.0 W/cm2
  • general rule: intensity = 1.0 w/cm2‑
30
Q

US Tx time

A

5 – 8 minutes

  • depends on size of treatment area
  • never Tx for 15 minutes
31
Q

Phonophoresis (Sonophoresis)

A

using soundwaves to drive medication into tissue

  • lacks supporting efficacy
32
Q

Combo: US + Stim

A

US head becomes the treating lecture when used with the dispersal pad

  • trigger points
  • epicondylitis
  • superficial pain in areas
  • decrease adhesions
33
Q

low intensity pulsed ultrasound (LIPUS)

A
  • stimulation of fracture healing
  • good evidence backing it

Passive Care (5 decks)

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