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Modalities Spring Midterm > Therapeutic Ultrasound > Flashcards

Therapeutic Ultrasound Flashcards

1
Q

What is therapeutic ultrasound?

A

High frequency mechanical waves delivered by acoustic energy

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2
Q

What is the advantage of therapeutic ultrasound?

A

depth of tissue penetration, heats tissue 2-5 cm deep

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3
Q

What structures does therapeutic US provide superior heating to?

A

structures with high collagen content

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4
Q

What is the frequency of US?

A

1 million - 3.3 million vibrations per second

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5
Q

What is the piezoelectric crystal inside the US made of?

A

synthetic plumbium zirconium titanate 2-3 mm thick

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6
Q

What does the crystal in US do?

A
  • converts electric energy to acoustic energy using high frequency AC current applied
  • mechanically deformed
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7
Q

What is special about piezoelectric?

A

ability to change shape in response to electric current
- expands and contracts at the same frequency as applied current
- when expands - molecules in front of it are compressed
- when compressed - molecules are rarefied

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8
Q

What does piezoelectric travel as?

A

a longitudinal wave

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9
Q

What is the effective radiating area?

A
  • don’t cover an area greater than 2x the sound head surface for treatment (2-3 times the ERA)
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10
Q

What is the spatial peak intensity regarding the beam nonuniformity ratio? Where is it greatest? lowest?

A
  • peak intensity of the US output over the area of the transducer
  • usually greatest in the center of the beam and lowest at the edges
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11
Q

What is the spatial average intensity regarding the beam nonuniformity ratio?

A
  • average intensity of the US output averaged over the on/off time of the pulse
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12
Q

What is the BNR?

A

the peak/avg of the spatial average intensity

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13
Q

What is the max BNR of the transducer?

A

between 5:1 and 6:1

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14
Q

What happens to the body’s absorption of the US with wave frequency with 3 MHz?

A

increases

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15
Q

What tissue does less energy go to with 3MHz?

A

deeper tissues

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16
Q

What depth are US wave absorbed at with 3MHz?

A

2-3 cm

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17
Q

What is the rate of absorption with 3MHz compared to 1MHz?

A

3-4x faster

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18
Q

What type of frequencies penetrate deeper?

A

LOWER

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19
Q

What is the effective treatment depth of 1MHz>

A

6 cm

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20
Q

What is the rate of absorption with 1MHz?

A

slower

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21
Q

What is attenuation?

A

as US enters the body, it gradually decreases in intensity due to attenuation
- frequency and tissue dependent
- increases with collagen content of tissue and higher frequencies

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22
Q

What does attenuation occur due to?

A
  • absorption, reflection, or refraction of the wave
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23
Q

What happens to the mechanical energy when US is absorbed into tissues?

A

converted to heat

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24
Q

What is the heat produced dependent on?

A
  • energy delivered and absorption coefficient
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25
Q

What is the energy delivered depend on?

A

US intensity and duty cycle

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26
Q

What does the absorption coefficient depend on?

A

collagen content and US frequency

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27
Q

What is responsible for around half of attenuation?

A

absorption

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28
Q

What is the other half of US attenuation due to (aside from absorption)?

A
  • reflection and refraction
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29
Q

What is reflection?

A
  • US beam redirected from a surface at angle equal and opposite of the original beam
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30
Q

When does reflection usually occur?

A

at tissue interfaces where impedance to sound changes
- WHY WE NEED US GEL

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31
Q

Where is the most reflection in the body?

A

Between bone and soft tissue
- MORE HEAT ACCUMULATES HERE

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32
Q

What are thermal effects of US?

A
  • increased metabolic rate
  • decreased pain and muscle spasms
  • change of nerve conduction velocity
  • improved circulation
  • increased soft tissue extensibility
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33
Q

What is US good for healing thermally?

A
  • tendons
  • lig
  • joint capsule
  • fascial
  • scar tissue
34
Q

What is heating in muscle tissue defined as ? ___ degrees celcius

A

4

35
Q

How long do clinicians usually treat muscle?

A

8 mins

36
Q

How long does it take to get to 3.5 degrees celsius with US?

A

11 mins

37
Q

How fast can superficial muscles be heated using 3MHz?

A

in 6 mins

38
Q

What is cavitation? (non thermal effect of US)

A

alternating compression and expansion of gas bubbles in tissue fluids caused by mechanical pressure, makes cell membranes more permeable

39
Q

What is microstreaming? (nonthermal effect of US)

A

eddying that occurs around any vibrating object

40
Q

What is acoustic streaming? (nonthermal effect of US)

A

movement of fluids along boundaries of cell membranes resulting from mechanical pressure waves
- produces alterations in cell membrane activity
- increased cell wall peremability
- increased intracellular calcium
- increase macrophage response
- increased protein synthesis

41
Q

What are nonthermal effects of US?

A
  • increase intracellular calcium levels
  • increase skin and cell membrane permeability
  • mast cell degranulation
  • promotes macrophage responsiveness (good for inflammatory phase)
  • promotes protein synthesis by fibroblasts
  • accelerates tissue healing and reduces the length of the inflammatory process
42
Q

What should we be aware of with thermal US?

A
  • continuous frequency
  • cautious of hotspots
  • use primarily before stretching of shortened soft tissue, before scar tissue mobilization and for pain control
43
Q

What should we be aware of with non-thermal ultrasound?

A
  • pulsed frequency (20% duty cycle)
  • no concern for hotspots
  • used for alternating membrane permeability to accelerate tissue healing
44
Q

What are some clinical uses of US?

A
  • soft tissue shortening (apply with tissue in lengthened position, continuous)
  • tendon and lig healing
  • bone fx
  • joint inflammation (pulsed)
  • phonophoresis
45
Q

When would we do soft tissue shortening US?

A
  • due to immobilization after casting or sx
  • shortened joint capsule, ligs, tendons
  • do stretch while US applied and stay in stretch after
  • 10 min US at 1.5 W/cm2
  • better ROM than without
46
Q

How much do we want to heat the tissue with soft tissue shortening?

A

dosage that increases tissue temp by 3-8 degrees C

47
Q

What are parameters for US for soft tissue shortening?

A

1MHz continuous at 1.5-2.5W/cm2 or 3MHz at 0.5-1.0 W/cm2

48
Q

How can US assist in altering pain transition or perception?

A
  • stimulation of thermal receptors
  • increased soft tissue extensibility
  • change in nerve conduction through increased temp
  • modulation of inflammation (nonthermal)
49
Q

What are the treatment parameters for US for pain control?

A
  • continuous duty cycle
  • 1MHz or 3MHz depending on tissue depth
  • 0.5-3.0 W/cm2 intensity for 3-10 mins
  • 8 min rule for billing
50
Q

What is the conflicting evidence for US for soft tissue healing and inflammation?

A

on efficacy of applying US to peri wound area
- reduction in wound size

51
Q

What is the strong evidence for soft tissue healing and inflammation?

A
  • US promoted healing of surgical incisions and relieve pain from scars when applied to chronic tissue injuries month or years after surgery
52
Q

What is the treatment parameters for US for soft tissue healing and inflammation?

A
  • indirect or peri wound technique
  • pulsed duty cycle
  • 3MHz
  • 0.5-1.0 W/cm2 fo 3-10 mins
    3x a week for 6-16 weeks
53
Q

What has US been reported to do for tendinopathies?

A

reduce tendon inflammation
- very effective for med/lat epicondylitis
- US and cross friction massage more effective than laser therapy

54
Q

What is the treatment parameters for US for tendon inflammation during acute phase?

A
  • dont aggravate and increase inflammation
  • pulsed (nonthermal)
  • 0.5-1.0 W/cm2 for 3-10 mins
55
Q

What are the treatment parameters for US for tendon inflammation during the chronic/subacute phase?-

A
  • continuous
  • increase in intensity as tolerated
  • combine with stretching assist in resolving chronic tendinosis
56
Q

What type of US is good for healing bone fractures?

A

low-intensity pulsed US (LIPUS?) can reduce fracture healing time
- very safe

57
Q

What are the treatment parameters of US for healing bone fx?

A
  • pulsed (nonthermal)
  • 1.5 MHz (DEEP)
  • 0.15 W/cm2 intensity for 15-20 mins per day
58
Q

What is phonophoresis?

A
  • application of US in conjunction with a topical drug preparation as the US transmission medium
59
Q

What are the benefits of phonophoresis? How does it work?

A
  • higher initial drug concentration at the delivery site initially, quickly moved around the body by vascular system
  • avoids stomach problems
  • avoids initial metabolism by the liver
  • works by thermal/nonthermal effect of increased permeability of the stratum corneum
60
Q

What types of medicines is phonophoresis mainly used by the therapist to deliver?

A

corticosteroids and local analgesics

61
Q

What conditions can phonophoresis be used to treat?

A

such as tendinitis, CTS, etc.

62
Q

What number of treatments is phonophoresis limited to?

A

6

63
Q

What are the treatment parameters for phonophoresis?

A
  • medication mixed in with US gel
  • pulsed duty cycle (nonthermal)
  • 3MHz (superficial)
  • 0.5-1.0 W/cm2 for 5-10 minutes
  • low intensities and longer time more effective for medication into skin
64
Q

What are contraindications for US?

A
  • malignant tumor
  • pregnancy
  • CNS issue if exposed by laminectomy above L2
  • Over methyl Methacrylate cement or plastics in joint replacement components
  • pacemaker or implantable cardiac rhythm device
  • thrombophlebitis
  • over the eyes
  • near the reproductive organs
65
Q

What are the precautions for US on epiphyseal plates?

A
  • high dose US will damage the open epiphyseal places, low dose at up to 0.5 W/cm2 was found to be safe
65
Q

What are the precautions for US on acute inflammation?

A

no US settings that could create heat

66
Q

What are the precautions for US for fractures?

A
  • only as described in fracture healing
67
Q

What are the precautions on US in breast implants?

A
  • high dose US should not be applied over a breast implant
68
Q

What are adverse effects of US?

A
  • burns if high intensity US is being used and the head is not used - KEEP THE HEAD MOVING, dont apply to areas with impaired sensation
  • standing waves if the US wave is reflected back and superimposed on the incident wave entering the tissue, avoid by moving US head throughout
  • Cross contamination of bacteria - clean heads and gel bottle
69
Q

Why do we need to move the US head at all times?

A
  • if stationary, center gets more US transmission, can overheat and burn patient
70
Q

What is the rate at which we need to move the US head to avoid burns?

A
  • ~4cm/sec
  • between 2-8 cm/sec and equal amount of US is absorbed
71
Q

How many treatments should we have before an effect should be able to be seen?

A

1-3 treatments an effect should be detectable

72
Q

How often can we use nonthermal US for earlier stages of healing?

A

daily if needed

73
Q

What is the recommended times per week for thermal US during the subacute/chronic healing stages?

A

3x/week

74
Q

What is the intensity for 1MHz frequency?

A

1.5 W/cm2- 2.5 W/cm2

75
Q

What is the intensity for 3MHz frequency?

A

0.5 to 1.0 W/cm2

76
Q

Greater frequency requires ________ intensity to achieve similar heat

A

less

77
Q

What is used to determine the final US intensity for thermal US?

A

The patients self report of warmth

78
Q

What will the patient complain of if the intensity is too high? Why?

A

a deep ache from overheating the periosteum = reduce intensity to avoid burns

79
Q

After __ - __ minutes if the patient does not feel heat, the intensity is too LOW

A

2-3

Modalities Spring Midterm (6 decks)

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