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PHTY2240 MSE > L4/5: Therapeutic ultrasound > Flashcards

L4/5: Therapeutic ultrasound Flashcards

1
Q

What are the 3 uses of ultrasound?

A
  1. Therapeutically used for real‐time imaging
  2. Medical uses for destroying tissue
  3. Similar to laser (search for kidney stones)
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2
Q

It was shown that patients who already knew about ultrasounds had ____ (better/worse) outcomes.

A

better

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3
Q

What is ultrasound?

A

sound energy of frequencies <20,000Hz mechanical energy produced by longitudinal waves which compress and rarefy materials

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4
Q

Therapeutic US has frequencies between____ and ____ MHz

A

0.75; 3

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5
Q

What are 5 things that US produce?

A
  1. Piezo‐electric crystals (e.g. Quartz) are crystalline solids which respond by changing thickness in response to an applied voltage
  2. Thickness changes in an oscillatory manner
  3. Crystal cut in thickness to naturally vibrate as a desired frequency
  4. Held in contact with metal faceplate of transducer
  5. Transforms electric to mechanical energy
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6
Q

What are the 2 types of ultrasound?

A
  1. Therapeutic
  2. Diagnostic
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7
Q

What are 4 characteristics of ultrasound?

A
  1. Longitudinal waves
  2. Mechanical compressions and rarefaction
  3. Requires a medium for transmission e.g. water, gel
  4. Follows same rules of reflection, absorption, refraction and dispersion
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8
Q

What does ultrasound reflection and refraction look like? How does this help therapeutically?

A

Access deep tissue

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9
Q

What does the absorption of US look like? What does this lead to?

A

leads to heat generation in the tissue

Can penetrate deeper than hot packs..etc - ~5 cm

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10
Q

What are 4 features that the ultrasound units consist of?

A
  1. Oscillating voltage to drive the transducer
  2. Controlling circuit which can turn on oscillator on or off to give pulsed US (2ms)
  3. Resistance circuit to control the amplitude (w/cm2)
  4. Meter which measures electrical oscillations NOT the vibration of the crystal
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11
Q

What does an ultrasound head look like?

A

ADD

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12
Q

Sound waves need a _____ to be conducted.

A

medium

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13
Q

___ is a poor conducting medium. _____ and ____ are the best mediums.

A

Air; US gel; water

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14
Q

What is ultrasound attenuation?

A
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15
Q

What is acoustic impedence?

A

How much is absorbed by the tissue

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16
Q

The transmission of sound waves depends on on the _____ of the tissue and the _____ of the beam

A

acoustic impedance; direction

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17
Q

At boundaries between tissues – some _____ and ______ occurs, which may May alter both the intensity and direction of the beam

A

reflection; refraction

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18
Q

Bone or tissue that are full of protein absorb ultrasound ____ (more/less) readily. Why must we be careful?

A

more

Must be careful if bone is superficial can heat up

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19
Q

Sound waves can pass _____ (well/poorly) through fatty tissue

A

well

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20
Q

Clinical implication ensure sound head is ______ (parallel/perpendicular) to skin to ensure maximum penetration

A

perpendicular

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21
Q

What are the 5 treatment parameters of US?

A
  1. Mode
  2. Frequency
  3. Intensity
  4. Duration
  5. Treatment area size
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22
Q

What are the 2 types of mode for US?

A
  1. Continuous
  2. Pulsed
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23
Q

What are 2 characteristics of the continuous mode of US?

A
  1. Sound energy remains constant
  2. US energy produced 100% of time
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24
Q

What are 2 characteristics of the pulsed mode of US?

A
  1. Energy is periodically interrupted
  2. No US energy during ‘off’ period
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25
Q

When and why is the continuous mode used in treatment?

A

Chronic conductions –> produce heat when used with higher intensities

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26
Q

Why should the continuous mode not be used in acute/subacute conditions?

A

Will create too much heat and possibly aggravate the symptoms (eg. inflammation)

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27
Q

When and why is the pulsed mode used in treatment?

A
  • Acute and subacute
  • Pulse more times but less duration Eg. 1/4 on and 3/4 off Limited the heating effects
  • Allows tissues to cool down
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28
Q

Why should the pulsed mode not be used in chronic conditions?

A

Not effectiveness enough as it doesn’t create heat

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29
Q

What are the 2 ratios used for acute injuries (Immediately following injury) when using pulsed US?

A

1:3 and 1:4

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30
Q

What is the ratio used for subacute injuries (Immediately following injury) when using pulsed US?

A

1:1

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31
Q

What is duty cycle in regards to US?

A

Percentage of time that US is generated (pulse duration) over pulse period

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32
Q

What is the equation for duty cycle?

A
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33
Q

What is the mark: space ration?

A

ratio of the pulse length to the interval (2ms pulses) eg 1:3

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34
Q

What is the range of frequency?

A

0.75Mhz – 3Mhz

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35
Q

What is frequency in regards to US?

A

determines the depth of tissue penetration not the intensity (higher intensity deliver

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36
Q

What frequency do you use for superficials tissues?

A

3MHz

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37
Q

What frequency do you use for superficials tissues?

A

1MHz

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38
Q

The depth of tissue penetration is dependent on US ______.

A

frequency

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39
Q

What is the half-value depth?

A

depth of penetration at which intensity is decreased by half

How deep the wave will go until 1/2 of the wave is absorbed

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40
Q

Tissues with high protein (collagen) and low water absorb the US ___ (more/less) readily (bone, cartilage)

A

more

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41
Q

Tissues with water and fat will absorb US ____ (more/less) readily and will allow US to penetrate ______ (further/less)

A

less; further

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42
Q

What is approximate average depth (cm) when using a 1MHz US?

A

6.5 cm

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43
Q

What is approximate average depth (cm) when using a 3MHz US?

A

3cm

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44
Q

What are the depths when using 1MHz and 3MHz in different materials (water, fat, muscle, skin, tendon, cartilage and bone)

A
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45
Q

The half depth value also vary depending on ______of fibers within beam (if in line with muscle fibre HVD is three times higher than when applied at right angles (most common therapeutically)

A

alignment

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46
Q

What is the intensity in regards to US?

A
  • Rate at which energy is being delivered per unit area
  • Watts per centimetre squared W/CM2
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47
Q

What is the spacial average intensity (SAI)?

A

Divide power output by total ERA

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48
Q

What is the safety limit of the SAI in therapeutic US?

A

3.0W/CM2

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49
Q

In medical applications of US, what intensity is used to surgically destroy tissue?

A

>10W/CM2

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50
Q

In medical applications of US, what intensity is used for diagnostic purposes?

A

<0.1W/CM2

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51
Q

What is the rule for intensity?

A

lowest intensity and highest frequency to produce desired result

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52
Q

As a rule, the _____ (highest/lowest) intensity and _____ (highest/lowest) frequency to produce desired result

A

lowest; highest

53
Q

What are the general guidelines used for intensity of acute conditions?

A

0-0.5W/CM2

54
Q

What are the general guidelines used for intensity of chronic conditions?

A

0.5-1W/CM2

55
Q

______ W/cm2 doses are associated with adverse affect on tissue healing

A

1.5

56
Q

When if doing in water or through water bag – increase intensity by ____%

A

20

57
Q

What is something important to remember about intensity when doing US in water or through a water bag?

A

Increase the intensity by 20%

58
Q

What are the 2 types of pulsed US?

A
  1. SATA Spaced averaged time averaged
  2. SATP Space averaged temporal peak
59
Q

What is an important to remember when using the UQ machines (which are all SATP)?

A

need to adjust intensity when doing pulsed treatments (eg. pulsed at 50% –> intensity must be doubled to ensure the approximate dose is still maintained)

60
Q

If we want the average intensity to be 1 W/cm on an SATP with duty cycle 1:1 (50%), what should we do to ensure that all the treatment is received?

A

Multiple intensity by 2.

61
Q

If we want the average intensity to be 1 W/cm on an SATP with duty cycle 1:4 (20%), what should we do to ensure that all the treatment is received?

A

Multiple intensity by 5.

62
Q

What is duration in regards to US?

A

Length of treatment

63
Q

What are 4 variables that determine the length (duration) of treatment?

A
  1. Size of area to be treated
  2. Ultrasound Frequency
  3. Intensity in w/cm2 to be delivered to target tissue
  4. Desired temperature increases
64
Q

Ultrasound at 3Mhz heats tissue three times _____ (faster/slower) than 1Mhz

A

faster

65
Q

Usually calculated between ____ and ____ per effective radiating area (ERA)

A

30sec ; 2 mins

66
Q

_____ (longer/shorter) time for more acute conditions in US

A

shorter

67
Q

When using US, it is important to consider the _____of the damaged tissue not the pain area

A

size

68
Q

What is the treatment area size?

A

Surface area to deliver US energy to

69
Q

How is the treatment area size measured?

A

by the number of ERAs to cover the treatment area

70
Q

May be difficult to produce heating effects over ____ (larger/smaller) areas (~6 times head size)

A

larger

71
Q

What is the effective radiating area?

A

Surface area that transmits a sound wave from the crystal to the tissues

Always smaller than applicator head

72
Q

What does a good and poor ERA look like?

A
73
Q

How do you test the effective radiating area?

A

Sticky tape and fill head with water and turn on –> should look like bubbles/vibrations

74
Q

What are the 5 treatment parameters in US?

A
  1. Mode
  2. Frequency
  3. Intensity
  4. Duration
  5. Treatment area size
75
Q

What is the time frequency for chronic injuries for US?

A

Alternate days

76
Q

What is the time frequency for recent injuries for US?

A

ASAP and 1‐2 x daily

77
Q

If there is improvement in symptoms after US, what is the progression?

A

Same dose

78
Q

If there is worsening in symptoms after US, what is the progression?

A

Reduce or discontinue

79
Q

If there is no change in symptoms after US, what is the progression?

A

Increase one parameter

80
Q

Consider the parameters required to reduce pain and increase mobility of joint capsule (hip OA).

FIXXXXX

A

1MHz –> deep

Continuous 6 ERA x 1 min = 6 mins

81
Q

Compare with parameters to treat a patient with acute supraspinatus tendinopathy

A

3MHz –> Superficial

82
Q

What are the 2 biological effects of US?

A
  1. Thermal
  2. Non thermal
83
Q

What are the 5 non-thermal biological effects of US?

A
  1. cavitation
  2. acoustic streaming
  3. pain reduction
  4. standing waves
  5. micromassage
84
Q

What are the 4 thermal effects of US?

A
  1. Amount of heating depends on the heat capacity of tissues
    • Heat capacity = the amount of heat energy required to raise the temperature of 1kg of the substance by 1 degree
  2. Higher the water content, the higher the heat capacity ‐ Muscle has higher heat capacity than bone so its temperature increase, for the same amount of heat energy, is less
  3. Frequency
  4. Intensity
  5. Duration
85
Q

What is heat capacity?

A

Heat capacity = the amount of heat energy required to raise the temperature of 1kg of the substance by 1 degree

86
Q

Higher the water content, the _____ (higher/lower) the heat capacity ‐ Muscle has ____ (higher/lower) heat capacity than bone so its temperature ____ (increase/decrease), for the same amount of heat energy, is______ (more/less). Give an example.

A

higher; higher; increase; less

Superficial (3Hz) vs Deep (1MHz) –> 3MHz will heat up quicker

87
Q

Heat transfer depends on ____blood flow. Tissues with good blood flow (eg muscle) will be cooled _____ (more/less) rapidly than more poorly vascularised tissue (eg tendons and ligaments) because temperature effects will be dissipated _____ (quicker/slower).

A

local; more; quicker

88
Q

Tissue distribution and shape – the depth of fat, skin and muscle thickness, fascial planes and presence of bone will effect temperature ____ (increase/decrease) in a specific area.

A

increase

89
Q

In the human body the rate of tissue heating will be mediated by blood flow and heat conduction, which will reduce the peaks and troughs of the _____ and ____ characteristics of the tissues

A

absorption; reflection

90
Q

Similarly moving the ultrasound head around will reduce irregularities in _____ and _____ at fascial planes

A

absorption; reflection

91
Q

What is the effect of an 1 C increase (mild heat)?

A

Increases metabolism, reduces mild inflammation

92
Q

What is the effect of an 2-3 C increase (moderate heat)?

A

Reduces pain and muscle spasm, increases blood flow

93
Q

What is the effect of an 4 C increase (vigorous heat)?

A

Increases ROM and tissue extensibility

94
Q

What are 7 primary advantages of US for heat (anatomy structure)?

A
  1. Tendons
  2. Muscles
  3. Ligaments
  4. Joint Capsules
  5. Joint Menisci
  6. Nerve roots
  7. Periosteum
95
Q

Can be selectively heated without significant temperature increase in ____ or _____

A

skin; fat

96
Q

What are 3 effects of non-thermal pulsed US?

A
  1. Cavitation, microstreaming, acoustic streaming
  2. Increased intracellular calcium
  3. Promotes cell function and tissue healing
97
Q

What are the 2 non-thermal effects of cavitations?

A
  1. Stable
    • Bubbles (106)oscillate to and fro within pressures waves
    • associated with acoustic streaming
  2. Unstable (transient)
    • volume of bubble increases rapidly and collapses
    • due to high pressure and temp changes
    • reduced by pulsing US and keeping head moving
98
Q

What is acoustic streaming?

A

steady unidirectional movement of fluid within US field

99
Q

What are 2 types of acoustic streaming?

A
  1. Bulk streaming – that is visible when testing the output in water
  2. Microstreaming – microscopic level. Exerts stress on cell membrane and washes away ions and molecules that have accumulated outside the cell.

Evidence from in vitro studies show increased secretion from mast cells, increased calcium uptake and greater growth factor production by macrophages

100
Q

Acoustic streaming proposed to have an effect on ______of cell membranes

A

permeability

101
Q

Acoustic streaming alter the rate of ____ of ions across cell membrane eg Ca, Na • Stimulate repair processes • Alter electrical activity in nerves

A

diffusion

Flush out the inflammatory products and encourage healing

102
Q

What are is micromassage?

A

Theoretical concept that waves of compression and rarefaction causing rapidly changing pressures on cells and tissue structures have a mechanical effect – form of micromassage

103
Q

What is the purpose of micromassage?

A

Reduces oedema, muscle relaxation?

104
Q

What are 3 adverse effects?

A
  1. Burns (always move the sound head)
  2. Standing waves
  3. Cross‐contamination/infection
105
Q

What are 5 characteristics of standing waves?

A
  1. Reflected wave superimposed on incident wave
  2. Result in waves with peaks of high pressure and others of no pressure
  3. Stasis of cells in blood vessels or marked heating
  4. Endothelial damage leading to thrombus formation
  5. Periosteal burns
106
Q

What are 4 characteristics of of periosteal pains and burns?

A
  1. Ache or sharp pain when applying US due to heating at bone surface
  2. Due to reflection at bone/soft tissue interface and shear waves
  3. Also bone absorbs US easily
  4. Care in superficial bony regions
107
Q

Cross contamination and infection is possible with use of ultrasound. What are 3 ways this can happen?

A

Transducer head, transmission gel, gel bottle tips

108
Q

What are 4 universal infection control precautions?

A
  1. Clean transducer head with alcohol wipe prior to treatment
  2. Gel bottle tip
  3. Wound care
  4. Can treat through plastic dressing or water bag
109
Q

What are 4 therapeutic effects of ultrasound?

A
  1. Pain relief
  2. Tissue healing
    • Inflammation
    • Repair processes
  3. Effects on scar tissue
  4. Fracture healing (low intensity ultrasound)
110
Q

What are 4 characteristics of pain reduction?

A
  1. Due to effects of heat if produced
  2. Increased blood flow (wash away chemical irritants)
  3. Affects electrical activity of nerves (pain gating)
  4. Speeding up inflammatory process

Eg. Carpal tunnel syndrome‐ effects on pain and grip strength

111
Q

What are 3 stages of tissue repair?

A
  1. Acute inflammatory stage
  2. Granulation stage (24hr-3 days after injury)
  3. Remodelling stage
112
Q

What are the 3 effects of US on the acute inflammatory stage?

A
  1. Increase calcium ion diffusion across cells
  2. Release of histamine (mast cells), increased macrophage response
  3. Increase normal rate of healing (pro‐inflammatory)
113
Q

What are the 2 effects of US on the granulation stage (24hr-3days after injury)?

A
  1. Increased collagen production by fibroblasts
  2. Better organisation of collagen bundles
114
Q

What is an effect of US on the remodelling stage?

A

Effect of heat on deeper tissues (eg tendons) particularly if combined with stretch

115
Q

What are 5 characteristics of phonophoresis?

A
  1. Use of US to transfer topical medications into tissue e.g. antiinflammatory cream
  2. Commonly used drugs are steroids, anti‐inflammatories and local anaesthetics
  3. Low ultrasound frequencies better for effective drug penetration
  4. Gels more efficient than creams (creams may effect US transmission)
  5. Use US to drive drugs deeper into the body (eg. shingles–> very severe and painful –> use US)
116
Q

What is 6 features of shock wave therapy (another type of US)?

A
  1. High intensity (painful) - Kickstarts healing process
  2. Don’t move it around (applied with a gun)
  3. Used for Achilles tendinopathy, plantar fasciitis
  4. Used for more chronic conditions
  5. Passive treatment to enhance active treatment
117
Q

What are 6 clinical indications of phonophoresis?

A
  1. Acute soft tissue injury
    • Ankle sprains, knee strains
  2. Localised musculoskeletal conditions‐tendon and ligament injuries
    • Lateral epicondylalgia , Calcific tendonitis supraspinatus
  3. Scar tissue
    • e.g. Duypytrens, plantar fasciitis
  4. Wound healing
    • Varicose ulcers and pressure sores
  5. Pain relief
  6. Mastitis, post natal perineal
118
Q

What are 8 contraindications of phonophoresis?

A
  1. Malignant tumours (Risk of dissemination)
  2. Pelvic region during pregnancy
  3. Over an inbuilt stimulator eg pacemaker (plastic and metal parts in body)
  4. Lack of thermal sensation
  5. Circulatory insufficiency (thrombophlebitis)
  6. Tendency to blood clotting
  7. Exacerbation of existing condition
  8. Unable to communicate
  9. Eyes/testes Ovaries are quite deep (more about developing foetus if relevant)
119
Q

What are 6 precaution of phonophoresis?

A
  1. Metal implants (if superficial)
  2. Joint replacement (plastic components, joint cement)
  3. Superficial bone
  4. Bony epiphysis (Might not have joined together properly) in children and adolescents
  5. Longitudinal movement along blood vessels
  6. Breast implants
    • Can heat up fluid and cause them to burst
120
Q

What are 3 reasons for using a coupling agent when applying a US?

A
  1. to prevent reflection back into US transducer
  2. Could damage crystal
  3. Reflection will occur at interface of mediums due to differences acoustic impedance
121
Q

What are 3 reasons why the transducer head must be perpendicular to skin?

A
  1. Cosine law
  2. Maximum penetration
  3. Reduce reflection
122
Q

What are 3 reasons why you head to always keep the sound head moving (preferably slowly in circle or lines)?

A
  1. Due to reflection and rarefaction of ultrasound waves the pattern of energy absorption is irregular‐ keeping the head moving helps to even this out
  2. Prevent formation of standing waves
  3. Prevent unstable cavitation or excess heating
123
Q

What are 4 techniques of application?

A
  1. Direct contact
  2. Water bath
  3. Water bag
  4. Solid sterile gel ‐ polyacrylamide gel in 3.3 mm sheet, 96% water, sterile, impermeable to bacteria
124
Q

What are 5 features in the method for the application of US with a water bath?

A
  1. Used if the surface contour makes it difficult to follow with ultrasound head
  2. Immerse limb in bath of warm water
  3. Increase intensity by 20%
  4. Hold ultrasound head about 1cm from the skin surface
  5. Keep ultrasound head moving
125
Q

What are 5 features in the method for the application of US with a water bath?

A
  1. Fill bag or glove with water (don’t overfill)
  2. Avoid air bubbles
  3. Place gel on patient and on bag
  4. Apply ultrasound head to bag
  5. Move ultrasound head across bag or move bag with ultrasound head still
126
Q

What is an example of what recording for US?

A

Pulse (1:1 50%) SATP

Intensity 3MHz

Where: Lateral ligament

S: Sensation: tested and okay

W: Warmings: given and understood

S: Subjective measure

O: Objective measure

127
Q

What are the warnings for continuous US?

A

Same as hot pack

128
Q

What are the warnings for pulsed US?

A

Don’t want to feel sharp pain and heat

129
Q

What is said in the warning when using US?

A

When having ultrasound you will usually feel …. (nothing other than the applicator pressure / very little / some heat). If you feel any discomfort or it feels hot under the applicator you must immediately tell me, otherwise, you may be in danger of being burnt.

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PHTY2240 MSE (17 decks)

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