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Passive care exam 2 > ultrasound > Flashcards

ultrasound Flashcards

1
Q

how does ultrasound work?

A

uses sound waves at high frequencies- acoustical energy

electrical current is passed through a crystal causing it to vibrate

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2
Q

ultrasound is a deep heating modality, what is it traditionally used to treat?

A

muscles, tendons, ligaments, joint capsules scar tissue etc.

penetrates skin and subcutaneous tissue

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3
Q

what is the most common heating modality used by 63% of chiropractors?

A

ultrasound

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4
Q

what is the 2nd most common heating modality in the US?

A

ultrasound

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5
Q

what is the most common heating modality in the US used by 71% of chiropractors?

A

moist hot packs

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6
Q

what is the frequency range for ultrasound machines used for musculoskeletal treatments?

A

0.8 MHz- 3.3 MHz

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7
Q

how are sound waves generated with ultrasound?

A

through the vibration of the crystal- usually quartz, lead zirconate, lead titanate, barium titanate or nickel cobalt

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8
Q

what is calculated by dividing the time sound is delivered by the total treatment time?

A

duty cycle

150ms/1000ms = 15%

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9
Q

what is the duty cycle of continuous ultrasound?

A

100%

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10
Q

which ultrasound type results in tissue heating?

A

continuous ultrasound

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11
Q

which ultrasound type has mechanical and non-thermal effects?

A

pulsed ultrasound

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12
Q

what is the term for mechanical deformation of a crystal causing an electric current to form?

A

piezoelectric effect

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13
Q

what is the term for alternating current passing through a crystal that results in a fast contraction and expansion of the crystal?

A

reverse piezoelectric effect- this vibration produces high frequency sound waves

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14
Q

what is the treatment area or “fresnel zone”?

A

near field

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15
Q

what is the fraunhofer zone?

A

far field

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16
Q

what is the peak intensity or max intensity measured in watts per cm2?

A

spatial peak intensity (Isp)

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17
Q

how is the spatial average intensity (Isa) calculated?

A

Isp x duty cycle

1.4W/cm2 x 50%= 0.7 W/cm2

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18
Q

what does ERA stand for?

A

effective radiating area

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19
Q

what does BNR stand for?

A

beam nonuniformity ratio

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20
Q

what is the area of the sound head that produces sound energy?

A

effective radiating area- always smaller than the ultrasound head but ideally only slightly smaller

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21
Q

what is the amount of variability of a beam used to compare different quality of different machines?

A

beam nonuniformity ratio BNR

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22
Q

what is the ratio between the peak intensity of the beam divided by the average intensity of the beam?

A

BNR

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23
Q

what is the ideal BNR?

A

1:1 but within range of 2:1- 8:1 is acceptable

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24
Q

the lower the BNR the more uniform the intensity of the sound wave, what 3 things does this allow for?

A

eliminates hot spots
allows for higher dosage without discomfort
greatest comfort and safety

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25
Q

what does PAMBNR stand for?

A

peak area of the maximum beam nonuniformity

26
Q

what describes the area of the sound head covered by peak intensity?

A

PAMBNR- Peak Area of the Maximum Beam Nonuniformity

27
Q

large PAMBNR means what?

A

covers a larger area of the sound head and less uniform heating

28
Q

air is a poor conductor of ultrasound, what are 2 things we can do to combat this?

A

using a coupling medium to prevent reflection of sound waves by air- gel or gel pads
keep sound head flat against the skin (90 degrees)

29
Q

underwater ultrasound is direct or indirect?

A

indirect- using plastic basin or bucket

30
Q

what is the distance needed with underwater ultrasound?

A

0.5-3 cm

31
Q

what is the amount of sound energy being emitted from the sound head and what is it measured in?

A

amplitude- measured in Watts

32
Q

more Watts =

A

more heating NOT greater penetration

33
Q

what is the typical frequency of ultrasound and what does it dictate?

A

1-3 MHz and it dictates the depth of heating

34
Q

what dictates the depth of heating and time required to cause an increase in tissue temperature?

A

frequency

35
Q

what is the difference between using high vs low frequency?

A

high 3MHz= absorbed more rapidly; superficial tissue

low 1MHz= absorbed slower; deeper tissue

36
Q

which frequency is for superficial tissue?

A

high

37
Q

which frequency is for deep tissue?

A

low

38
Q

higher protein concentration and higher density = higher or lower absorption rate?

A

higher

39
Q

what tissue types absorb the most heat?

A

bone, tendon, ligament, joint and capsule

40
Q

what tissue types absorb the least heat?

A

skin and fat

41
Q

when US wave encounters a boundary between tissues energy will scatter by?

A

reflection or refraction

42
Q

what is the reversal of the direction of propagation of the ultrasound wave?

A

reflection

43
Q

what is the change of ultrasound wave from a straight path when passing obliquely from one medium to another?

A

refraction

44
Q

US energy is reflected at soft tissue-bone interface leading to _____?

A

increased heating

45
Q

what leads to the concentration of ultrasound at the point of refraction?

A

the bending of the ultrasound energy- refraction

46
Q

what degree increase in temperature leads to an increase in metabolic activity?

A

1 degree

47
Q

what degree increase is associated with reduced muscle spasm, increased blood flow and decrease in chronic inflammation?

A

2-3 degrees

48
Q

what degree increase alters viscoelastic properties of collagen?

A

4 degrees

49
Q

though pulsed ultrasound has very little heating of tissues, what are 3 things that it does do for tissue?

A

stimulation of fibroblast activity
increase blood flow
increase proteins associated with injury repair

50
Q

how does pulsed ultrasound work to effect tissue?

A

through acoustical streaming and stable cavitation

51
Q

what is the movement of fluids along cell membranes due to mechanical pressure exerted by sound waves?

A

acoustical streaming- movement occurs in direction of sound waves

facilitates fluid movement and increases cell permeability

52
Q

what is the rhythmic expansion and contraction of bubbles during repeated pressure changes over many acoustic cycles?

A

stable cavitation

53
Q

what type of cavitation is associated with low frequency high intensity ultrasound and is not therapeutic?

A

unstable ultrasound

54
Q

what are the contraindications for ultrasound?

A 
malignancy 
hemorrhage
ischemia
thrombus
infection
gonads
eye 
pelvic, abdomen, lumbar of pregnant women 
spinal cord after laminectomy 
plastic and cemented implants 
near or over electrical implants
unknown etiology
55
Q

what is the peak intensity you should not exceed?

A

8.0 W/cm2

56
Q

what is the range of intensity used?

A

0.5-2.5 W/cm2

57
Q

what is the approximate treatment are size?

A

2-3 times the size of the ERA

58
Q

what is the general treatment time parameters?

A

5-8 minutes; never more than 15 minutes

59
Q

what is the term for using sound energy to drive medication into tissue

A

phonophoresis/ sonophoresis

60
Q

what are ultrasound and e-stim combos used for?

A

trigger points
epicondylitis
superficial pain
decrease adhesions

61
Q

what is LIPUS- low intensity pulsed ultrasound used for?

A

stimulation of fracture healing; home units that can be sent home with patients

62
Q

what is NCLFUS- noncontact low frequency ultrasound used for?

A

wound cleaning and debridement- US propels saline across wound

Passive care exam 2 (6 decks)

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