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Therapeutic Modalities > Ultrasound & Diathermy > Flashcards

Ultrasound & Diathermy Flashcards

1
Q

What is ultrasound used for?

A

diagnostic imaging-3.5MHz to 10MHz
loosening jt replacements in need of revision
therapeutic effects

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2
Q

Therapeutic ultrasound ranges in what Hz?

A

750,000 to 3,000,000Hz

Most frequently used are 1 MHz & 3MHz

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3
Q

What kind of sound is ultrasound?

A

Acoustic sound

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4
Q

Therapeutic Ultrasound

A

Considered a deep heating agent
Thermal and non-thermal effects
converts electrical energy to acoustical energy

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5
Q

What is a transducer?

A

converts one form of energy to another

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6
Q

Piezoelectric crystal

A

a crystal capable of contracting and expanding. Creates the “piezoelectric effect”

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7
Q

What is the reverse piezoelectric effect?

A

as the AC reverses polarity, the crystal expands and contracts producing US energy
travels through tissues and is absorbed.

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8
Q

Effective Radiating Area (ERA)

A

area of sound head that produces ultrasonic waves; expressed in cm2

  • portion of the heads surface area that produces US wave (always lesser than actual size of sound head)
  • energy output greatest at center of ERA (temp too)
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9
Q

Describe energy from US?

A

multiple waves come from head
energy diverges as it moves away from the source
becomes less consistent farther away from the head
Not uniformed-most energy emitted toward center of sound head

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10
Q

Beam nonuniformity ratio (BNR)

A

the consistency of the US output; ratio b/w highest intensity in an US beam and the output reported on the meter
lower the ratio the more uniform the beam is
8:1 is unsafe

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11
Q

Whats good about a lower BNR

A

makes the treatment more comfortable by reducing hot spots and reducing risk of periosteal pain

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12
Q

What are hot spots?

A

because of the existence of high-intensity areas in the beam—-gotta keep it moving

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13
Q

What is required to be on FDA label?

A 
output frequency
ERA
BNR
Beam profile
Calibration and date of last service
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14
Q

What tissues are capable of greater absorption?

A

higher protein density tissues have higher rate of absorption
-tendon, ligaments, muscle tissues

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15
Q

What tissues absorb less US energy?

A

higher water content and low protein content like blood and fat

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16
Q

Why do cartilage and bone reflect US energy?

A

Because they are SO highly dense with protein the energy strikes the surface and is likely to be reflected.

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17
Q

What is frequency for US?

A

defined as the # of waves per second

Hz or PPS
Hz: cycles per second
MHz=1,000,000 cycles per second

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18
Q

What frequency do 1 and 3 have?

A

1 MHz= low frequency, more deep (4cm)

3 MHz= high frequency, more superficial (2cm)

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19
Q

Characteristics of 3MHz

A

3 MHz heats tissue at least 3x faster than 1 MHz so absorption occurs much faster
absorbed superficially
heating effects do not last as long as 1 MHz

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20
Q

Dosage (intensity)

A

Watts/surface area (W/cm2)
Higher the dose means higher amount of sound energy delivered to tissues in less time.
Longer treatment time needed for lower intensities
Common=1.5
Doses greater than 2.5-3.0 may cause tissue damage

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21
Q

What are some common intensities?

A

.5-.75= knee, elbow, iliac crest, wrist, AC joint, ankle (BONY)
.75-1.0=forearm, shldr, anterior lower leg (bone closer to surface)
1.0-1.5=calf, upper arm, lateral leg (more muscle)
1.5-2.0= thigh, buttocks (more fat)
2.0-2.5=thigh, buttocks on larger bodies

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22
Q

Treatment time and thermal effects

A

3Mhz is most effective the higher the intensity the faster the temperature increases

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23
Q

Treatment Area parameters

A

No greater than 2-3x the ERA
Move sound head in slow manner to prevent hot spots
Maintain contact with skin
Larger areas= decreased acoustic energy reaching tissues and less temp increases—so perform separate tx

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24
Q

What are the 3 coupling methods for US

A

Direct Coupling
Pad (bladder) method
Immersion method

25
Q

Direct Coupling

A

Transducer with gel in direct contact with skin

decreases in irregular shaped areas and areas with a lot of hair—move sound head slowly

26
Q

Movements of transducer

A

moving too rapidly decreases the total amount of energy absorbed per unit area
pt complains of pain or excessive heat–decrease intensity but increase time
keep constant pressure

27
Q

Pad (bladder) method

A

Pads are formed from US gel and packed tightly in order to hold shape

28
Q

Advantages of Pad method

A

conforms to irregular shaped area and limits the size of treatment area allowing more energy to be transmitted

29
Q

Immersion Method

A

treat irregular shaped areas
sound head ~1” away from area
sound head should be facing target tissue and remain at 90 degree angle

30
Q

Continuous vs pulsed US

A

determines thermal vs non-thermal effects
Continuous=thermal 100%
pulsed=non-thermal at cellular level % of 100% dependent upon treatment goal

31
Q

Thermal mode

A

effective in heating the dense collagenous tissues
requires high intensity
continuous

32
Q

Thermal effects: mild heating

A

mild heating of 1 C= increase metabolic activity, initiation of inflammatory process

33
Q

Moderate heating

A

2-3 C= increased blood flow, decreased pain, decreased muscle spasm, decreased chronic inflammation

34
Q

Vigorous heating

A

3-4 C= results in improved viscoelastic properties of collagen

35
Q

Non-thermal effects

A

primarily occurs with pulsed US

little heat is produced due to dissipation occuring during off times

36
Q

Cavitation

A

formation of gas filled bubbles that expand and compress, causing pressure changes in tissue fields

Stable and Unstable

37
Q

Stable Cavitation

A

rhythmic contraction and expansion of gas bubbles; facilitates fluid mvmt and membrane transport=Good

38
Q

Unstable Cavitation

A

formation of bubbles at the low pressure part of the US cycle; results in bubble collapse and tissue damage–> bad

39
Q

Acoustical Micro-streaming

A

unidirectional mvmt of fluids along the boundaries of cell membranes

US causes interstitial fluids to flow
Fluids strike cell membranes—altering their permeability to Na and Ca ions (important to healing process)

40
Q

Cells response to acoustical streaming

A 
increases cell membrane permeability
alters cell membrane diffusion rate
increased histamine release
mast cell degranulation
increased rate of protein synthesis
41
Q

Indications of US

A

prior to stretching and manual therapy when pt has restricted ROM
Scar tissue and jt contracture
identifying stress fxs

42
Q

Precautions of US

A

always use lowest intensity which produces a therapeutic response
educate pt on what they will feel
do not use over metal implants or pt with pacemakers

43
Q

Contraindications

A 
Acute conditions
ischemic areas
impaired circulation
DVT
over active infections
around heart, eyes, skull, and genitalia
pregnancy
over fx sites (unless used to identify)
cancer
44
Q

Combo US/Electrical Stimulation

A

used to treat:
trigger points
muscle spasms

output parameters:
thermal US
motor level electrical stim

45
Q

Phonophoresis

A

US used to deliver medication
opens pathways to drive molecules into tissues
not likely to damage or burn skin like iontophoresis could

46
Q

Common medications for phonophoresis

A

dexamehtasone (analgesic)

hydrocortisone (anti-inflammatory)

47
Q

Short wave Diathermy

A

local heating by high frequency electromagnetic waves

increase in local blood flow from tissue heating is primary benefit (thought to be)

48
Q

Continuous diathermy

A

used mainly with chronic injuries
increases tissues temperature
increased risk of burns

49
Q

Pulsed diathermy

A

may or may not increase temp

pulses allow for increased tx intensity and duration

50
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 well, heat retained 3x longer

51
Q

Disadvantages of diathermy

A

expensive
can only treat one pt at a time
potential for burns

52
Q

Pulsed SWD

A

used to heat deep tissues
-higher the pulse frequency, the greater the tissue heating
Heats tissues at depths of 3-5 cm
Tissue temp controlled by length of application
-max increases 4-6 C

53
Q

2 types of shortwave diathermy

A

induction field generators

capacitive field generators

54
Q

Induction field generators

A

places the pt in the electromagnetic field
produce greatest heat w/in muscle directly beneath the coil
induction cable or drum—drum is most commonly used

55
Q

Greatest heating occurs in tissues with what?

A

good electrical conductance=muscles, blood vessels, and nerves

56
Q

Capacitive Field Generators

A

body is actually placed in electric field and is a part of the circuit—placed b/w 2 electrodes of opposite charge

-tissues with greatest resistance create most heat as current flows through path of least resistance—not recommended for fat people

57
Q

When should you use diathermy?

A

if skin or underlying soft tissue is tender
areas where subcutaneous fat is thick and deep heating required—induction method
when needing to increase tissue temp over a large area

58
Q

Effects of Diathermy

A

alters collagen properties, allowing it to elongate

requires stretching during and/or immediately after tx

59
Q

Contraindications of Diathermy

A 
metal implants or metal jewelry
cardiac pacemakers
ischemic areas 
PVD
tendency to hemorrhage
pregnant
sensory loss
cancer

Therapeutic Modalities (12 decks)

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