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Ultrasound & Diathermy Flashcards

(59 cards)

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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

Study These Flashcards
A

Direct Coupling
Pad (bladder) method
Immersion method

25
Direct Coupling
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
Movements of transducer
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
Pad (bladder) method
Pads are formed from US gel and packed tightly in order to hold shape
28
Advantages of Pad method
conforms to irregular shaped area and limits the size of treatment area allowing more energy to be transmitted
29
Immersion Method
treat irregular shaped areas sound head ~1" away from area sound head should be facing target tissue and remain at 90 degree angle
30
Continuous vs pulsed US
determines thermal vs non-thermal effects Continuous=thermal 100% pulsed=non-thermal at cellular level % of 100% dependent upon treatment goal
31
Thermal mode
effective in heating the dense collagenous tissues requires high intensity continuous
32
Thermal effects: mild heating
mild heating of 1 C= increase metabolic activity, initiation of inflammatory process
33
Moderate heating
2-3 C= increased blood flow, decreased pain, decreased muscle spasm, decreased chronic inflammation
34
Vigorous heating
3-4 C= results in improved viscoelastic properties of collagen
35
Non-thermal effects
primarily occurs with pulsed US | little heat is produced due to dissipation occuring during off times
36
Cavitation
formation of gas filled bubbles that expand and compress, causing pressure changes in tissue fields Stable and Unstable
37
Stable Cavitation
rhythmic contraction and expansion of gas bubbles; facilitates fluid mvmt and membrane transport=Good
38
Unstable Cavitation
formation of bubbles at the low pressure part of the US cycle; results in bubble collapse and tissue damage--> bad
39
Acoustical Micro-streaming
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
Cells response to acoustical streaming
``` increases cell membrane permeability alters cell membrane diffusion rate increased histamine release mast cell degranulation increased rate of protein synthesis ```
41
Indications of US
prior to stretching and manual therapy when pt has restricted ROM Scar tissue and jt contracture identifying stress fxs
42
Precautions of US
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
Contraindications
``` 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
Combo US/Electrical Stimulation
used to treat: trigger points muscle spasms output parameters: thermal US motor level electrical stim
45
Phonophoresis
US used to deliver medication opens pathways to drive molecules into tissues not likely to damage or burn skin like iontophoresis could
46
Common medications for phonophoresis
dexamehtasone (analgesic) | hydrocortisone (anti-inflammatory)
47
Short wave Diathermy
local heating by high frequency electromagnetic waves | increase in local blood flow from tissue heating is primary benefit (thought to be)
48
Continuous diathermy
used mainly with chronic injuries increases tissues temperature increased risk of burns
49
Pulsed diathermy
may or may not increase temp | pulses allow for increased tx intensity and duration
50
Advantages of diathermy
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
Disadvantages of diathermy
expensive can only treat one pt at a time potential for burns
52
Pulsed SWD
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
2 types of shortwave diathermy
induction field generators | capacitive field generators
54
Induction field generators
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
Greatest heating occurs in tissues with what?
good electrical conductance=muscles, blood vessels, and nerves
56
Capacitive Field Generators
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
When should you use diathermy?
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
Effects of Diathermy
alters collagen properties, allowing it to elongate | requires stretching during and/or immediately after tx
59
Contraindications of Diathermy
``` 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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