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Biophysical Agents > Unit 3 Lecture > Flashcards

Unit 3 Lecture Flashcards

1
Q

define ultrasound

A
  • sound (not heard by humans) with a frequency greater than 20,000 Hz per second
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2
Q

what is ultrasound described by?

A
  • intensity
  • frequency
  • duty cycle
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3
Q

what is a duty cycle?

A

the proportion of the total treatment time to the amount of time that the ultrasound is actually on

  • 100% constantly on
  • 50% 1:1
  • 20% 1:4 (can be less than 20%)
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4
Q

how deep can the penetration of an ultrasound be on soft tissue?

A

up to 2-5 cm

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5
Q

describe a thermal ultrasound

A

continuous duty cycle
- increased tissue temp
- increased metabolic rate
- increased circulation
- increased soft tissue extensibility
- decreased pain
- decreased spasms
- altered NCV (nerve conduction velocity)

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6
Q

clinical application of thermal ultrasounds

A

decrease pain & increase soft tissue extensibility

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7
Q

describe a non-thermal ultrasound

A

pulsed duty cycle (20-50%)
- increased intracellular CA levels
- increased skin & cell membrane permeability
- increased macrophage permeability
- facilitates tissue healing
- modifies inflammation
- enhances transdermal drug delivery
- cavitation
- acoustic streaming
- microstreaming

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8
Q

which parameter of ultrasound determines whether it will be thermal or non-thermal?

A

duty cycle

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9
Q

cavitation

A

oscillation (movement back & forth) of gas bubbles that expand & contract because of changes in the sound field which leads to altered cellular function

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10
Q

acoustic streaming

A
  • a steady & circular flow of cellular fluids in a sound field induced by ultrasound
  • thought to alter cellular activity by transporting material from one part of the ultrasound field to the other
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11
Q

microstreaming

A
  • these movements are small-magnitude movements & are known to alter cell membrane permeability & cellular activity
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12
Q

ERA

A

the area of the transducer that the energy of the ultrasound radiates from (it’s always smaller than the area of the treatment head)

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13
Q

BNR

A

Beam Nonuniformity Ration
- the ratio of the spatial peak intensity to the spatial average intensity (usually 5:1 or 6:1)
- the crystal expands & compresses material, then contracts & rarifies material

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14
Q

attenuation

A
  • as sound travels through material, it slowly loses intensity (by absorption, reflection & refraction
  • is greatest in tissues with high collagen content & with the use of high ultrasound frequencies
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15
Q

describe reflection, refraction, & absorption

A
  • REFLECTION: occurs anytime sound travels from 1 medium to another & the medium densities are very different
  • REFRACTION: occurs when the ultrasound beam is delivered at an angle; the angle that the wave enters the tissue with is different than the angle that the waves continues with through the tissue
    • the wave becomes redirected (if the angle is too great, refraction can turn into reflection)
  • ABSORPTION: transmission of the wave into the tissue (what we want to happen)
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16
Q

how is ultrasound different from other agents?

A
  • reaches deeper tissues & heats smaller areas than other superficial thermal agents
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17
Q

describe high & low ultrasound absorption coefficients

A
  • high: high collagen, low water content & heats more
  • low: low collagen, high water content & heats less
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18
Q

what are the frequencies of an ultrasound & how is one chosen?

A
  • 1 MHz or 3 MHz
  • chosen based on how deep the area is or the type of structure being targeted
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19
Q

describe 1MHz

A
  • lower frequency = deeper = HIGHER intensity
  • 2-5cm deep
  • intensity 1.5-2.5 W/cm2
  • takes longer for temperature increase
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20
Q

describe 3 MHz

A
  • higher frequency = superficial = LOWER intensity
  • 1-2cm deep
  • intensity 0.5-1.0 W/cm2
  • maximum temperature increase is faster
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21
Q

what are factors that affect the amount of temperature increase?

A
  • varies according to frequency, intensity, and duration
  • rate is proportional to the absorption coefficient at the applied frequency
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22
Q

what are general clinical applications that would call for US?

A
  • soft tissue heating
  • pain control
  • underwater US
  • surgical incisions
  • tendon & ligament injuries
  • tendonitiis
  • tendon healing post-op
  • bone fractures
  • phonophoresis
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23
Q

describe US use for soft tissue heating & the recommended parameters

A

continuous
- increases tissue temperature & extensibility
- increased tissue length is maintained better if force is applied while tissue temp is elevated & stretch is maintained for 5-10 minutes after US while tissue is cooling
- muscle: 3 minute window of staying warm
- tendon/ligament: 5 minute window of staying warm

recommended parameters
- 3MHz/ 0.5-1.0W/cm2/ 5-10min
- 1MHz/ 1.5-2.5W/cm2/ 5-10min

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24
Q

describe US use for pain control & the recommended parameters

A

continuous
- may control pain by altering pain transmission/perception or changes to the pain-causing condition

recommended parameters
- 1 or 3MHz/ 0.5-3W/cm2/ 3-10mins

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25
Q

describe use for an underwater US

A
  • use when treatment area is smaller than the sound head or an irregular area
  • make sure outlet has a GFI, sound head is 1 inch from body part, and the transducer is moving parallel to surface being treated
  • DO NOT USE A METAL BASIN
    not as good of a transmitter of US wave compared to gel
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26
Q

describe US use for surgical incisions & the recommended parameters

A

pulsed
- shown to facilitate angiogenesis
- found to reduce pain from surgical scars years after procedures

recommended parameters
3MHz/ 0.5-0.8W/cm2/ 3-5mins

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27
Q

describe US use for tendon & ligament injuries

A

pulsed
- assists in healing after surgical incisions & repair
- helpful in decreasing tendon inflammation
research findings are mixed

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28
Q

describe US use for tendonitis

A

parameter selection is very important
- acute - pulsed with low intensity
- chronic - continuous with high intensity (and stretching)

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29
Q

describe US use for bone fractures

A

pulsed
- use of low dose ultrasounds over healing fx sites is recommended to accelerate healing

30
Q

describe US use for phonophoresis & the recommended parameters

A

pulsed
- application of US with a topical drug as the medium
- meds will be at a higher concentration & have a systemic effect
- DO NOT perform on a pt already taking the same type of medicine in a different form

recommended parameters
-3 MHz/ 0.5W/cm2/ 5mins

31
Q

name commonly used drugs with phonophoresis

A
  • NSAIDS - ketoprofen gel
  • corticosteroids - dexemthasone
  • anti-inflammatory
  • biofreeze
32
Q

name the adverse effects of ultrasound & how to prevent them

A
  • BURNS: check sensation & mentation before treatment, keep the sounded head moving, and use the correct intensity
  • BLOOD CELL STATIS: use the correct speed while keeping the head moving
  • CROSS-CONTAMINATION: clean the transducer head & head of gel bottle with alcohol before & after use
33
Q

contraindications for ultrasound (PPP, JTEC, RM)

A
  • pacemaker
  • plastic components
  • pregnancy
  • joint cement
  • thrombophlebitis
  • eyes
  • CNS tissue
  • reproductive organs
  • malignant tumor
34
Q

precautions for ultrasound (FABE)

A
  • fractures
  • acute inflammation
  • breast implants
  • epiphyseal plates
35
Q

define electrical current

A

the flow of charged particles through a conductor

36
Q

define charge

A

the amount of unbalanced electricity in the body

37
Q

define polarity

A

positive or negative

38
Q

define anode & cathode

A

anode: the positive electrode
cathode: the negative electrode

39
Q

define resistance

A

opposition of a material to the flow of the electrical current

40
Q

define impedance

A

resistance to an alternating current

41
Q

what are the 3 effects of e-stim?

A
  • nerve depolarization
  • muscle depolarization
  • ionic effects
42
Q

describe nerve depolarization

A
  • electrical currents depolarize nerve membranes & produce action potentials
  • action potential is propagated along the axon until it reaches its terminus
  • the body will respond to this the same way it responds to action potentials that are caused by physiological stimuli
43
Q

describe resting membrane potential

A

at rest, the inside of a nerve is -60 to -90Mv compared to outside

44
Q

describe the absolute refractory period

A

when the nerve is depolarized, no more action potentials can be generated

45
Q

describe the relative refractory period

A

after depolarization (before returning to the resting membrane potential) there is a brief period of membrane hyperpolarization

a stronger stimulus than normal is needed for an action potential

46
Q

describe the strength duration curve

A

the minimum amount of strength (amplitude) & pulse duration needed to depolarize the nerve

47
Q

what is the predictable order of the strength duration curve?

A
  • sensory: low amplitude & short pulse durations (less than 80)
  • motor: higher amplitude & longer pulse durations (150-350)
  • noxious: even higher amplitude & even longer pulse durations
48
Q

describe muscle depolarization

A
  • INNERVATED MUSCLE
    • will respond by muscle contraction to short pulses
    • the current causes depolarization of their motor nerves (Neuromuscular Electrical Stimulation (NES))
  • DENERVATED MUSCLE
    • will only contract in response to pulses of electricity lasting 10ms or longer & require a special stimulator
    • the longer duration of pulses of electricity depolarize the muscle cell directly (Electrical Muscle Stimulation (EMS))
49
Q

describe ionic effects of e-stim

A

can occur in tissue when a net charge is left in the tissue

50
Q

describe direct current

A
  • monophasic
  • flows in ONE direction into the tissue
  • has 1 phase & 1 polarity (+ or -)
  • USE FOR: iontophoresis, stimulation of denervated mm, & wound healing
51
Q

describe alternating current

A
  • biphasic
  • a continuous uninterrupted flow of charged particles (+ and -)
    what it puts into the tissue, it pulls out
  • 3 types: IFC, Premodulated, Russian
52
Q

describe IFC

A
  • alternating current
  • 2 channels, 4 electrodes
  • an intersecting medium frequency current
  • Beat frequency created by the difference of frequencies of the channels
  • used for bigger areas
  • USE FOR: pain control
53
Q

describe premodulated current

A
  • alternating current
  • 1 channel, 2 electrodes
  • medium frequency
  • same wave from as IFC
  • e-stim produces Beat
  • used for smaller areas
  • USE FOR: pain control
54
Q

describe russian current

A
  • alternating current
  • medium frequency of 2500MHz
  • delivered in 50 bursts per second
  • each burst is 10ms long & is separated from the next burst by a 10ms interburst interval
  • 10 seconds on, 50 seconds off for 20-30 minutes
  • used for larger muscle groups
  • USE FOR: strengthening
55
Q

describe pulsed current

A
  • interrupted flow of charged particles
  • may be balanced or unbalanced
  • may flow in 1 or both directions
  • may be symmetrical or asymmetrical
  • 4 types: biphasic, balanced symmetrical/asymmetrical, unbalanced asymmetrical, monophasic (HVPC)
56
Q

describe biphasic pulsed current

A

charged particles move in one direction & then in the oppsote direction

57
Q

describe a balanced asymmetrical current

A

the charges of the phases are EQUAL in AMOUNT and OPPOSITE in POLARITY resulting in a net charge of 0

58
Q

describe an unbalanced asymmetrical current

A

the charges of the phases are not equal & there is a net charge left in the body

59
Q

describe a monophasic current (HVPC)

A

charged particles move only in ONE direction or flow back & forth during each pulse

60
Q

biphasic pulsed current uses

A

pain control & muscle strengthening

61
Q

HPVC uses

A

tissue healing & edema management

62
Q

define frequency

A

the number of pulses per second

63
Q

define pulse duration

A

the time from the beginning of the first phase to the last phase of a pulse

64
Q

define phase duration

A

the duration of 1 phase within a pulse

65
Q

define interpulse interval

A

time between pulses

66
Q

define interphase interval

A

time between phases of a pulse

67
Q

define ramp up time

A

the time it takes for the current amplitude to increase from 0 to its maximum amplitude

68
Q

define ramp down time

A

the time it takes for the current amplitude to decrease from its maximum amplitude to 0

69
Q

define modulation

A

any pattern of variation in one or more of the stimulation parameters

70
Q

define amplitude

A

the magnitude of current or voltage

71
Q

describe the differences in a physiological and e-stim produced contraction

A
  • (P) type l fibers (ST: Slow Twitch) are activated first (more fatigue & atrophy resistant)
  • (E) type ll fibers (FT: Fast Twitch) are activated first because of the recruitment of the nerve fibers with the largest diameter axons (fatigue & atrophy quickly)
  • (P) contraction is gradual & smooth
  • (E) contraction has a rapid onset
  • (P) asynchronous firing
  • (E) synchronous firing

Biophysical Agents (3 decks)

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