question

attenuation is the result of

answer

absorption, reflection, and refraction, with absorption accounting for about 50% of attenuation. Attenuation is greatest in tissues with a high collagen content and with the use of high ultrasound frequencies. Repulsion is not a cause of ultrasound attenuation.

question

what are the ideal treatment parameters for using ultrasound for teating pressure ulcers?

answer

3 MHz, 0.5 to 1.0 W/cm², pulsed 20% Overall, the studies published so far indicate that pulsed ultrasound may facilitate wound healing, but good evidence of this effect is lacking. The treatment parameters that have been found to be effective for this application are 20% duty cycle, 0.8 to 1.0 W/cm² intensity, 3 MHz frequency, for 5 to 10 minutes.

question

For optimal effect, when should stretching be applied

answer

During heating by ultrasound and be maintained for 5 to 10 minutes after ultrasound application while the tissue is cooling

question

pulsed ultrasound (effect on temperature)

answer

minimizes temperature increase (intensity and frequency stays the same)

question

when using ultrasound for its thermal effects what is the temperature that you should try to achieve?

answer

The minimal therapeutic level is 40° C and should not exceed 45° C.

question

should ultrasound be applied on children?

answer

Although controversial, it is recommended that high-dose ultrasound not be applied over growing epiphyseal plates. Because the age of epiphyseal closure varies, radiographic evaluation rather than age should be used to determine if epiphyseal closure is complete.

question

what are the ideal treatment parameters for using ultrasound before stretching shortened tissues?

answer

1 to 2 W/cm², continuous Continuous ultrasound is the only one that generates thermal effects such as increased tissue extensibility. Pulsed ultrasound has primarily nonthermal effects.

question

To penetrate deeper tissue using ultrasound

answer

Use a lower frequency The lower the frequency, the longer the wavelength of the sound waves, the more readily ultrasound penetrates deeper into the tissue. With a higher frequency, the sound waves have a shorter wavelength and are absorbed more superficially.

question

all of the following are desired effects of ultrasound

answer

increased cell membrane permeability, increased collagen production, increased mast cell degranulation.

question

blood stasis`

answer

adverse effect of ultrasound, as is infection or cross-contamination between patients.

question

how is drug penetration is increased

answer

by ultrasound-induced cavitation and enhanced skin permeability. Since phonophoresis causes drugs to become systemic, a therapist must know what other drugs a patient is taking before treating with phonophoresis.

question

all of the following statements are true about phonophoresis

answer

Hydrocortisone preparations tend to transmit ultrasound poorly a physician must know what other drugs a patient is taking in order to treat with phonophoresis drugs delivered via phonophoresis become systemic

question

depth of penetration and temperature

answer

1 MHz frequency will penetrate deeper than 3 MHz although temperature elevation will be less With 3 MHz ultrasound, as compared to 1 MHz ultrasound, and in tissues with higher collagen content, the depth of penetration is lower, although the maximum temperature achieved is higher. One MHz frequency ultrasound is considered best for heating tissues up to 5 cm deep, and 3 MHz frequency is considered best for heating tissues only 1 to 2 cm deep.

question

how do you determine if ultrasound is reaching therapeutic levels?

answer

Use of appropriate settings does not prove effectiveness. The best way to determine if ultrasound is reaching therapeutic levels is to have a baseline for desired outcome and measure it objectively following treatment. Subjective reporting of sensations is another, more subjective way, of monitoring for effect. Using only one therapy at a time allows that therapy to be observed in a controlled setting.

question

ERA

answer

The effective radiating area is always smaller than the area of the treatment head because the crystal does not vibrate uniformly and must be smaller than the size of the outside of the sound head.

question

Non-thermal effects of ultrasound are believed to be caused by

answer

stable cavitation, microstreaming, and acoustic streaming. Increased tissue extensibility is a thermal effect.

question

what type of heat transfer happens with ultrasound

answer

Ultrasound generates thermal effects indirectly through the conversion of kinetic energy in sound waves into frictional energy within deep tissues, releasing heat in the process. In contrast, conduction and convection transfer heat from one material of higher temperature directly to a material of lower temperature.

question

what is the most common adverse effect of ultrasound

answer

Although adverse effects are rare, the most common adverse effect is a burn. To minimize the risk of burning a patient, always move the ultrasound head and do not apply thermal-level ultrasound to areas with impaired circulation or sensation. Reduce the ultrasound intensity in areas with superficial bone or if the patient complains of any increase in discomfort with the application of ultrasound.

question

what are the ideal treatment parameters for ultrasound to treat inflammation

answer

It is recommended that ultrasound be applied in a pulsed mode at a low intensity (0.5 to 1.0 W/cm²) during the acute phase of tendon inflammation to optimize healing and minimize the risk of aggravating the condition.

question

what are the ideal treatment parameters of ultrasound to treat pain via stimulation of cutaneous thermal receptors?

answer

Only continuous ultrasound provides significant thermal effects to activate thermoreceptors. The treatment parameters that have been found to be most effective for control of pain are continuous ultrasound at 0.5 to 2.0 W/cm² intensity and 1.5 MHz frequency.

question

what dose of ultrasound should be used for fracture healing?

answer

Numerous studies over the last 25 or more years have demonstrated that low-dose ultrasound can reduce the fracture healing time in animals and humans. There is now a fixed dose ultrasound device available for home use by patients to promote fracture healing.

question

what frequency of ultrasound should be used to penetrate deeper tissues

answer

1 MHz The lower the frequency, the longer the wavelength of the sound waves, the more readily ultrasound penetrates deeper into the tissue. With a higher frequency, the sound waves have a shorter wavelength and are absorbed more superficially.

question

How many hertz are in ultrasound?

answer

20,000 Hz. Just over what we can hear.

question

intensity is measured in

answer

W/cm ^2

question

frequency

answer

MHz

question

duty cycle

answer

percentages (default is 20%)

question

ERA

answer

effective radiating area cm^2 is usually smaller than the head or transducer

question

BNR

answer

Beam Nonuniformity Ratio - difference between spatial peak intensity (top) and spatial average intensity (bottom) sort of like margin of error. ideally 3:1 BNR.

question

Thermal effects of ultrasound

answer

-caused by continuous waves -increased tissue temperature due to absorption coefficient (affected by tissue type), Intensity, frequency, -same properties as other heating agents : increase vascularization, healing, pain relief, tissue extensibility.

question

Nonthermal effects of ultrasound

answer

-does not retain heat because of duty cycles -due to cavitation, microstreaming, acoustic streaming - increased intracellular calcium -promotes cell function

question

indications for ultrasound

answer

soft tissue shortening, pain control, dermal ulcers, surgical skin incisions, tendon and ligament injuries, bone fractures, carpal tunner syndrome, phonophoresis

question

Ultrasound effects on inflammation

answer

-enhance reabsorption of interstitial fluids, -increase intracellular calcium levels, -promote macrophage responsiveness and fibroblast activity in acute inflammation -non-thermal mechanisms increase tissue permeability

question

Ultrasound effects on pain

answer

-raises pain threshold - thermal properties -completing stimulus - gate theory - postulated selective absorption by Ad and C fibers (change nerve transmission possibly due to changes in sodium channel function)

question

ultrasound effects on subacute inflammatory edema

answer

thermal US is contraindicated if edema is due to inflammation (okay if arterial or lymphatic) -reduces old residual edema with thermal and nonthermal properties

question

ultrasound effects on healing open wounds

answer

thermal effects increase blood flow, and metabolism non-thermal effects - increase activity in tissue repair cells (fibroblasts and satellite cells), protein synthesis

question

ultrasound effects on tendon repair

answer

Timing is important- best results are achieved immediately after repair or injury - prolongued use has no effect (>5weeks) non-thermal application is most effective in the acute stage thermal effects are most effective if they're combined with stretching in the chronic stage or with presence of scar tissue

question

ultrasound effects on extensibility of collagenous tissue

answer

-enhanced due to thermal effects -postulated relaxation of peptide bonds -selective absorption by collagen tissue -sustained stretch during US and for 5-10 min post - CW 3MHz, .5-1.0 W/cm^2 -CW 1MHz, 1.5 - 2.5 E/cm^2

question

intensity and frequency

answer

are inversely proportional if frequency is high, intensity must be low if frequency is low, intensity must be high

question

Contraindications for the use of ultrasound

answer

malignancy, pregnancy, CNS tissue (not even crossing over). joint cement, plastic, pacemaker, thormbophlebitis, eyes and reproductive organs

question

precautions for the use of ultrasound

answer

acute inflammation, epiphyseal plates (must be fully closed), fractures, breast implants,

question

Adverse effects of ultrasound

answer

burns (always move the sound head), standing waves (interaction of oncoming ultrasound waves with those reflected back from a tissue interface- creates risk of tissue cavitation)- cause blood stasis (keep head moving,)c cross-contamination/infection

question

application technique

answer

evaluate the patient determine appropriateness and safety apply ultrasound transmission medium, select sound head, select treatment parameters (som US machines will only let you do this if the head is already in contact with the skin circling), turn on machine, move sound head, document

question

treatment parameters

answer

area treated ultrasound frequency ultrasound intensity ultrasound duty cycle treatment duration if underwater response to intervention

question

treatment for soft tissue shortening

answer

Thermal - CW (100%)- -3 MHz (1-2cm) - .5 W/cm^2 -5-10 min/2 x ERA -1MHz (5cm) -1.5 - 2.0 W/cm^2 -5-10 min/2 x ERA

question

treatment for delayed tissue healing and prolongued inflammation

answer

Nonthermal - PW (20%) -3MHz (1-2cm) -.5- 1.00 W/cm^2 -5-10 min/2 x ERA -1MHz (5cm) -.5 - 1.00 W/cm^2 -5-10 min/2 x ERA

question

treatment for fracture healing

answer

Nonthermal - PW (20%) -3MHz (1-2cm) -.2 W/cm^2 -5-10 min/2 x ERA -1MHz (5cm) -.2W/cm^2 -5-10 min/2 x ERA

question

dosage of ultrasound depends on

answer

-intensity and time -time depends on size of treatment area -for thermal at least 3-5 minutes (consider frequency) - maximum physiological effects are achieved in 10 min. - patient should feel mild warmth within 2-3 min (sooner if using 3MHz)

question

number of treatments of ultrasound

answer

depends on goals should have some detectable effect within 1 to 3 treatments -total RX duration depends on goals (wound healing takes longer) -thermal should only be used for subacute or chronic -nonthermal can be used for acute daily is common -no research for phonophoresis?

question

Frequency considerations (1 MHz vs 3 MHz)

answer

-depth of penetration -temperature increase -3 MHz is absorbed 3x faster than 1 MHz -3 MHZ has faster thermal effects more superficially -Greater heat effects in a smaller volume of tissue because it does not penetrate as far). -Studies have shown it takes avg. 3 min for significant -temp rise w 3 MHz at 2.0 W/cm^2 (10 for 1MHz) -use lower intensities when using 3 MHz

question

Target intensities

answer

-chronicity of condition -goal of RX -thickness of tissue -1 MHz: 1.5 - 2.0 W/cm^2 -3 MHz: .5 W/cm^2 (may increase intensity) -ultimate determinant is patient feedback -non-thermal US requires prescribed intensity

question

Pulsed Wave protocols

answer

PW- <50% duty cycle usually will not produce heat but may be intensity dependent (10 - 20% will not produce heat) -stimulates tissue regeneration (ulcers) -stimulates repair process (tendon repair) -increase metabolism (wounds) -increase membrane permeability (acute inflammation, phonophoresis) For wounds: - 3 MHz: .8 - 1.0 W/cm2 : 20% -brief durations 30 - 60 s/ERA (5-10 min total) -daily or every other day -wound bed (gel sheet) or periwound

question

Continuous wave to raise tissue temperature

answer

-will have non-thermal effects with both -ntensities of .5 to .8 W/cm^2 may not produce heat -extensibility of collagen structures (prior to stretching) -decrease joint stiffness (OA) -Increase blood flow (spasm, healing) -decrease pain (raise pain threshold) -produce mild inflammatory response like other thermal agents

question

US for tendon rupture repair

answer

-Frequency depending on depth (1 for deep 3 for shallow) -continued or pulsed depends on the stage of healing - .5 - 2.5 W/cm^2 3-5 min (because area is small)

question

acoustic streaming

answer

steady circular flow of cellular fluids induced by ultrasound -larger in scale than microstreaming -alters cellular activity by transporting material from one part of the ultrasound field to the other

question

microstreaming

answer

microscale eddying that takes place near any small vibrating object (around gas bubbles set into oscilation by cavitation)

question

cavitation

answer

formation, pulsation, growth, of gas bubbles they get smaller during compression and larger during rarefaction. if cavitation is stable - bubbles do not burst if cavitation is unstable - bubbles grow over a # of cycles and suddenly implode -may alter cell membrane permeability

question

ultrasound definiiton

answer

high frequency sound wave that can be described by intensity, frquency, duty cycle, effective radiating area and beam uniformity ratio. (heats smaller deeper areas than superficial heating agents) amont of energy being delivered depends on time of application

question

duty cycle

answer

proportion of treatment time that the ultrasound is on 20% - 2 milliseconds on 8 milliseconds off continuous is on 100% of the time

question

BNR

answer

peak intensity of the ultrasound output over the area of the transducer to the average intensity of the ultrasound output over the area of the transducer ratio. 3:1 is acceptable- means that some areas penetrate up to 3 cm even if we chose only 1.

question

attenuation

answer

It is the result of absorption, reflection and refraction. -Higher in tissues with high collagen content and with the use of high frequencies.

question

absorption coefficient

answer

materials with high AC allow heat to travel deeper but the heat is not as spread out (opposite for low AC) - the same amount of energy is being deposited but the absorption coefficient alters the distribution

question

temperature that yields the fastest rate of heating

answer

25 C of 77F Applying ultrasound in water cools the superficial skin applying ice before ultrasound may cause loss of sensation so it should be done cautiously

question

phonophoresis

answer

can be done with both thermal and non-thermal provides high drug concentration at delivery site avoids gastric irritation and first pass metabolism by liver should be avoided if patient is already taking medication by another means

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