Term
|
Definition
refers to acoustic (sound) waves that travel at a frequency greater than 20,000 Hz
Hz = (cycles/second) |
|
|
Term
| Clinical ultrasound falls under what category of physical agents used for thermal effects? |
|
Definition
|
|
Term
|
Definition
| the use of ultrasound that is used in the delivery of medicine to tissues |
|
|
Term
|
Definition
the number of completed wave cycles that pass a fixed point in 1 second.
Ex: 2 cycles in a 1 second interval
= 2 Hz |
|
|
Term
| Two frequencies of therapeutic US used often: |
|
Definition
|
|
Term
|
Definition
(M=mega=million Hz, 3 million cycles per second)
- affects superficial tissues (1-3 cm deep) |
|
|
Term
|
Definition
(1 million cycles per second)
-affects deeper tissues (3-5 cm deep) |
|
|
Term
| Frequencies below _______ are not used due to potential for tissue damage. |
|
Definition
|
|
Term
| US production via reverse piezoelectric effect |
|
Definition
| - electric energy applied to the piezoelectric crystal in the transducer causes expansion and contraction of the crystal which produces mechanical energy (US waves). Electrical energy is effectively changed to acoustic energy. |
|
|
Term
| The oscillating mechanical wave results in ... |
|
Definition
| compression of molecules next to the crystal within transducer. |
|
|
Term
| Followed by rarefraction of molecules next to the crystal during release of compressive forces |
|
Definition
| Movement of mechanical energy waves will continue until they are absorbed. |
|
|
Term
| Velocity through bone is faster than through water. |
|
Definition
| Velocity through water is faster than velocity through air. |
|
|
Term
| Why use a couplant (gel) between transducer & skin? |
|
Definition
- minimizes air that travels through & allows US to travel at greater velocity
- reduces risk of damage to crystal in transducer |
|
|
Term
| Biophysical characteristics of US are influenced by: |
|
Definition
- type of tissue through which US is transmitted
- angle of incidence for the US energy |
|
|
Term
|
Definition
| the gradual decrease in the intensity as US travels through a material |
|
|
Term
| Once absorbed, US cannot penetrate deeper tissues |
|
Definition
| Once absorbed, US cannot penetrate deeper tissues |
|
|
Term
Ranking of body tissues that absorb US
Highest to Lowest |
|
Definition
Bone (best absorbing tissue)
Peripheral Nerve
Cartilage
Tendon
Skin
Skeletal muscle
Fat
Blood
Water (poorest absorbing material) |
|
|
Term
| absorption of vibrating energy produces.. |
|
Definition
|
|
Term
|
Definition
| if a molecule is smaller than the US wavelength, energy cannot be absorbed upon contact |
|
|
Term
| Attenuation occurs to a greater degree at higher frequencies and causes.. |
|
Definition
| less energy to be available for penetration |
|
|
Term
| If the molecule is smaller than the sound wave, energy will be scattered. |
|
Definition
| If the molecule is larger than the sound wave, energy will be absorbed. |
|
|
Term
|
Definition
the redirection of an incident beam away from a surface at an angle equal and opposite to the angle of incidence
If US is delivered at an angle less than 90, reflected energy can be absorbed by nearby tissues. |
|
|
Term
| if energy is delivered at an angle greater than 90... |
|
Definition
reflected energy will return to it's source
- reflected energy and energy from transducer produces standing waves
- severe tissue damage |
|
|
Term
|
Definition
deflection of energy as it passes into a second medium
- US wave enters the tissue at one angle and continues through the tissue at a different angle |
|
|
Term
|
Definition
- acceleration of metabolic rate
- reduction/control of muscle spasm
- alteration of NCV
- increased circulation
- increased soft tissue extensibility |
|
|
Term
| Thermal effects of US can heat up to ... |
|
Definition
3-5 cm deep.
1 MHz heats up to 5 cm
3 MHz heats up to 1-2 cm
- Max temp is higher with 3 MHz |
|
|
Term
|
Definition
| US energy must be absorbed by the tissue |
|
|
Term
| Amount of heat produced in the tissue is dependent on what 3 things: |
|
Definition
- total amount of US energy
- thermal conductivity of tissue
- rate of perfusion of blood to tissue |
|
|
Term
| On average, soft tissue temp has been shown to increase... |
|
Definition
| by approx. 0.2 degrees C per minute with US delivered at 1W/cm2 at 1 MHz |
|
|
Term
| Non Thermal Effects of US are used for? |
|
Definition
| altering membrane permeability to accelerate tissue healing |
|
|
Term
|
Definition
| the oscillating US energy passes thru tissue creating molecular movement resulting in micromassage or microstreaming |
|
|
Term
| increased skin and cell membrane permeability |
|
Definition
| US energy agitates/stirs the ions within the tissue which can alter membrane permeability |
|
|
Term
| Non Thermal Effects of US |
|
Definition
- increase intracellular calcium level
- increase mast cell degranulation
- promote macrophage response
- increase rate of protein synthesis
- increase nitric oxide synthesis
- stimulate proteoglycan synthesis |
|
|
Term
|
Definition
| formation, growth, pulsation and collapse of gas or vapor-filled cavities in the fluids in a sound field |
|
|
Term
| cavitation may occur when: |
|
Definition
- transducer is kept in stationary position
- e-stim is used in combo with US
- high intensity at a therapeutic frequency (low freq) |
|
|
Term
|
Definition
use of the mechanical waves produced by US to enhance transdermal penetration of a topical medication into soft tissue
- opens pathways to drive molecules into the tissue |
|
|
Term
| US increases transdermal drug penetration by: |
|
Definition
| increasing permeability of stratum corneum through caviation |
|
|
Term
|
Definition
pulsed US (20%)
- drugs delivered by this become systemic |
|
|
Term
| Non-invasive techniques for medication introduction |
|
Definition
-corticosteroids
-salicylates
-analgesics |
|
|
Term
| Advantages of phonophoresis |
|
Definition
- higher concentration @ delivery site
- avoid gastric irritation
- avoid 1st pass metabolism by liver
- avoid pain/trauma/risk associated with injection
- allows delivery to larger area than injection and less likely to burn vs. iontophoresis |
|
|
Term
|
Definition
-treatment of inflammation
-early stages of tissue healing
-increase circulation
-dermal ulcers/open wounds
-increase soft tissue extensibility
-bursitis, tendonitis, ligament sprain
-muscle strain/spasm
-heamtomas
-chronic peripheral artery disorder |
|
|
Term
| Why treatment of Inflammation is an indication for US |
|
Definition
NON-THERMAL EFFECTS
-pulsed/micromassage
-change in membrane permeability
-allow for reabsorption of interstitial fluid
THERMAL EFFECTS
-continuous mode for inflammation and edema and RA |
|
|
Term
| Why Early Stages of Tissue Healing is an indication for US |
|
Definition
-acceleration of angiogenesis
-stronger development of tissue
-US during later stages may decrease tensile strength of tendons
-US may accelerate inflammatory (initial response to injury) and proliferative (produce news cells to replace damaged) stage |
|
|
Term
| Why US Increases extensibility of soft tissue |
|
Definition
sustained stretching of muscle during US can increase tendon length better than stretching applied after US tx
- joint contractures |
|
|
Term
|
Definition
cardiac pacemakers
malignant tumors
thrombophlebitis
infections
prone to hemorrhage
epiphysis of growing bones in children
Patients that have had radiation
directly over eyes or genitalia
over spinal cord or CNS tissue
pregnant
breast implants
acute inflammation |
|
|
Term
| why pts with cardiac pacemakers are contraindicated for US |
|
Definition
- not good for your pt to cause malfunction of this
- should not be applied below the ribs directed toward the heart |
|
|
Term
| why US is contraindicated ... epiphysis of growing bones in children |
|
Definition
- US may disturb growth of bone at epiphyseal plate
-some studies suggest safe at low tx intensities |
|
|
Term
| why US is contraindicated over eyes/genitalia |
|
Definition
- may cause cavitation within fluids of eyes
- may affect gamete development |
|
|
Term
| why US in contraindicated for pregnant pts |
|
Definition
do not apply over area where it may reach fetus:
abdomen
pelvis
lumbosacral |
|
|
Term
|
Definition
fractures
over tendon repair
cement/plastic or metal implants
pt with cardiac disease |
|
|
Term
| why fracture is a precaution for US |
|
Definition
- recent studies suggest low dose can reduce fracture healing time
- high intensity may disrupt union of fracture
- high intensity over fracture will cause pain |
|
|
Term
| continuous mode ultrasound |
|
Definition
greatest heat-producing potential of 2 modes
used when HEATING is desired
soundwave is not interrupted, more energy is delivered to pts tissue during tx time |
|
|
Term
|
Definition
-non-continuous mode.
-used when NONTHERMAL effects are indicated
-the amount of energy delivered is based on duty cycle
-common duty cycle -10%,20%,50%
-less heat is produced by pulsed mode US than by continuous mode US
-choice for acute inflammatory conditions when heating is contraindication |
|
|
Term
|
Definition
| the percent of time that US is on during a given time |
|
|
Term
| How much total US energy you deliver to the pt is measured in |
|
Definition
|
|
Term
|
Definition
W=power=amount of energy in US beam
cm2=ERA of sound head |
|
|
Term
|
Definition
|
|
Term
| 1 degree celsius total temp increase produces mild heating effect |
|
Definition
hematoma or subacute injury
-low intensity for initial tx or when mild heating effects desired |
|
|
Term
| 2-3 degrees celsius total temp increase produces moderate heating effect |
|
Definition
| - chronic inflammation, pain, trigger points |
|
|
Term
| 4 degrees celsius total temp increase produces max/vigorous heating effect |
|
Definition
stretch collagen (tissue extensibility)
joint contractures |
|
|
Term
|
Definition
larger sound head has a larger ERA (effective radiating area)
ERA is smaller than the surface of the sound head
ERA is less than area of the crystal |
|
|
Term
| if two sound heads of diff sizes are delivering the same intensity of US... |
|
Definition
| the larger sound head is delivering more total US energy during the same amount of time |
|
|
Term
| BNR (Beam Non-uniformity Rate) |
|
Definition
the ratio of the peak power to the average power in the US beam
- produces hot spots or higher than average intensity
< 6:1
industry < 5:1 |
|
|
Term
| direct contact US application method |
|
Definition
-use of a coupling agent (gel); a medium for sound waves to travel through
-minimizes potential for air molecules
-continuous movement of transducer
-pt must be able to tolerate direct pressure to area |
|
|
Term
|
Definition
for tx of:
wounds,
irregular shaped areas,
where pt cannot tolerate direct pressure |
|
|
Term
| things to remember with water immersion: |
|
Definition
- applicator should be 0.5-1 in from tx area
-perpendicular to tx area
-brush air bubbles away from transducer
-increase intensity by 0.5 W/cm2 over what direct contact would require |
|
|
Term
| bladder/use of fluid filled cushion |
|
Definition
-used to treat odd shaped areas
-use coupling agent bt:
skin and bag
bag and applicator |
|
|
Term
| why should we never use stationary method? |
|
Definition
| potential for hot spot to form or cavitation |
|
|
Term
| US frequency of tx session |
|
Definition
2-3 times a wk
-until pt symptoms resolve
-until function is restored
-if no change after 3 tx, discontinue US
-MAX OF 14 US sessions
-potential of anemia
-take 2 wk break before beginning another session |
|
|
Term
|
Definition
- 5 min per ERA heats tissue effectively
decrease time for tendon
-break up large tx areas |
|
|
