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56 Cards in this Set

  • Front
  • Back
History of US

first use?
frequency of use as a phys. agent?
1st large scale application of US was for SONAR
Sound Navigation and Ranging (WWII)
Found to heat tissue and has wide clinical application
Studies show that US is by far the most widely used physical agent
What is Therapeutic Ultrasound ?

main idea?
The use of sound waves to affect tissue.
US is defined as sound with a frequency of greater than 20,000 cycles per sec. Measured in HZ. (20,000 Hz)
At what frequency of sound do humans hear?
16 to 20,000 Hz
Therapeutic US is delivered at what frequencies?
1.0 MHz or 3.0 MHz (1 MHz = 1,000,000 Hz)
How is Therapeutic US generated?
An alternating electrical current is applied to the crystal in the transducer of the US head. As the alternating current polarizes and depolarizes it expands and contracts the crystal producing a sound wave
Piezoelectric effect

main idea?
A piezoelectric material, such as crystal has the ability to change shape in response to an electrical current or mechanical force.
is bone a piezoelectric material?
PTA decision making

4 major points
Small head transducer or large head transducer?
3.0 MHz or 1.0MHz frequency
Continuous or pulsed?
What intensity? (W/cm2)
Small or large head?

The ERA is slightly smaller that the area of the treatment head.(p.190)
Small or large head?

maximum area that can be effectively treated?

common head sizes?
Can only treat any area approx. twice the size of your sound head effectively.

2,5 or 10 cm. head
1.0 or 3.0 MHz

what is the main difference between the two frequencies?
The lower the frequency, the greater the depth of penetration. The higher the frequency, the easier the sound waves are to absorb.
what is the maximum effective depth of treatment for 1.0 MHz?
max depth of penetration is 5cm.
what is the maximum effective depth of treatment for 3.0 MHz?
max depth of penetration is 1-2 cm.
how much more does 3.0 MHz increase heat over 1.0 MHz?
3.0 MHz frequency increases heat 3-4 times greater than the 1.0 MHz.
Continuous vs. Pulsed

when is one used over the other?
In general, continuous US is used for it’s thermal effect, pulsed is used for it’s non-thermal effect.
Thermal effects of US

impact on metabolic rate?
impact on pain and muscle spasm?
-Acceleration of metabolic rate

-Reduction or control of pain and muscle spasm
Thermal effects of US

impact on NCV?
impact on circulation?
impact on soft tissue extensibility?
-Alteration of nerve conduction velocity

-increased circulation

-Increased soft tissue extensibility
Thermal effects of US

role of collagen content and US absorption?
US is selective in the tissues it most heats, according to the tissues ultrasound absorption coefficient.
-Tissues with a high collagen content have high US absorption.

-Those with high water content do not absorb US well.
Tissues that absorb US efficiently

5 main types
joint capsule
Tissues that dont absorb US efficiently

2 main types
Fat is a very poor US absorber.

Muscle has a low absorption coefficient and is usually too large an area for US to be effective.
Other Factors Affecting US Absorption

how do the following affect US?

-Blood circulating through the tissue will cool the tissue. ...muscle

-Conduction from one warmed area to another will increase heat. …bone
Other Factors Affecting US Absorption

how does REFLECTION affect US?
Reflection of ultrasound waves in regions of soft tissue-bone interfaces will increase heat in surrounding tissue.

where/when will US be reflected?
Ultrasound will be reflected back where it meets acoustic impedance.
does therapeutic US travel well through air?
US at therapeutic frequency does not travel well through air and will have 100% reflection at the air-skin interface. Therefore a transmission medium must be used. Studies show 77 degrees is optimal for gel. ?.
what % of US waves will be reflected at tissue/ bone interfaces?
There is 35% reflection of the US waves at tissue bone interfaces, surrounding tissues will have increased heating.
Nonuniform heating

6 main factors affecting thia
Non uniform output from the US
Variety of tissue types
Reflection of sound waves
Thickness of tissue layers
how does the PTA overcome nonuniform heating with the use of US?
Moving the sound head throughout the application helps to equalize the heat distribution and minimize hot spots

main idea?
A measure of the decrease in ultrasound intensity as the ultrasound wave travels through the tissue.

it is the result of what 3 factors?
Absorption ( conversion of sound waves to heat)


Refraction at tissue interfaces, changes in density of tissue
On average soft tissue temperature has been shown to increase by how many degrees Celsius per minute with US at 1/W/cm2 ?
0.2 degrees C per minute
Agents in Conjuction with US

do heating packs or warm gel affect the heating of deep tissues?
Agents in Conjuction with US

impact of cold water or ice when used with US?
Use of cold water or ice may reduce impact of temperature increase in US
Nonthermal Effects

main idea when using in this mode?
Increase intracellular calcium, increase skin cell membrane permeability, increase mast cell degranulation, increase chemotactic factor and histamine release, increase macrophage responsiveness, and increase the rate of protein synthesis by fibroblasts…all essential components of tissue healing
Tissue Healing

what pulse % and frequency has been shown to be effective during the inflammatory phase of repair?
20% with intensities of .5 to .75 W/cm2
Does pulse US or continuous US have greater affect on membrane permeability?
Pulsed ultrasound has been shown to have significantly greater effects of membrane permeability than continuous US.
Pulsed US

5 main uses
-Facilitate healing of dermal ulcers
-Healing of incision sites
-Healing of tendon injuries
-And at very low intensities, used for healing fractures.
Clinical Applications for US

impact on soft tissue shortening?
US effective for heating tissues like tendons, joint capsule and ligaments
What are the treatment parameters with US found to be effective for soft tissue?
1 or 3MHz – depending on tissue depth
1.0 – 1.5 W/cm2,
5 to 10 minutes
Followed by stretching
Clinical Applications for US

impact on PAIN CONTROL
US may modify pain by altering its transmission or perception or modifying the underlying condition
What are the treatment parameters with US found to be effective for pain?
1 or 3 MHz
.5 to 2.0 W/cm2
3 to 10 minutes
Clinical Applications for US

US may accelerate healing of vascular and pressure ulcers.
What are the treatment parameters found to be effective for wound healing with US?
3 MHz
Pulsed 20%
.8 to 1.0 W/cm2
5-10 minutes
coupling sheet, gel around wound
Clinical Applications for US

US may accelerate angiogenesis.
What are the treatment parameters found to be effective for healing of surgical incisions with US?
In studies used 1.0 MHz
Pulsed 20%
.5 to .8 W/cm2
3 to 5 minutes, 3 to 5 times per week.
Clinical Applications for US

US may promote enhanced recovery and may impact greater resolution of calcium deposits. Pulsed mode at low intensity is recommended during the acute phase
What are the treatment parameters found to be effective for tendon injuries with US?
1 or 3 MHz
Pulsed 20%
.5 to 1.0 W/cm2
3 to 5 minutes
Clinical Applications for US


-Pulsed US may help with resorption of calcium deposits

- Very Low-dose US can reduce fracture healing time. Home unit was approved in 1994 by FDA
What are the treatment parameters with US found to be effective for bone growth?
1.0 MHz
Pulsed 20%
.15 W/cm2
15-20 minutes daily
Higher intensity will cause pain/decrease healing
What are the treatment parameters with US found to be effective for carpal tunnel syndrome?
1.0 MHz
1.0 W/cm2
Pulsed 25%
15 minutes for 20 sessions

main idea
Uses a topical drug as the conduction medium
US increases the permeability of the stratum corneum – superficial layer that acts as a protective barrier – does not carry or push the medication through the skin.
Provides higher initial drug concentration at site, avoids gastric irritation, avoids metabolism by the liver, avoids risks of injection.
Distributed throughout the body through circulation

general precaution?

Make sure you don’t over medicate via different transmission modes.
3 MHz to optimize absorption
Pulsed 20%
.5 to .75 W/cm2
5 to 10 minutes for 6 treatments.
Ultrasound- Contraindications

9 major points
Malignant tumor
CNS tissue
Joint cement
Plastic components
Reproductive Organs
Ultrasound -Precautions

4 major points
Acute inflammation – thermal effect
Epiphyseal plates – studies showed damage occurred at intensities higher than 3.0 W/cm2 – (FDA)
Fractures – generally causes pain unless intensity is very low
Breast implants - rupture
general rules of thumb when using US for THERMAL EFFECTS

DEEP- 1.0 MHz, 1.5 W/cm2

SUPERFICIAL- 3.0 MHz, .5 W/cm2

general rules of thumb when using US for NON THERMAL EFFECTS

20% Pulse, .5 W/cm2
General Guideline for Duration of Treatment...
SMALL- 5 min
LARGE- 10 min