Lecture 5 - Ultrasound Continued Flashcards
List coupling agents
Gel Petroleum based creams Water based lotions Immersion in Water –¼ inch to ½ inch from treatment area Temperature of Coupling Agent Phonophoresis
What is phonophoresis?
Processes by which we administer topical medication directly to the lesion site
- sometimes people cant take pills orally due to contraindication, same for injection so this is an alternative
Why do you think phonophoresis gets medication to the area faster?
-the whole idea is to bypass the bodies digestive process
How do you think phonophoresis works?
Driving medication directly through the tissue
What is one thing that limits phonophoresis effectiveness?
- limited by the frequency of the sound head your using with regard to depth of penetration
What do you feel during each application to the quadriceps?
Continuous - Gentle warming
In general don’t feel a whole lot other then gentle heating
The patient will likely feel nothing and you will need to be able to explain why
What is Half –Value, Half Layer Rate
Frequency dependent
Always want to target 50% with regard to depth of lesion
why would you not want to target a lesion deeper then half value layer?
- Not very effective - when you calculate chosen intensity calculate it based upon depth you can reach with a particular frequency
the higher the frequency the less ____ of penetration
depth
What is the penetration depth according to Starkey for 1MHz and 3MHz
1.5cm to 2cm with a 3Mhz with a 1MHz head 5cm - that is the max or half value distance as referenced in starkey
What does ERA stand for?
Effective radiating area (The amount of head that actually emulates the sound wave
Recognize ERA and actual size of the head are not the same
Why is ERA important?
Dictates how large of a lesion you can treat - which is 2x the size of the ERA
What is BNR?
Mass produced crystals will always have microimperfections and these imperfections will cause random peaks in the sound waves
What ratio of BNR is the limit?
8:1
elsa personally wouldnt use it beyond a ratio of 6:1
What does a BNR of 8:1 mean?
8:1 means 8 times the normal intensity
EXAM Q: What is Elsa and Starkey’s limit for BNR?
6:1
Ultrasound is used as one part of the rehabilitation process before exercising because….
- Thermal effects: increase tissue temperature
- Allows tissue to stretch easier, gaining increase in rang of motion priming well for exercise - Mechanical effects: even non-thermal effects break up waste products increasing cell diffusion and easily dissipated with subsequent exercise
- The waste products is causing some of the limitation in ROM
- Increased ROM will prime the patient for exercise
What must you know prior to ultrasound application?
Physiological effects
Therapeutic effects
Needs of the injured tissue
Why must you know the needs of the injured tissue prior to ultrasound application?
Heat in general and ultrasound respond to different type of tissues in different ways so knowing the type of tissue that is injured will help you get to where you want to go
What must you find out to determine dosage for ultrasound?
- Establish stage of healing
- Depth of the lesion
- Damage to tissue
The goals of the treatment and the ____ of the ultrasound must align
Dosage
- first and foremost determine aims of treatment
Increased frequency = ____ wavelength
Decreased
Increased frequency = ____ in height of waves
Decreased
Increased frequency = ____ tissue depth of penetration
Decreased
Increased frequency means the beam is more ____
Collimating (Parallel in nature)
Increase frequency = _____ absorption
Increase
Most important point is thermal and mechanical effects occur with _____ and no thermal effects, mechanical only with _____
Continuous
Pulsed
Describe continuous ultrasound
Continuous waves
Thermal effects
- Pressure changes
- Amplitude
- Micromassage
- Acoustic streaming
Describe pulsed ultrasound
Interrupted waves (bursts)
1:5 = 1/5 on and 4/5 off
% = 20% duty cycle
Non-thermal effects only
- Pressure changes
- Amplitude
- Micromassage
- Acoustic streaming
How much heat will 20% duty cycle generate?
None
How much heat will 50% duty cycle generate
A little
T/F increased duty cycle means more heat Ex. 80% produces more heat then 30%
True
When would you use pulsed ultrasound?
If you still have inflammation, if heating the area causes pain, if all you want to do is generate mechanical effects - for examples in a post-op fracture… you can use to break up scar tissue
Why would you not want to ultrasound a 7 day old fracture?
You would not want to disrupt a fracture in the early stage of healing. Once the fracture is stable.
- new research that pulse ultrasound speeds up rate of healing
- you have to look at parameters of the modality. dosages in and around the 0.01 - 0.03 w/cm squared were used in study. our machines at sheridan only go as low as 0.1 w/cm squared.
What should you ensure before using ultrasound on a fracture?
you want to make sure there is no risk of shock and that the fracture is stable - so it could be used relatively quickly (such as day 3)
What is attenuation with regard to ultrasound?
Attenuation: decrease in the US energy as a result of: Reflection Refraction Absorption Transmission
As wave is transmitted through the various tissues, there will be a _______ (or an attenuation) in energy intensity.
decrease
Attenuation occurs due to absorption or dispersion and scattering of the sound waves as a result of _____ or _____
reflection or refraction
Attenuation results in reduction of one-half its previous intensity in a certain distance (called ______)
“half-value distance” or HVD
Capability of the energy to penetrate to deeper tissues is determined by the _____ of the ultrasound as well as the _______ of the tissue through which it is traveling
Frequency.
Characteristics
Attenuation is ____ and ____ dependent
Frequency and tissue dependent
Absorption takes place at a _____ level
molecular
The greater the collagen content the greater the ______
absorption
Inverse relationship between absorption and ______
penetration
There is an increase in absorption with an increase in _______ –less energy is transmitted to the deeper tissue
frequency
fat does not absorb as much as we work our way ______
deeper
______ in nerve tissue will absorb a fair amount of energy - so need to be cautious
proteins
You will get better absorption with a (higher/lower)______ frequency - so better with _mhz rather then _mhz
higher. so better with a 3mhz rather then 1mhz
Ultrasound: List 4 properties that have the greatest amount of absorption
Ligaments
Cell membranes
Joint capsules
Highly collagenous tendons
every substance every bit of tissue has within itself acoustic impedence - it is this impedence that is going to change the ultrasound and reduce the _____ it carries through
energy
everytime you go through a different ____ you will get some sort of attenuation
interface
Amount reflected and amount transmitted is determined by the ________ of the two materials on either side of the interface
acoustic impedances
Describe reflection of energy
Some of the wave power is reflected back into the original medium
Reflection is dependent on the difference in acoustic impedance between the tissues on either side of the interface. If the tissue is of the same make-up ____ reflection will occur
less
____ in tissue will cause waves to be reflected back to the crystal
Air.
When arthroscopic surgery is conducted they blow a lot of air into the joint so need to be aware of this.
Reflection –Important Interfaces
Bone-periosteuminterface Tissue-air interface Transducer head to air interface Bone-soft tissue interface Connective tissue interface
When ultra ultrasounding tissue up against bone, we know that bone will absorb the ultrasound quite readily but also because of its density you will get a degree of _____
Reflection
If you are ultrasounding a ligament next to a bone what do you think is happening to the bone absorbing the high energy and heat?
The bone heats up
Muscles require high intensity ultrasound but if they are right up against bone you are heating up the bone and this will reuslt in ____
bone pain
Reflection: Bone Periosteal interface
__% reflected, ___% absorbed
30% reflected, 70% absorbed
Reflection: Bone –Periosteal Interface
Load to the periosteum is equal to the ____power plus the reflected power
incident
Reflection: Bone –Periosteal Interface
Shear wave is generated at the boundary resulting in heat which is absorbed by the periosteum resulting in ______ ___
periosteal overheating
____% reflection occurs at the tissue air interface
99.9%
Tissue air interface creates localized high intensities and ____ waves
shear
Tissue air interface is also occurring if you don’t make good contact with the ______
Sound head
What is refraction?
deviation of the sound wave
Enters and leaves at different angles
Comes in at right angles = travels straight
Comes in on an angle = refracts
Ultrasound wave transmission determined by:
acoustic impedance of the tissue
High impedance = ____ in transmission of US
Increase
Solids = \_\_\_\_ impedance Water = \_\_\_\_ impedance Air = \_\_\_\_ impedance
Solids = high impedance
Water = medium impedance
Air = low impedance
How can the therapist avoid standing waves?
Keep the sound head moving
How do standing waves occur?
Occurs when ultrasound traveling through tissues of various impedance
When reflected wave meets incoming incident wave
Standing waves _____ intensity of the energy creating areas of high and low pressure (hot spots)
increase
Preventing Standing Waves: Movement of the transducer is ____ dependent
BNR
Preventing Standing Waves: Moving the transducer too ____ decreases the total amount of energy absorbed per unit area.
rapidly
Preventing Standing Waves: Should only ever treat an area no bigger than ___ the size of the ______ (ERA)
2x
Transducer head
Preventing Standing Waves: Slow movement = more control = even ____ throughout area
distribution
Preventing Standing Waves: Fast moving transducer will not allow adequate _____ and sufficient heating will not occur (Prentice)
absorption
Preventing Standing Waves: Rate of transducer movement is slow: maximum of ___ cm/sec. If the transducer is raced over the skin, ultrasound effects will be reduced. (Behrens and Michlovitz)
3-4 cm/sec
List the non thermal effects of ultrasound
Acoustic Streaming (Microstreaming)
Cavitation
ultrasound modality of choice over hot pack because of the ______
Mechanical effects
microstreaming is a good thing cavitation can be ____
good and bad
_____ cavitation = good
destructive cavtitation is unstable and bad
stable
What is acoustic streaming
The unidirectional movement of fluids along the boundaries of cell membranes resulting from the mechanical pressure wave in an ultrasonic field
In biological tissue this acoustic streaming is very small and is therefore referred to as _______
microstreaming
Circular flow of bubble with acoustic streaming cause a change in cell _____ structure and function
cell membrane
List 3 things micro streaming increases.
What does it promote?
What does it reduce?
Increases cell diffusion rate
Increased fluid interchange
Increases sound absorption
As a result you get the promotion of healing and some reduction of pain
the bublles forming in our in lab experiment was an example of _____
cavitation
Bubbles that form with cavitation will expand and ____ -
Contract
What will the bubble formed through cavitation stimulate and facilitate?
it will stimulate the cells
facilitates healing process through transfer through the cell
What is cavitation?
Formation of gas bubbles that expand and compress due to ultrasonically induced pressure changes in tissue fluids
Describe stable cavitation:
Bubbles expand and contract in response to regularly repeated pressure changes over many acoustic cycles without growing to critical size
Cavitation results in an increased flow in the fluid around these vibrating bubbles resulting in _____
microstreaming
bubbles can implode due to increased intensity of the wave - the higher the intensity the more chances of _____ cavitation occuring
unstable
For cavitation to occur when do you think the intensities would have to be higher? in a pulsed environment or continuous environment -
Pulsed
unstable cavitation will occur more often in ____ intensities - whenever possible you should avoid _____ ultrasound due to these increased intensities
higher
pulsed ultrasound
Describe unstable cavitation
Violent large excursions in bubble volume before implosion and collapse occurs after only a few cycles.
Creates increased pressure and high temperatures which cause local tissue damage
How can you prevent unstable cavitation?
Lowest intensity possible
Avoid standing waves
Revert to higher frequency sound head thus reducing intensity
Using a low rate continuous setting allows you to keep the intensity low
What are non-thermal biophysical effects of ultrasound?
Facilitation of tissue repair
Increase in cell permeability –an increase in the cells permeability allowing an influx of calcium
Stimulate the release of histamine
Increase in the degranulation of mast cells
Increase in the phagocytic activity
Increase in the number of fibroblasts causing an increase in protein synthesis which directly impacts tissue healing
Swelling reduction through the increase of blood flow
Bone Repair –only after a certain stage
To achieve a therapeutic effect from ultrasound, the tissue temperature has to be maintained at
___ to ____ degrees for at least _ minutes.
40 to 45 degreesfor at least 5 minutes.
List thermal effects of ultrasound
Increase metabolic rate increase circulation decrease pain increase enzyme activity increase extensibility of tissue increase viscoelastic properties
Decrease joint adhesions, thus created an increase in joint range Increase tissue healing Increase collagen extensibility Muscle spasm reduced
EXAM Q: Where are ultra sounded greatest effects noted?
Wound Healing –greatest effects noted as it related to tendon, ligament, cartilage
What does ultrasound do in the Inflammatory phase
Stimulates release of histamine from mast cells
What does ultrasound do in the Proliferation phase
Reduction in the size and production of scar tissue
What does ultrasound do in the remodeling phase
Change in collagen fibrepatterns giving rise to greater tissue elasticity
EFFECTS OF ULTRASOUND ON VARIOUS TISSUE TYPES: Adipose Tissue
–very little energy absorbed
EFFECTS OF ULTRASOUND ON VARIOUS TISSUE TYPES: Nervous Tissue
–similar to that found with other heat generating modalities
-effect on nervous tissues is same as other modalities with one exception - because of content of nerve you never want to ultrsound directly overtop a nerve
EFFECTS OF ULTRASOUND ON VARIOUS TISSUE TYPES: Autonomic nervous system
Autonomic Nervous System –caution with patients who suffer from diabetes
With regard to circulation what do you never want to ultrasound over?
A major blood vessel
Contraindications for ultrasound
1) Specialized tissue
2) Cancer, Radiation
3) Infection
4) Viscera, Pregnancy
5) Cardiac Pacemaker
6) Thrombosis
7) Arteriosclerosis
8) Carotid Sinus, Stellate Ganglion
9) Laminectomy
Important contraindications for ultrasound
1) Specialized tissue
2) Cancer, Radiation
4) Pregnancy
6) thrombosis - could dislodge a clot
9) laminectomy - Post-op proceedure where the lamina of a segment has been removed
Why is this a problem?
Spinal cord is exposed
Ultrasound treatment precautions
Effused Joint Bursitis Epiphyseal plate Arthritic Joints Implants Burns Major Blood Vessels and Nerves Therapist precautions
Can you can use ultrasound on a bursa -
Yes
How can you use ultrasound on a Bursa so it doesnt expand?
Pulsed
inflammation of the bursa will like pulsed ultrasound
Prior to application of ultrasound what should you do?
Prepare US unit Prepare patient Tell them you desired outcomes Contraindications Get permission Position patient comfortably and to allow for one minute stretch
What is the dosage using the charting system based upon?
Based on aims of treatment Stage of healing Desired outcomes Frequency (depth of lesion) Tissue type Interfaces Coupling Agent
Ultrasound protocol:
1.Aim of Treatment –thermal or non-thermal 2.Determine depth of lesion –Frequency 3.Position the patient 4.Explain treatment and get permission to apply 5.Go thru contraindications
Ultrasound dosage must account for:
Tissue type-Organized collagen absorbs more ultrasound than muscle
Boney reflection
Refraction at interfaces
Coupling –gel, water
Depth of lesion –different frequencies
If treat in water then ____ the intensity and make the water temperature appropriate
increase
Increased collagen requires ___ intensity
less
Tendon absorbs __ times more ultrasound than muscle
3 times
Suggested ultrasound dosage for muscle
superficial -3.0MHz
.8 -1.0 w/cm2
deep -1.0 MHz
.8 –1.5 w/cm2
for 5 minutes
Suggested ultrasound dosage for tendon, ligament, capsule or adhesions
superficial -3.0 MHz
.3 -.5 w/cm2
deep -1.0 MHz
.4 -.8 w/cm2
for 5 minutes
Ultrasound application precautions
Never turn on the ultrasound unit until the sound head has coupling media and head is against the skin surface
Do not heat or chill the treatment area with a hot pack or cold pack first
Ultrasound treatment schedule
Inflamed -treat every other day
-pulsed 20% duty cycle
Demolition, healing-treat daily
-low intensity continuous
ChronicCondition -treat daily
-mild -medium and high intensity continuous
Reevaluate the dosage and use every ____ treatments
3
___ treatments maximum to determine if condition is improving and the use is appropriate
12
Describe the stretch window. How long does it last?
Window of tissue viscoelasticity and heat (Draper)
Last minute of treatment and for 5 more minutes
Will thermal effects last longer with a 1Mhz or 3Mhz?
Will you get to therapeutic range faster with a 1Mhz or 3Mhz?
Thermal effects last long (decay slower) with a 1 MHz treatment vs. a 3MHz treatment although you will get to therapeutic range faster with a 3MHz treatment
Would you ultrasound a hematoma?
If so when?
You can on a continuous setting with a low intensity. AFTER 8-10 days.
Should be checking the site before U/S to see if there is a buildup and how deep it is.
What happens if you ultrasound a deep hematoma before it is safe to do so?
Could produce Myositis ossificans in the muscle belly.
