Ultrasound and Diathermy Flashcards
Absorption
Conversion of mechanical energy of ultrasound into heat
Absorption coefficient
The degree to which a material absorbs ultrasound
Absorption coefficients are different for different materials and ultrasound frequencies
Angiogenesis
The development of new blood vessels at an injury site
Attenuation
The decrease in ultrasound intensity as ultrasound travels through tissue
Acoustic streaming
The steady circular flow of cellular fluids induced by ultrasound
The flow is larger in scale that microstreaming
It is thought to alter cellular activity by transporting materials from one part of ultrasound field to another
What is the beam nonuniformity ratio (BNR)?
The ratio of the spatial peak intensity to the spatial average intensity
Usually b/t 5:1 and 6:1
FDA requires max BNR for an ultrasound transducer be specified on the device
Cavitation
The formation growth, and pulsation of gas-filled bubbles caused by ultrasound
Compression
Increase in density of a material as ultrasound waves pass through it
What is the depth of tissue at which the ultrasound intensity is half its initial intensity
Half life
Microstreaming
Microscale eddying that takes place near any small, vibrating object
Occurs around gas bubbles set into oscillation by cavitation
Near field/ far field
The ultrasound beam initially converges and then diverges
Convergent region is known as near field
Divergent field is known as far field
What are other names for the convergent region?
Frensel zone
What is another name for the divergent?
Fraunhofer zone
How do you calculate the length of the near field?
Radius of transducer (squared)/ wavelength of ultrasound
What is the application of ultrasound with a topical drug to facilitate transdermal drug delivery?
Phonophoresis
Piezoelectric
The property of being able to generate electricity in response to a mechanical force Or being able to change shape in response to an electrical current (as in an ultrasound transducer)
What is a decrease in density of material as ultrasound waves pass through it?
Rarefaction
Reflection
The redirection of an incident beam away from a surface at an angle equal and opposite to the angle of incidence.
Ultrasound is reflected at tissue interfaces, with most reflection occurring where the greatest difference is present b/t the acoustic impedance of adjacent tissues
Refraction
the redirection of a waves at an interfaces
When refraction occurs, the ultrasound waves enters tissue at one angle and continues through the tissue at a different angle
Standing wave
Intensity maxima and minima at fixed positions one half wavelength apart
When does a standing wave occur?
When the ultrasound transducer and reflecting surface are exact multiples of wavelengths apart, allowing the reflected wave to superimpose on the incident wave entering the tissue
How can standing waves be avoided?
By moving the ultrasound head throughout the treatment
Ultrasound
Sound with a frequency greater than 20,000 cycles per second that, when applied to the body, has thermal and nonthermal effects
Transducer
a crystal that converts electrical energy into sound .This term is also used to describe the part of an ultrasound unit that contains the crysteal
What can another name for the transducer?
Sound head
What is continuous delivery of ultrasound throughout the treatment period?
Continuous ultrasound
Duty cycle
The proportion of the total treatment time that the ultrasound is on
Can be expressed as a % or a ratio
ie- 20% or 1:5 is on 20% of the time off 80%
Effective radiating area
The area of the transducer from which the ultrasound energy radiates
Since the crystal does not vibrate uniformly, the ERA is always smaller than the area of the treatment head
Frequency
the number of compression-rarefaction cycles per unit of time, expressed in cycles per second or hertz
What is the amount of acoustic energy per unit time? How is it expressed?
Power
It is expressed in watts (w)
Intensity
The power per unit area of the sound head
It is expressed in watts per cm squared (w/cm2)
The World Health Organization limits the average intensity output by therapeutic ultrasound unit to ______.
3w/cm2
What is the usual frequency range for therapeutic ultrasound?
1 to 3 million cycles per second ie- 1 to 3 MHz
What does increasing the frequency of ultrasound cause?
A decrease in the depth of its penetration and concentration of ultrasound energy in superficial tissues
Pulse ultrasound
Intermittent delivery of ultrasound
Minimizes its thermal effects
What are some examples of direct interventions based on the POC?
physical agents, modalities (ther ex, gait & transfer training)
What are some indirect interventions based on the POC?
patient & family education, documentation, coordination & communication w/ others
Spatial average temporal average (SATA) intensity
The spatial average intensity of the ultrasound averaged over the ON time and the OFF time of the pulse
How does the Nagi model help us understand what is happening with the patient?
It allows us to understand what is happening at all levels of the individual, help us appreciate functional limitations and understand individual implications on roles & societal expectations
At what level do physical agents act in the Nagi model?
pathology, impairment, functional limitation, disability, handicap
The application of physical agents primarily has these positive effects?
modification of tissue inflammation & healing, relief of pain, alteration of collagen extensibility, or modification of muscle tone
Name a few nonthermal effects of ultrasound that may alter membrane permeability?
Acoustic streaming, cavitation, and microstreaming
Non-thermal also: Increases rate of protein synthesis by fibroblast
Increases intracellular calcium, skin and cell membrane permeability, mast cell degranulation, chemotactic factor and histamine factor release
Increase macrophage responsiveness
Sound energy is best absorbed in which type of tissues?
Tissues with high collagen content
ie- bone, tendons, ligaments, joint capsules
APTA position statement on the use of clinical modalities
physical agents alone do not constitute effective PT, should be applied in conjunction w/ other direct interventions
What information would go into the subjective portion of the note?
Pre & post treatment; pain scale
What information would go into the objective portion of the note?
pre & post treatment performance, ROM, quality of movement data, specify what you did, details of HEP
What information would go into the assessment portion of the note?
Did the pt have any improvements in impairments or functional activities? Is the patient progress slow or fast as expected? Why is skilled care needed?
What information would go into the plan portion of the note?
What happens next
What is the benefit of the 3MHz ultrasound frequency.
Although depth of penetration is lower the maximum temperature achieved is higher
What does the inflammatory phase consist of?
1-6 days post tissue damage, vasodilation to vasoconstriction, edema (increased permeability in vessels & interstitial tissues, histamine released), platelets & neutrophils release factors to initiate clotting, phagocytosis , macrophages
What does the proliferation phase consist of?
3-20days, collagen deposited to replace damaged tissue, epithelialization, wound margins contract, neovascularization, fibroplasia & collagen fill the bottom & sides of the wound
What does the maturation phase consist of?
9day-2yrs post injury, remodeling of the wound, unneeded collagen is reabsorbed, with new tissue maturation, new tissue resembles original tissue to allow resumed normal function
Spatial average intensity
The average intensity of the ultrasound output over the area of the transducer
Spatial peak intensity
The peak intensity of the ultrasound output over the area of the transducers.
The intensity is usually greatest in the center of the beam and lowest at the edges of the beam
Spatial average temporal average (SATA) intensity?
The spatial average intensity of the ultrasound averaged over the on time and the off time of the pulse
What is chronic inflammation?
persists after acute inflammation especially if the injuring agent is still present or it’s an immune response to a foreign body or due to an autoimmune trigger
What is the result of chronic inflammation?
increased collagen production, more dense scar & possible adhesions
What are some examples of local factors that influence healing?
type, size, location of injury, infection, vascular supply, movement/excess pressure, temperature deviation, topical medications, electromagnetic energy, retained foreign body
What are some examples of systemic factors that influence healing?
age, infection or disease, metabolic status, nutrition, hormones, medication, fever, O2
Spatial average temporal peak (SATP) intensity
Measures the amount of energy delivered to the tissues during the ON time of the pulse
What are precautions for ultrasound use?
Acute inflammation- heat exacerbates inflammation
Epiphyseal plates
Fractures- low dose accelerates healing/ high dose causes pain, impairs healing of fracture
Breast implants- high heat could cause implant to rupture
What does low intensity pulsed ultrasound produce?
Non-thermal effects that facilitate tissue healing, modifies inflammation, and enhances transdermal drug deliver
Name a few nonthermal effects of ultrasound that may alter membrane permeability?
Acoustic streaming, cavitation, and microstreaming
Sound energy is best absorbed in which type of tissues?
Tissues with high collagen content
As ultrasound travel through material, it gradually decreases in intensity. What is this called?
Attenuation
In the tissue the thermal sensors are _________.
More superficial
Heating superficial tissues conducts heat to the deeper tissues
1MHz of ultrasound is best for heating tissues _______.
Deeper tissues, Up to 5cm deep
3MHz of ultrasound is best for heating tissues _______.
Superficial tissues, Only 1-2 cm deep
What is the benefit of the 3MHz ultrasound frequency.
Although depth of penetration is lower the maximum temperature achieved is higher
What area on the transducer corresponds to the location in which sound waves add together?
Hot spot
What shape is the beam of ultrasound
Uneven, looks like an upside down, mini- mountain range (I didn’t make that up, its straight from her ppt)
What will happen is if you leave the transducer in one spot on a patient on a continuous duty cycle?
It will burn the patient
What are the thermal effects of ultrasound?
Ability to increase tissue temperature in tissues with high absorption coefficients
ie- high collagen content tissues; tendons, ligaments, joint capsule, fascia, scar tissue
General summary of thermal vs. non-thermal ultrasound
Thermal- primarily used prior to stretching shortened tissue and reduction of pain
Non-thermal- primarily used for altering membrane permeability to accelerate tissue healing to facilitate healing of dermal ulcers, surgical skin incisions, tendon injuries, and bone fractures
In ultrasound, what determines the depth of penetration?
Frequency
On average the soft tissue temperature increases how much per minute?
Increases at .2 degrees C or .9 degrees F per minute of ultrasound delivered at 1W/cm2 at 1MHz
What are the ultrasound treatment parameters for stretching using a 3MHz and 1MHz frequency?
3MHz= 0.5 to 1.0 w/cm2
1MHz= 1.5 to 2.5 w/cm2
applied for 5 to 10 minutes
Stretching performed during US and 5-10 after tissue cools
What are the ultrasound treatment parameters for dermal ulcers?
20% duty cycle
3MHz- 0.8 to 1.0 w/cm2 intensity
5 to 10 min duration
What did recent systematic reviews of the randomized controlled trials on the treatment of venous and pressure ulcers conclude?
There is no good evidence of a benefit of ultrasound therapy in these types of dermal ulcers (also straight from ppt so why the f*#! are they telling us to use US)
What are the ultrasound treatment parameters for surgical skin incisions?
0.5 to 0.8 w/cm2 intensity
Pulsed 20% for 3 to 5 minutes
3 to 5 times per week
Ultrasound treatment parameters for tendon and ligament injuries
Pulsed low intensity 0.5 to 1.0 w/cm2 during ACUTE phase of tendon inflammationContinuous US at high enough intensity to increase tissue temp applied in combo w/ stretching to assist w/ CHRONIC tendinitis*if the problem is accompanied by soft tissue shortening b/c of scarring
Ultrasound for bone fractures
Low dose US 1.5 MHz frequency
0.15w/cm2 intensity
20% duty cycle
15 to 20 min daily
Ultrasound for carpal tunnel syndrome (CTS)
1MHz frequency
1.0 w/cm2 intensity
Pulsed mode, 1:4 (25% duty cycle) for 15 min per session
What information will influence your US treatment choices?
Know tissue type
Does US work on this tissue?
Tissue depth you want to heat
How balance thermal vs nonthermal
Intensity related to the selection of 1 or 3 MHz and duty cycle
Duration related to approximate increase in temp and size of transducer
Will the patient have an immediate sensation of warmth w/ US?
No it may take 2-3 minutes
With US, what is the significance of patient complain of deep aching feeling?
Deep ache means US intensity is too high
Turn down to avoid burning tissue
What are US considerations over shallow bones?
Decrease intensity
How many treatments of US should a patient receive?
If the patient is worsening or not improving with in 2-3 treatments, reevaluate approach or have PT/Physician reevaluate
What are US treatment parameters for phonophoresis application?
3MHz frequency Pulsed 20% duty cycle 0.5- 0.75 w/cm2 intensity 5 to 10 min Avoid heating of any inflammatory condition
Phonophoresis is primarily used for____?
The delivery of corticosteroid and NSAIDs to treat tissue inflammation associated w/ condition such as tendinitis and bursitis
For US application technique if the patient has a soft tissue shortening impairment at the 1-2 cm depth level what should the ultrasound effect, duty cycle, frequency, intensity, and duration of treatment be?
Effect = Thermal Duty Cycle = 100% Frequency = 3MHz Intensity = 0.5 w/cm2 Duration 5 to 10 min/2 x ERA
For US application technique if the patient has delayed tissue healing w/ prolonged inflammation at the 1-2 cm depth level what should the ultrasound effect, duty cycle, frequency, intensity, and duration of treatment be?
Effect = Non thermal Duty Cycle = 20% Frequency = 3MHz Intensity = 0.5- 1 w/cm2 Duration 5 to 10 min/2 x ERA
Decreased tissue temperature results in vasoconstriction to the localized area as well as which other parts of the body?
Areas distant to the area being cooled
Name the effects of cold on the neuromuscular function of the body
decreasing nerve conduction velocity, elevating the pain threshold, altering muscle force generation, decreasing spasticity, and facilitating muscle contraction
For US application technique if patient has a soft tissue shortening impairment at the 5 cm depth level what should the frequency, intensity, and duration of treatment be?
Frequency = 1MHz
Intensity = 1.5- 2 w/cm2
Duration 5 to 10 min/2 x ERA
Continuous short wave diathermy (SWD)
The clinical application of continuous short wave electromagnetic radiation to increase tissue temp
For US application technique if the patient has a soft tissue shortening impairment at the 5 cm depth level what should the ultrasound effect, duty cycle, frequency, intensity, and duration of treatment be?
Effect = Thermal Duty Cycle = 100% Frequency = 1MHz Intensity = 1.5- 2 w/cm2 Duration 5 to 10 min/2 x ERA
Diathermy
The application of shortwave or microwave electromagnetic energy to increase tissue temp, particular deep tissues
Continuous short wave diathermy
The clinical application of continuous short wave electromagnetic radiation to increase tissue temp
Duty cycle
the proportion of time energy is being delivered
On time/(on time + off time)
Inductive coil applicator
a coil through which an alternating electrical current flows, producing a magnetic field perpendicular to the coil.
Inducing electrical eddy currents in the tissue within or in front of the coil.
This type of applicator can be used to apply shortwave diathermy
Low frequency electromagnetic radiation
Electromagnetic radiation that is NONionizing and that cannot break molecular bonds or produce ions.
This includes extremely low frequency waves, short waves, microwaves, infrared, visible light, and ultraviolet
Magnetron
An applicator that produces a high frequency alternating current in an antenna
Microwave diathermy
300 MHz – 300 GHz
2450 MHz (FCC law)1 m – 1mm wavelength
Non-ionizing Can be continuous or pulsed
Indications for diathermy?
Pain control Edema control Soft tissue healing Nerve and Bone healing Osteoarthritis
Shortwave diathermy
3 kHz – 300 MHz
27.12 MHz (FCC law)1 m – 100 km wavelength
Non-ionizing
Can be continuous or pulsed
What are the thermal effects of diathermy?
Heats deeper tissues
Increases vasodilation and rate of nerve conduction
Elevation of pain threshold, alteration of muscle strength, acceleration of enzymatic activity
Increase soft tissue extensibility
At higher frequencies, will be more superficial
What are the nonthermal effects of diathermy?
Pulsed, low average intensity
Increased microvascular perfusion
Altered cell membrane function and cellular activity
Contraindications for thermal diathermy
Metal implants
Implanted or transcutaneous neural stimulators, ie pacemaker
Pregnancy, malignancy, eyes, testes
Growing epiphyses
Contraindication for non thermal pulsed shortwave diathermy
Deep tissues such as internal organs
Used as a substitute for conventional therapy for edema and pain
Pacemakers, electronics devices, or metal implants
Precautions for ALL forms of diathermy
Obesity
Near electronic or magnetic equipment
Copper bearing intrauterine contraceptive devices
