Ultrasound Flashcards
Therapeutic ultrasound frequency between (?) and (?) megahertz (MHz)
Ultrasound
Therapeutic Ultrasound:
(-) Therapeutic ultrasound = frequency between 0.7 and 3.3 megahertz (MHz)
- Megahertz = 1 million Hz
Attenuation:
- What is it = ?
- Occurs via = ?
Ultrasound
(a) Attenuation: Decreased signal intensity as ultrasound travels through tissues
- Note: attenuation varies by tissue type
(b) Attenuation occurs via
- absorption
- reflection, and
- refraction
(c) Air is poor conductor of ultrasound, therefore need conducting medium.
Effects of Ultrasound
What modalities:
- Conduction = ?
- Convection = ?
- Conversion = ?
- Radiation = ?
Ultrasound
Conduction =
- Hot Packs / Cold Packs
- Paraffin
Convection =
- Whirlpools
- Fluidotherapy
Conversion =
- Diathermy
Radiation =
- Infrared heat lamps
Conversion
Rate of tissue temperature increase depends on = ?
Ultrasound
Conversion:
(a) Not affected by the temperature of the thermal agent.
(b) Rate of heat transfer depends on the power of the energy source.
(c) Rate of tissue temperature increase depends on:
- Size of the are being treated
- Size of the applicator
- Efficiency of transmission from the applicator to the patient
- Type of tissue being treated
(d) DOES NOT require direct contact between the thermal agent and the body.
(e) DOES require an intervening material to be a good transmitter of that type of energy.
Thermal Effects of Ultrasound
Thermal effects can vary by parameters used:
- 3 MHz = What depth ?
- 1 MHz = What depth ?
Ultrasound
Thermal Effects of Ultrasound:
(a) Physiologic studies indicate thermal ultrasound can increase tissue temperature.
- Best at heating tissues with high ultrasound absorption coefficients (collagen > water).
- Ultrasound heats smaller, deeper areas better than superficial heat.
(b) Thermal effects can vary by parameters used
- 3 MHz = 1-2 cm tissue depth
- 1 MHz = 2-5 cm tissue depth
(c) Note:
- 3 MHz is associated with increased overall tissue temperatures, therefore may need to use decreased intensity (W/cm2) at 3 MHz compared to 1 MHz.
Thermal Ultrasound Considerations = ?
Ultrasound
Thermal Ultrasound Considerations:
(a) Keep soundhead moving to avoid hot spots
- Speed of sound head moving does not appear to affect temperature produced
(b) Patient’s report of warmth used to determine final ultrasound intensity (W/cm2).
- Note: Frequency of 3 MHz associated with increased overall tissue temperatures, therefore may need to use decreased intensity (W/cm2) at 3 MHz compared to 1 MHz
Non-thermal Ultrasound Effects
Non-thermal effects from mechanical events, include = ?
Ultrasound
Non-thermal Ultrasound Effects:
(a) Non-thermal effects from mechanical events, include
- Cavitation,
- Microstreaming, and
- Acoustic streaming
(b) Ultrasound with low average intensity increases cell membrane permeability and macrophage responsiveness.
(c) Obtain non-thermal effects by decreasing duty cycle (% time on)/
- Heat generated during on time / dispersed during off time.
Research
Ultrasound for…
- Knee OA = ?
- CTS = ?
- Chronic LBP = ?
- Adhesive Capsulitis = ?
Ultrasound
Ultrasound:
- Knee OA = Low Evidence
- CTS = Poor Evidence
- Chronic LBP = No Quality Evidence
- Adhesive Capsulitis = Improvements in ROM, shoulder disability, and pain in both groups(experiment & control)
Ultrasound
Contraindications = ?
Ultrasound
Adverse effects of ultrasound include = ?
Ultrasound
Adverse Effects of Ultrasound:
- Burns most common (hot spots)
- Potential for cross-contamination.
Ultrasound Application Considerations = ?
Ultrasound
Ultrasound Application Considerations:
- Thermal or non-thermal effects desired?
- Treatment depth desired?
- What is size of treatment area?
- Treatment time?
Describing Ultrasound
- Intensity = ?
- Frequency = ?
- Duty cycle = ?
- Duration = ?
Ultrasound
Intensity:
- Quantity of energy delivered per unit area (W/cm2)
Frequency:
- Determines depth of ultrasound (MHz)
Duty cycle:
- Described in terms of percentage on time (continuous or pulsed)
Duration:
- Length of treatment
Ultrasound Application
Impairments = Soft tissue shorting & Pain
- Effects of ultrasound = ?
- Duty Cycle = ?
- Depth of problem = 2-5 cm
- Frequency = ?
- Intensity = ?
- Duration = ?
Ultrasound
Ultrasound Application:
Impairments = Soft tissue shorting & Pain
- Effects of ultrasound = Thermal
- Duty Cycle = 100%
- Depth of problem = 2-5 cm
- Frequency = 1 MHz
- Intensity = 1.5-2.0 W/cm^2
- Duration = 5-10 min/2 x ERA
Ultrasound Application
Impairments = Soft tissue shorting & Pain
- Effects of ultrasound = ?
- Duty Cycle = ?
- Depth of problem = 1-2 cm
- Frequency = ?
- Intensity = ?
- Duration = ?
Ultrasound
Ultrasound Application:
Impairments = Soft tissue shorting & Pain
- Effects of ultrasound = Thermal
- Duty Cycle = 100%
- Depth of problem = 1-2 cm
- Frequency = 3 MHz
- Intensity = 0.5 W/cm^2
- Duration = 5-10 min/2 x ERA
Ultrasound Application
Impairments = Delayed tissue healing & prolonged inflammation
- Effects of ultrasound = ?
- Duty Cycle = ?
- Depth of problem = 1-2 cm
- Frequency = ?
- Intensity = ?
- Duration = ?
Ultrasound
Ultrasound Application:
Impairments = Delayed tissue healing & prolonged inflammation
- Effects of ultrasound = Non-thermal
- Duty Cycle = 20%
- Depth of problem = 1-2 cm
- Frequency = 3 MHz
- Intensity = 0.5-1.00 W/cm^2
- Duration = 5-10 min/2 x ERA
Ultrasound Application
Impairments = Delayed tissue healing & prolonged inflammation
- Effects of ultrasound = ?
- Duty Cycle = ?
- Depth of problem = 2-5 cm
- Frequency = ?
- Intensity = ?
- Duration = ?
Ultrasound
Ultrasound Application:
Impairments = Delayed tissue healing & prolonged inflammation
- Effects of ultrasound = Non-thermal
- Duty Cycle = 20%
- Depth of problem = 2-5 cm
- Frequency = 1 MHz
- Intensity = 0.5-1.00 W/cm^2
- Duration = 5-10 min/2 x ERA
Duty Cycle
Duty Cycle
- Is either (?) or (?)
- Determind by = ?
Ultrasound
Duty Cycle:
(a) Either continuous (100%) or pulsed (20%)
- Select according to treatment goal
(b) Thermal Effects = Continuous (100%)
- Intensity remains constant throughout treatments
- Increase tissue temperature
(c) Nonthermal effects of tissue healing = Pulsed (20%)
- Produces intensity 20% of the time (on + off time)
- Increase intracellular calcium levels
- Increase skin and cell membrane permeability
Duty Cycle
- Continuous (100%), increases = ?
- Pulsed (20%), increases = ?
Ultrasound
(a) Continuous (100%) – Thermal Effects
- Increase tissue temperature
(b) Pulsed (20%) - Nonthermal effects of tissue healing
- Increase intracellular calcium levels
- Increase skin and cell membrane permeability
Frequency
- Determines = ?
- 1-2 cm deep = _ ? _ MHz
- 3-5 cm deep = _ ? _ MHz
Ultrasound
Frequency:
(a) Determines depth of the ultrasound
- Higher frequency is more rapidly absorbed
(b) Attenuation
- Higher water content areas = low rate of absorption
- More dense tissues = higher rate of absorption
(c) Select based on depth of tissue
- 1-2cm deep = 3MHz = Shallow tissue
- 3-5cm = 1 MHz = Deeper tissue
Intensity
Lower intensity at = ?
Ultrasound
Intensity:
(a) Quantity of energy delivered per unit area
- Not uniform power
- Some areas more intense than others
(b) Lower intensity at higher frequency
- Great temp increase from energy absorbed in smaller, more superficial volume.
- Considered for areas with superficial bone
(c) Increase intensity based on pt considerations
- Asking patients if they feel it.
- Feel nothing? Increase it.
- Too hot? Decrease it
Intensity
True or False:
A lower-intensity at higher frequency results in energy being absorbed in smaller, more superficial volume and results in greater temp increases.
Ultrasound
Intensity:
True -
- A lower-intensity at higher frequency results in energy being absorbed in smaller, more superficial volume and results in greater temp increases.
Thermal -
(a) Increase tissue temperature
- Increase warmth within in 2-3 minutes
- Should not feel any increasing discomfort
- 1 MHz = 1.5-2.0 W/cm2
- 3 MHz = 0.5 W/cm2
Non-Thermal -
(a) 0.5 to 1.0 W/cm2
- As low as 0.15 W/cm2 for bone healing
(b) Remember
- No tissue warming, works at cellular level
Notes -
- Lower-intensity at higher frequency – energy is absorbed in smaller, more superficial volume and results in greater temp increases.
- Increase up/down depending on pt reports – nothing after 2-3 minutes, then increase; discomfort reported? = Then decrease it.
- Superficial bone – low intensity may be sufficient for comfortable heating.
Read notes in PP
Intensity
- Area of the crystals that produce energy = ?
- Ratio between spatial-peak intensity and spatial average intensity = ?
Ultrasound
Intensity:
(a) Effective Radiating Area (ERA) =
- Area of the crystals that produce energy
- Smaller than total size of the head
- Concentrated near the center
- Treat an area 2-4x the size of the sound head
Spatial-peak intensity
- Intensity of the ultrasound beam at its highest point
Spatial-Average Intensity
- Intensity on an ultrasound unit in W/cm2
(b) Beam Nonuniformity Ratio (BNR) =
- Ratio between spatial-peak intensity and spatial average intensity.
Described on the machine
- 2:1 to 8:1 average ranges
- 5:1 and 6:1 are common
Lower BNR
- More favorable as patients will experience less hot spots and discomfort.
Higher BNR
- Move the transducer head faster to avoid undesireable effects “hot spots”.
Intensity - Effective Radiating Area (ERA)
- Spatial-peak intensity = ?
- Spatial-Average Intensity = ?
Ultrasound
Intensity:
(a) Effective Radiating Area (ERA) =
Spatial-peak intensity
- Intensity of the ultrasound beam at its highest point
Spatial-Average Intensity
- Intensity on an ultrasound unit in W/cm2
Intensity - Beam Nonuniformity Ratio (BNR)
- Described on the machine as = ?
- With a lower BNR, patients will experience less = ?
- With a higher Higher BNR, it’s important that we (PT’s) = ?
Ultrasound
Intensity: - Beam Nonuniformity Ratio (BNR):
(a) Described on the machine =
- 2:1 to 8:1 average ranges
- 5:1 and 6:1 are common
(b) Lower BNR =
- More favorable as patients will experience less hot spots and discomfort.
(c) Higher BNR =
- Move the transducer head faster to avoid undesireable effects “hot spots”.
Duration depends on = ?
Ultrasound
Duration:
(a) Duration depends on:
- Treatment goal
- Size of area to be treated
- The ERA of the sound head
(b) Generally – 5-10 minutes for each treatment area 2x/ the ERA of sound head.
- Treatment area = 20 cm^2
- Sound head = 10 cm^2
- Duration = 5-10 min.
(c) Increase duration if…
- Lower intensity (consider bone healing at 0.15 W/cm2)
- Larger treatment areas
- Higher tissue temperature desired
(d) Decrease duration if…
- Higher intensity
- Smaller areas
- Lower tissue temp
Duration
- Increase duration if = ?
- Decrease duration if = ?
Ultrasound
Duration:
(c) Increase duration if…
- Lower intensity (consider bone healing at 0.15 W/cm2)
- Larger treatment areas
- Higher tissue temperature desired
(d) Decrease duration if…
- Higher intensity
- Smaller areas
- Lower tissue temp
Area to be treated
- Depends on = ?
- DO NOT = ?
Ultrasound
Area to be treated:
(a) Depends on ERA of sound head
(b) Do not…
- exceed 4x the area of the sound head
- Treat 1.5 x less the size of the sound head
(c) Move soundheadoverlapping by half
(d) Usecoupling agent
Coupling Agents
- Coupling Agents = ?
- Direct Coupling Agents = ?
- Indirect Coupling Agent = ?
- Water immesion = ?
Ultrasound
Coupling Agents:
(1) Coupling Agents =
- Decrease attenuation and acoustical impedance
- Eliminates air between transducer and target area
(2) Direct Coupling Agents =
- Gel, Lotion
- Apply prior to turning on
- Keep transducer parallel with surface of skin
- If NOT maintained, energy will be reflected and can damage transducer and patient
(3) Indirect Coupling Agent=
- For small area, irregularly shaped, or unable to tolerate direct pressure.
- Water immersion
- Gel/water filled bladders, gel pads
- Cushion Contact
(4) Water immesion=
- Rubber or plastic, not metal, container
- Move parallel to skin,0.5-3.0cm away
- Wipe away air bubbles
- Increase intensity as much as 50%
Move the sound head
Speed approximately = ?
Ultrasound
Move the Sound Head:
(a) Speed approximately = 4cm/sec
- Quick enough to avoid stopping
- Slow enough to maintain contact
Stopped or too slow?
- Increased intensity in that one area
- Result in burning
- Reduced efficacy of treatment
Too quickly?
- Ineffective treatment
Treatment Amount
- Thermal Ultrasound = ?
- Nonthermal Ultrasound = ?
- When in the healing process
- How many times / week
Ultrasound
Treatment Amount:
(a) Thermal Ultrasound
- Later in healing process
- Commonly 2-3x/week
(b) Nonthermal ultrasound
- Earlier in process
- Once a day - Should note positive response in first 3 sessions
(c) Failure to receive response ?
- Change parameters
- Choose another intervention
Stationary Method = ?
Stationary Method:
Not recommended
- Uneven heating
- Undesirable effects
- Pain or tissue damage
- VERY small treatment area
- Pulsed ultrasound with low intensity
Potential Conditions for Ultrasound = ?
Ultrasound
Potential Conditions for Ultrasound:
- Soft tissue shortening
- Pain control
- Dermal ulcers
- Surgical skin incisions
- Tendon and ligament injuries
- Resorption of calcium deposits/calcific tendonitis
- Bone fractures
Pain Control
Based on this, what are we thinking = ?
Ultrasound
Pain Control:
- Want increase tissue temperature for relaxation, tissue extensibility.
- Based on this, what are we thinking?
- Thermal, so continuous duty cycle.
- Frequency depends on depth of tissue (1 MHz up to 5 cm, 3 MHz for 1-2 cm depth).
- Intensity likely 1.5-2.0 W/cm2 (0.5-1.0 W/cm2 if using 3 MHz).
Dermal Ulcers
Based on this, what are we thinking = ?
Ultrasound
Dermal Ulcers:
- Robust and conclusive evidence lacking – more likely to use electrical stimulation as modality of choice for wound healing.
- Want mechanical effects
- Based on this, what are we thinking?
- Non-thermal, so pulsed duty cycle (20%)
- Frequency at 3 MHz as ulcer superficial
- Intensity 0.5-1.0 W/cm2
Surgical Skin Incisions
Based on this, what are we thinking = ?
Ultrasound
Surgical Skin Incisions:
- Some evidence for effectiveness
- Want mechanical effects
- Based on this, what are we thinking?
- Nonthermal, so pulsed duty cycle (20%)
- Frequency depends on depth of tissue (1 MHz up to 5 cm, 3 MHz for 1-2 cm depth)
- Intensity 0.5-1.0 W/cm2
Tendon and Ligament Injuries
Based on this, what are we thinking = ?
Ultrasound
Tendon and Ligament Injuries:
- Consider acuity of injury in determining treatment parameters.
- Acute: likely want non-thermal for healing and mechanical effects.
- Chronic: likely want thermal for increasing temperature and extensibility.
Bone Fractures
Based on this, what are we thinking = ?
Ultrasound
Bone Fractures:
- Low-dose ultrasound
- Unlikely to see in typical regular practice
- Phonophoresis = ?
- Settings = ?
Ultrasound
Phonophoresis: Application of topical (transdermal)medication via ultrasound
- Anti-inflammatory & analgesics
(a) Enhances distribution through the skin
- High concentration of medication delivery
(b) Non-thermal settings:
- 20% duty cycle, 3 MHz, 0.5-0.75 W/cm2
- Effective conductors of acoustic energy
Limited evidence
Documentation
What needs to be included = ?
Ultrasound
Documentation:
- Area of the body treated
- US Frequency
- US intensity
- US duty cycle
- Treatment duration
- Pt response
Describe the application process = ?
Ultrasound
Application:
(1) Properly explain your treatment and reason for modality.
- Clear contraindications
(2) Comfortably position patient for effective treatment
- Proper draping/towels as needed
(3) Inspect skin before and after treatment
- Remove jewelry or any metals in area
- CLEAN THE SKIN
(4) Set up machine to appropriate settings
- Do not start yet
(5) Place gel on skin and/or transducer
- Move gel around
(6.a) Start moving ultrasound head on skin
- Then start treatment
- Check in on intensity after 2-3 minutes
(6.b) Need to pause?
- While still moving sound head, hit pause – you can now remove sound head
- Once you are ready to start, make sure you are moving sound head then start
(7) Finish
- Hit stop while still moving sound head
- Clear to remove sound head
- Wipe off gel, check the skin, reassess function
Ultrasound - Summary
Ultrasound
Ultrasound - Summary:
- Therapeutic use of soundwaves
- Produces thermal and nonthermal effects
- Continuous duty cycle = thermal effects, 20% duty cycle = nonthermal effects.
- Frequency based on tissue depth, 3 MHz = 1-2 cm, 1 MHz = up to 5 cm.
- Intensity depends on frequency and whether thermal effects sought.
- Robust evidence lacking, likely a situationally appropriate modality.
