Procedures: Ultrasound Flashcards
Ultrasound was first used when and by who?
19th Century by the United States using SONAR
Why were the damaging underwater life?
Because sound waves were heating it up
More recently, it was found that ultrasound could be used clinically why?
Because it can heat tissue w/ a high collagen content, such as tendons, ligaments, or fascia
Power
The amount of energy per unit of time(Watts)
Intensity
the power per unit area of the sound head(Watts/cm2)
Frequency (def.)
the # of compression rarefaction cycles per unit of time(Relates to depth of penetration)
What is the therapeutic ultrasound frequency?
Between 0.7 and 3.3 MHz
What frequency is considered best for treating tissue up to 5 cm deep?
1 MHz
What frequency is considered best for treating tissue up to 1-2 cm deep?
3 MHz
Increasing the frequency causes what?
Higher concentration of US in the superficial tissue
Duty Cycle
The proportion of the total tx time the US is on
How can duty cycle be expressed?
As a percentage or a ratio.
Ex.20% or 1:5
20% means it is on 20% of the time and off 80%
Continuous Ultrasound
The delivery of ultrasound throughout the entire tx period
100% duty cycle
Continuous Ultrasound produces what effects on tissue?
Thermal effects
Pulsed Ultrasound
the intermittent delivery of US throughout the tx period
general see 10%, 20%, or 50% in clinic
Pulsed Ultrasound minimizes what and provides what effect?
It minimizes thermal effects and provides nonthermal effects
Effective Radiating Area
The area of the transducer where the energy radiates
this area is smaller than the area of the treatment head
Spatial Peak Intensity
The peak intensity of the US output over the area of transducer
Beam Nonuniformity Ratio (BNR)
The ration of the spatial peak intensity to the spatial average intensity
(For most units, this is usually between 5:1 & 6:1)
If BNR is 5:1 , w/ the spatial average intenisty set at 1 W/cm2, the spatial peak intensity is what?
As high as 5 W/cm2
Absoption
The conversion of mechanical energy into heat
Reflection
Redirection of the US beam away from the surface at an angle equal & opposite to the beam
What do we use to prevent reflection?
Gel or lotion
Refraction
redirection of an US beam
when the beam enters the tissue at one angle it is redirected within the tissue in a new angle
Attenuation
The degree in the US intensity as it travels through the tissue(occurs as a result of absorption, reflection, and refraction)
Standing Wave
occurs when the ultrasound transducer & a reflecting surface are the exact wave length apart
How can Standing Waves be avoided?
Move the US head around in a steady pace
Cavitation
Gas filled bubbles that are formed by the US
Stable Cavitation is thought to be on of the mechanisms for what?
Nonthermal effects of US
Phonophoresis
the application of topical drug w/ US ( can be absorbed systemically)
Ultrasound Can:
- Accelerate metabolic rate
- Reduce Pain
- Alter nerve conduction rates
- Increase circulation
- increase tissue extensibility
Ultrasound is ideal for heating tissue w/ increased collagen such as?
- Tendons
- Ligaments
- Joint Capsules
- Fascia
- Scar tissue
Why is it not ideal for heating muscles?
Because muscle has a low absorption coefficent
Factors that affect the ultrasound’s temperature increase includes:
- Tissue Type
- Frequency
- Intensity
- Duration
What will happen if the intensity is too high?
The patient will complain of deep pain
What will happen if the intensity is too low?
The patient may not feel an increase in tissue temperature
The longer the duration….
The higher the tissue heating(5 to 10 min duration)
Nonthermal Effects of US(part 1)
- Increased intracellular calcium lvls, which stimulates the syntheses of proteins
- Increasing skin & membrane permeability
- Increasing mast cell degranulation
Nonthermal Effects of US(part 2)
- Promoting macrophage responsiveness
- Increasing the rate of protein synthesis by fibroblasts and tendon cells
What frequency should be used when treating tissue up to 5 cm deep?
1 mhz
What frequency should be used when treating tissue up to 1-2 cm deep?
3.3 Mhz
What duty cycle is recommended for nonthermal effects?
20%
Parameters for: Soft Tissue Stretching
Frequency: 1 MHZ
Intensity: 1.5
Parameters for: Pain Control
Continuous 100%
Frequency: 1 to 3 MHZ (depending on tissue depth)
Intensity: .5 to 3.0 W/cm2
Duration: 3 to 10 min
Parameters for: Dermal Ulcers
Pulsed 20%
Frequency: 3 MHZ
Intensity: 0.8 to 1.0 W/cm2
Duration: 5-10 min
Parameters for: Surgical Skin Incisions
Pulsed 20% Frequency: No conclusion on which is best Intensity: 0.5 to 0.8 W/cm2 Duration: 3-5 min Time: 3-5 times per week
Parameters for: Tendon Injuries Post-op
Continuous or Pulsed
Frequency: 1 or 3 MHZ
Intensity: 0.5 to 2.5 W/cm2
Duration: 3 to 5 min
Parameters for: Ligament Injuries Post-op
Pulsed US 0.5 to 1.0 W/cm2
Parameters for: Bone Fractures
Pulsed 20%
Frequency: 1.5 Mhz
Intensity: .15w/cm2
Duration: 15-20 minutes, Daily
Parameters for: Phonophoresis
Pulsed 20%
Frequency: 1 or 3 Mhz
Intensity: 0.5 to 0.75 w/cm2
Duration: 5-10 min
What intensity should be used for 1 mhz
1.5 w/cm2
What intensity should be used for 3 Mhz?
0.8 w/cm2
In what ways can US be applied to dermal ulcers?
Applying gel & US to the intact skin around the wound
Put a coupling sheet directly over a wound
Performing US near the wound under water
it is thouht that US is beneficial for surgical skin incisions because it has the ability to do what?
Improve blood circulation
Limited ischemic necrosis
Facilitation of tissue repair
How doe the delivery of US differ for acute and chronic tendonitis?
Acute: Pulsed; low intensity
Chronic: Continuous; higher intensity
What role does the stratum corneum play in phonophoresis
I dont know hahaha
What are the contraindication of US?.
Malignant tumor, pregnancy
CNS tissue, Joint cement or plastic components
Pacemaker, Throbophlebitis
Eyes, Reproductive organs
What are the precautions of US?
Acute inflammation
Growth plates in children
Fractures
Breast implants
