Title: ULTRASOUND Biophysical Effects
1ULTRASOUND Biophysical Effects
- Both thermal and nonthermal effects occur in the
body - Nonthermal Effects
- Changes within the tissues resulting from the
mechanical effect of ultrasonic energy - Thermal Effects
- Changes within the tissues as a direct result of
ultrasounds elevation of the tissue temperature
2ULTRASOUND Biophysical Effects-Nonthermal
- Nonthermal Effects
- Used in acute injuries or when increasing the
tissue temperature is unwanted - Two methods of doing this
- Using a pulsed output and normal intensities
- Using 100 duty cycle with low intensities (0.3
w/cm2)
3ULTRASOUND Biophysical Effects-Nonthermal
- Nonthermal US energy leads to two interrelated
events - Acoustical Streaming - one directional flow of
tissue fluids caused by the sound wave - The flow of bubble in the acoustical streams
cause changes in cell membrane permeability - Cavitation result of the pressure changes
caused by the sound waves which results in gas
bubbles moving in a cyclical manner - Stable vs Unstable (Transient) Cavitation
4ULTRASOUND Biophysical Effects-Nonthermal
- Physiological Effects
- Stimulates phagocytosis
- Increases cell membrane permeability
- Increases the movement of minerals and proteins
in and out of the cell - Glycosaminoglycan and hydroxyproline are
increased following low dose US - Mild acceleration of the inflammatory stage helps
the body reach proliferation sooner - See Table 7-4
5ULTRASOUND Biophysical Effects-Thermal
- Thermal Effects
- Amount of temperature increase depends on
- Duty Cycle, Intensity, Frequency
- Vascularity and type of tissues
- Size of tx area, speed of soundhead
- 1 MHz up to 5 cm deep, retains heat longer
- 3 MHz 2-3 cm deep
6ULTRASOUND Biophysical Effects-Thermal
- To achieve a therapeutic effect temp must be
increased for a minimum of 3-5 min. - 3 MHz heats 3-4 times faster
- Lower treatment intensities require a greater
duration - The friction between the molecules results in a
temperature increase - Collagen rich tissues are preferentially heated,
adipose tissue is transparent to US
7ULTRASOUND Effects on the Injury Response Cycle
- Cell Response
- Increased cell membrane permeability for both
thermal and nonthermal US - Thermal
- Increased cell metabolism and inflammation
- Nonthermal
- Increased histamine release, calcium and rate of
protein synthesis
8ULTRASOUND Effects on the Injury Response Cycle
- Inflammation
- No thermal US acutely
- Effects later in injury cycle
- Early onset of proliferation
- Stimulation of fibroblast activity
- Positively influence macrophage activity
- Increases the collagen synthesis and increased
tensile strength
9ULTRASOUND Effects on the Injury Response Cycle
- Blood Flow
- Continuous can increase blood flow for up to 45
minutes - Pulsed US may effect blood flow through its
effect on the cell membrane - Application of cold first?
10ULTRASOUND Effects on the Injury Response Cycle
- Pain Control
- May have some direct effect to the nerves or as a
result of other effects - Direct effects are through eliciting changes
within the nerve fiber themselves - Indirect effects
- Increase blood flow more oxygen less chemical
pain - Decreased muscle spasm
11ULTRASOUND Effects on the Injury Response Cycle
- Muscle Spasm Why?
- Tissue Elasticity
- Increased extensibility in collagen-rich tissues,
including scar tissue - Must be increased 7.2F (4C)
- Must be used with passive stretching, within 3
minutes - Repeated treatments is often necessary
- May want to place tissue on stretch during the
treatment
12ULTRASOUND Effects on the Injury Response Cycle
- Wound Healing
- Some wounds have responded well to US
- 100 US at 1.5 w/cm2 for 5 min, for 1 week (1
MHz) - 100 at 0.5 w/cm2 for 2 weeks also appeared to
help
13ULTRASOUND Phonophoresis
- Application of US to assist in the diffusion of
medication through the skin - Non-invasive method that does not effect the
liver - Occurs due to the effect US has on the skin which
allows the medication to diffuse through - Skin factors can affect diffusion of medication
- Has been found to push meds up to 6 cm deep
14ULTRASOUND Phonophoresis
- Thermal
- Increase kinetic energy of the local cells and
the medication, open entry points, increase
circulation, increase capillary permeability - Nonthermal
- Enhances diffusion across the membranes, increase
cell membrane permeability
15ULTRASOUND Phonophoresis
- Medications
- Table 7-7
- Application
- Direct Method
- Invisible Method
16ULTRASOUND Phonophoresis
- Does it work??
- Salicylate (Myoflex)
- Hydrocortisone
- Dexamethasone
- Low frequency US units may assist in the
transmission of medications
17ULTRASOUND Contraindications
- Acute injuries (Thermal US)
- Areas of impaired circulation
- DVT or cancerous tumors
- Over the eyes, heart, skull and genitals
- Pelvic, abdominal area in menstruating or
pregnant women - Over active fracture or stress fractures
(exception) - Over growth plates in adolescents??
- Use with caution over vertebrae
18ULTRASOUND Controversies in Treatment
- US must be used properly in order to have a good
therapeutic effect on the patient - Read Article
- Ten Mistakes Commonly Made with Ultrasound Use
Current Research Sheds Light on Myths
19ULTRASOUND Application
- Treatment Area
- 2-3 times the ERA of the sound head
- Coupling Methods
- Optimal agent is distilled water
- US head should not leave the body
- Why?
- Irregular shape body parts?
20ULTRASOUND Coupling Agents and Methods
- Direct Coupling
- Use of US gel
- Use enough gel
- Body hair can limit US delivery
- Try not to have air bubbles
- Use slight pressure on sound head
- Water Immersion
- Good for irregular body parts
- Sound head is 1 away from skin _at_ 90 angle
21ULTRASOUND Coupling Agents and Methods
- Bladder Method
- Water filled bag or plastic bag coated with US
gel - Good for irregular areas such as AC joint
- Can not have air pockets
22ULTRASOUND Output Parameters
- Frequency
- Depth and rate of heating
- 1 MHz vs 3 MHz
- Table 8-2
- Treatment Duration
- Table 8-3
23ULTRASOUND Output Parameters
- Duty Cycle
- Output Intensity
- Figure 8-6
- For thermal ultrasounds the patient should feel
warmth!
24ULTRASOUND Output Parameters
- Dose-Oriented Treatments
- Still an inexact method
- Deals with treating the tissue area to a certain
temperature - Some units you can program this way
- Needs more research
25ULTRASOUND Ultrasound and Electrical Stimulation
- Treatment of trigger points and superficial
painful areas - Ultrasound head serves as as electrode
- Try to fatigue the trigger points to a point they
no longer will fire or spasm - Placing the tissue at stretch may be a benefit in
decreasing trigger point spasms
26ULTRASOUND Application
- Duration
- 3 to 12 minutes
- Frequency
- Once/day for 10 to 14 days
- Precautions, Indications, and Contraindications
are in your text (Pg. 181)