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ULTRASOUND Biophysical Effects

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Changes within the tissues resulting from the mechanical effect of ultrasonic energy ... Vascularity and type of tissues. Size of tx area, speed of soundhead ... – PowerPoint PPT presentation

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Title: ULTRASOUND Biophysical Effects


1
ULTRASOUND 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

2
ULTRASOUND 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)

3
ULTRASOUND 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

4
ULTRASOUND 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

5
ULTRASOUND 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

6
ULTRASOUND 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

7
ULTRASOUND 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

8
ULTRASOUND 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

9
ULTRASOUND 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?

10
ULTRASOUND 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

11
ULTRASOUND 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

12
ULTRASOUND 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

13
ULTRASOUND 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

14
ULTRASOUND 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

15
ULTRASOUND Phonophoresis
  • Medications
  • Table 7-7
  • Application
  • Direct Method
  • Invisible Method

16
ULTRASOUND Phonophoresis
  • Does it work??
  • Salicylate (Myoflex)
  • Hydrocortisone
  • Dexamethasone
  • Low frequency US units may assist in the
    transmission of medications

17
ULTRASOUND 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

18
ULTRASOUND 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

19
ULTRASOUND 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?

20
ULTRASOUND 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

21
ULTRASOUND 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

22
ULTRASOUND Output Parameters
  • Frequency
  • Depth and rate of heating
  • 1 MHz vs 3 MHz
  • Table 8-2
  • Treatment Duration
  • Table 8-3

23
ULTRASOUND Output Parameters
  • Duty Cycle
  • Output Intensity
  • Figure 8-6
  • For thermal ultrasounds the patient should feel
    warmth!

24
ULTRASOUND 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

25
ULTRASOUND 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

26
ULTRASOUND Application
  • Duration
  • 3 to 12 minutes
  • Frequency
  • Once/day for 10 to 14 days
  • Precautions, Indications, and Contraindications
    are in your text (Pg. 181)
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