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Therapeutic Ultrasound (Part 2)

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Therapeutic Ultrasound (Part 2) By Ass.Prof.Dr.Gehan Mosad At the end of this lecture the student should be able to Therapeutic Effects of US Ultrasound has a variety ... – PowerPoint PPT presentation

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Title: Therapeutic Ultrasound (Part 2)


1
Therapeutic Ultrasound(Part 2)
  • By
  • Ass.Prof.Dr.Gehan Mosad

2
At the end of this lecture the student should be
able to
3
Therapeutic Effects of US
  • Ultrasound has a variety of biophysical effects
  • A- Thermal effects
  • B- Nonthermal effects
  • The most effect of continuous US is on tissue
    temperature however, nonthermal effects can also
    occur with the use of continuous ultrasound.
  • Pulsed US has mainly nonthermal effect, but it
    also produces a minimal sustained changes in
    tissues temperature, it probably does have a
    small brief heating effect during the on time of
    a pulse

4
Thermal Effects of US
  • As the energy within the sound waves is passed
    and absorbed by the tissues, it will cause
    oscillation of the molecules of that tissues
    about their mean position, clearly any increase
    in the molecular vibration will result in heat
    generation.
  • The thermal effects of ultrasound are the same as
  • those obtained with other heating modalities
    including
  • acceleration of metabolic rate
  • reduction or control of pain and muscle spasm
  • alteration of nerve conduction velocity
  • increased circulation
  • increased soft tissue extensibility

5
Thermal Effects of US (cont.)
  • The structures heated by US are different from
    other heating modalities
  • US reaches more deeply and heats smaller areas
    than most superficial heating agents.
  • US also heats tissues with high US absorption
    coefficients more than those with low absorption
    coefficients tissues
  • Tissue with high absorption coefficients are
    generally those with a high collagen content
    while tissues with low absorption coefficients
    generally have a high water content such as
    muscles.
  • Thus
  • US is particularly well-suited to heat such as
    tendons, ligaments joint capsules and
    fascia
  • US is generally not the ideal physical agent for
    heating muscle tissue because muscle has a
    relatively low absorption coefficient also, most
    muscles are much larger than the available
    ultrasound transducers.

6
Factors affecting amount of temperature increase
  • The increase in tissue temperature produced by
    the absorption of ultrasound varies according to
  • Type of tissue (absorption coefficient)
  • Frequency
  • Intensity
  • Duration of the ultrasound.
  • Blood circulating through the
  • Reflection US waves in regions of soft
    tissue-bone interfaces
  • Thus, higher temperatures are achieved
  • in tissue with high collagen content
  • with high frequency
  • with high intensity
  • with long duration

7
Non-Thermal Effects of US
  • When ultrasound is delivered in a pulsed mode,
    with a 20 duty cycle, the heat generated during
    the on time of the cycle is dispersed during the
    off time, resulting in no measurable net increase
    in temperature.
  • Thus, pulsed US is used to produce nonthermal
    effects that including the following
  • increase intracellular calcium,
  • increase skin and cell membrane permeability
  • increase mast cell degranulation,
  • increase histamine release
  • increase macrophage responsiveness,
  • increase the rate of protein synthesis by
    fibroblast

8
Non-Thermal Effects of US (cont.)
  • Nonthermal effects of US are the result of the
    mechanical events produced by US, including,
    cavitations, acoustic streaming and micro
    massage.
  • 1- Cavitation
  • The formation of gas filled bubbles within the
    tissues body fluids during the phase of
    relaxation or rarefaction of US waves
  • There are 2 types of cavitation
  • Stable and non stables which have very different
    effects.

9
Non-Thermal Effects of US (cont.)
  • Stable cavitation
  • It occurs at therapeutic doses of US. This
    is the formation growth of gas bubbles by
    accumulation of dissolved gas in the medium. The
    cavity acts to enhance the acoustic streaming
    phenomena as such would appear to be
    beneficial.
  • Unstable (transient) cavitation
  • It is the formation of bubbles at the low
    pressure part of the US cycle. These bubbles then
    collapse very quickly releasing a large amount of
    energy which is detrimental to tissue viability.
  • This phenomenon occurs at higher US intensities
    with stationary head.
  • Pulsing also reduces the risk of damage due to
    cavitation.

10
Non-Thermal Effects of US (cont.)
  • 2- Acoustic streaming
  • It is a small scale eddying of fluids near a
    vibrating structure such as cell membranes the
    surface of stable cavitation gas bubble. Or, it
    is the steady, circular flow of cellular fluid
    induced by US.
  • 3- Micro-massage (Microstreaming).
  • It is a mechanical effect in which the sound
    wave traveling through medium will cause
    molecules to vibrate, possibly enhancing tissue
    fluid interchange.
  • The result of combined effects of stable
    cavitation and acoustic streaming is the
    alteration of cell membrane permeability and
    increased cellular activity which in turn
    responsible for the therapeutic effect of US.

11
Physiological Effects of Ultrasound
  • 1- Effect on blood flow
  • 2- Pain control
  • 3- Effect on adhesion and scar tissue
  • 4- Effect on wound healing
  • 5- Effect on fracture healing

12
Physiological Effects of Ultrasound (cont.)
  • 1-Effect on blood flow
  • Thermal effect.
  • Alteration of cell permeability
  • Histamine release

13
Physiological Effects of Ultrasound (cont.)
  • 2- Pain control
  • Direct effect
  • Increase pain threshold
  • Decrease transmission of pain impulse along nerve
    fibers
  • produce counterirritant effect (gate theory for
    pain inhibition)
  • Indirect effect
  • It results from the other effect of US which
    could lead to removing the source of pain such
    as
  • removing waste products and edema reduction,
  • improving tissues healing
  • decrease muscle spasm
  • breaking down adhesion.

14
Physiological Effects of Ultrasound (cont.)
  • 3-Effect on Adhesion and scar tissues
  • Collagen has high US absorption coefficient
  • The thermal effect of US lead to increasing
    extensibility of collagen rich tissues
  • Thus US could be used prior to range of motion
    exercises and stretching exercises.
  • Also, US is used to help improving the quality
    of the scar, resulting in a slightly stronger
    more elastic scar.

15
Physiological Effects of Ultrasound (cont.)
  • Effect on wound healing
  • Pulsed ultrasound at low intensities (0.8 W/cm²)
    enhance healing of wound by
  • stimulating collagen production by fibroblasts,
  • increases the intracellular calcium ion levels
  • improve the local blood supply
  • encourage the growth of new capillaries
  • stimulates the MYOFIBROBLASTS to contract,
    giving rapid initial wound strength.

16
Physiological Effects of Ultrasound (cont.)
  • Fracture healing
  • The use of ultrasound accelerate the rate of
    fracture repair when US delivered at low
    intensity (0.03 W/cm²) at 1.5MHz pulsed at a
    ratio of 14. for 20 minutes.
  • Using higher ultrasound doses(1 2 W/cm²) could
    have an adverse effect on the fracture healing
    process

17
Indications of Ultrasound
  • Muscle spasm
  • Trigger areas
  • Neuroma
  • Scar tissue
  • Joint contractures
  • sympathetic nervous system disorders
  • Acute and chronic and soft tissues injuries.
  • Acute and chronic inflammation
  • Wound and ulcers healing.
  • Fracture healing.
  • Neurogenic pain

18
Contraindications of Ultrasound
  • Pregnancy when used over the pelvic or lumbar
    area.
  • Over areas of acute infection
  • Areas of severely impaired circulation
  • Over malignant tumors
  • Over growing epiphyseal plates
  • Areas around the eyes, heart, and genitals
  • Tissues at risk of haemorrhage
  • Venous thrombosis

19
Precautions for US applications
  • It is recommended to avoid using high doses of US
    or sufficient intensity in the following cases
  • Acute inflammation
  • Epiphyseal plates
  • Fractures
  • Breast implants
  • The most common adverse effect is a burn, which
    may occur in the following conditions
  • high-intensity, continuous ultrasound is applied.
  • if a stationary application technique is used.
  • in areas with impaired circulation or sensation
  • with superficial bone

20
Techniques of ultrasound applications
  • a-Direct contact
  • b. Water immersion
  • c. Water bag
  • d. Solid sterile gel as coupling

21
a-Direct contact
22
a-Direct contact
23
Water immersion
24
Ultrasound in conjunction with other physical
therapy agents
25
Phonophoresis
  • It is the application of ultrasound with a
    topical drug in order to facilitate transdermal
    drug delivery up to 6 cm.
  • In the application of phonophoresis, the
    medication is in form of gel or cream.
  • Preheating the area to increase the absorption of
    the medication
  • Use only approved ultrasound transmission media.
  • The direct coupling method is recommended
  • Ensure that the skin is well moistened avoid
    areas of dry skin.
  • Lower frequency and Pulsed US lead to deeper
    penetration.
  • High intensity is recommended.
  • The duration depends on the size of the area to
    be treated.

26
Case study
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