119049924 ultrasound phonophoresis physiotherapy
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ULTRASOUND
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SOUND & ULTRASOUND Periodic mechanical disturbance of an elastic medium
such as air.
Ultrasound refers to mechanical vibrations of a higher frequency, beyond the range of human hearing
Frequency - Typically 1 or 3 MHz
Wavelength - @ 1MHz would be 1.5mm and @ 3 MHz would be 0.5 mm.
velocity of ultrasound - Sound waves can travel more rapidly in a more dense medium. The velocity varies from
331 m/sec in air 1450 m/sec in fat, 1570 m/sec in blood
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Transducer (sound head): A crystal that converts electrical energy into sound
Power: The amount of acoustic energy per unit time. This is usually expressed in Watts.
Intensity: The power per unit area of the sound head. This is usually expressed in Watts/centimeter2.
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Spatial Peak Intensity: The peak intensity of the ultrasound output over the area of the transducer. The intensity is usually greatest in the centre of the beam and lowest at the edges of the beam.
Spatial Average Intensity: The average intensity of the ultrasound output over the area of the transducer.
Beam Nonuniformity Ratio (BNR) : The ratio of the spatial peak intensity to the spatial average intensity .
For most units this is usually between 5:1 and 6:1,
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Continuous Ultrasound:
Pulsed Ultrasound: Pulsing the ultrasound minimizes its thermal effect.
Duty Cycle: The proportion of the total treatment time that the ultrasound is on. This can be expressed either as a percentage or a ratio.
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Spatial Average Temporal Peak (SATP) Intensity: The spatial average intensity of the ultrasound during the on time of the pulse.
Spatial Average Temporal Average (SATA) Intensity: The spatial average intensity of the Ultrasound averaged over both the on time and the off time of the pulse.
SATP x duty cycle = SATA
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Effective Radiating Area (ERA) area of the sound head that
produces ultrasonic waves; expressed in square
centimeters (cm2) Always lesser area than
actual size of sound head Large diameter heads –
column beam Small diameter heads –
more divergent beam Low frequency (1 MHz) –
diverge more than 3 MHz
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Near Field/Far Field: The near field, also
known as the Fresnel zone is the convergent region and
the far field, also known as the Fraunhofer zone, is the divergent region
Length of near field = Radius of transduce2 / Wavelength of ultrasound (r2 /λ)
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Acoustic Impedance
It is a measure of the resistance of particles of medium to mechanical vibrations
This resistance increases in proportion to the density of medium and
velocity of ultrasound in the medium
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Reflection most reflection occurring where there is the
greatest difference between the acoustic impedance of adjacent tissues.
In the body, most reflection i.e. 1% in soft tissue / fat interface about 35%, occurs at soft tissue-bone
interfaces there is 100% reflection of ultrasound at
the air skin interface and only 0.1% reflection at the transmission
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Standing Wave
When reflected ultrasound meets further waves being transmitted, a standing wave (hot spot) may be created, which has potential adverse effects upon tissue.
Such effects can be minimized by ensuring that
the apparatus delivers a uniform wave, using pulsed waves and moving the transducer during treatment
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Standing Wave
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Absorption Absorption
coefficients are tissue and frequency specific.
They are highest for Tissues with highest collagen content and
Increase in proportion to the ultrasound frequency
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Refraction
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Attenuation Attenuation is the result of
absorption, reflection, and refraction, with absorption accounting for about one-half of attenuation.
Attenuation coefficients are tissue and Frequency specific.
They are higher for tissues with a higher collagen content and
increase in proportion to the frequency of the ultrasound
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Half value depth this is the tissue depth
at which 50% of the ultrasound delivered at the surface has been absorbed.
The average 1/2 value depth of
3MHz ultrasound is at 2.5 cm and
1MHz ultrasound as 4.0 cm
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1 MHz 3 MHz
Muscle 9.0 mm 3.0 mm
Fat 50.0 mm 16.5 mm
Tendon 6.2 mm 2.0 mm
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Quantity of
Ultrasound(fraction of beam being
further propagated)
1.0
.5
.25
.125
1st HalfValue
2nd HalfValue
3rd HalfValue
4th HalfValue
Tissue depth
The quantity of the ultrasound beam decreases as the depth of the medium (tissue) increases.
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Generation of UltrasoundGeneration of Ultrasound Pizoelectric effect - generated by pizoelectric crystalsPizoelectric effect - generated by pizoelectric crystals
occurs when an electric current is passed through the crystaloccurs when an electric current is passed through the crystal crystal expands & contracts at frequencies that produce crystal expands & contracts at frequencies that produce ultrasoundultrasound
pizoelectric crystal in transducer head Wavelength
ultrasound transducer
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Production
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Ultrasound Machine & Coupling Agent
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Types of Ultrasound BeamsTypes of Ultrasound Beams
Continuous WaveContinuous Wave - no interruption of beam: - no interruption of beam: best for best for maximummaximum heat buildup heat buildup
Pulsed WavePulsed Wave - intermittent “on-off” beam - intermittent “on-off” beam modulationmodulation builds up less heat in tissues used for builds up less heat in tissues used for post post
acuteacute injuries injuries
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Pulsed Wave
Mark Space ratio
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Physiological Effects of UltrasoundPhysiological Effects of Ultrasound
Thermal effectsThermal effects (minimum 10 min - 2.0 watts - 1 MHz) (minimum 10 min - 2.0 watts - 1 MHz) ▲▲ blood flowblood flow
▼▼ inflammation and inflammation and ▼▼ hematoma (remains controversial?) hematoma (remains controversial?)
▲▲enzyme activityenzyme activity ▲▲sensory and motor nerve conduction velocitysensory and motor nerve conduction velocity ▲▲extensibility of connective tissue & possibly scar tissueextensibility of connective tissue & possibly scar tissue ▼▼ joint stiffnessjoint stiffness ▼▼ muscle spasmmuscle spasm ▼▼painpain
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Non-thermal effectsNon-thermal effects cavitations
alternating expansion & compression of small gas bubbles
may cause ▲ cell membrane & vascular wall permeability (▲ nutrient and oxygen
delivery) unstable cavitations may cause
tissue damage unstable cavitations – large,
violent changes in bubble volume
Micro streaming bubble rotation of fluid
movement along cell membrane boundaries (▲ nutrient and oxygen delivery)
changes in cell permeability & ion flux reduces healing time
gas buble expansion
gas buble compression
bubble rotation & associated fluid movement alongcell membranes
Cavitation Microstreaming
Non-thermal Effects of Ultrasound
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Non-thermal effectsNon-thermal effects
Possible therapeutic benefits of non-thermal effects
difficult to make distinction from thermal benefits
▲ capillary density & ▲ cell permeability ▲ fibroblastic activity and associated
collagen production ▲ cortisol production around nerve bundles
reduce inflammation
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Output FrequencyDurationDuty CycleOutput Intensity
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Output Frequency Determines the treatment depth 1 MHz Output
Deep (5 to 7 cm) tissues○ Rotator cuff, vastus intermedius, gastroc
3 MHz OutputSuperficial (up to 3cm deep) tissues
○ Patellar tendon, MCL, brachialis
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Treatment Duration Depends on:
Size of the treatment areaOutput intensityTherapeutic goals
Vigorous heating1 MHz output
○ 8 to 10 minutes3 MHz output
○ 3 to 4 minutes
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Direct CouplingImmersion MethodPad/Bladder Method
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Coupling Methods Ultrasonic energy cannot pass through
the air A coupling medium is required Medium should be water-based Coupling method should confirm to the
body area The body area should be clean and
relatively hair-free
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Direct Coupling Gel or Creams Only use approved
coupling agents Apply liberally to area Remove air bubbles
by passing sound head over area (before power is increased)
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Direct Coupling
Move the sound head s-l-o-w-l-y4 cm/sec
Moving the head faster decreases heating
If the patient describes discomfort, decrease the output intensity
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Coupling Ability of Various MediaSubstance
Transmission Saran Wrap 98 Lidex ge, fluocinonide (.05%) 97 Thera-Gesic 97 Mineral oil 97 US Transmission gel 96 US Transmission lotion 90 Chempad-L 68 Hydrocortisone powder (1%) 29 Hydrocortisone powder (10%) 7 Eucerin cream 0 Myoflex 0 White petrolatum gel 0
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Immersion Technique Used to treat irregularly
shaped areas The limb is immersed in a
tub of degassed water If tap water is used,
increase the output intensity by 0.5 w/cm2
Transducer is held appx. 1” from the body part
Avoid the formation of air bubbles
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Pad (Bladder) Method
A mass of conductive gelCommercial padsSelf-made bladders
Conforms to the treatment area
Commercial pads help limit the size of the treatment area
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Contraindications Acute injuries (100% duty
cycle) Ischemic areas Areas of impaired
circulation including arterial disease
Over areas of deep vein thrombosis
Anesthetic areas Over cancerous tumors Over sites of active
infection or sepsis Over the spinal cord or
large nerve plexus in high doses
Exposed metal that penetrates the skin (e.g., external fixation devices)
Areas around the eyes, heart, skull, or genitals
Over the thorax in the presence of an implanted pacemaker
Pregnancy when used over the pelvic or lumbar areas
Over a fracture site before healing is complete
Stress fracture sites or sites of osteoporosis
Over the pelvic or lumbar area in menstruating female patients
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Precautions Symptoms may increase after the initial
treatments. Use caution when applying ultrasound around
the spinal cord, especially after laminectomy. The use of ultrasound over metal implants is
not contraindicated Keep the sound head moving
Use caution when applying ultrasound over epiphyseal plates of growing bone
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PHONOPHORESIS
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PHONOPHORESIS
It is the movement of drugs through skin into the subcutaneous tissues under the influence of ultrasound
Also known as sonophoresis or ultrasonophoresis
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Pathways of drug penetration
1.Through stratum corneum
2.Transfollicular
3.Through sweat gland
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Advantages
Avoid risk and inconvenience of IV therapy
Bypass liver in terms of elimination Less chance of overdose or underdose Allow easy termination Permit both local and systemic
treatment effects
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Effectiveness Depends upon Anatomical area treated Hydration of the skin Health or pathological condition of the skin State of cutaneous and systemic
metabolism Patient’s age
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Methods of application Adequate quantity of drug rubbed into the
skin over the target area Same gel mixed with standard ultrasound
gel placed over transducer head as coupling medium
US is then applied as a direct contact method
Standard intensity is 1 to 2 w/cm² Standard duration is 5 to 10 minutes Lower ultrasonic frequencies and pulsing
lead to deeper penetration
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Phonophoretic agentsDrug Indication Reactions/
contraindications
Hydrocortison Anti inflammatory Skin rashes
Lidocaine/xyclocaine Acute pain
Methyle salicylate Chronic painfull MS disorders
Sensitivity to aspirin
Zinc oxide/siloderm Open wounds Allergy to metals
Iodine Adhesion,calcification,adhessive capsulitis
Allergic to sea food
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