2. Sound
• Sound is by definition “the periodic
mechanical disturbance of an elastic medium
such as air”
• Sound requires a medium for its transmission
and cannot cross a vacuum.
• The wavelength is the distance between the
two closest points on a wave that are
performing the same motion at any instant in
time
3. Sound
• The frequency is the number of times a particle
undergoes a complete cycle in one second.
• The velocity of a wave is the speed at which the wave
moves through the medium.
• The velocity of sound in some media are:
Air
344 m/s
Water
1410 m/s
Muscle
1540 m/s
4. Ultrasound
• The upper limit of hearing is just over 20kHz (
20000 cycles per second).
• Ultrasound is well above this.
• Therapeutic frequencies being in the region of
1MHz or 3MHz
6. The production of Ultrasound
• For a 1 MHz machine a vibrating source with a
frequency of one million cycles per second is
needed.
• This is achieved using either a quartz or a
barium titanate crystal.
• These crystals deform when subjected to
varying potential difference – a piezo-electric
effect
7. Piezoelectricity
• Piezoelectricity is a natural phenomenon found in
certain mineral crystals, but may also be synthesized
commercially.
• The crystal transforms mechanical energy into
electrical energy and it reverse, electrical into
mechanical.
8. Piezoelectricity
• If a piezoelectric crystal were to
be compressed or deformed by
mechanical means, a small
electric charges would result
within the crystal; conversely, if
an electric charge were to be
imposed on the crystal, a
vibration
of
mechanical
deformity of the molecular
structure of crystal would
ensure.
9. Transformation of electrical energy
into sound
• The high frequency current of 1MHz
alternating current is imposed on PZT crystal
of the transducer or soundhead, thereby
transforming the energy in the crystal to
vibration.
• Thus the electrical energy of the original
current is transformed into a vibratory sound
wave ( ultrasound)
10. Reflection of Ultrasound
• Sound obeys the law of reflection, if an
ultrasonic beam travelling through one
medium encounters another medium which
will not transmit it reflection takes place.
• Air will not transmit ultrasonic waves, so in
ultrasonic treatment great care is taken to
avoid leaving air between the treatment head
and the patient.
11. Attenuation of ultrasound
• The space-averaged intensity of ultrasound
produced from a transducer is measured in
watts/cm²
• As the ultrasonic beam passes through a
medium its intensity is reduced (attenuated)
by two mechanisms
Absorption
Scatter
12. Attenuation of ultrasound
• These two factors reduce the intensity of the
ultrasonic beam, so that at certain depth
below the surface the intensity of the
ultrasonic beam has been reduced to half.
• This depth (d) is called the half value
thickness.
• Half-value distance may be of significance
when using ultrasound to treat deeply placed
structure
13. Penetration & Absorption
• Ultrasound waves have been
reported to penetrate as deep as
4-6 cm into the tissues.
• The factors of absorption,
refraction, reflection and
dispersion must be consider at all
times.
• Tissues with high fluid content
such as blood and muscle will
absorb sound waves better than
will less hydrated tissues.
16. Coupling media
• Ultrasound waves are not transmitted by air, thus
some couplant which does transmit them must be
interposed
• Unfortunately no couplant affords perfect
transmission & only a percentage of the original
intensity is transmitted to the patient.
Aquasonic gel
Glycerol
Distal water
Petroleum jelly
Air
72.6%
67 %
59 %
0 %
0 %
17. Pulsed Ultrasound
• Most ultrasonic generator allow the
selection of either a continuous or a
pulsed ultrasound output.
Continuous Output
• A pulsed output usually consist of 2
ms of ultrasound followed by an 8
ms silence.
Pulsed Output
18. Physiological Effects
• Ultrasound have four basic physiologic effects
Chemical Reactions
Biological Responses
Mechanical Responses
Thermal Effects
19. Chemical Reaction
• Just as test tube is shaken in the laboratory, to
enhance chemical action.
• Ultrasound vibration stimulate tissue to
enhance chemical reactions and processes
therein and ensure circulation of necessary
elements and radicals for recombination
20. Biological Responses
• The permeability of membranes is increased
by ultrasound, which enhances transfer of
fluid and nutrients to tissues.
• This quality is of importance in the process of
Phonophoresis, where molecules are literally
pushed through the skin by the sound wave
front for therapeutic purposes.
21. Biological Responses
• Acoustic streaming
This effect produced by the
ultrasonic beam is unidirectional
flow of tissue components which
occurs particularly at the cell
membrane. Streaming has been
shown to produce changes in the
rate of protein synthesis and could
thus have a role in the stimulation
of repair.
22. Mechanical Responses
• Cavitation is a common condition in which a bubble
gas is produced in the tissues as a result of
insonation.
• Stable cavitation is not dangerous to the tissues, as
the bubbles remain intact and oscillate harmlessly in
the ultrasonic field.
• Transient cavitation is dangerous to the tissues, as
the bubble grows and collapes rapidly in the
ultrasonic beam and this is thought to cause very
great increase in the tempreture
23. Mechanical Responses
• The micromassage effect of ultrasound occurs
at a cellular level where the cells are
alternately compressed and then pulled
further apart. This effect on intracellular fluids
and thus to reduce oedema.
• Ultrasound has been found to be effective at
reducing both recent traumatic oedema and
chronic induced oedema.
24. Mechanical Responses
• It has been shown that a standing wave
produced in the tissues can produce inhibition
of blood flow.
• Pulsing the ultrasonic beams or moving the
treatment head should prevent this occurring.
25. Mechanical Responses
• Tendon Extensibility
The sclerolytic action of ultrasound
apparently increases the extensibility of
tendons, crucial to those that have been
shortened by inflammation, strain, or disease,
and providing the clinician with an excellent
formula for management of spasm
26. Thermal effects
• As ultrasonic waves are absorbed they are
converted to thermal energy (heat)
• The amount of heat produced depends upon
factors such as the number of times the
transducer passes over a part and on the
space-average intensity (watt/cm²)
• Reflection of ultrasound may occur at tissue
interfaces, producing a concentrated heating
effect at that point.
27. Thermal effects
• As reflection from the bone occurs there is
double the intensity of ultrasound in the
periosteum region, which may cause localized
over-heating and can manifest itself as a
periosteal pain.
• It is best to avoid passing the ultrasonic head
over subcuteneous bony points
28. Thermal effects
• Pulsed ultrasound has little thermal effects, as
any heat produced by the 2ms of ultrasound is
carried away by the circulation in the 8ms
rest.
• Pulsed ultrasound may thus be indicated in
the treatment of acute conditions where a
thermal effect is not required
29. • PRECAUTIONS AND WHY
•
Open wounds
•
Impaired cognitive The patient must be able to communicate any
ability uncomfortable sensation under the transducer.
•
Pregnancy
•
Sterile saline must fill the wound for transmission of
the acoustical energy.
During the later stages of pregnancy there is no data
to indicate that there would be any adverse effects
as long as the treatment area does not include the
abdomen, ankle,* or lower back (1 MHz).
Peripheral vascular The presence of peripheral vascular disease is not a
disease
problem in itself; however, if the treatment area is
involved, the patient’s tissues may not be able to
maintain homeostasis or respond to an increase in
tissue temperature.
30. • PRECAUTIONS AND WHY
•
Advanced age
As long as the patient is alert and their sensation is
intact, ultrasound should not cause any difficulties.
.
•
Over joint or metal
Implants
Ultrasound may cause heterogeneous heating within
the joint if a cementing media was used. To avoid this,
use 3 MHz ultrasound, which does not have sufficient
depth to reach the internal aspects of joints.
Metal implants tend to elevate in temperature faster
than bone, but they also dissipate the heat faster,
making them safe for ultrasound application.
31. PRECAUTIONS AND WHY
•
Pain with pressure
•
Lack of sensation
Ultrasound involves the movement of a transducer
along the surface of the skin. If this type of pressure
is painful for a patient, an underwater technique with
ultrasound can be employed.
Ultrasound may be administered in a thermal or a
non-thermal mode. If administered in a thermal mode,
the patient must be able to report pain as a potential
adverse response.
32. Contraindications Why?
•
Pregnancy
There is no physical therapy indication for application of
ultrasound over a pregnant uterus, and there is no data to
indicate what effect, if any, the therapeutic application of
ultrasound would have on a fetus.
•
Metastasis
Thermal applications of ultrasound can
potentially elevate tissue temperature, increase circulation
to the area, and thus may enhance the growth or spread
malignancy to other tissues.
•
Lack of sensation
If the patient is unable to report pain,
they can easily burn with thermal applications of ultrasound.
33. Contraindications Why?
•
Thrombus
The application of ultrasound directly over a thrombus
may cause the clot to dislodge and move to the heart,
lungs, or brain.
•
Pacemaker
There is no indication to apply ultrasound directly over a
pacemaker. The potential for interference between the
pacemaker and the ultrasound device exists.
•
Psoriasis
Ultrasound must be applied to the skin via an acoustical
media without airspace. Psoriatic skin may have too
many irregularities to permit passage of the ultrasound
into the patient.
34. Clinical application of US
•
•
•
•
•
•
•
Soft tissue shortening
Pain control
Surgical skin incisions
Tendon injuries
Resorption of calcium deposits
Bone fractures
Carpal tunnel syndrome
35. Soft tissue shortening
• Soft tissue shortening can be the result of
immobilization, inactivity or scarring, and can cause
joint Range-of-motion (ROM) restrictions, pain, and
functional limitations.
• Because ultrasound can penetrate to the depth
of most joint capsules, tendons, and ligaments,
since these tissues have high ultrasound absorption
coefficients, ultrasound can be an effective physical
agent for heating these tissues prior to stretching
36. Soft tissue shortening
• The deep heating produced by 1 MHz
continues ultrasound at 1.0 to 2.5W cm² has
been shown to be more effective at increasing
joint ROM than the superficial heating
produced by infrared.
37. Pain control
• Ultrasound may control pain by altering its transmission or
perception or by modifying the underlying condition causing
the pain. These effects may be the result of stimulation of the
cutaneous thermal receptors or increased soft tissue
extensibility due to increased
tissue temperature, the
result of changes in nerve conduction due to increased tissue
temperature
or the non-thermal effects of ultrasound, or the result
of modulation of inflammation due to the non-thermal
effects of ultrasound.
38. Surgical skin incisions
• The effect of ultrasound on the healing of surgical
skin incisions has been studied in both animal and
human subjects.
• Ultrasound has been shown to accelerate the
evolution of angiogenesis a vital component of early
wound healing.
• Angiogenesis is the development of new blood
vessels at an injury site that serves to reestablish
circulation and thus limits ischemic necrosis and
facilitate repair.
39. Tendon injuries
• Ultrasound has been reported to assist in the healing
of tendons after surgical incision and repair Although
some studies with both animal and human subjects
have reported treatment success others have failed
to support these findings.
• It is recommended that ultrasound be applied in a
Pulsed mode at a low intensity during the acute
phase of tendon inflammation in order to minimize
the risk of aggravating the condition and to
accelerate recovery
40. Resorption of calcium deposits
• Ultrasound may facilitate the resorption of
calcium deposits.
• Although the mechanism underlying calcific
deposits resorption is not known, decrease in
pain and improvements in function may be
due to the reduction in inflammation
produced by ultrasound.
41. Bone fractures
• Although prior reports have recommended
that ultrasound not be applied over unhealed
fracture because they have failed to provide
data to support this recommendation and
because recent studies have demonstrated
that low-dose ultrasound can reduce the
fracture healing time in animals and humans,
the use of low-dose ultrasound to accelerate
fracture healing is now recommended.
42. Carpal Tunnel Syndrome
• Continuous ultrasound has generally not been
recommended for the treatment of carpal
tunnel syndrome because of the risk of
adversely impacting nerve conduction velocity
by overheating. However a resent study found
that pulsed ultrasound produced significantly
greater improvement
43. Testing the apparatus
• Testing should always be carried out prior to
treatment
• The simplest way of finding out whether
ultrasound is in fact being produced is to use a
water bath and to reflect an ultrasonic beam
up to the surface where it should produce
ripples
44. Technique of Application
• DIRECT CONTACT
if the surface to be treated is fairly regular
then a coupling medium is applied to the skin
in order to eliminate air between the skin and
the treatment head.
the treatment head is moved in small
concentric circles over the skin in order to
avoid concentration at any one point
45. Water bath
• A water bath filled with distal water is used if
possible. Ordinary tap water presents the
problem that gas bubbles dissociate out from
the water.
• The technique of application is that the
treatment head is held 1 cm from the skin and
moved in small concentric circles.
46. Dosage
• This is the most controversial area when
discussing ultrasound. The argument of
whether pulsed or continuous modes should
be used and the intensities of ultrasound
required to produced beneficial effects.
• The experience of the physiotherapist is
probably very important in this area.
47. Dosage in acute condition
• As with any acute condition treatment is
applied cautiously to prevent exacerbation of
symptoms. In initial stages a low dose (0.25 or
0.5 watt/cm²) is used for 2-3 times
• Progression of dosage is unnecessary if the
condition improves.
• Aggravation of symptoms is not always a bad
sign as it may indicate that repair processes
are taking place.
48. Dosage in chronic condition
• Chronic conditions can be treated with either
a pulsed or a continuous beam.
• With a continuous beam, the maximum
intensity which should be used is that which
produced a mildly perceptible warmth. This
usually occurs around 2 watt/cm²
• A dose of 2 watts/cm² for 8 minutes is usually
considered
56. Description
• Use of therapeutic ultrasound to assist in
diffusion of medication through the skin
• Increases the diameter of skin to allow the
medication to pass
– Pores
– Hair follicles
– Sweat glands
57. Biophysical Effects
• Medication is introduced over a large area
– Relative to an injection
• Noninvasive
• Medication may not be filtered by the liver
– Reducing metabolic elimination of the medicine
58. Transdermal Application
• Medication must diffuse through:
– Enzymatic barrier of the epidermis
– Stratum corneum
• Rate-limiting barrier to absorption
• Medications must be able to diffuse across this barrier
• Medication is stored in subcutaneous tissues
for some time before being diffused deeper
59. Skin Influences
• Medication uptake is improved when the skin
is:
– Well hydrated
– Highly vascularized
– Relatively thin
– “Younger” skin tends to have better diffusion
characteristics than “older” skin.
61. Phonophoresis Medications
• Either prescription or nonprescription
• Low molecular size and weight
– Most medications used can be applied
transdermally without ultrasound
• Controlled medications require a prescription
for the patient being treated
• Medication is often mixed in an inert base
– Base must be able to transmit ultrasonic energy
63. Application Tips
• Moist heat pack prior to application:
– Increase blood flow
– Increase kinetic energy
• Following treatment
– Leave medication on skin
– Cover with an occlusive dressing
– Moist heat pack re-application may assist in
further absorption
64. Contraindications
• The same contraindication apply when giving
phonophoresis as apply when giving
ultrasound
• If local skin anesthetizing drug are being
driven by ultrasound it must be remembered
that the skin sensation under the treatment
head will gradually be lost high intensities
should not therefore be used for these drugs
65. Some Conditions Treated With
Phonophoresis
•
•
•
•
•
Achilles Tendonitis
Foot/Toe Sprains/Achilles Sprains and Strains
Ankle/shoulder/Calf/Neck Sprains and Strains
Bursitis
Post-injury conditions (dislocations,inflammation of
muscles, tendons, etc)
• Tendonitis (acute or chronic)
• Plantar Fasciitis (Heel Spurs)
66. Some Conditions Treated With
Phonophoresis
•
•
•
•
Hip Sprains, Thigh Sprains/Strains
Ligament Strains
OsteoArthritis
Post-exercise recovery (when the workout goes a bit
too far)
• Rheumatoid Arthritis
• Shoulder Capulitis
• Golfers Elbow
67. Some Conditions Treated With
Phonophoresis
•
•
•
•
Carpal Tunnel Syndrome
Tarsal Tunnel Syndrome
Tension Headaches
Lower back pain of neurological origin (i.e. root pain,
discopathies, sciatica)
• Upper and Lower Back Strains
• Wrist/ Hand/Elbow/Shoulder Sprains and Strains