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BYODUENYI CHRISTIAN

PHYSIOTHERAPY DEPARTMENTBENUE STATE UNIVERSITY TEACHING

HOSPITAL(BSUTH), MAKURDI.

Therapeutic Ultrasound in Physiotherapy

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Introduction

Ultrasound is used in medicine for:DiagnosisDestruction of tissueTherapy

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Definition

Ultrasound is a mechanical vibration at any frequency above the audible sound range

Ultrasound therapy (UST) is the application of ultra frequency sound waves (1 – 3MHZ) to tissues in order to promote healing and reduce pain and swelling.

Therapeutic Us used in physiotherapy ranges from 0.5 to 5MHZ but most us machine are set at 1MHZ and/or 3MHZ

Classified as a deep heating modality

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Production of ultrasound

The inverse piezoelectric effect is used in production of ultrasonic sound waves.

Examples of piezoelectic materials are quartz,barium titanate and lead zirconate titanate (PZT).

Application of high frequency alternating current to the PZT crystal of the transducer transforms the electrical energy into vibratory sound wave (ultrasound)s

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Transmission of US wave

Through solid, liquid and gases in form of compression and separation of molecule

Normally cylindrical and longitudinal in fashion

Velocity higher in materials of high densityAir 340 m/s, water 1410m/s, muscle 1540m/s,

Bone 3500m/s.

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Properties of ultrasound beam

ReflectionRefraction AttenuationAbsorption Passing through the tissue US energy is

dissipated = attenuationHalf Value Distance = 4cm for 1MHZ and

2cm for 3MHZAcoustic Impedance(Z)

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Depth of penetration

1MHZ= deeper tissues at depth 3 to 5cm

3MHZ= superficial Tissues at depth 1 to 2cm

Depth of Penetration is inversely proportional to frequency

Near and Far Field Wave fonts from

different parts travel different distances causing interference between adjacent fonts

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Near and far field

The near field also known as the Fransel zone is the convergent region

The far field known as the fraunhofer zone is the divergent region

Length of Fresnel zone = r2 / λ where r=radius of transducer.

Therapeutic us utilizes the near field

Frequency of US and radius of transducer need to be considered for tissue depth above 6.5cm(shortest)

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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 72.6% Glycerol 67 % Distilled water 59 % Petroleum jelly 0 % Air 0 %

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Characteristics of a coupling media

1. Acoustic impedance similar to tissue2. High transmissivity for US3. Low suceptibility to bubble formation4. Chemically inactive in nature5. A hypoallergic character6. High viscosity7. Cheap8. Relative sterility

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US beam parameters

Mode type : continuous and pulsed. Pulsed Mark Space(M:S) ratio: 1:1, 1:2, 1:4 etc.

Power: amount of acoustic energy per unit time (watts)

Intensity: power per unit area of the ultrasound head (watts/cm2). Space average intensity and time averaged/space average intensity(pulsed).

Frequency: number of compression-rarefaction cycles per unit of time, usually expressed in cycles per second (Hertz)

Effective radiating area (ERA): The area of the transducer from which the US energy radiates

Duty cycle: The proportion of total treatment the ultrasound was on

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Depth of penetration

Majority of the ultrasound generators used in physiotherapy are set at a frequency of 1MHZ and/or 3MHZ.The depth of penetration of ultrasound beam is inversely proportional to the frequency1MHZ ultrasound beam has a depth of penetration of 3-5cm and absorbed in deeper tissues3MHZ ultrasound beam with a depth of penetration of 1-2cm and is absorbed in the superficial tissues

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Treatment Protocols

Preparation of the MachinePreparation of the PatientSet up the treatmentTermination of treatmentDocumentation

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Protocols Preparation of the machine Position Inspect Be assured of functionality Bring all accessories closer:• Aquasonic gel• Cotton wool• Methylated spirit• Water in a bowl Preparation of the patient Inform your patient Remove metals Expose the Rx part Remove hair if necessary Wash or swab Inspect the Rx part Check for intact sensation Demand co-operation

Set-up up the Rx Secure pt.'s comfort and

stability of Rx part Plug dead, supply and

power on Select Rx programme Apply coupling media Ensure the transducer is in

contact with the coupling media on the skin

Start now Keeping asking how the

pt.'s feels

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protocols

Termination Return intensity to

zero Remove transducer Cut the mains supply Clean the skin and

the transducer Inspect

Documentation Date Machine Intensity Frequency Mode duration Coupulant Region Response of Rx`

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Application

Principles Rx surface parallel to the skin Even pressure maintained to

exclude air and balance irregularities in sonic field

Transducer moved continuously over the skin surface

Rate of movement must be slow enough to allow tissue to deform and fast enough to avoid hot spots

Pattern of movement- series of overlapping parallel strokes, circles or figure 8

Techniques of Application1. Direct contact2. Water bath: degased

water of comfortable temperature, transducer held 1cm parallel to the skin inside the water keeping

3. Water bag

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Dosage Factors to consider Receny of injury Depth of tissue Nature of the lesion Size of the area Attenuation Area of transducer Acute conditions Intensity: 0.25 or 0.5

watts/cm2 Time: 2-3minutes Failure to improve progress

to 0.8watts/cm2 or increase time to 4 0r 5minutes

Chronic conditions Start dose: 0.8watts/cm2

for 4minutes Failure to improve

progress to 1watts/cm2 for 4minutes, 1watts /cm2 for 6minutes, to 1.5watts/cm2 for 6minutes, 1.5watts/cm2 for 8minutes, 2watts/cm2 for 8minutes

Note: A dose of 2watts/cm2 for 8minutes is maximum permitted

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Physiological effects

Chemical ReactionsBiological ResponsesMechanical ResponsesThermal Effects

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Physiological effects

Chemical reactionUltrasound vibration stimulate tissue to enhance chemical reactions and processes and ensure circulation of necessary elements and radicals for recombination.

Biological responses Increase membrane

permeability which enhances transfer of fluid and nutrients to tissues

Acoustic Streaming: is unidirectional flow of tissue components which occurs particularly at the cell membrane. Streaming produce changes in the rate of protein synthesis and could thus have a role in the stimulation of repair.

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Physiological effects

Mechanical responses micro massage: cells are

alternately compressed and then pulled further apart. This increase mobility of intracellular fluids and thus helps to reduce oedema.

Tendon extensibility: ultrasound apparently increases the extensibility of tendons, muscles and scar tissues.

Thermal effects: as ultrasonic waves are absorbed they are converted to thermal energy (heat)

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Clinical application of US

Soft tissue injuries Oedema Varicose ulcers Pain control Chronic rheumatoid and arthritic conitions Tendon injuries Resorption of calcium deposits Bone fractures Carpal tunnel syndrome phonophoresis

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Contraindications

Vascular conditionsRadiotherapyTumoursPregnancyCardiac disease ImplantAnaesthetic areaAcute sepsis

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Time to Demonstrate

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Ask your Questions and make your contributions

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A Big Thank You