BTL 5000 User manual

BTL-5000

Ultrasound

Therapy

USER'S GUIDE

v111z1RK14/01/2003

ULTRASOUND THERAPY – USER'S GUIDE

CONTENTS:

1 USER'S GUIDE....................................................................................................................................................3

1.1 Mechanism of Action ........................................................................................................................................3

1.2 Methods of Application .....................................................................................................................................4

1.2.1 According to Application Area and Movement of the Emitter Head ...........................................................4

1.2.2 According to Application Area....................................................................................................................5

1.2.3 According to Contact Between Emitter Head and Body Surface ............................................................... 5

1.3 Ultrasound Frequency ......................................................................................................................................5

1.4 Modes of Operation ..........................................................................................................................................5

1.5 Emitter Head Size............................................................................................................................................. 6

1.6 Application Time ............................................................................................................................................... 6

1.7 Intensity ............................................................................................................................................................6

1.8 Frequency of Treatments..................................................................................................................................6

1.9 Combined Therapy ........................................................................................................................................... 6

1.9.1 Ultrasound + Low-frequency Currents.......................................................................................................6

1.9.1.1 Mechanism of Action............................................................................................................................ 7

1.9.1.2 Intensity................................................................................................................................................7

1.9.2 Ultrasound + Amplitude Modulated Mid-frequency Currents (2-pole Interference)....................................7

1.9.2.1 Mechanism of Action............................................................................................................................ 7

1.9.2.2 Intensity................................................................................................................................................7

1.9.3 Ultrasound + TENS (Transcutaneous Electrical Nerve Stimulation)..........................................................8

1.9.3.1 Mechanism of Action............................................................................................................................ 8

1.9.3.2 Intensity................................................................................................................................................8

1.10 Specific Contraindications for Ultrasound Therapy ........................................................................................8

1.10.1 Absolute ...................................................................................................................................................8

1.10.2 Relative ....................................................................................................................................................9

1.11 Therapy Prescription ....................................................................................................................................10

1.12 Instructions for the Patient ...........................................................................................................................10

1.13 Treatment Procedure ...................................................................................................................................10

2 SETUP OF ULTRASOUND GENERATOR .......................................................................................................11

2.1 Setup and Control of Ultrasound Therapy ......................................................................................................11

2.1.1 Ultrasound ...............................................................................................................................................11

2.1.1.1 Carrier Frequency ..............................................................................................................................11

2.1.1.2 Duty Factor ........................................................................................................................................11

2.1.1.3 Intensity..............................................................................................................................................11

2.1.1.4 Time ...................................................................................................................................................11

2.1.1.5 Pulse Frequency ................................................................................................................................ 11

2.1.1.6 With Electro........................................................................................................................................11

2.1.1.7 Course of Signal.................................................................................................................................12

2.1.1.8 Physiological Effects ..........................................................................................................................12

2.1.2 Ultrasound Sequence .............................................................................................................................. 12

2.2 Specific Settings ............................................................................................................................................. 12

2.2.1 Ultrasound Head Calibration ...................................................................................................................12

2.2.1.1 Start of Calibration .............................................................................................................................12

2.2.1.2 Finishing of Calibration.......................................................................................................................13

2.2.1.3 Saving of Calibration Values .............................................................................................................. 13

3 TECHNICAL PARAMETERS ............................................................................................................................14

3.1 Parameters of Ultrasound Generator..............................................................................................................14

3.2 Step of Setting of the Adjustable Values.........................................................................................................14

3.3 Parameters of Ultrasound Heads ...................................................................................................................15

4 ACCESSORIES .................................................................................................................................................16

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ULTRASOUND THERAPY – USER'S GUIDE

1 USER'S GUIDE

Continuing education is a very important aspect of healthcare delivery. Many excellent resources are today available to expand a user's knowledge about many aspects of ultrasound therapy. BTL recommends a thorough review of this guide prior to operating the equipment and a search of educational reading material on the internet.

1.1 MECHANISM OF ACTION

Mechanical waves of a frequency higher than 20 000 Hz are called ultrasound. Application of ultrasound does not generate any electric current in tissues, and thus it is classified as mechanotherapy. The frequency usually used in physiotherapy is 0.8 – 3 MHz.

When the air gap between the emitter head and the body surface is eliminated, the emitter head vibrations are transmitted into the tissue and propagate to the depth in the form of longitudinal waves. All cells in the path of ultrasonic beam begin to oscillate. This causes micro-massage followed by transformation of gel into sol (jelly structures become liquid), transformation of mechanic energy into thermal, and deep warming of tissues.

The amount of generated heat depends on the amount of absorbed energy. Other effects of ultrasound (degassing of solutions, formation of cavities in liquids, and local alkalization) are negligible with ultrasound doses and intensities used in physical therapy.

In order to avoid side effects, it is important to realize that molecular oscillation occurs not only in the path of ultrasonic beam, but also in places that are distant from the area of application as a result of transmission by body fluids. This may lead to restoration of former epistaxis or acceleration of menstruation.

The features of ultrasound beam and its distance from the emitter head determine the ultrasound field as being either

close or distant.

Close ultrasound field is characterized by low beam divergence and big intensity variations due to interferential

effects. The length of close field is directly proportional to effective radiation area (ERA – see below) of the emitter head and inversely proportional to frequency. For example, the length of close field with 4 cm 1 MHz frequency is approximately 10 cm, and for the emitter head with 1 cm

ERA and 1 MHz frequency it is

approximately 2 cm.

Distant ultrasonic field is characterized by increasing beam divergence, gradual decrease of intensity, and almost no interferential effects.

Therapeutic effects take place mainly in the close field. The ultrasonic beam in the close field has significant interferential effects (interference of applied and reflected waves) - both constructive and destructive. It results in nonhomogenous ultrasonic beam where peak levels of intensity (local increase of intensity caused by constructive interference) may be many times higher than the pre-set value.

Beam Non-uniformity Ratio (BNR) states how many times the peaks of intensity exceed the pre-set values. This value characterizes an ultrasound head with a given frequency. The BNR value of a good quality ultrasound head is lower than 5. It means that if the pre-set intensity of the unit is 1 W/cm is not higher than 5 W/cm

, the intensity in any part of the ultrasonic beam

The BNR of older ultrasound heads and some newer ones (some manufacturers do not mention the BNR value) is often 20 or even more!

The Effective Radiating Area (ERA) is always smaller than the actual surface area of the emitter head (the ERA is determined by the size of the piezoelectric crystal or ceramic table that generates ultrasound by oscillating). The ultrasound dose (power emitted to a surface area) is, therefore, related to the ERA and not to the actual surface area of the emitter head.

The phenomena of ultrasound refraction and reflection are caused by ultrasound wave transmission from one tissue into another and by different transmission speed in these tissues. When applying ultrasound, it is necessary to eliminate the air gap between the emitter head and the skin. Therefore, modern ultrasound heads have built-in optic and/or acoustic check of insufficient contact, possibly with automatic termination of application time countdown.

ERA emitter head and

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ULTRASOUND THERAPY – USER'S GUIDE

Due to interference in the close ultrasound field (it reaches the highest level in the place of soft tissue/bone boundary up to 35%), ultrasonic beam power increases (constructive interference) or decreases (destructive interference).

In order to avoid tissue lesions at peak levels of intensity, it is necessary to move the emitter head continuously.

As a result of reflection and constructive interference, local increase in intensity and temperature may occur, particularly in the place of periosteum/bone boundary. This increase can lead to periosteum pain during ultrasound application. If this occurs, the intensity must be immediately lowered.

Ultrasound is primarily absorbed in deeper tissues. Since these tissues usually do not include thermoreceptors, it is impossible to perceive local rise in temperature. The patient feels pain only if the local temperature exceeds 45 nociceptive receptors are irritated. Most authors agree that a short-term rise in local temperature to 45

C and

C is not

dangerous.

In the area of classic inflammation (edema, erythema, local rise in temperature, pain or dysfunction) additional heat production is contraindicated, and thus only pulsed ultrasound (athermic) can be applied if necessary.

During peracute phase of post-traumatic conditions (up to 24-36 hours) the pulsed ultrasound application is contraindicated (vibrations hinder capillary proliferation and may cause delayed bleeding).

Local rise in temperature and micro-massage have several physiological effects:

• Improvement of local circulation and thus also metabolism. Rise in temperature enhances vasodilatation

(more evident in continuous ultrasound).

• Increase in capillary permeability and increased resorption of extravasation fluid.

• Improvement of local circulation and decrease in orthosympathetic activity resulting in significant muscle

relaxation.

• Decrease in local ischaemia pain.

• Transformation of gel into sol (due to transformation of fibrinogen into fibrin, haematomas and edemas change

into gel; ultrasound dissolves this gel and speeds up resorption). As the transformation of fibrinogen into fibrin is a basis of healing process (scar formation), it is not advisable to apply ultrasound for peracute post-traumatic conditions.

• Improvement of tissue regeneration capabilities as a result of the above-mentioned effects.

Ultrasound has also several non-therapeutic effects that can have negative impact, such as:

• Tissue lesion - Mechanic and/or thermic tissue lesion can occur when the intensity is too high. Especially

sensitive is the nervous system (peripheral nerve) situated right on the bone (interference!) below the surface (close field!). Impulse transmission speed in the corresponding nerve decelerates, then occurs total (reversible) impulse transmission blockage and finally irreversible disintegration of the neuron (myelin coats are preserved). Therefore be extremely cautious when applying ultrasound e.g. on paravertebral muscles after laminectomy when nerve structures lose their natural bone protection. Similarly, bone projections located just under the skin (ankles, epicondyles, spondyle spines, etc.) are also sensitive.

• Leukocyte mobility impairment – this can be minimized by sufficient movement of the emitter head.

• Other effects (mainly caused by overdosage) are: decrease in glycaemia, increased fatigue, nervousness,

changes in appetite, constipation, increased tendency to catch colds.

1.2 METHODS OF APPLICATION

1.2.1 According to Application Area and Movement of the Emitter Head

Static application - The head is fixed to the treated area by a special holder and it is not moved. Due to the

above-mentioned adverse effects it is the least suitable form of application.

Semistatic application - is used when the application area corresponds to the ERA of the emitter head. The therapist continuously moves the emitter head, in spiral along the perimeter of an imaginary circle.

Dynamic application - the application area is bigger than the ERA of the emitter head. The therapist moves the emitter head in spirals in the treatment area. The application time is prolonged proportionally according to how many times is the application area bigger than the ERA of the head.

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ULTRASOUND THERAPY – USER'S GUIDE

1.2.2 According to Application Area

Local application - Ultrasound is applied to the affected area. It is the most common way of application,

particularly suitable for local muscle spasms, chronic post-traumatic edemas, etc.

Segmental application - Ultrasound is applied to the outflows of nerve radices of the affected area (e.g. Sudeck syndrome, Morbus Reynauld, etc. The application is paravertebral and homolateral; in the area of C

- Th

for pathologies of upper limbs and in the L3 - S1 area for lower limbs.

Neural application - is based on the effect of decrease in impulse transmission speed in the peripheral nerve where ultrasound is applied. As the dividing line between the lowering of conductivity and irreversible nerve damage (asymptomatic) is very small, this method of application is considered dangerous, and it is used only exceptionally (e.g., phantom pain).

Radicular application - Ultrasound is applied subsequently to the corresponding spinal root and manifested Head zone. For application above the spinal root, the same risks and limitations apply as for neural application.

1.2.3 According to Contact Between Emitter Head and Body Surface

Direct contact - is provided by a contact medium (ultrasound gel). This is a common way of ultrasound

application, and it is not necessary to mention it in ultrasound therapy prescription. For combined therapy (ultrasound + electrotherapy) it is recommended to write "conductive gel" in the prescription because some gels do not conduct electricity. The BTL ultrasound gel is conductive; if this gel is not available you can use ECG gel or another water-based gel instead. However, never use paraffin oil, because it is non-conductive and could damage the head.

Subaqual application. This method has a range of advantages: It uses mainly the distant ultrasound field where interference does not occur. Furthermore, there is no need to press the emitter head against the skin in order to maintain sufficient contact (this pressure is unpleasant or even painful for post-traumatic conditions). In addition, this application is not limited by uneven surfaces, and ultrasound can be easily applied to these surfaces, such as to interphalangeal joints.

Disadvantages of subaqual application include difficult handling of a special porcelain bath, limitation of ultrasound application to acral body parts, and the risk of the therapist's hand lesions if the hand is put in water. (It is strictly prohibited due to reflection and interference of ultrasonic waves against walls of the porcelain bath!) Some emitter heads (even newer) are claimed to be water resistant, but if they do not have a holder, they do not provide safe subaqual ultrasound application.

Ultrasound can be also applied via a thin-walled rubber bag (surgical gloves, condom) filled with boiled water. However, when using this method, it is necessary to eliminate the air gap between the bag and skin (use gel) and between the emitter head and the bag. This method is often perceived as very time-consuming.

1.3 ULTRASOUND FREQUENCY

Older ultrasound units employ a fixed frequency, usually 0.8 – 1 MHz. Newer ones are multifrequency units, the selected frequency is determined by the target tissue; 1 MHz frequency is used for deep tissues and 3 MHz frequency for superficial tissues.

1.4 MODES OF OPERATION

a) continuous - It is characterized by heat generated deeply in tissues. It is contraindicated in inflamed areas

and everywhere else where local warming is undesirable.

b) pulsed - together with shortening of pulse length there occurs decrease in so called Duty factor. As a result,

thermic effect is suppressed and when Duty factor is below 12.5% (1:8), athermic effect can be expected.

Duty factor (DF) can be set in pulsed mode of operation. Its value states for how many percent of the period duration the ultrasound signal is being generated. When setting therapy parameters of BTL units, the ratio of ultrasound signal duration to the period length is stated in brackets. This ratio is used in parameters of recommended ultrasound therapies of BTL units. In case of continuous setting of the parameter, only the percentage expression is used.

Example:

Duty factor 25% (1:4) means that 25% (1/4) of the period is ultrasound and the rest of the period is pause.

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