metron

Metron Medical Australia Pty LtdA.C.N.050 240 527

P.O. Box 2164, 57 Aster Avenue

Carrum Downs Victoria Australia 3201Tel: (03) 9775 1234 Fax: (03) 9775 1990Int: 61 3 9775 1234 Int: 61 3 9775 1990

OPERATING MANUAL

METRON VECTORSURGE 5

COMBINED INTERFERENTIAL&

TNS ELECTROTHERAPY UNIT

MODEL VS-470

Prepared byMetron Medical Australia P/L

Version 1V5 SEPTEMBER 2011

Metron ____________ Vectorsurge 5

WARRANTY STATEMENT

Metron Medical Australia Pty Ltd., will warrant this device/instrument/appliance (excluding accessories) against defects in manufacture for a period of two years from the date of purchase.

Accessories including patient leads, cables and electrodes will be covered under this warranty for a period of three months from the date of purchase.

- PROVIDING -

The instrument has not been serviced by persons not authorised by Metron MedicalAustralia Pty Ltd., and has not been misused or tampered with and has been used on the correct voltage as branded on it.

- THIS WARRANTY EXCLUDES -

Parts of the device/instrument/appliance failure of which in the opinion of the dealer or manufacturer is a result of misuses or abuse or any other reason not directly attributed to fault in manufacture. Batteries are excluded from this warranty except where it can be demonstrated that any battery failure was caused by a malfunction in the Metron equipment. This warranty also excludes glass or ceramic portions.

- IN THE EVENT OF FAILURE -

The complete device/instrument/appliance should be returned to the dealer from which it was purchased or to the nearest authorised service agent, together with a full report, freight paid and insured.

- UNDER NO CIRCUMSTANCES -

Shall Metron Medical Australia Pty Ltd., or their agents or dealers be liable in any manner whatsoever for any compensation or damages to any person occasioned by this device/instrument/appliance for any loss, injury or any damage occasioned by or as a result of the misuse or abuse of this device/instrument/appliance.

- LOSS IN TRANSIT -

The warrantor does not accept any responsibility for loss or damage to the device/instrument/appliance in transit.

Any express or applied conditions, statements or warranty, statutory or otherwise (save specifically provided above) is hereby excluded.

____________________________________________________________Version: 1V5 September 2011

Metron _____________ Vectorsurge 5

CONTENTS

Section Page

1. Specifications ............................................................................................................... 1

2. Operational Information................................................................................................. 62.1 Electromagnetic Interference ...........................................................................62.2 Inflammable Gases and Anaesthetics ............................................................62.3 Prevention of Cross Infection ......................................................................... 62.4 Damage to the Therapy Device .................................................................... 62.5 Correct Mains Voltage .................................................................................... 6

3. Introduction ....................................................................................................................73.1 General ............................................................................................................. 73.2 Quality Assurance ............................................................................................8

4. General Features ......................................................................................................... 94.1 General ............................................................................................................. 94.2 Function of the Controls and Displays .........................................................10

4.2.1 Patient Circuits .................................................................................. 104.2.2 Current Intensity ............................................................................... 104.2.3 Targeting the Desired Treatment Area.............................................104.2.4 Surged Output .................................................................................114.2.5 The Treatment Timer ........................................................................114.2.6 Bipolar and Quadripolar ...................................................................124.2.7 Dual Operation ................................................................................. 134.2.8 “FOCUS” Button and Vector Rotation .......................................... 144.2.9 Current Monitoring ............................................................................144.2.10 “STOP” Button .................................................................................144.2.11 Output Selection (A/B) Button ....................................................... 154.2.12 Using Stored Programs; “PROGRAM” Button ............................154.2.13 Storing Own Programs: “PROGRAM” Button .............................164.2.14 Prestored Programs .........................................................................16

4.3 Prestored Programs ......................................................................................174.4 Practitioner Stored Programs ........................................................................18

5. Operating Procedures ...............................................................................................215.1 General ...........................................................................................................215.2 Use of Stored Programs .............................................................................. 215.3 2 Pole Treatment ...........................................................................................215.4 Dual Stimulator Mode ................................................................................... 225.5 Storing Programs ...........................................................................................235.6 Electrodes ...................................................................................................... 235.7 Electrode Use/Preparation ........................................................................... 245.8 Suction Electrodes .........................................................................................245.9 Using the Vectorsurge in Dual Mode .......................................................... 245.10 Monitoring, Adjusting and Terminating Output Current ..............................25



CONTENTS

Section Page

6 Conventional Interferential Therapy .........................................................................26

6.1 Operational Information .................................................................................266.1.1 Indications For Use For Interferential Therapy ...............................266.1.2 Contraindications .............................................................................. 266.1.3 Therapeutic Warnings ......................................................................266.1.4 Precautions ........................................................................................276.1.5 Adverse Reactions ..........................................................................27

6.2 Operating Procedures ...................................................................................286.2.1 Interferential Beat Frequency Selection ......................................... 286.2.2 Interferential Carrier Frequency Selection ...................................... 286.2.3 Applying Interferential Therapy ......................................................29

7 TNS Therapy .............................................................................................................32

7.1 Operational Information .................................................................................327.1.1 Indications For Use For TNS Therapy ...........................................327.1.2 Contraindications .............................................................................. 327.1.3 Therapeutic Warnings ......................................................................327.1.4 Precautions ........................................................................................337.1.5 Adverse Reactions ..........................................................................33

7.2 Operating Procedures ...................................................................................337.2.1 TNS Stimulation Frequency Selection ...........................................337.2.2 TNS Pulse Width Selection ............................................................337.2.3 Applying Interferential TNS ............................................................ 34

8. Electrotherapy ............................................................................................................37

8.1 Conventional Interferential Therapy .............................................................378.1.1 Introduction ........................................................................................378.1.2 Depth Efficiency ............................................................................... 378.1.3 Vector Rotation .................................................................................378.1.4 Surging ..............................................................................................388.1.5 Beat Frequencies .............................................................................398.1.6 Carrier Frequencies ..........................................................................408.1.7 Phase Switching ...............................................................................42

8.2 Conventional TNS Therapy .........................................................................438.2.1 General ..............................................................................................438.2.2 Effect of Pulse Width ....................................................................... 448.2.3 Effect of Pulse Frequency ............................................................... 45

8.3 Interferential TNS Therapy ........................................................................... 48

8.3.1 Obtaining a TNS Interferential Effect .............................................. 488.3.2 Using Interferential TNS Therapy ...................................................49

8.3.2.1 Energy Considerations ................................................... 508.3.2.2 Physiological Responses ...............................................50

9. References ...51

Declaration of Confromity ............................................................................. 52Authorised Representative ..........................................................................53


1. SPECIFICATIONS

MAINS POWER SUPPLY REQUIREMENTS:

Voltage 90 - 264 Volts ACFrequency 50/60 HzPower 75 VA Nominal

FUSES:

Primary External 2 of 1 A 5x20 mm Delay

Secondary 1 of 4 A 5x20 mm Delay

MAINS TRANSFORMER:

Integrated switchmode power supply complying with international standard IEC 601-1: 1988 (EN 60601-1) and all subsequent amendments.

Secondary voltages 48 Volts @ 1.7A

OUTPUT SPECIFICATION - INTERFERENTIAL:

Maximum current in each patient circuit 80 mAIndicator resolution 1 Segment = 4 mAIndicator accuracy +/- 10% for currents greater than 10 mAMaximum voltage in each patient circuit 160 V peak-to-peakCurrent Surge Programmes Disabled or Enabled

Enabled Rise 0 - 20 secondsOn 0 - 40 secondsFall 0 - 20 secondsOff 0 - 40 seconds

Waveform Beat FrequenciesPreset Ranges 0 - 15 Hz

0 - 150 Hz80 - 150 Hz

Adjustable Range 0 - 300 HzCurrent Waveform Type Modulated Rectangular, 50% Duty Cycle Waveform Pulse Frequencies 2.5, 4 or 10 kHzFrequency accuracy Better than +/- 1%Waveform Pulse Widths 50, 125 or 200 µs

Current Delivery Modes 2 Pole (Amplitude Modulated) or 4 Pole (Phase Modulated)

OUTPUT SPECIFICATION - TNS:

Maximum current in each patient circuit 80 mAIndicator resolution 1 Segment = 4 mAIndicator accuracy +/- 10% for currents greater than 10 mAMaximum voltage in each patient circuit 160 V peak-to-peak


____________________________________________________________________Version: 1V5 September 2011 Page 1 of 47

Current Waveform Type Modulated Rectangular, 50% Duty CyclePulse Shape BiphasicWaveform Pulse Widths 50, 125 or 200 µsPulses per Burst 1Pulse Frequencies

Preset Ranges 0 - 15 Hz0 - 150 Hz80 - 150 Hz

Adjustable Range 0 - 300 HzCurrent Surge Programmes Disabled or Enabled

Enabled Rise 0 - 20 secondsOn 0 - 40 secondsFall 0 - 20 secondsOff 0 - 40 seconds

Frequency accuracy Better than +/- 1%

TIMER:

Operating range 0 - 40 minutesTimer accuracy Better than +/- 1%

CURRENT LIMIT AND ALARM FEATURE SPECIFICATION:

Stimulator types Interferential and TNS

Meter peak reference current enable level Current set > 12.5% of full scale

Output current limit activates when Output current > 95% of full scale orOutput current > Meter peak reference

Output current alarm activates when Output current/Surge factor < 1/2 Peak current and Modulation frequency > 5 Hz

ELECTRICAL SAFETY:

Manufactured to Australian standards:

AS 3200.1 - 1990 Approval and test specification - Electromedical equipment - General requirements (direct equivalent of IEC 601-1, 1988, Second edition).

IEC 601-2-10 - 1987 Medical Electrical Equipment, Partr 2: Particular requirements for the safety of nerve and muscle stimulators.

Applied parts Patient Connections

Applied part classification BF

Chassis classification

1



DIMENSIONS:

Width 370 mmHeight 120 mmDepth 250 mm

WEIGHT:

Packed 3.5 kgUnpacked 2.5 kg

ENVIRONMENTAL CONDITIONS:

Operating: Temperature Range 10 - 40 oCRelative Humidity 30% - 90%

Transport & Storage: Temperature Range 0 - 70 oCRelative Humidity 10% - 100%



OUTPUT WAVEFORMS:

Conventional Interferential

Output: 40 mA Load : 500 Ohms Vertical Scale : 20 V/Div Horizontal Scale : 320 us/Div (2.5 KHz), 100 us/Div (4 KHz), 80 us/Div (10 KHz)

Premodulated Interferential

Output: 40 mA Load : 500 Ohms Vertical Scale : 20 V/Div Horizontal Scale : 320 us/Div (2.5 KHz), 100 us/Div (4 KHz), 80 us/Div (10 KHz)



Russian

Output: 40 mA Load : 500 Ohms Vertical Scale : 20 V/Div Horizontal Scale : 400 us/Div Modulation Frequency: 50 Hz

TNS

Output: 30 mA Load : 500 Ohms Vertical Scale : 10 V/Div Pulse Width : 200 us Pulse Frequency : 120 Hz Horizontal Scale : 2 ms/Div



2. OPERATIONAL INFORMATION

2.1 Electromagnetic Interference

The Vectorsurge 5 complies with IEC 601-1-2: 1993 but this does not guarantee that other equipment in the vicinity will not be affected by the electromagnetic emissions from this unit. Similarly, other equipment in the vicinity may effect the operation of the Vectorsurge 5.

It is recommended that all equipment used near this unit complies with the relevant electromagnetic compatibility requirements for that equipment and to check before use that no interference is evident or disruptive. Increasing the distance between offending devices, and keeping interconnecting leads as short as possible will help reduce the effect.

2.2 Inflammable Gases and Anaesthetics

The Vectorsurge 5 is NOT SUITABLE for use in the presence of inflammable gases and anaesthetics.

2.3 Prevention of Cross Infection

Even though the patient electrodes do not contact open wounds or broken skin it is still possible for them to carry infections by the mere fact that they contact bare skin.

The electrodes should be thoroughly cleaned after a treatment session with one patient is completed prior to a new session beginning with another patient. They can be cleaned with any standard medical grade surface disinfectant. The electrodes are not suitable for autoclaving.

2.4 Damage to the Therapy Device

If when the unit is unpacked, or if it is mishandled at any stage of its life, and there appears to be physical damage to the machine it should not be used. Use should only commence or continue after it has been thoroughly checked by an appropriately qualified technician to ensure its functional and safety performance has not been impaired.

2.5 Correct Mains Supply Voltage

It is important that the Vectorsurge 5 be operated from a mains supply which has a nominal supply voltage equal to that indicated on the label on the Vectorsurge 5 rear panel. Safety and performance specifications are only valid if these voltages are the same.



3. INTRODUCTION

3.1 General

The Vectorsurge 5 combined interferential and TNS therapy unit is the most advanced of its kind and offers special features not found on other machines. Unlike most other machines, the interferential currents available from the Vectorsurge can be selected for both beat frequency and carrier frequency. It is the carrier frequency which sets the discrimination between sensory, motor and pain thresholds. It is the beat frequency which determines the physiological response to stimulation - whether twitch muscle contractions, a forceful tetanic contraction or analgesia and muscle relaxation.

The Vectorsurge also functions as a dual stimulator and as an interferential TNS unit. In dual mode, the Vectorsurge acts as two independent stimulators. In interferential TNS mode, short-duration biphasic TNS pulses can be applied with the depth efficiency of conventional interferential stimulation.

This manual describes the use of interferential therapy, conventional TNS and interferential TNS. It also describes technical aspects of the Vectorsurge and how to use the Vectorsurge 5 unit. Please read the manual carefully before using the machine.

The manual is not intended as a substitute for textbooks on the subject of interferential therapy (some are listed as references at the end of the manual). Rather it is a guide to safe and proper usage for those familiar with the techniques, principles and uses of interferential therapy.

As with any electrotherapeutic modality, interferential currents should only be applied by therapists who are qualified practitioners and who are familiar with appropriate settings of the machine controls.

If you, as a user of the Vectorsurge 5 and this manual, have any relevant comments or questions, on either the equipment or the manual, your communication with us would be welcomed. You may contact us by mail or fax as detailed below:

Metron Medical Australia Pty LtdP.O. Box 2164CARRUM DOWNS AUSTRALIA 3201

Fax: (03) 9775 1990 from within Australia or+61 3 9775 1990 International



3.2 Quality Assurance

It is recommended that a program of regular and appropriate quality assurance, including calibration and electrical safety inspections, be instituted for this equipment. It is recommended that calibration of this equipment be performed at least once every twelve months. Information on the type and frequency of electrical safety testing may be obtained from Australian Standard AS 3551 (1988) - Acceptance and In-Service Testing, Electromedical Equipment or from relevant locally published Standards.

A hospital Biomedical Engineering Department or a third party service organisation nominated by the manufacturer or distributor should be capable of performing the necessary calibration, testing and documentation. A program of electrical safety inspections is recommended to confirm continued operator and patient safety. Local statutory requirements for electrical safety inspections may also apply.



4. GENERAL FEATURES

4.1 General

The Metron Vectorsurge 5 is a combined interferential therapy unit which offers four modes of stimulation: conventional interferential and interferential TNS; bipolar interferential, bipolar TNS and Russian. Conventional and bipolar (premodulated) interferential need no introduction and they are available at the touch of a button. Conventional (bipolar) TNS is also selectable, either in single or dual channel mode. Russian stimulation is likewise a well accepted stimulation mode. Interferential TNS is something new. Now you have TNS stimulation which can be focussed between four electrodes to target the region of maximum stimulation. These treatment options are described in the 'background information' section of this manual (page 37).

The Vectorsurge 5 carries on the tradition of its predecessors. It is a lightweight, portable machine designed for simplicity and reliability of operation. It uses the latest microprocessor technology and incorporates sophisticated programming to anticipate your needs and guarantee performance.

The Vectorsurge dispenses with the multiplicity of knobs and switches used on conventional interferential therapy units. Instead a single rotary control and four pushbuttons are used to choose the treatment; either by selecting from ten stored treatment programs or by manually setting all the treatment variables in a simple and straightforward manner.

The diagram below shows the arrangement of controls and displays on the front panel.



4.2 Functions of the Controls and Displays

4.2.1 Patient C ircuits

On the right hand side of the front panel is a bar graph display which shows the output current delivered to the patient. In 4 POLE mode the display shows the average current for the two pairs of electrodes. In 2 POLE mode if output display “a” is selected then the display shows the channel “a” output current. Likewise for “b”. In DUAL mode, both outputs “a” and “b” are active and the “output selection ” button can be pressed to separately show the current in each channel.

Current may be applied to the patient either via the two pairs of patient-circuit output sockets on the front of the machine or via a socket on the rear. Standard electrode configurations (quadripolar, paired bipolar) can be connected to the separate channel “a” and “b ” output sockets on the lower front panel. Alternatively the output may be connected through the rear socket to a Metron Vacupulse suction unit for simple and rapid electrode placement.

The patient circuits are designed to meet the requirements of apparatus with class BF patient protection as specified in Standards Association of Australia publications AS 3200-1 and in International Electrotechnical Commission Standard IEC 601-1.

Note Several symbols are used on the lower front panel which are defined asfollows:

This symbol indicates that the instructions for use should beconsulted before operation is attempted.

This symbol indicates that the applied parts (patient connections) of this equipment are rated as Type “BF” which means that the patient connections are suitable for placement on the external surface of the body.

4.2.2 Current Intensity

The current intensity is set by pressing the “start-focus ” button (located on the right hand side of the front panel) and adjusting the "intensity-set " control. The amount of current in the patient circuits is indicated on the bar graph display.

In 4 POLE mode, the output meter shows the average current in the two patient circuits. In DUAL mode, the “output display ” button can be pressed to switch between the two outputs and monitor the current in each circuit.

4.2.3 Targeting the Desired Treatment Area

In 4 POLE mode, the focus of the pattern of stimulation can be shifted by vector rotation (see the 'background information' section, page 37). The clover-leaf stimulation pattern is rotated by holding the "start-focus " button depressed and

adjusting the " intensity-set " control. This will enable the practitioner to target the desired treatment area. This feature can also be used to equalize the sensation under the electrodes. If the patient feels more stimulation from one electrode pair, for example due to electrode placement or variations in tissue impedance, the variation can be compensated by holding the "start-focus " button depressed and rotating the "intensity-set " control.



4.2.4 Surged Output

Current may be applied to the patient either in continuous mode or surged mode.

When the SURGE is off, the output intensity is held at a constant level. When the SURGE is on, the current intensity changes rhythmically at a rate selected by the operator. The output current display shows the current variation during the surge cycle and also has a flashing marker, indicating the maximum current to be reached during the surge cycle. Complete flexibility in surging is available as the surge rise time, on time, fall time and off time can each be set independently with the time display showing the values chosen.

A bar graph display next to the surge time indicators is used both to show the surge cycle and to show whether surging is on or off. This display actively cycles when surging is on and is constantly illuminated to maximum when surging is off. During surged intensity treatment, the bar graph display always ranges from zero to maximum, regardless of the selected output intensity. This makes it easy to follow the surge cycle, even at very low output intensities when the OUTPUT current meter would be difficult to use for this purpose.

A further important safety feature is that the peak intensity during the surge cycle is the same as obtained in continuous mode i.e. when the SURGE is off. When surging is being used, the cycle will not begin until after the intensity has been set to the maximum value required. This means that the intensity can be set with confidence that it will not surge to higher currents as would occur if the intensity was increased during the cycle when the intensity was not at maximum. If the output current is adjusted during treatment, surging stops and holds at peak while the adjustment is made. A few seconds after adjustment is completed, surging automatically resumes with a flashing marker showing the peak intensity which has been set.

4.2.5 Treatment Timer

The treatment timer is located immediately above the SURGE setting indicators.

When first switched on, the treatment time display will show the treatment time stored in program 0, together with the treatment settings stored in this program. You can store your most frequently used treatment settings as program 0 so that they are immediately available at switch-on and no manual setting is required (see pages 15 and 16).

The treatment time can be changed by pressing the “set-pause ” button until the TREATMENT (min) indicator is flashing and then rotating the "intensity-set " control. Clockwise rotation will increase the treatment time. Rotating the "intensity-set " control anticlockwise will decrease the treatment time.

Once the “start-focus ” button is pressed, patient output can be set and timing begins. The timer will count down and terminate the patient current when the selected time has elapsed. Treat can also be paused with the “set-pause ” button : if the treatment is paused by pressing this button, the timer stops and does not continue until the “start-focus ” button has been pressed again and current is reapplied to the patient.

The end of the treatment period is indicated by a clearly audible signal.

4.2.6 Bipolar and Quadripolar Operation

In order to obtain a true interferential effect and greatest depth efficiency in treatment it is necessary to use two pairs of electrodes positioned so that the currents flowing between each pair interfere within the tissue volume being treated (see background information, page 37). This is described as quadripolar treatment and for this it is necessary to set the 4 POLE/2 POLE/DUAL selector to 4 POLE. When used in this



mode, minimum stimulation is produced immediately beneath the electrodes. The machine is operating in conventional interferential mode and maximum stimulation is produced in a clover-leaf shaped pattern centred at the intersection of the current pathways (figure 1, page 37). The production of maximum stimulation at depth has always been a major advantage of interferential currents. For true interferential treatment, first INTERFERENTIAL then 4 POLE should be selected.

By using electrically isolated patient circuits, the Vectorsurge 5 is also able to produce interferential TNS i.e. stimulation in a clover-leaf shaped pattern centred at the intersection of the current pathways but using biphasic TNS pulses rather than bursts of interferential current. In this way, the advantages of conventional TNS can be combined with the depth efficiency of interferential currents and it also has the ability to move and focus the region of maximum stimulation by vector rotation. Selecting TNS then 4 POLE allows this option.

In some circumstances it may be convenient to use just two electrodes for bipolar stimulation: depth efficiency may be a secondary consideration. In these cases the 4 POLE/2 POLE/DUAL selector should be set to either 2 POLE or DUAL. When interferential mode is selected together with 2 POLE or DUAL, the two interferential currents are mixed within the machine and a beat frequency signal is sent to the output. In 2 POLE mode, the signal appears on channel A.

It should be noted that in 2 POLE (or DUAL) mode, different size electrodes can be used i.e. a large 'indifferent' electrode and a smaller 'active' electrode positioned over the motor point or area to be treated. If a smaller active electrode is used consideration of current and power density for that electrode should be considered prior to use. The maximum power density recommended is 0.25 watts/square cm (W/cm2) of electrode area.

If the worst case patient impedance, for power transfer, is assumed then for a round electrode the maximum current that should be used, in milliamps, approximately equates to:

Imax = 14 x Electrode Diameter in cm

4.2.7 Dual Operation

When DUAL mode is selected, the Vectorsurge functions as two completely separate bipolar stimulators. For example, the output of one channel can be 50 Hz TNS pulses, surged over a 30 second cycle time and a treatment time of 20 minutes while the other channel is bipolar interferential with a frequency sweep from 0-15 Hz, not surged and a treatment time of 15 minutes.

In DUAL mode, the treatment settings for each channel are independent and are chosen separately. Once DUAL mode has been selected the “set-pause ” button is pressed to step through treatment settings for channel “a”. Once this is completed, the “output display ” button is pressed to allow choice of the channel “b” settings.

After the treatment parameters for both channels have been set, the “start-focus ” button is pressed. The output display selection indicator will have “b” illuminated and the "intensity-set " control can be rotated to set the output current in channel “b”. Next the “output display ” button is pressed to select channel “a” and the channel “a” intensity is set by rotating the "intensity-set " control.

Alternatively, the machine can be operated in DUAL mode with one channel only used initially. Channel “a” settings can be chosen and the “start-focus ” button can be pressed to set the output current. At any time during treatment using channel “a”, the “output display ” button can be pressed to select channel “b ”. The treatment



parameters and treatment time can be set and the current applied in channel “b ” by pressing the “start-focus ” button and setting the stimulation intensity. Channel “a” operates independently and current ceases at the end of the channel “a” preselected treatment time.

During treatment, the “output display ” button can be pressed to monitor the current in each channel. If any adjustment is needed, the "intensity-set " control can be rotated to increase or decrease the current in the selected channel. Do not press “set-pause ” or “STOP” for this adjustment. Pressing “set-pause ” will reduce the output current in the selected channel to zero, but will not affect the other channel. If “set-pause ” has been pressed, pressing “start-focus ” will allow you to reset the current in the selected channel. Pressing “STOP” will terminate the flow of current in both channels and to resume treatment the particular channel must be selected (by pressing the “output selection ” button) followed by pressing the “start-focus ” button to enable current to be applied and then by rotating the "intensity-set " control.

If you wish to simultaneously switch-off the current in both channels, simply press the “STOP” button below the output intensity display. The “STOP” button is the master 'output off' control. To switch off the current in one channel, select the

particular channel (using the “output selection ” control) then press the “set-pause ” button.

If DUAL mode is in use, to switch from DUAL mode to 2 pole or 4 pole treatment you have to first switch off the current in both circuits. Press “STOP” to do this, then select 2 pole or 4 pole treatment.

4.2.8 'FOCUS' Button and Vector Rotation

When 4 POLE mode is selected, either conventional interferential or interferential TNS can be selected. In either case, four electrodes are applied and the stimulation pattern produced depends on the vector sum of the two applied currents. Because of this, the regions of maximum stimulation are in the form of a 'clover-leaf' shaped pattern centred at the intersection of the current pathways (see the 'background information' section of this manual, page 37).

The clover-leaf stimulation pattern can be manually rotated by increasing the current in one channel and simultaneously decreasing the current in the other. In this way it is possible to move and focus the region of maximum stimulation by vector rotation.

To rotate the vector field and so change the focus of stimulation, press and hold down the "start-focus " button then rotate the " intensity-set " control in either direction to rotate the vector field. The "start-focus " button must be held depressed during this rotation. Once the "start-focus " button is released, the " intensity-set " control reverts to controlling the output intensity.

4.2.9 Current Monitoring

Another important safety feature of the Vectorsurge is the provision of 'intelligent current monitoring' on the output circuits. Once the output intensity has been set, the Vectorsurge monitors the output current in each circuit and, if the current in either channel changes by more than a calculated amount, an alarm sounds and the current intensity is reduced to zero. Thus if an electrode becomes detached, or loosens and does not make adequate skin contact, the alarm will be activated. It is, however, normal for the current to change slightly during treatment (this can come about through changing tissue impedance due to increased blood flow in the region, perspiration, etc.) and is likely to affect both channels to a similar extent. Such changes are ignored so as to minimize 'nuisance' interruptions to patient treatment.

Bad electrode contact is thought to be the reason for relatively rare but nonetheless



serious reports of 'burns' or skin irritation as a result of transcutaneous electrical nerve stimulation. The provision of intelligent current monitoring, together with the automatic alarm, minimizes the risk of skin irritation or damage.

4.2.10 “STOP” Button

The “STOP” button, located immediately below the output current display, is the quick and easy method of terminating current flow from the patient circuits.

Pressing “STOP” will terminate the current from channels A and B regardless of whether the Vectorsurge is being used in quadripolar, bipolar or dual stimulator mode. It is the master 'off' control.

In DUAL mode, it is possible to stop the current output of just one channel without affecting the other by first selecting the channel using the A/B selector button, then pressing the “set-pause ” button. This will stop current flow in the selected channel. In 4 POLE mode, pressing “set-pause ” will terminate current flow in both channels.

4.2.11 Output Selection (a/b) Button

When DUAL output is selected, both channel “a” and channel “b” are activated and the output intensity of each channel can be set separately. In DUAL mode, the channel “a” treatment parameters are set first and channel “a” is indicated on the output display. The output intensity of channel “a” can be set when the channel “a” indicator is illuminated by pressing “start-focus ” and then rotating the " intensity-set " control until the desired current level is reached. To set channel “b”, press the “output selection ” button and the 'b' indicator will be illuminated. Next press the “start-focus ” button and rotate the "intensity-set " control until the desired current level in channel “b” is reached. To switch between channels “a” and “b“ : subsequently and adjust the intensity, it is only necessary to press the “output selection ” button to chose the desired channel then rotate the "intensity-set " control.

4.2.12 Using Stored Programs: “PROGRAM” Button

The “program ” button of the Vectorsurge 5 is a powerful feature. Ten treatment programs are stored in the Vectorsurge for immediate recall. The Vectorsurge comes with a set of preinstalled programs, but you can tailor these to suit your needs and create a set of preferred treatment programs for immediate selection. The programs are numbered 0 to 9. The settings in program 0 are the ones which automatically appear when the Vectorsurge is switched on. If you have a particularprogram which you use most frequently, this should be stored as program 0. This means that if this program is to be used, all you need to do is to switch on the machine, press “start-focus ” and adjust the output current to the desired intensity.

If you want to use a different prestored program, this can be selected using the “program ” button. First switch on the machine. Next press the “program ” button to tell the Vectorsurge that you want to recall a preset program. Program 0 will be automatically selected. The TIMER/PROGRAM display will flash between "P0" and the preprogrammed (program 0) treatment time while the treatment settings shown on the displays (surge, sweep range, frequency, etc.) will be those stored in program 0. To select one of programs 1 to 9, simply rotate the " intensity-set " control and the TIMER/PROGRAM display will show "P1", "P2" and so on, up to "P9". In each case the settings shown on the displays (the timer, surge, sweep range and frequency controls etc.) will be those in the stored program. Once the desired program has been selected, simply press the “start-focus ” button and rotate the "intensity-set " control to set the output intensity. If a 2 POLE program has been selected, this will set the channel A intensity.

To recall two programs for DUAL stimulation, first select DUAL output then press the



“program ” button to select the channel A settings. Next press the “output selection ” button to select channel “b” then press the “program ” button to select the program you want for channel “b”. Press “start-focus ” then rotate the " intensity-set " control to set the output intensity of channel “b”. Next press the “output selection ” button to select channel “a”, press “start-focus ” then rotate the "intensity-set " control to set the output intensity of channel “a”.

4.2.13 Storing Your Own Programs: “PROGRAM” Button

The “program ” button of the Vectorsurge 5 is a powerful feature. Ten treatment programs are factory provided and stored for instant recall. Should you wish to change or replace any of these programs and customize the Vectorsurge to your own needs, you have this option.

To store your own treatment program, first set the treatment parameters to those you want, either by manually stepping through each of the treatment settings using the “set-pause ” button and the "intensity-set " control or by selecting a preset program then using the “set-pause ” button and the "intensity-set " control to change particular settings. After setting the Vectorsurge, the treatment parameters can be stored by pressing the “program ” button. When the “program ” button is pressed, "P 0" will appear on the TIMER/PROGRAM display. If you wish to store the program as program 0, the one which automatically appears when the Vectorsurge is switched-on, press the “program ” button again and it will be stored as program 0. The Vectorsurge beeps twice to indicate that the program has been stored. If you wish to store the program under some other number between 1 and 9, rotate the " intensity-set " control to change the program number to the one you want then press the “program ” button again. A double beep indicates that the program has been stored.

4.2.14 Prestored Programs

The Vectorsurge 5 stores ten treatment programs in memory. A set of programs is preinstalled but, as described above, you can change any of these to create your own personal set of programs. We recommend that the program which you use the most is stored as program 0 as this is the one which is automatically selected when the Vectorsurge is switched on. To treat a patient using program 0, once the patient has been prepared and the electrodes secured, simply switch on the Vectorsurge, press”start-focus ” then adjust the output intensity by rotating the "intensity-set " control. To select a different prestored program, after switching on the Vectorsurge, press the “program ” button and rotate the " intensity-set " control to select the desired treatment program. As the " intensity-set " control is rotated, the programs are displayed and the treatment settings for each are shown on the Vectorsurge displays.

The ten factory prestored programs are listed following. If you change one or more of the stored programs, you can make your own ready-reference list of stored programs using the proforma on pages 18 to 20.



4.3 PRESTORED PROGRAMS

____________________________________________________________________

PROGRAM 0 4 pole interferential

treatment time: 15 min carrier frequency: 4 kHzsweep range: 0 - 150 Hz surging: none

____________________________________________________________________



____________________________________________________________________



____________________________________________________________


treatment time: 15 min carrier frequency: 2.5 kHzsweep range: fixed 30 Hzsurging: rise time: 1 sec on time: 2 sec

fall time: 0 sec off time: 1 sec____________________________________________________________________


treatment time: 15 min carrier frequency: 2.5 kHzsweep range: 0 - 30 Hz surging: none

____________________________________________________________________

PROGRAM 5 russian stimulation/bipolar interferential

treatment time: 15 min carrier frequency: 2.5 kHzsweep range: fixed 50 Hzsurging: rise time: 2 sec on time: 0 sec

fall time: 0 sec off time: 0 sec

____________________________________________________________________

PROGRAM 6 russian stimulation/bipolar interferential

treatment time: 15 min carrier frequency: 4 kHzsweep range: fixed 30 Hzsurging: rise time: 2 sec on time: 5 sec

fall time: 1 sec off time: 12 sec____________________________________________________________________

PROGRAM 7 4 pole TNS (interferential TNS)



treatment time: 15 min pulse width: 50 us (carrier = 10 kHz)sweep range: 80-150 Hz surging: none

____________________________________________________________


treatment time: 15 min pulse width: 125 us (carrier = 4kHz)sweep range: fixed 30 Hzsurging: rise time: 2 sec on time: 1 sec

fall time: 0 sec off time: 0 sec

____________________________________________________________________


treatment time: 15 min pulse width: 50 us (carrier = 10 kHz)sweep range: 80-150 Hz surging: none

____________________________________________________________________ 4.4 Practitioner Stored Programs

Circle as applicable or record the treatment setting in the space provided.

PROGRAM ___ ________________________________

4 pole / 2 pole interferential / TNS treatment time: _______ minsurging: on / none sweep range: ________ Hzcarrier frequency: ___ kHzsurging: rise time: _____ sec on time: _____ sec

fall time: _____ sec off time: _____ secNotes:

____________________________________________________________________

PROGRAM ___ ________________________________



____________________________________________________________________

PROGRAM ___ ________________________________

4 pole / 2 pole interferential / TNS treatment time: _______ minsurging: on / none sweep range: ________ Hzcarrier frequency: ___ kHz



surging: rise time: _____ sec on time: _____ secfall time: _____ sec off time: _____ sec

Notes:

____________________________________________________________________

PROGRAM ___ ________________________________



____________________________________________________________________

PROGRAM ___ ________________________________



PROGRAM ___ ________________________________



____________________________________________________________________

PROGRAM ___ ________________________________





____________________________________________________________________

PROGRAM ___ ________________________________



____________________________________________________________________

Note: that if you wish to revert to the original factory-stored programs (and erase your prestored programs), this can be achieved as follows. Switch off the Vectorsurge. Hold down the “program ” button and switch on the machine. A long beep indicates that the factory preset programs have been reinstalled. Release the “program ” button.



5. OPERATING PROCEDURES

5.1 General

Step by step sets of instructions for operating the Vectorsurge 5 are given on this and the following pages. It is recommended that you read these instructions carefully to completely familiarize yourself with the detailed features of operation of the unit.

5.2 Use of Stored Programs

With the Vectorsurge 5, you have the option of automatic selection of preset programs. These can be the set provided with the Vectorsurge or your own customized set which can be changed, at any time, should you wish. The treatment settings for each program can be viewed simply by selecting the program. Settings will be shown on the displays on the front panel. Simply switch on the Vectorsurge and step between programs by pressing the “program ” button to inspect the settings in each.

Here are the steps in a little more detail:

1. Plug the apparatus into the mains and switch on the power. The default settings on power up are the treatment settings stored in program 0. The output indicator will be flashing, showing conventional interferential or TNS mode. The other indicators will show the particular treatment settings.

2. Program 0 is automatically selected. To select another program, press the “program ” button and rotate the " intensity-set " control. The TIMER/ PROGRAM display will show the program selected (programs 0, 1, 2 through to 9).

3. Once the required program has been selected, the output current intensity can be set. Press the “start-focus ” button momentarily. Next adjust the current intensity to the required level by rotating the "intensity-set " control.

A description of the factory preset programs is given on pages 17 and 18 of this manual. Pages 18 to 20 are where your own programs can be recorded. We suggest that you photocopy pages 18 to 20 and make a record of your stored programs. These can be kept in the storage compartment of the Vectorsurge for ready reference and replaced if you should change your prestored programs. Remember that you can review the prestored programs by pressing the “program ” button and rotating the “intensity-set ” control.

5.3 2 Pole Treatment

For stimulation of relatively superficial and easily accessible structures, it is often convenient to use just two electrodes for bipolar stimulation. In 2 POLE mode there is the choice of premodulated interferential or conventional TNS. When interferential mode is selected together with 2 POLE output, the two interferential currents are mixed within the machine and a beat frequency signal is sent to the output.

In 2 POLE mode, different size electrodes can be used i.e. a large 'indifferent' electrode and a smaller 'active' electrode positioned over the motor point or area to be treated.

To select bipolar interferential or conventional TNS treatment, switch on the machine, and chose a preset treatment program (as described previously) or set the machine manually by choosing the treatment settings. The manual setup procedure is as outlined previously under 'conventional interferential' and 'interferential TNS': the only difference being that 2 POLE should be selected in step 1.

If two channels of 2 pole treatment are required then DUAL mode should be selected.



5.4 Dual Stimulator Mode

When DUAL mode is selected, the Vectorsurge functions as two completely separate bipolar stimulators. The patient can thus be treated in two areas simultaneously and you have the choice of completely different stimulation of each area. For example, the output of one channel can be 50 Hz TNS pulses, surged over a 30 second cycle time and a treatment time of 20 minutes while the other channel is bipolar interferential with a frequency sweep from 0-15 Hz, not surged and a treatment time of 15 minutes. Alternatively, the two channels can have the same treatment settings with only the output intensity being different. Whichever the case, the current intensity must be set separately for each channel. To select DUAL treatment, switch on the machine, press “set-pause ” and select DUAL output. Next press the “program ” button to chose a preset treatment program (as described previously) or set the machine manually by choosing the treatment settings. The manual setup procedure is as outlined previously under 'conventional interferential' and 'interferential TNS': the only difference is that DUAL is selected in step 1.

Setting channel ‘a”

Once DUAL mode has been selected the “set-pause ” button is pressed to step through treatment settings for channel “a”. During this time, the channel “a” indicator under the “output selection ” button will be illuminated. Once channel “a” settings have been chosen the “start-focus ” button can be pressed and the channel “a” intensity can be set by rotating the "intensity-set " control. Alternatively, channel “b ” can be set-up before any output is delivered.

Setting channel “b’

Next press the “output selection ” button to allow choice of the channel “b” settings. The channel “b” indicator will become illuminated and the settings will initially be identical to those set for channel “a”. If these are the correct settings, press “start-focus ” and rotate the "intensity-set " control to set the channel “b” intensity. If different settings are required, press the “set-pause ” button to step through and adjust each of the treatment settings for channel “b”.

After the treatment parameters have been set, the “start-focus ” button is pressed. The output display indicator will show the relevant channel and the " intensity-set " control can be rotated to set the output current in this channel. Next the “output selection ” button can be pressed to select the other channel and its intensity can be set by rotating the " intensity-set " control.

During treatment

During treatment, the “output selection ” button can be pressed to monitor the current in each channel. If any adjustment is needed, the " intensity-set " control can be rotated to increase or decrease the current in the selected channel. The output display indicators show which channel is selected. Pressing “set-pause ” will reduce the output current in the selected channel to zero, but will not affect the other channel. Pressing “start-focus ” will allow you to reset the current in the selected channel. The two channels can thus be used and adjusted quite separately.

If you wish to simultaneously switch-off the current in both channels, simply press the “STOP” button below the output intensity display. The “STOP” button provides the means of immediately terminating the current in each channel. To terminate current flow in just one channel, the “set-pause ” button is pressed to switch off the current flow in the channel shown under output display.

To adjust the intensity of either channel, simply select the channel by pressing the “output selection ” button and rotate the "intensity-set " control.



5.5 Storing Programs

Ten treatment programs are factory provided and stored for instant recall. Should you wish to change or replace any of these programs and customize the Vectorsurge to your own needs, follow these simple steps:

1. First set the treatment parameters to those you want, either by manually stepping through each of the treatment settings using the “set-pause ” button and the "intensity-set " control or by selecting a preset program then using the “set-pause ” button and the "intensity-set " control to change particular settings.

2. Press the “program ” button "P 0" will appear on the TIMER/PROGRAM display. If you wish to store the program as program 0, the one which automatically appears when the Vectorsurge is switched-on, press the “program ” button again momentarily and it will be stored as program 0 replacing the previously stored program. Successful storage will be indicated by a double beep. A single beep indicates that storage has not been successful. If you wish to store the program under some other number between 1 and 9, rotate the " intensity-set " control to change the program number to the one you want then press the “program ” button again.

3. You may wish to record the program settings which you have stored and make notes as to its use. Record sheets, which can be photocopied in case stored programs are changed at a future date, are provided as pages 18 to 20 of this manual. Pages 17 and 18 show the factory preset programs.

5.6 Electrodes

The Vectorsurge is supplied with a set of four separate circular conductive rubber electrodes (Carbonflex electrodes) as standard equipment. Larger electrodes, 75 mm diameter, are available as an option. This combination provides the flexibility necessary to treat the widest range of conditions encountered by the physiotherapist.

Four separate conductive rubber electrodes are used when large volume treatment or treatment of deeply located structures is required. The electrode size required depends on the area to be treated. Small electrodes would be selected for treatment of, for example, the elbow or ankle joints. Large electrodes are more appropriate for areas such as the low back or quadriceps. Electrodes should be positioned in diagonally opposite pairs so that the currents intersect in the region to be treated. Bear in mind that the current spreads within the tissue and that maximum stimulation is in four lobes midway between electrode pairs (see figure 1 of the background information, page 37).

Two electrodes are used for bipolar treatment. Bipolar treatment is used when depth efficiency of stimulation is not a prime consideration and/or when the structure to be treated is such that it would be difficult to position four diagonally opposing electrodes. The therapist has the option either of using two equal size electrodes, both positioned over the region to be treated or of using a small "active" electrode over the area to be treated and a larger "indifferent" electrode positioned elsewhere. The use of two unequal size electrodes results in maximum stimulation immediately beneath the smaller electrode. The large electrode should be positioned away from motor points or sensitive tissue regions.

5.7 Electrode Use/Preparation

Before using Carbonflex electrodes, or if the electrodes are to be reused, they should be thoroughly washed in a mixture of water and mild soap. The Carbonflex electrodes are non-sterile. However, they can be autoclaved, if required.

The skin at the electrode site should be washed with mild soap and water to reduce skin resistance. A liberal amount of conductive electrode gel should be applied to the electrode. Note that many ultrasound gels are not sufficiently conductive for electrical stimulation. Only use a gel which is stated to be suitable for the purpose.



Electrodes may be secured in place over the appropriate stimulation sites with velcro straps, elastic bandages or hypoallergenic spunlace tape. The strapping should be tight enough to keep the whole of the electrode surface in contact with the patient to ensure a uniform distribution of current.

5.8 Suction Electrodes

The Vectorsurge 5 can be used with a Metron Vacupulse suction unit for simple and rapid electrode placement. Please note that the Vacupulse suction unit is currently not available. Suction cup electrodes avoid the need for either electrode gel and straps to secure the electrodes or expensive disposable adhesive electrode pads. The operator's manual for the Vacupulse describes how to use the unit in conjunction with the Vectorsurge.

5.9 Using the Vectorsurge in Dual Mode

When dual mode is selected, the Vectorsurge operates as two separate stimulators which can operate concurrently. The output of one channel can be TNS pulses, while the other channel is bipolar interferential or the two channels can be the same. Completely different treatment settings can be made for each channel.

Once dual mode has been selected the “set-pause ” button is pressed to step through treatment settings for channel “a”. Once this is completed, the “output selection ” button is pressed to allow choice of the channel “b” settings.

After the treatment parameters for both channels have been set, an output should be set. Press the “output selection ” button to select the appropriate channel and then press the “start-focus ” button. Rotate the "intensity-set " control to set the output current in the selected channel. Next press the “output selection ” button to select the other channel. Press “start-focus ” and rotate the "intensity-set " control to set the output current in this channel.

Pressing “STOP” will terminate the flow of current in both channels. To terminate current flow in one channel, select the channel using the “output selection ” button and press “set-pause ”. To change from DUAL to 4-pole or 2 pole mode, the output of both channels must be off.

5.10 Monitoring, Adjusting and Terminating Output Current

During treatment, the “output selection ” button can be pressed to monitor the current in each channel. If any adjustment is needed, the " intensity-set " control can be rotated to increase or decrease the current in the selected channel. Pressing “set-pause ” will reduce the output current in the selected channel to zero, but will not affect the other channel. Pressing “start-focus ” will allow you to reset the current in the selected channel.

If you wish to simultaneously switch-off the current in both channels, press the “STOP” button below the output intensity display.

If you wish to adjust the current in either channel without first reducing it to zero, select the channel by pressing the “output selection ” button then rotate the "intensity-set " control.



6. CONVENTIONAL INTERFERENTIAL THERAPY

6.1 OPERATIONAL INFORMATION

6.1.1 Indications For Use For Interferential Therapy

The indications for use of this device are:

1. Relaxation of muscle spasm.

2. Prevention or retardation of disuse atrophy.

3. Increasing local blood circulation.

4. Muscle re-education.

5. Immediate post-surgical stimulation of calf muscles to prevent venous thrombosis.

6. Maintaining or increasing range of motion.

The Vectorsurge 5 should only be used under medical supervision for adjunctive therapy for the treatment of medical diseases and conditions.

6.1.2 Contraindications

The Vectorsurge 5 should not be used on patients with cardiac demand pacemakers.

6.1.3 Therapeutic Warnings

Before the application of the Vectorsurge 5 to a patient for therapeutic purposes the following factors should be duly considered and evaluated:

1. The long term effects of chronic electrical stimulation are unknown.

2. Stimulation should not be applied over the carotid sinus nerves, particularly in patients with a known sensitivity to the carotid sinus reflex.

3. Stimulation should not be applied over the neck or mouth. Severe spasms of the laryngeal and pharyngeal muscles may occur and the contractions may be strong enough to close the airway or cause difficulty in breathing.

4. Stimulation should not be applied transthoracically in that the introduction of electrical current into the heart may cause cardiac arrhythmias.

5. Stimulation should not be applied transcerebrally.

6. Stimulation should not be applied over swollen, infected, or inflamed areas or skin eruptions, e.g. phlebitis, thrombophlebitis, varicose veins, etc.

7. Stimulation should not be applied over, or in proximity to, cancerous lesions.

6.1.4 Precautions



6.1.4 Precautions

The following precautions should considered and implemented as appropriate:

1. Safety of the use of the Vectorsurge 5 during pregnancy has not been established.

2. Caution should be used for patients with suspected or diagnosed heart problems.

3. Caution should be used for patients with suspected or diagnosed epilepsy.

4. Caution should be used in the presence of the following:

a) When there is a tendency to hemorrhage following acute trauma or fracture;

b) Following recent surgical procedures when muscle contraction may disrupt the healing process;

c) Over the menstruating or pregnant uterus; and

d) Over areas of the skin which lack normal sensation.

5. Some patients may experience skin irritation or hypersensitivity due to electrical stimulation or electrical conductive medium. The irritation can usually be reduced by using an alternative conductive medium, or alternate electrode placement.

6. Electrode placement and stimulation settings should be based on the guidance of the prescribing practitioner.

7. The Vectorsurge 5 should be kept out of the reach of children.

8. The Vectorsurge 5 should be used only with the leads and electrodes recommended for use by the manufacturer.

6.1.5 Adverse Reactions

Skin irritations and burns beneath the electrodes have been reported with the use of powered muscle stimulators.



6.2 OPERATING PROCEDURES

6.2.1 Interferential Beat Frequency Selection

Complete flexibility of frequency selection is an important feature of the Vectorsurge. Beat frequencies available are in the range 0 to 300 Hz, depending on the setting of the 'upper' and 'lower' frequency selectors.

The most commonly used interferential frequency sweeps of 0-150 Hz, 80-150 Hz or 0-15 Hz are preset in the machine and may be obtained simply by selecting them.

When different frequencies or frequency ranges are required the SWEEP RANGE indicator should be set to SELECT. In this position, pressing the “set-pause ” button causes the 'upper' light to flash and the highest frequency of the sweep range can be selected by pressing the “set-pause ” button then rotating the " intensity-set " control until the desired upper limit is displayed. Next the lower frequency is set by pressing the “set-pause ” button to choose 'lower' and rotating the "intensity-set " control anticlockwise until the desired lower limit is displayed. Once the upper frequency has been selected, pressing the “set-pause ” button allows selection of the lower frequency.

Fixed frequencies are obtained by setting the upper and lower frequencies to the same value and this happens automatically. When the “set-pause ” button is pressed and the upper frequency is selected, the lower frequency is also set to the chosen frequency. So for fixed frequency selection, set the 'upper' frequency to that required then press the “set-pause ” control. The 'lower' frequency is automatically set the same value as the upper frequency so no adjustment is required. Simply press “set-pause ” to continue with treatment selection and set the carrier frequency.

Frequently used frequency protocols can, of course, be kept in the Vectorsurge as stored programs which can be recalled at the push of a button.

6.2.2 Interferential Carrier Frequency Selection

Most interferential therapy machines operate with a fixed carrier frequency of 4 kHz. The Vectorsurge offers the operator the choice of either a 2.5 kHz, 4 kHz or 10 kHz carrier frequency. The carrier frequency is chosen simply by setting the FREQUENCY selector to the appropriate choice.

When the machine is being used for muscle re-education a carrier frequency of 2.5 kHz should be used.

When best discrimination between sensory, motor and pain responses is required a carrier frequency of 10 kHz should be used. This frequency is recommended for all treatment conditions where efficient and comfortable treatment is needed.

A carrier frequency of 4 kHz is a compromise between the best conditions for muscle stimulus and patient comfort.

6.2.3 Applying Interferential & Russian Therapy

The Vectorsurge 5 is, first and foremost, an interferential therapy machine. To select interferential treatment, switch on the machine, and chose a preset interferential treatment program (see above) or set the machine manually by choosing the treatment settings. The procedure for manual setup is outlined below.

1. When the machine is switched on, the PATIENT MODE indicator will be flashing. Rotating the “ intensity-set ” control allows the appropriate selection to be made. Once selection has been made press the “set-pause ” button to move onto the next parameter selection.



Note: If DUAL mode is selected only 2 pole output mode will be available.

2. The next selection involves choosing the OUTPUT MODE required. Select INTERFERENTIAL (or RUSSIAN if required) using the “intensity-set ” control. Once completed press the “set-pause ” button to move to the next selection.

Note: It is not necessary to step through all of the steps detailed. Once the settings are as required, the output can be initiated at any time by pressing the “start-focus ” button and the desired output current can be set by manipulation of the “intensity-set ” control. 3. The TREATMENT time indicator will now be flashing. If a change in the treatment time

from that shown is desired, rotate the "intensity-set " control clockwise or anticlockwise (clockwise to increase, anticlockwise to decrease) until the appropriate value is shown. If no further changes are needed initiate treatment or press “set-pause ” to proceed to the next step.

4. The SURGE TIME parameters will now be available for selection. Surging can then be switched on or off by rotating the "intensity-set " control. Anticlockwise rotation turns surging off, clockwise rotation turns surging on, indicated by the RISE, ON, FALL and OFF indicators being illuminated .

If surging is switched off (RISE, FALl, ON and OFF indicators are not illuminated, only the SELECT indicator flashing), depressing the “set-pause ” button will take you to sweep range selection.

If surging is switched on (RISE, ON, FALL and OFF indicators are all illuminated), press the “set-pause ” button and the RISE indicator will flash. Rotate the " intensity-set " control to change the rise time, which is shown (in seconds) on the TIMER/PROGRAM display. Proceed to set the on time, fall time and off time in the same way i.e. press the “set-pause ” button to move to the next setting and rotate the "intensity-set " control to change the setting to the value required. Once the surge times have been selected, depressing the “set-pause ” button will move to sweep range selection. If no further changes are needed at this stage treatment can be initiated by pressing the “start-focus ” button.

Note: Users should be aware that surge durations longer than several seconds, including continuous stimulation, may result in muscle fatigue. Relaxation of muscle spasm is the only valid indication for surge durations greater than several seconds.

5. The sweep range selection can now accessed. If the sweep range indicated is the one desired press the “set-pause ” button to proceed to the next step. To change the chosen sweep range, rotate the " in tens i ty -set " control to the setting required. If a preset sweep range (0-15 Hz, 0-150 Hz or 80-150 Hz) is selected activation of the “set-pause ” button will step to the next selection.

If a sweep range is required which is not a preset one, chose SELECT then press “set-pause ” and the upper frequency indicator will flash. The upper frequency can then be adjusted by rotating the " intensity-set " control. Pressing the “set-pause ” button again allows the lower frequency to be set. The lower frequency is adjusted by rotating the “intensity-set ” control. Pressing the “set-pause ” button will lock in the values chosen and move the sequence to the next parameter, output configuration.

6. Set the output configuration , 4 pole or 2 pole, to the desired value by rotating the "intensity-set " control clockwise or anticlockwise. Press the “set-pause ” button to move to the final selection, carrier frequency.

7. Set the carrier frequency to the desired value by rotating the " intensity-set " control clockwise or anticlockwise.



8. Now that the treatment conditions have been selected, the output current intensity can be set. Depress the “start-focus ” button momentarily. The output current intensity can be set to an appropriate level by rotating the "intensity-set " control.

Note: If the SURGE is set on, the maximum intensity can be set with confidence: the surge cycle does not begin until approximately ten seconds after the peak intensity has been set. At this point the output current will drop to zero at a rate determined by the FALL setting and the surge cycle will begin with the first OFF period. If subsequent adjustment to the intensity is needed, it can be made by rotating the "intensity-set " control.

Rotating the "intensity-set " control clockwise will result in the current increasing only to the previously set peak value. Not until the peak value has been reached can a higher current be set. Rotating the "intensity-set " control anticlockwise will, however, result in an immediate decrease in the output.

9. If the targeted tissue is not stimulated optimally, or if greater stimulation intensity is felt under one electrode or pair of electrodes, the interferential currents can be balanced by pressing the "start-focus " button and rotating the " intensity-set " control. The 'focus' adjustment provides a means of optimally targeting the tissue volume to be treated. It also allows compensation for different tissue conductance between the electrode pairs. When the patient feels equal (or no) sensation under the electrodes, the targeted tissue should be optimally stimulated.

10. During treatment the intensity setting may need to be increased slightly to compensate for accommodation effects. For example, with a typical treatment of 20 minutes duration the intensity may need to be increased once, after the first five minutes of treatment. This is achieved simply by rotating the "intensity-set " control.

11. At the end of the treatment period:

* remove the electrodes from the patient.

* if the machine is not to be used again for some time, switch off.



7. TNS THERAPY

7.1 OPERATIONAL INFORMATION

7.1.1 Indications For Use For TNS Therapy

The indications for use of this device are:

1. Relief of chronic intractable pain, acute post traumatic pain or acute post surgical pain.

The Vectorsurge 5 should only be used under medical supervision for adjunctive therapy for the treatment of medical diseases and conditions.

7.1.2 Contraindications

The contraindications for using the Vectorsurge 5 to provide TNS therapy are;

1. Any electrode placement that applies current to the carotid sinus (neck).

2. Any patients who have a cardiac demand-type pacemakers.

3. Any electrode placement that causes current to flow transcerebrally (through the head).

4. Any situation where pain syndromes are undiagnosed, until etiology is established.

7.1.3 Therapeutic Warnings

Before the application of the Vectorsurge 5 to a patient for therapeutic purposes the following factors should be duly considered and evaluated:

1. The long term effects of chronic electrical stimulation are unknown.

2. The safety of TNS devices for use during pregnancy or birth has not been established.

3. TNS therapy is not effective for pain of central origin. (This includes headache).

4. Stimulation should not be applied transthoracically in that the introduction of electrical current into the heart may cause cardiac arrhythmias.

5. TNS devices should only be used under continued supervision of a licensed practitioner.

6. TNS devices have no curative value.

7. TNS is a symptomatic treatment and as such suppresses the sensation of pain which would otherwise serve as a protective mechanism.

8. The user must keep the device out of the reach of children.

9. Electronic monitoring equipment (such as ECG monitors and ECG alarms) may not operate properly when TNS stimulation is in use.

7.1.4 Precautions

The following precautions should considered and implemented as appropriate:



1. Isolated cases of skin irritation may occur at the site of electrode placement following long-term application.

2. Effectiveness is highly dependent upon patient selection by a person qualified in the management of pain patients.

3. The Vectorsurge 5 should be used only with the leads and electrodes supplied and recommended for use by the manufacturer.

7.1.5 Adverse Reactions

Skin irritations and burns beneath the electrodes have been reported with the use of powered muscle stimulators.

7.2 OPERATING PROCEDURE

7.2.1 TNS Stimulation Frequency Selection

When used in TNS mode, the stimulation frequency is set in the same way as the interferential beat frequency. Thus preset frequency sweeps of 0-150 Hz, 80-150 Hz or 0-15 Hz can be selected directly or other frequency ranges or a fixed frequency can be set.

As with interferential treatment, frequently used TNS frequency protocols can be kept in the Vectorsurge as stored programs which can be recalled at the push of a button (see pages 17 to 20).

7.2.2 TNS Pulse Width Selection

When used in TNS mode, the stimulus waveform is a rectangular biphasic pulse with pulse widths selectable from 200 µs, 125 µs or 50 µs. The pulse width is chosen simply by setting the FREQUENCY(PULSE WIDTH) selector to the appropriate choice. When different frequencies are chosen, the Vectorsurge produces one biphasic pulse at the frequency selected. The duration of the biphasic pulse is 1/frequency and the width of the individual pulses is one half of this. Thus if TNS mode is selected and a frequency of 10 kHz is chosen, the TNS pulse will be biphasic with a 50 µs positive pulse followed by a 50 µs negative pulse.

The interferential frequency and the corresponding widths of the TNS biphasic pulses are as follows:

2.5 KHz 200 us4 KHz 125 us10 KHz 50 us

The effect of pulse width is described more fully in the 'background information' section of this manual, beginning on page 37.

7.2.3 Applying Interferential TNS

A special feature of the Vectorsurge 5 is the ability to apply rectangular biphasic current pulses ('conventional TNS') in interferential mode. Thus you can combine the advantages of conventional TNS treatment with the ability to target the stimulating current in the region of intersection of the two current pathways. With conventional TNS, greatest stimulation is produced immediately beneath the electrodes. With interferential TNS, the region of maximum stimulation has the familiar clover-leaf pattern traditionally associated with conventional interferential stimulation. This feature is explained in more detail in the



'background information' section beginning on page 37.

To select interferential TNS treatment, switch on the machine, and chose a preset interferential TNS treatment program (as described previously) or set the machine manually by choosing the treatment settings. The procedure for manual setup is outlined below.

1. When the machine is switched on, the PATIENT MODE indicator will be flashing. Rotating the “ intensity-set ” control allows the appropriate selection to be made. Once selection has been made press the “set-pause ” button to move onto the next parameter selection.

Note: If DUAL mode is selected only 2 pole output mode will be available.

2. The next selection involves choosing the OUTPUT MODE required. Select TENS using the “intensity-set ” control. Once completed press the “set-pause ” button to move to the next selection.

Note: It is not necessary to step through all of the steps detailed. Once the settings are as required, the output can be initiated at any time by pressing the “start-focus ” button and the desired output current can be set by manipulation of the “intensity-set ” contro

3. The TREATMENT time indicator will now be flashing. If a change in the treatment time from that shown is desired, rotate the "intensity-set " control clockwise or anticlockwise (clockwise to increase, anticlockwise to decrease) until the appropriate value is shown. If no further changes are needed initiate treatment or press “set-pause ” to proceed to the next step.

4. The SURGE TIME parameters will now be available for selection. Surging can then be switched on or off by rotating the "intensity-set " control. Anticlockwise rotation turns surging off, clockwise rotation turns surging on, indicated by the RISE, ON, FALL and OFF indicators being illuminated .

If surging is switched off (RISE, FALl, ON and OFF indicators are not illuminated, only the SELECT indicator flashing), depressing the “set-pause ” button will take you to sweep range selection.

If surging is switched on (RISE, ON, FALL and OFF indicators are all illuminated), press the “set-pause ” button and the RISE indicator will flash. Rotate the " intensity-set " control to change the rise time, which is shown (in seconds) on the TIMER/PROGRAM display. Proceed to set the on time, fall time and off time in the same way i.e. press the “set-pause ” button to move to the next setting and rotate the "intensity-set " control to change the setting to the value required. Once the surge times have been selected, depressing the “set-pause ” button will move to sweep range selection. If no further changes are needed at this stage treatment can be initiated by pressing the “start-focus ” button.

Note: Users should be aware that surge durations longer than several seconds, including continuous stimulation, may result in muscle fatigue. Relaxation of muscle spasm is the only valid indication for surge durations greater than several seconds.

5. The sweep range selection can now accessed. If the sweep range indicated is the one desired press the “set-pause ” button to proceed to the next step. To change the chosen sweep range, rotate the " in tens i ty -set " control to the setting required. If a preset sweep range (0-15 Hz, 0-150 Hz or 80-150 Hz) is selected activation of the “set-pause ” button will step to the next selection.

If a sweep range is required which is not a preset one, chose SELECT then press “set-pause ” and the upper frequency indicator will flash. The upper frequency can then be adjusted by rotating the " intensity-set " control. Pressing the “set-pause ” button again allows the lower frequency to be set. The lower frequency is adjusted by



rotating the “intensity-set ” control. Pressing the “set-pause ” button will lock in the values chosen and move the sequence to the next parameter, output configuration.

6. Set the output configuration , 4 pole or 2 pole, to the desired value by rotating the "intensity-set " control clockwise or anticlockwise. Press the “set-pause ” button to move to the final selection, pulse width.

7. Set the pulse width to the desired value, 200, 125 or 50 us, by rotating the "intensity-set " control clockwise or anticlockwise.

8. Now that the treatment conditions have been selected, the output current intensity can be set. Depress the “start-focus ” button momentarily. The output current intensity can be set to an appropriate level by rotating the "intensity-set " control.

Note: If the SURGE is set on, the maximum intensity can be set with confidence: the surge cycle does not begin until approximately ten seconds after the peak intensity has been set. At this point the output current will drop to zero at a rate determined by the FALL setting and the surge cycle will begin with the first OFF period. If subsequent adjustment to the intensity is needed, it can be made by rotating the "intensity-set " control.

Rotating the "intensity-set " control clockwise will result in the current increasing only to the previously set peak value. Not until the peak value has been reached can a higher current be set. Rotating the "intensity-set " control anticlockwise will, however, result in an immediate decrease in the output.

9. If the targeted tissue is not stimulated optimally, or if greater stimulation intensity is felt under one electrode or pair of electrodes, the interferential currents can be balanced by pressing the "start-focus " button and rotating the " intensity-set " control. The 'focus' adjustment provides a means of optimally targeting the tissue volume to be treated. It also allows compensation for different tissue conductance between the electrode pairs. When the patient feels equal (or no) sensation under the electrodes, the targeted tissue should be optimally stimulated.

10. During treatment the intensity setting may need to be increased slightly to compensate for accommodation effects. For example, with a typical treatment of 20 minutes duration the intensity may need to be increased once, after the first five minutes of treatment. This is achieved simply by rotating the "intensity-set " control.

11. At the end of the treatment period:

* remove the electrodes from the patient.

* if the machine is not to be used again for some time, switch off.



8. ELECTROTHERAPY

8.1 CONVENTIONAL INTERFERENTIAL THERAPY

8.1.1 Introduction

Interferential therapy is an important part of the range of treatment modalities available to the practising physiotherapist. Interferential apparatus provides the means of focussing-in on and selectively stimulating deeply located tissue. By using two pairs of electrodes and two distinct patient circuits, maximum stimulation of the patient's tissue is achieved in a region at the intersection of the two current pathways.

8.1.2 Depth Efficiency

Figure 1 illustrates the depth efficiency of true interferential stimulation (i.e. quadripolar) as compared with that produced by conventional apparatus (TNS. units or faradic apparatus), or interferential apparatus used in bipolar mode.

Figure 1: Regions of maximum stimulation.(a) Quadripolar interferential stimulation (b) Bipolar stimulation

With conventional (bipolar) treatment (Figure 1(b)) greatest stimulation is achieved in regions close to each electrode (i.e. superficially). This is because the current spreads within the patients tissue so that the regions of highest current density, and thus greatest stimulation, are close to each electrode.1

Interferential therapy works on the premise that if two currents are applied to the patient the region of greatest current density and hence greatest stimulation will be at the intersection of the two current pathways. By applying two currents at right angles, maximum stimulation is produced in deeply located tissue rather than in the superficial tissue beneath each electrode.

8.1.3 Vector Rotation

The pattern of electrical stimulation produced by interferential therapy is in the form of a clover-leaf (Figure 1(a)). This pattern is commonly referred to as a static interference field. This means that maximum stimulation of the patient's tissue is not produced simply

at the centre of the current pathways but is produced in four distinct lobes positioned along lines between adjacent electrodes (Figure 2(a)). The reason for this is that the interfering currents add vectorially, producing a maximum stimulation in the four regions shown.

The rotation of this vector field is achieved by rhythmically increasing and decreasing the current in one pair of electrodes while the current in the opposite pair of electrodes is kept constant.

Figure 2 below shows the effect of vector rotation.



(a) (b)

areas of maximum stimulation

current pathways

Rotation of the interference field as shown provides stimulation of the tissue not treated when only a static field is used.

Slow rotation of this interference field is clearly inefficient as it takes several seconds for the stimulation pattern to rotate through the tissue, thus the tissue is treated in stages as if by a series of static vector fields.

The high speed rotation of the vector field in the Vectorsurge 5 ensures that all of the tissue in the treatment region is stimulated almost simultaneously. With the vector field rotating at 200 times per second, the nerve fibres are continuously stimulated at the beat frequency, because the interval between successive stimulations by the vector field as it passes through the individual nerve fibres is sufficiently short to ensure that the beat frequency is not interrupted.

The continuous and simultaneous stimulation of the tissue in this manner is extremely efficient and of superior therapeutic benefit than with slow speed vector rotation. This improved efficiency in the Vectorsurge 5 over all other interferential units means that improvement in condition will be recognised earlier when Vectorsurge 5 is used.

8.1.4 Surging

To be suitable for muscle re-education an electronic stimulator should be capable of producing a stimulus intensity which increases and decreases gradually over a period of several seconds. Faradic stimulators achieve this by surging the output intensity in a gradual manner but the stimulation produced is superficial (Figure 1) and the stimulus frequency is fixed in the tetanic frequency range (normally 50 Hz). Some interferential machines are claimed to be suitable for muscle re-education when used with a low beat frequency range (normally 0-10 Hz) but no surging of the output is provided.

The Vectorsurge 5 offers complete flexibility in the choice of stimulus frequencies and in addition offers the option of surging the output and choosing an appropriate surge rate. Thus a tetanic frequency (e.g. 30 Hz) or a slow motorneurone frequency range (5-15 Hz) or a frequency range spanning the two (for example 5-35 Hz) can be selected and the output can be surged to allow rest periods between stimuli and to minimize accommodation affects.

8.1.5 Beat Frequencies

(i) Sweep Ranges

Traditionally, interferential units have offered three sweep ranges: a low frequency sweep (normally 0-10 Hz or 0-15 Hz), a high frequency sweep (normally 80-100 Hz or 80-150 Hz) and a wide sweep (0-100 Hz or 0-150 Hz). Since these low, high and wide sweeps are often required they are provided on the Vectorsurge 5 and can be selected simply and directly. The preset frequency sweeps on the Vectorsurge 5 are 0-15 Hz, 80-150 Hz and 0-150 Hz.



Static field

Effect of vector rotation

A fourth position on the beat frequency selector allows the operator to set different sweep ranges or a fixed beat frequency. Both the lower and upper frequency can be set to any value up to 300 Hz. Thus the beat frequency may be fixed anywhere in the range up to 300 Hz or may be set to sweep over a narrow range (e.g. 0-10 Hz, 5-35 Hz, 100-150 Hz) or any wider range which might be required (e.g. 0-100 Hz, 50-150 Hz, 100-200 Hz). A fixed beat frequency is obtained when both the lower frequency and upper frequency are set to the same value.

(ii) Low Frequencies

A sweep range of 0-15 Hz is recommended for producing gentle twitching/ tugging responses for increasing blood flow.

A sweep range of 5-15 Hz is recommended for muscular re-education via stimulation at slow motorneurone frequencies. The process of atrophy due to denervation or disuse includes a progressive change in the metabolic properties of skeletal muscle, most notably oxidative properties.

(iii) Intermediate Frequencies

Frequencies in the range 30 to 100 Hz are suitable for producing forceful muscle contraction. In this frequency range the response is a tetanic contraction. To avoid fatigue and discomfort and to produce comfortable graded, sequential contractions the surge facility should be used.

The best Vectorsurge carrier frequency for maximum muscle torque production is 2.5 kHz and selection of lower beat frequencies will result in a less rapid onset of

fatigue. For these reasons a beat frequency sweep of 30-50 Hz at a carrier frequency of 2.5 kHz is recommended for production of strong muscle contraction.

(iv) Higher Frequencies

It was originally believed that the optimum beat frequency for analgesic stimulation was 80-100 Hz, however recent research indicates that higher beat frequencies (up to 150 Hz) are more effective for controlling pain.

A sweep range of 80-150 Hz at an intensity which produces mild tingling with little or no motor stimulation is recommended for pain control. The output need not be surged. The carrier frequency should be set at 10 kHz.

Because of the overlap in appropriate frequency ranges for electroanalgesia (80-150 Hz) and motor responses (30-100 Hz) a frequency sweep which combines two treatments can be chosen. To combine a gentle and comfortable motor response with mild analgesia a frequency sweep of 80-150 Hz is recommended. The output intensity should be high enough to produce an appropriate motor response and surged at a low or medium rate.

For a maximum electroanalgesic effect with no motor response a sweep range of 250-300 Hz is recommended, with the intensity set at a comfortable sensory level and below the motor threshold.

8.1.6 Carrier Frequencies

Until now, interferential therapy machines have used an operating frequency of typically 4 kHz to 5 kHz and the waveforms used have been sinusoidal in shape. This frequency range and waveform was thought to be best for reducing physical discomfort to the patient.

In recent times it has been shown that higher carrier frequencies around 10 kHz are optimum



for minimizing physical discomfort3 and that lower carrier frequencies around 2.5 kHz are best suited to producing maximum muscle torque4. 4 kHz to 5 kHz thus represents a compromise between these two best frequencies.

Moreno-Aranda and Siereg3 first showed that although greater muscle force is produced at lower frequencies, a higher carrier frequency (around 10 kHz) was capable of producing good muscle contractions with minimum sensation of pain. More recently Ward and Robertson5, using a different experimental procedure, showed that discrimination between motor and pain thresholds was maximum at frequencies near 10 kHz. Figure 3 shows a graph of pain threshold/motor threshold versus frequency.

The results shown as figure 3 were obtained using small electrodes located over the brachioradialis motor point and stimulating with alternating currents in the frequency range 1 kHz to 35 kHz. It is clear from the graph that best discrimination between pain and motor responses is achieved with frequencies in the range 8 kHz to 12 kHz.

Figure 3: Pain threshold/motor threshold versus frequency for stimulation over Brachioradialis motor point (adapted from Ward and Robertson5).

1 2 5 10 20 40

0.8

1.0

1.2

1.4

1.6

+

+ ++

+++

++++++

+++

+

+++

+++

+++

+ +

+

+

pain

thre

shol

dm

otor

thre

shol

d

frequency (kHz)

Figure 4: Maximum electrically induced torque of the wrist extensors at carrierfrequencies of 2 kHz, 4 kHz and 10 kHz (from Ward and Robertson4).



1 2 4 10

20

40

60

torq

ue (

% o

f M

VC

)

frequency (kHz)

Ward and Robertson4 compared carrier frequencies in the range 1 kHz to 15 kHz for torque production in the wrist extensors and found the lowest frequencies to be appreciable more efficient. A graph of maximum electrically induced torque versus frequency is shown in figure 4. The advantage of a 2.5 kHz carrier frequency over 4 kHz or 10 kHz is clearly apparent. The torque at 2.5 kHz is almost 20% greater than at 4 kHz and approximately 40% greater than at 10 kHz.

Carrier frequencies of 2.5, 4 or 10 kHz can be selected on the Vectorsurge 5 simply by choosing from the three options. Hence the carrier frequency can be chosen to provide optimum stimulation characteristics depending on the condition to be treated.

8.1.7 Phase Switching

Older interferential machines generate two sinusoidal alternating currents with slightly differing frequencies. When the two currents intersect in the patients' tissue they interfere, producing a beat frequency signal in the biological frequency range. The waveforms used are sinusoidal in shape.

The Vectorsurge 5 has two innovative features designed to improve the stimulation efficiency and comfort of interferential therapy:

* The carrier waveform is rectangular rather than sinusoidal in shape. It is well known that a rapidly rising stimulus waveform is more efficient than one which rises slowly. This is because nerve fibres can accommodate to a slowly rising stimulus. The use of a rectangular waveform thus minimizes accommodation and produces maximum stimulation efficiency.

* The carrier waveforms are identical in frequency but are shifted in and out of phase at the beat frequency. Rapid phase shifting of the signals results in a beat-frequency stimulus which switches rapidly from minimum to maximum. Again, the effect of this rapid phase shifting is to minimize accommodation of nerve fibres and maximize efficiency.

Figure 5 shows the rectangular signal waveforms produced by the Vectorsurge 5 and how



they are combined to produce a rectangular beat frequency envelope. When the currents are applied to the patient via two pairs of electrodes (4 pole operation) the phase shifted signals combine and the beat frequency envelope is generated in the patient's tissue, in the region of intersection of the current pathways. The clover-leaf pattern of stimulation in the region of intersection is shown in figure 1 previously.

When the machine is switched to 2 pole operation the beat frequency signal is generated within the machine and applied directly to the patient via one pair of electrodes. In 'dual' mode the beat frequency signal is available at both outputs of the machine, so either output A or output B can be used, or both outputs used simultaneously for treating two areas of the patient. It should also be noted that different beat frequencies or frequency sweeps can be chosen for each channel. In dual mode, the frequency sweeps (and all other treatment settings) can be independently set for each channel.

Figure 5: Combination of two phase-shifted signals to produce a rectangular beat-frequency envelope.

In summary the Vectorsurge 5 has a range of carrier frequencies and beat frequencies which ensure optimum treatment conditions to be achieved in every case. This, together with surging of the output, rapid phase switching of the carrier waveforms and the option of bipolar or quadripolar treatment makes the Vectorsurge 5 the most advanced machine available for interferential stimulation.

8.2 CONVENTIONAL TNS THERAPY

8.2.1 General

Transcutaneous electrical nerve stimulation (TNS) strictly refers to any form of through-the-skin nerve stimulation. However in common usage, the term 'TNS stimulator' is often used in a more restricted sense, to identify a device which produces short duration rectangular pulsed current, either monophasic or biphasic, with pulse frequencies typically in the range 0-100 Hz. Many of these devices are pocket-size, battery operated units with limited output, intended for pain control and safe for home usage by the patient. Some clinical TNS stimulators have output intensities high enough to elicit a forceful muscle contraction. Here we adopt the common usage definition and use the term 'TNS therapy' to refer to stimulation using short-duration rectangular pulsed current.

The Vectorsurge 5 produces short-duration rectangular biphasic pulses with pulse widths of



50 µs, 125 µs or 200 µs. The pulse frequency is selectable in the range 0-300 Hz and frequency sweeps in this range can also be selected. Figure 6 shows the TNS pulses produced by the Vectorsurge. The biphasic stimulus pulse ensures charge neutrality and no risk of electrolytic effects which could produce skin irritation under the electrodes.

Figure 6: Output stimulus waveforms produced in TNS mode.

The Vectorsurge provides 'top-end' TNS performance by offering:

* pulse width selection down to 50 µs * stimulation frequencies as high as 300 Hz together with the ability to set a sweep

range* surging of the output* an output intensity high enough to meet all clinical needs.

8.2.2 Effect of Pulse Width

If skin surface electrodes are attached to a patient and stimuli of increasing intensity are applied, three distinct responses may be obtained. Each response has a different threshold for its onset.

As the stimulus intensity is increased the first response normally noticed is sensory. The patient perceives the electrical stimulation before any muscular or pain response is elicited. A further increase in intensity will result in the onset of either a motor response or pain. This depends on the electrode placement. Motor fibres have larger diameters than pain fibres and are intrinsically more easy to stimulate but if the motor fibres are deeply located, pain fibres closer to the electrodes may be stimulated first. If the electrodes are placed over a motor point i.e. a point where the motor nerves are located superficially, then the order of stimulation will normally be sensory then motor then pain.

The sequence of responses and their separation in terms of the intensity required actually depend on four factors: the placement of electrodes, the electrode size, the stimulus pulse width and the stimulus frequency.

* Electrode placement is important in that to obtain a pronounced motor response, without pain, the electrodes should be over a motor point or region where the motor nerve supply is located superficially.

* The electrode size should be as large as possible to avoid concentrating the current in a small superficial region and preferentially stimulating pain fibres in the region.

* The stimulus pulse width should be sufficiently small. Experimentally it has been shown that best discrimination between sensory, motor and pain responses is



achieved using relatively narrow stimulus pulses. This point is discussed further below.

* The stimulus frequency would be expected to influence discrimination because the nerve fibres associated with sensory, motor and pain responses have different refractory periods. To date, no studies of discrimination as a function of pulse frequency have been published.

The importance of pulse width was highlighted in studies by Alon et al7 and Howson8. The differences in electrical characteristics of nerve fibre types and their different depths of location in tissue results in separate strength-duration curves for sensory, motor and pain responses. Representative curves similar to those obtained by Alon et al7 and Howson8 are shown in figure 7. Both of these studies used electrodes placed over a motor point so that the order of stimulation was sensory, motor, then pain. The (peak pulse) current required to reach each threshold was measured for a range of pulse widths in the range 5 µs to 1000 µs (1 ms).

Two things are apparent from the graphs shown. First that the order of stimulation is sensory, then motor, then pain at all pulse durations. Second, that as we go to smaller pulse widths the separation between the curves increases.

Figure 7: Strength-duration curves for sensory, motor and pain responses.

It is clear that as one goes to smaller pulse widths the ease of discrimination between sensory, motor and pain responses is increased.

This observation regarding pulse width has an important practical implication for therapy. If long duration pulse widths are used then smaller changes in intensity will be needed to change from a sensory response to a motor or pain response. If short duration pulses are used, much larger changes in intensity will be needed to recruit motor and pain fibres. So if the objective is to produce a sensory response with minimal motor or pain responses then short duration pulses are preferred. Short duration pulses will also be capable of producing an effective motor response with minimum pain sensation.

To the extent that pain modulation is achieved by the activity of sensory fibres, with greater



sensory activity inhibiting pain perception, we have an explanation as to why sensory nerve fibre stimulation reduces the sensation of pain. Even without a proven and comprehensive explanation in terms of neurophysiological mechanisms, it has been established empirically that the sensation of pain can be reduced by sensory stimulation in various forms. A variety of different stimuli including massage, heat, ice, lineaments and TNS have been implicated in reducing the subjective sensation of pain. The common factor is sensory stimulation. Sensory nerve fibre stimulation has thus been established as serving an important role in pain suppression. By using relatively narrow pulses (50 µs or less), selective stimulation of sensory fibres can be achieved. Thus short duration pulses can be argued to be most effective for pain control via stimulation of sensory neurones.

8.2.3 Effect of Pulse Frequency

Pulse frequency is important as different physiological responses are produced in different frequency ranges. Sensory fibres can respond to higher frequency stimuli than can motor or pain fibres. At low frequencies, sensory, motor and pain fibres can be stimulated with each stimulus pulse of current. As the frequency is increased, pain and motor fibre responses do not keep track with the electrical stimuli. Above approximately 10 Hz, pain fibre activity ceases to increase. Above approximately 100 Hz, motor fibre activity becomes less than the stimulus frequency. Sensory fibres continue to fire in response to each pulse of current but the pain and motor fibres do not. Hence, while sensory nerves will continue to produce action potentials at relatively high frequencies (by biological standards), pain and motor nerves reach an upper limit to their firing at appreciably lower frequencies.

The effect of rectangular pulse stimulus frequencies well above 100 Hz has not been examined in any detail but the balance of evidence suggests that the higher the frequency, the greater the selective stimulation of sensory fibres. By producing a maximum rate of firing of sensory fibres, maximum inhibition i.e. gating, of pain fibre signals is achieved.

For therapeutic applications, three frequency ranges are distinguished.

The sub tetanic frequency range: 0-15 Hz.

This is the frequency range associated with a gentle prickling sensation at the sensory level and twitch muscle contractions at the motor level. For a gentle twitching, tugging motor response, such as might be used to increase blood flow, this frequency range can be used. The output can be continuous (no surging is needed) as the motor response is discrete, rather than tetanic.

This is also the frequency range over which pain fibres operate. Pain fibres, because of their small diameter, conduct nerve impulses at relatively low speed and fire at low frequencies. That pain control can be effected by electrical stimulation has been demonstrated in a number of clinical studies. Low stimulus frequencies (1-15 Hz) have been reported as effective, as have higher frequency stimuli (80-150 Hz). The physiological explanation is different for each.

In the case of low frequency stimulation, pain relief is though to be achieved by pain fibre stimulation, resulting in adaptation at the cortical level and suppression of the response to pain fibre input. To obtain effective stimulation of pain fibres requires a long duration stimulus pulse (> 100 µs, see figure 7) rather than the short duration pulses intended for selective stimulation of sensory nerves. The maximum pulse width of the Vectorsurge, 200 µs, should be selected for this purpose.

The tetanic frequency range: 30-80 Hz.

As the stimulation frequency is increased, the motor response produced at sufficiently high intensities changes from a twitch response to a fused motor, or tetanic, response. Slow twitch muscle fibres fuse at frequencies as low as 20-30 Hz, while fast twitch fibres do not fuse until the frequency is 50 Hz or more. Thus for a smooth, forceful muscle contraction, frequencies in the range 30-80 Hz are needed. Higher frequencies are not normally used for muscle contraction as the rate of fatigue increases with increasing frequency. For a sustained motor



response with minimum fatigue, the lowest frequencies which can produce a fused contraction are to be preferred.

When frequencies in this range are used, the output is normally surged to allow periods of rest between periods of contraction. A surge rise time of a 1 or 2 seconds or more should be chosen to avoid startling the patient. The surge fall time is normally unimportant and can be set to zero.

To work the muscle hard, for example to reduce the rate of atrophy of immobilized muscle, the surge on time should be equal to the combined rise, fall and off times. This produces an effective stimulation to rest ratio of 1:1 as most of the rise and fall time results in negligible force production.

The analgesic frequency range: 80 Hz and above.

In the case of higher frequency stimulation (80 Hz and above), electroanalgesia is believed to be produced by pain impulse modulation. The theory is essentially that stimulation of sensory fibres results in inhibition of transmission of pain fibre signals to the brain. If pain fibres only are active, the brain interprets the signal as pain and a pain sensation is perceived. If sensory fibres are also activated the sensation perceived is modified because less pain fibre signals are transmitted. The sensory fibre signals are able to 'gate' the transmission of pain fibre signals through neural integration of the nerve fibre signals. The greater the sensory input, the less sensitive the central nervous system is to pain fibre activity.

Electrical stimulation is routinely used for pain control, though the neurophysiological mechanism has not been fully explained. It is known that short duration stimuli (200 µs or less), administered at relatively high frequencies by biological standards (100 Hz or

more) are effective in reducing pain. The effect is not produced by suppressing pain fibre activity as such but rather by suppressing the subjective sensation of pain which is registered by the brain.

The perception depends on the totality of signals supplied by the different receptors and is explicable in terms of inhibitory and excitatory synapses in the nervous system. It is generally accepted that the greater the sensory input, the lower the sensation of pain i.e. the less sensitive the brain is to pain fibre signals. On this basis one might expect that stimulation of sensory nerve fibres at rates close to their maximum firing frequency (up to 300 Hz) would produce a maximum electroanalgesic effect. Motor and pain fibres would be unable to respond at such high frequencies so maximum sensory stimulation, relative to motor or pain, would be produced.

8.3 INTERFERENTIAL TNS THERAPY

In first of these notes (page 37) the depth efficiency of interferential stimulation was described. If two currents are applied to the patient, the region of greatest current density and hence greatest stimulation will be at the intersection of the two current pathways. By applying two currents at right angles, maximum stimulation is produced in deeply located tissue rather than in the superficial tissue beneath each electrode. Figure 1(a) shows the clover-leaf pattern of stimulation which is produced in the region where the two interferential currents combine. This is in contrast to the relatively superficial stimulation pattern produced in bipolar mode (figure 1(b)).

Conventional interferential therapy machines produce two channels of medium (kHz) frequency alternating current which are applied to the patient using a quadripolar technique to produce the clover-leaf vector field. The currents summate to produce a beat frequency signal within the patient's tissue. Figure 5 shows how this is achieved using the Vectorsurge.



8.3.1 Obtaining a TNS Interferential Effect

An innovative feature of the Vectorsurge 5 is the ability to produce a clover-leaf pattern of stimulation at depth using a conventional TNS waveform (figure 6). To achieve this effect, an interferential TNS stimulator must have two independent, electrically isolated outputs with the stimulus waveforms perfectly synchronized. Synchrony of the two waveforms is essential so that the currents can add vectorially and reinforce as shown in figure 8.

Currents from the two outputs will summate in the tissue, with a maximum effect being produced in the clover-leaf shaped interference field.

Figure 8: Reinforcement of synchronized currents in tissue.

It is important that the two output channels of the machine be electrically isolated as current will 'take the path of least resistance'. If the channels are not electrically isolated, current will most readily flow between the electrodes which are closest to each other. The interferential effect shown in figure 9(a) will not occur as current will more readily flow between adjacent electrodes than opposite electrodes. Without or with less interference, maximum stimulation is more likely to occur under the electrodes as shown in figure 9(b).

Figure 9: Areas of maximum stimulation in tissue: (a) electrically isolated outputs and (b) not electrically isolated

The stimulation pattern shown in figure 9(b) is no different to that produced by a single channel, bipolar stimulator and using four electrodes.

8.3.2 Using Interferential TNS Therapy



The value of interferential TNS therapy as implemented on the Vectorsurge 5 is that all of the benefits of a high output clinical TNS stimulator are provided together with the ability to produce a region of maximum stimulation which is not restricted to the tissue immediately beneath the electrodes. The depth efficiency of interferential stimulation is

obtained using narrow-pulse, low average energy, TNS stimulation. In addition, the 'focus' control can be used to rotate the vector field and target the area to be treated without having to reposition the electrodes. The therapist can also manually rotate the vector field during treatment, to obtain maximum therapeutic benefit.

8.3.2.1 Energy considerations

Interferential TNS stimulation is advantageous as the average current and total electrical energy delivered to the patient is a minimum. The energy is less because single pulses (figure 6) are used rather than continuous AC (figure 5). In conventional interferential mode, if the peak current is 60 mA, the average current is also 60 mA as the output is continuous AC. For a TNS pulse frequency of 50 Hz and a pulse width of 200 µs, a peak current of 50 mA represents an average current of only 0.625 mA.

For patients with sensitive skin, where relatively high intensity stimulation is required, TNS pulses rather than conventional interferential currents should be chosen as the average current and consequently the average energy delivered to the patient's tissue is less.

Where skin type and sensitivity is less of an issue, and a maximum physiological response is desired, conventional interferential current is the modality of choice.

8.3.2.2 Physiological Responses

Conventional interferential currents and interferential TNS are similar in many respects. Electroanalgesia via stimulation of large diameter sensory fibres is achieved either with high beat frequencies or high pulse frequencies. A tetanic motor response is produced either with beat frequencies of 30-50 Hz and above or pulse frequencies in the same range. Twitch responses are produced at lower frequencies in either case.

The subjective sensations and physiological responses to conventional interferential currents and interferential TNS differ, however, in important respects and this affects the choice of modality for patient treatment. With TNS stimulation, as the frequency is increased the physiological response becomes markedly stronger because the average energy delivered to the patient's tissue increases in direct proportion to the stimulus frequency. Subjectively, the perception of stimulation intensity is greater because even though the pulse intensity is constant, the average energy delivered is greater. Thus if the pulse frequency is set to sweep from say 0-150 Hz, the patient's perception could change from mild at the lower frequencies to very uncomfortable at the high end. This effect is much less pronounced with conventional interferential stimulation as the current from each patient circuit, and the average energy delivered to the patient, remains constant. For this reason if a wide frequency sweep is required conventional interferential stimulation is recommended. For narrower sweep ranges (for example 80-150 Hz or 250-300 Hz), or fixed frequencies, either modality could be used.

We recommend that you apply electrodes to yourself and compare the sensations and responses to conventional and interferential TNS stimulation.



9. REFERENCES

1. Ward, A.R. 'Electricity, Fields and Waves in Therapy' Science Press (1986).

2. Nix, W.A. and Vbrova, G. 'Electrical Stimulation and Neuromuscular Disorders' Springer-Verlag (1986).

3. Moreno-Aranda, J. and Siereg, A. J. Biomech. 14, 579-585 (1981).

4. Ward, A.R. and Robertson, V.J. Arch. Phys. Med. Rehabil. 79, 1399-1404 (1998).

5. Ward, A.R. and Robertson, V.J. Arch. Phys. Med. Rehabil. 79, 273-278 (1998).

6. Kots, Y. Electrostimulation (Canadian-Soviet exchange symposium on electrostimulation of skeletal muscles, Montreal, Concordia University, 1977) Quoted in Kramer J, Mendryk SW. J. Orthop. Sports Phys. Ther. 4, 91-98 (1982).

7. Alon, G. et al. Aust. J. Physio. 29, 195-201 (1983).

8. Howson, D.C. in 'Transcutaneous Electrical Nerve Stimulation' Am. Phys. Ther. Assoc. (1979).

9. Low, J.A. and Reid, M.J. 'Electrotherapy explained'. (2nd ed.) Butterworth-Heinemann Ltd (1994).

10. Nelson, R.M. and Currier, D.P. 'Clinical electrotherapy'. (2nd ed.) Appleton & Lange (1991).



Metron Medical Australia Pty LtdA.C.N.050 240 527

P.O. Box 2164, 57 Aster Avenue

Carrum Downs Victoria Australia 3201Tel: (03) 9775 1234 Fax: (03) 9775 1990Int: 61 3 9775 1234 Int: 61 3 9775 1990

EC DECLARATION OF CONFORMITY

Metron Medical Australia Pty Ltd57 Aster AvenueCarrum Downs, Australia, 3201

declares that the medical devices described hereafter:

Metron Vectorsurge 5Interferential / TNS

Therapy Unit

Models: VS 470

is in conformity with the essential requirements and provisions of Council Directive 93/42/EEC

is subject to the procedure set out in Annex II of Directive 93/42/EEC under the supervision of Notified Body Number 0805, Therapeutic Goods Administration, Office of Devices, Blood & Tissues, Po Box 100 Woden, ACT 2606, Australia

Melbourne, 9th September 2007

Ashley WilliamsManaging Director

Metron Medical Australia Pty Ltd



0805The Metron Vectorsurge 5 Interferential / TNS Therapy Unit bears the above marking in accordance with the requirements of Council Directive 93/42/EEC.

Should you as the purchaser and/or user of this product wish to make any comment about the product or the manner in which it may be used our Authorised Representative within the European Union may be contacted as follows:

Metron Medicalc/- Patterson Medical Limited

Nunn Brook Road,Huthwaite. Sutton in Ashfield,NOTTINGHAMSHIRE, NG17 2HU, UNITED KINGDOM



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