7- Interrupted Direct Current

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    Interrupted directcurrentIDClecture 7

    dr. amal hm. ibrahim

    aebrahim123@hotmail.com

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    Objectives

    To define the different types of IDC.

    To know the IDC current characteristics

    and uses.

    To know the Faradic current characteristics.

    To know physiological effects of faradic

    current. To define the TENS current.

    To know physiological effects of TENS.

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    Interrupted Direct Current

    IDC

    The term interrupted direct current

    (IDC) is used to describe continuous

    unidirectional current when it isinterrupted to give pulses or phases

    of any duration, shape, or frequency.

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    Interrupted Direct Current

    IDC

    Interrupted direct current is

    commonly described the currents oflong duration (1msec or more).

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    Interrupted Direct Current

    IDC There are two types of long duration

    interrupted direct current:

    1- Rectangular wave pulses.

    2- Accommodation pulses.

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    Interrupted Direct Current

    IDC 1- Rectangular wave pulses: pulses of any

    duration between 1 and 600msec separated

    by pulse interval of any duration from 1 to

    many seconds. Used to stimulate sensory and

    motor nerves but it is unique in stimulation of

    denervated muscles.

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    Interrupted Direct Current

    IDC 2- Accommodation pulses: have many types

    like triangular, trapezoidal, and saw-tooth.

    The pulse duration ranged from 300 to

    1000msec. These pulses are used for

    stimulation of denervated muscle.

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    Faradic-type Current

    aebrahim123@hotmail.com

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    Faradic-type Current

    Faradic-type currents are short durationinterrupted direct current of pulses ranged

    from 0.1 to 1ms and frequency of 30 to 100

    Hz. With frequency 100Hz the time for eachcycle is 10ms so, with a 1ms pulse the interval

    period will be 9ms. The waveform of faradic-

    type current may be unidirectional or biphasic

    (asymmetrical)

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    Faradic-type Current

    The faradic-type currents are always

    surged when used for therapeutic

    purposes. The comfortable pulse iseither 0.1ms with frequency 70Hz or

    1ms pulse with frequency 50Hz.

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    Faradic-type Current

    The effective nerve stimulus is

    the spike of the voltage which

    can be about 1ms in duration, therest of the pulse having much

    lower voltage, does not causenerve stimulation.

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    Faradic-type Current

    Faradic current causes a titaniccontraction of stimulated muscle.

    Treatment by faradic current is called

    faradism.

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    Faradic-type Current

    The active electrode should be

    connected to the cathode as muscle

    contraction will be more easily produced

    with less current.

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    Physiological Effects of Faradic-type

    Current1. Stimulate innervated muscles whose motor

    nerves are intact producing titanic

    contraction. The number of motor units

    brought into action will depend on the

    strength of current and placement of

    electrodes.

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    Physiological Effects of Faradic-type

    Current Stimulation of motor points can

    be done by using guide chart

    indicate all superficial muscles of

    body

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    Physiological Effects of Faradic-type

    Current

    As mentioned before if you stimulate muscleby using fixed pad electrodes it is preferableto use constant current to be morecomfortable as the skin resistance fluctuates(change) the voltage will fluctuate tomaintain constant current.

    But if you move the pad, it is better to useconstant voltage because the current will bealtering.

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    Physiological Effects of Faradic-type

    Current2. Stimulation of sensory nerves to

    produce a mild prickling sensation

    for reducing pain feeling

    3. Stimulate motor nerves of large

    proximal muscles to reduce edema.

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    Clinical Uses of Faradic-type

    Current

    Faradic-type current is still frequently applied

    in the form of functional electrical stimulation

    (FES). In this technique the application of the

    faradic current is combined with the patient

    activity.

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    Clinical Uses of Faradic-type Current

    1. Facilitation of muscle contraction

    inhibited by pain like post operative

    or post-traumatic inability to achievevoluntary contraction of certain

    muscles.

    2. Early stage of muscle re-

    innervation.

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    Clinical Uses of Faradic-type Current

    3. Treatment of hysterical paralysis.

    4. Treatment of atrophied and weak

    muscles following long duration

    immobilization.

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    Clinical Uses of Faradic-type Current5. Treatment of muscle

    imbalance as in faulty posture

    (flat foot and scoliosis).

    NOTE: Faradic-type currents

    never used to stimulate

    denervated muscles.

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    Contraindications1- Skin lesions as cuts and abrasions

    to avoid the difference of skin

    resistance which may lead to moreconcentration of current on some

    points especially under electrodes

    causing discomfort and pain.

    2- Cardiac pacemaker.

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    Contraindications 3- Infection to avoid spread of

    infection by low frequency current.

    4- Superficial metal to avoidconcentration of current on metal

    and cause burn.

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    Transcutaneous ElectricNerve StimulationTENS

    aebrahim123@hotmail.com

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    Transcutaneous ElectricNerve StimulationTENS

    Transcutaneous electrical

    nerve stimulation (TENS) is anon invasive modern

    electrical method of

    managing both acute (short

    term pain) and chronic (long

    term pain).

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    Transcutaneous ElectricNerve StimulationTENS

    It is used for providing a degree

    of pain relief (symptomatic) by

    stimulating sensory nerves.

    TENS is an alternating current

    characterized by variable phase

    duration and a variable phase

    interval which can be used to

    vary frequency

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    Electrotherapy: Evidence-based Practice

    By Sheila Kitchen, Sarah Bazin, Edward Bellis Clayton

    Contributor Sheila Kitchen, Sarah Bazin

    Published by Elsevier Health Sciences, 2002

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    Transcutaneous ElectricNerve StimulationTENS

    The phase duration is very short, varying from

    0.01 to 0.4ms. The frequency is usuallyvariable and ranged from 2 to 200Hz. The

    maximum peak current is about 100mA.

    Although it is a small current but it is sufficient

    because the primary target for the therapy is

    the sensory nerves.

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    Electrotherapy: Evidence-based Practice

    By Sheila Kitchen, Sarah Bazin, Edward Bellis Clayton

    Contributor Sheila Kitchen, Sarah Bazin

    Published by Elsevier Health Sciences, 2002

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    Transcutaneous ElectricNerve StimulationTENS

    1- Conventional TENS

    It is a current withhigh frequency from

    50-100Hz, pulse

    duration around0.05ms and low

    intensity Electrotherapy: Evidence-based PracticeBy Sheila Kitchen, Sarah Bazin, Edward Bellis Clayton

    Contributor Sheila Kitchen, Sarah Bazin

    Published by Elsevier Health Sciences, 2002

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    Transcutaneous ElectricNerve StimulationTENS

    1- Conventional TENS

    The intensity is turned up slowly until a prickling or

    tingling sensation