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Interrupted directcurrentIDClecture 7
dr. amal hm. ibrahim
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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
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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
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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 is felt without painful feeling ormuscle contraction.
This current with low intensity, high frequency will
stimulate large low threshold mechanoreceptors A
fibers which go up in the spinal cord without synapse
and give collateral to A and C fibers to inhibit them.
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1- Conventional TENSThis mechanism is called pre-synaptic
inhibition by Hi-TENS or traditional or
conventional TENS. Conventional TENS isused for self treatment with
recommended duration from 30 to 60
minutes, once or twice a day or may beused for all 24 hours of the day.
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2- Acupuncture-like TENS
It is high intensity low frequency (less than10Hz, commonly 2-4Hz), with pulse duration
of around 0.2ms. The intensity is very high
close to the patient tolerance to stimulate Aand C fibers leading to the release of
endorphins and encephalin.
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The acupuncture-like
TENS is applied to
acupuncture point
which is
considered as a
place where a
small bundle of A
and sympathetic
efferent fibers
pierce the deep
fascia to becomemore superficial
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Acupuncture-like TENS is appliedonce per day for 20 to 30 minutes.Although this type of TENS is more
effective than conventional TENS, but
many patients can not tolerate the
high intensity. The acupuncture TENS
is applied for patient who do not
respond to conventional TENS.
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3- Burst TENS Burst TENS consists of a train or burst of pulses of2Hz (some times varying from 1-5Hz). Each burstlasts for 70 ms and as the internal frequency of the
bursts is at the usual conventional TENS frequency of
50- 100Hz, this result in release of endorphins at the
central level which have a pain reducing effect.
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Burst TENS is combines both
conventional and acupuncture-like TENS
and therefore provides pain relief byboth routs. Burst TENS is practically
suitable for the treatment of deeper-
lying painful regions (myofascial pain)and cases of chronic pain.
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The treatment duration is upto 30 minutes to be effectiveand treatment can be
repeated during the same
day.
http://2.bp.blogspot.com/-VHQQK3giI44/TezbVkNWU4I/AAAAAAAAAAc/fcbqJHVyw9s/s1600/tens-use.jpghttp://2.bp.blogspot.com/-VHQQK3giI44/TezbVkNWU4I/AAAAAAAAAAc/fcbqJHVyw9s/s1600/tens-use.jpghttp://2.bp.blogspot.com/-VHQQK3giI44/TezbVkNWU4I/AAAAAAAAAAc/fcbqJHVyw9s/s1600/tens-use.jpg7/27/2019 7- Interrupted Direct Current
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4- Modulated TENS In modulated TENSthe pulse width,frequency and
intensity are all
constantly andautomatically
varied. This type of
TENS is useful for
prevent adaptation
of the nerve to the
current.
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Application of TENSBefore applying TENS to any patientyou must make pain assessment to
evaluate the treatment results. There
are many methods for pain
assessment, the common subjective
way is known as visual analogue scale
or VAS.
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Application of TENSVisual analogue scale or VAS. (on which a 10 cm line,
start with no pain, in its middle tolerable pain and at
the end worst pain) and the patient marks the
intensity of pain between no pain and worst pain).
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Another subjective method is faces at which there
are six faces start with happy face and end with very
angry and crying face, the patient chose one who islike. The only objective way of pain assessment is the
measurement of range of motion.
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Electrode Placement Over painful points.
Over dermatome, myotome, or sclerotome.
Trigger or acupuncture points which can be
located by their lower resistance compared withsurrounding skin. To determine acupuncture
point we use an electronic probe.
Electrodes are placed over the line of nerve
superficially.
Electrodes are covered with gel and fixed to the
skin with adhesive tape or bandage. Electrodes
may be self adhesive and gelled.
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Indications
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Contraindications Undiagnosed pain.
Pregnancy (especially during first three
months of pregnancy).
Heart pacemaker.
The eyes or near to them.
Over carotid sinus to avoid cardiacarrhythmias.
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Contraindications Over pharyngeal region to avoid interfere
with normal breathing and swallowing.
Skin lesions or wounds (different
resistance).
Over non sensation area.
With implanted hear aid.
Over infected or inflamed area.
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Questions?????