AVANIANBAN CHAKKARAPANI

Lecture 5

Date:19.01.15

Time: 14.00 to 15.00

Venue: K342, UTAR, Bandar Sungai Long

TYPES OF LOW FREQUENCY

THERAPEUTIC CURRENTS

Learning Objective

To provide students with knowledge and

understanding of;

a. Faradic current;

b. Galvanic current;

c. Sinusoidal currents; and

d. Diadynamic currents

Learning Outcome

After successful completion of this topic students should be able to;

1. Explain the different types of therapeutic

currents namely, faradic, galvanic, sinusoidal

and diadynamic currents;

2. Describe the pulse characteristics, frequency

and dosage of the currents discussed;

3. Explain the uses of the currents discussed; and

4. Apply the different currents in real life situation

for treatment purposes.

Technical notes:

1. It is an alternating current named after

inventor Michel Faraday.

2. This unevenly alternating current consists

of 2 unequal phases in each cycle, with

the 1st phase having a EMF of 1ms

followed by train of damped oscillations

with a frequency of 1000Hz.

Faradic Type Currents

3. This short duration interrupted surged direct

and alternating currents are capable of

producing tetanic contraction.

Summary:

Faradic current is a short-duration interrupted

current, with a pulse duration ranging from 0.1

and 1 msec and a frequency of 50 to 100 Hz.

Faradic currents are always surged for treatment

purposes to produce a near normal tetanic-like

contraction and relaxation of muscle. Current

surging means the gradual increase and

decrease of the peak intensity.

Pulse Shape: Saw tooth, triangular or

trapezoidal.

Pulse length: 0.02 to1.0 ms.

Current frequency: 50 to 100Hz.

Pulse type: Unsurged or plain

faradic, surged faradic,

interrupted surged faradic.

Dosage: 15 to 20 contraction per

nerve trunk and or per

motor point of each

individual muscle per day.

Cease when voluntary

contraction is achieved to

a maximum of 90

contraction in summation.

Forms of faradic current Each represents one impulse:

1. In surged currents, the intensity of the successive impulses

increases gradually, each impulse reaching a peak value greater than

the preceding one then falls either suddenly or gradually.

2. Surges can be adjusted from 2 to 5-second surge, continuously

or by regularly selecting frequencies from 6 to 30 surges / minute.

Rest period (pause duration) should be at least 2 to 3 times as long as

that of the pulse to give the muscle the sufficient time to recover (regain

its normal state).

3.The most comfortable pulse is either 0.1-msec pulse, with a frequency of

70 Hz or 1-msec pulse with a frequency of 50 Hz.

1. For Stimulating Innervated Muscle.

2. Re-education Of Muscle Action.

3. Train New Muscle Function.

4. Strengthen Healthy Muscle.

5. Prevent Disuse Atrophy.

6. Maintain Or Improve Joint Mobility.

7. Prevent Or Stretch Adhesions.

8. Promotes Peripheral Circulation.

9. Prevent Fibrotic Changes.

10. Provide Proprioceptive Feedback.

Uses

Technical notes:

1. It is a direct current named after inventor

Dr.L. Galvani.

2. Its direction of polarity is constant and passing

continuously in one direction only, so termed as

constant direct current.

3. Because of its unidirectional property, when

applied to a muscle tend to contract and

remain in that position till it is brought to zero,

which seems to be very painful.

GALVANIC CURRENT

4. To relieve this a relaxation period is advisable and so the

current thus applied in a form of short duration with

regular pulse between two consecutive pulses where the

polarity is altered.

5.This altered polarity, paused, constant current is termed as

interrupted depolarized direct current or Interrupted

galvanic current.

6. The Constant Direct Current(CDC) is generally used for

iontophoresis and Interrupted Galvanic Current(IGC) is

generally used for denervated muscle stimulation in

regular clinical practice.

Pulse Shape: Saw toothed, triangular,

trapezoidal, rectangular

and depolarized.

Pulse lengths: 0.1 to 600 ms.

Current frequency: 30 impulses per

minute(also

variable) repetitions.

Pulse type: constant direct current, interrupted

direct current, surged interrupted

direct current, depolarized direct

current, surged interrupted

depolarized direct current.

Dosage: A regular 20-30 contractions with an

average of 90- 200 contractions per

muscle per day. Cease when motor

point responds to faradic current.

Uses:1. Constant direct currents are used for iontophoresis

2. Modifide direct current are used to stimulate denervated

muscles.

3. Maintain the properties of muscle.

4. Retards the denervation atrophy.

5. Helps the muscle to utilize all the substances and maintain

nutrition.

6. Improves absorption and activates pumping function of

muscle.

7. Prevents venous and lymphatic stasis.

8. Maintain the working hypertrophy of denervated muscles.

9. Maintain the extensibility of the muscles.

10.Improves local circulation.

11.Prevents contracture.

Sinusoidal currents :

Sinusoidal currents are evenly alternating wave

currents of 50Hz, the form of the mains current

(shown in fig below). This gives 100 pulses or

phases in each second of 10 ms each, 50 in

one direction and 50 in the other. It can be

produced from the mains by reducing the

voltage to 60 or 80 V with a step-down

transformer.

Diadynamic currents

Diadynarnic currents were introduced by Pierre

Bernard nearly 60 years ago.

These currents are basically variation of

sinusoidal currents and the waveform involves

single or double- phase rectification of an

alternating current.

For therapeutic purpose these currents are

made available in five different forms.

Fixed Monophase(MF): This is a half wave rectified alternating

current with a frequency of 50 Hz.

Fixed Diphase (DF): This is a full wave rectified alternating

current with a frequency of 50 Hz.

Short Pulse (SP): Equal phase of DF & MF are alternated

without intervening phases.

Long Periods(LP): This consists of 10s phases of MF

followed by a 5s phases of DF in which

the peak intensity is varied, with a

general tendency to rise and fall

Rhythmic Syncop:This consists of 1s phase of MF followed by a1s

rest phase.

THANK YOU………!