Low Frequency Therapeutic Currents

Low frequency currents

1. 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

2. Learning Objective To provide students with knowledge and understanding of; a. Faradic current ; b. Galvanic current ; c. Sinusoidal currents ; and d. Diadynamic currents

3. 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.

4. 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 1 st phase having a EMF of 1ms followed by train of damped oscillations with a frequency of 1000Hz. Faradic Type Currents

5. 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.

6. 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.

7. 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.  

8. 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

9. 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

10. 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.

11. 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.

12. 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.

13. 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.

14. 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.

15. 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.

16. 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

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

18. THANK YOU………!