IDC

(IDC) is used to describe continuous
unidirectional current when it is interrupted to give pulses or phases

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2. Interrupted Direct current 2

3. objectives What is Interrupted direct current Terminologies Wave form types Physiological effects Therapeutic and diagnostic uses General technique of application 3

4. Interrupted Direct Current IDC (IDC) is used to describe continuous unidirectional current when it is interrupted to give pulses or phases of any duration, shape, or frequency. commonly described the currents of long duration (1msec or more). 4

5. ON time The length of time an impulse is allowed to flow. It is the same as pulse duration 50ms 50ms Flow 50ms 5

6. Off time/ Interpulse duration The duration of no flow, is the same as inter-pulse duration 50ms 50ms 50ms No flow 6

7. Rise time/on ramp Is the duration the current takes to reach the desired intensity (0 to desired intensity) Rise time Decay time 7

8. Decay time/off ramp Is the time taken for the current to come down to base line(zero) Decay time 8

9. ELECTRIC PULSE Can be more fully describe according to PULSE DURATION : expressed in seconds INTENSITY : expressed in amperes or volts SHAPE : wave form 9

10. WAVE FORM Describe the rise and fall pattern of a pulse the shape of the wave form reflects the time required for the current to reach to maximum intensity 10

11. WAVE FORM There are two types of long duration interrupted direct current: • 1- Rectangular wave pulses. • 2- Accommodation pulses. 11

12. 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 Wave form with sudden rise in intensity are suitable for innervated muscles 12

13. 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. 13

14. EXCITABILITY OF NERVE SIGNAL RESTING MEMBRANE POTENTIAL CHANGE IN RESTING MEMBRANE POTENTIAL ACTION POTENTIAL GENERATE NERVE EXCITATION 14

15. POLARITY: Cathode is used as active electrode because it causes decrease in potential difference ACCOMODATION: The nerve and muscle tissue posses the property to adapt itself to slowly increasing stimulation intensities. This causes a decrease of excitability of the membrane, and thus requiring more intensity of stimulating current. Nerve fibre has a high accommodation rate. 15

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17. Motor point Is a region of a muscle where a great density of terminal motor end plates is found near the surface. Stimulation of motor point isolate a muscle or segment of a muscle It is generally present at the middle of the longitudinal axis of the muscle 17

18. Electro tonus Sub threshold nerve stimuli do not cause an action potential but they do affect the membrane potential. This phenomenon is known as electro tonus. 18

19. Catelectrotonus : The cathode produces a local depolarizing potential that rises rapidly but falls exponentially with time making the outer nerve membrane surface less positive lowers the threshold, which increases the nerve’s excitability known as catelectrotonus Anelectrotonus : The anode produces hyperpolarization making the outer membrane surface more positive, which has the reverse effect known as anelectrotonus 19

20. Physiological effects of IDC A change in the concentration of ions at the cell membrane when an electric current is passed. The ionic concentration occurring at the nerve membrane causes a muscle contraction 20

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23. Sensory nerve stimulation: Long pulse duration stimulates the sensory nerve and cause stabbing or burning sensation The sensory nerve irritation bring about an increase in dilation of superficial blood vessels which is manifested in the form of erythema 23

24. Motor nerve stimulation: Stimulation of motor nerve cause contraction in the muscle (in form of brisk twitches) Denervated muscle stimulation: IDC of sufficiently long pulse duration are required to produce muscle twitches 24

25. Hyperaemia Since this erythema is confined it indicates a capillary hyperaemia unlike that due to heat in which arteriolar dilatation occurs. The erythema causes vasomotor stimulation and increased circulation may promote improved nutrition of the area and speed up the resolution of inflammatory products . 25

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27. USES THERAPEUTIC: MUSCLE STIMULATION PAIN REDUCTION EDEMA REDUCTION DIAGNOSTIC: testing the electrical activity of muscles. 27

28. Contraindications 1-Skin lesions as cuts and abrasions to avoid the difference of skin resistance which may lead to more concentration of current on some points especially under electrodes causing discomfort and pain. 2- Cardiac pacemaker. 3- Infection to avoid spread of infection by low frequency current. 4- Superficial metal to avoid concentration of current on metal and cause burn. 28

29. GENERAL TECHNIQUE OF APPLICATION FOR IDC PREPARATION OF EQUIPMENT Select the apparatus that provides interrupted direct current impulses. Check to see that: No current is leaking onto the casing. The polarity is marked. The duration of impulses and the frequency controls are available as desired. The current output is smooth. Keep all controls at zero.  Connect wire and electrodes.  Select the appropriate probe, if used.  Make appropriate size of indifferent electrode.   29

30. PREPARATION OF PATIENT.   Have patient in an carefully selected position and that the position is comfortable, the part is adequately supported. Explain the patient in simple words about the treatment, its procedure and what sensation he/she will experience. Explain to the patient the characteristics of muscle twitches. Warn the patient not to touch the machine and not to manipulate any control, especially when both electrodes are tied to patients part. Report any other sensation then explained. Expose only the area to be treated, cover the rest of the body. Inspect the skin, avoid stimulation where the skin has rashes. Test skin sensation for “pin-prick”. Wash the area with soap and water then dry and then soak the area with warm saline for five minutes. Place the indifferent electrode to appropriate area and secure with bandage. 30

31. TREATMENT.   Before switching on the mains and selector switch, check to see that the intensity control is at zero . Select the desired duration of impulse . Set the repetition rate – frequency and rest periods . Turn the main switch and selector switch on . Place the probe near the motor point of the muscle . Give a total of 90 to 120 contractions (twitches) When all required muscles have been treated, switch the apparatus and mains off. Remove the indifferent electrode. Clean the area and note skin reaction, if any. 31

32. FREQUENCY : 1 pps = twitch REST PERIOD : Usually 3-5 sec REPETITIONS: 90-120 REPS TIME DURATION : 20 -30mins 32

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