Interrupted direct current

presented by Sana Shahzad , student of DPT at SBB Dewan University Karachi

1. INTERRUPTED DIRECT CURRENT SHAHEED BENAZIR BHUTTO DEWAN UNIVERSITY Presented by Sana Shahzad DPT Batch II Roll no B-22

2. INTRODUCTION The term interrupted direct current is used to describe continuous unidirectional current when it is interrupted to give pulse or phases of any duration, shape or frequency. Current amplitude Time

3. Interrupted direct current may be Short duration pulse Such pulse whose duration is less than 1 msec. Long duration pulse Such pulse whose duration is equal to or greater than 1 msec.

4. TYPES OF IDC  There are two types of IDC Rectangular wave pulse. Accommodation pulse.

5. RECTANGULAR WAVE PULSE:- Sudden rise and fall of intensity will lead to rectangular wave pulse. Duration may be 1 ms to 600 ms Used to stimulate the innervated muscles fiber and nerve fiber. Current amplitude Time

6. ACCOMMODATION PULSE:- Gradually rise and fall of intensity will lead to accommodation pulse. It may be triangular, trapezoid and saw tooth. Its duration is about 300 ms to 1000 ms. It is used to stimulate the denervated muscles fiber and nerve fiber. Trapezoid Triangular Saw-tooth

7. PHYSIOLOGICAL EFFECTS OF IDC STIMULATION OF SENSORY NERVE:- Rise in interrupted direct current will give stabbing and burning sensation. Dilation of superficial blood vessels. Erythema of the skin.

8. STIMULATION OF MOTOR NERVE. Contraction of muscle occur. Repetitive stimulation cause burst of muscle twitch followed by immediate relaxation.

9. SELECTION OF IMPULSES. FOR NERVE FIBER Short duration pulses from (0.02 ms-1ms )interrupted current will cause depolarization generation of action potential and induce a muscle contraction • When longer duration pulses are used the intensity of current required to produce muscle contraction is reduce • More current will be required if an impulse duration of shorter than 0.1 ms is used

10. FOR MUSCLE FIBER Muscle fiber do not respond to shorter duration stimulus at a tolerable intensity of current • Pulse duration of (0.02 to 1ms) do not cause excitation and muscle contraction unless very high intensity of current is given • Thus shorter the duration of impulse the higher the intensity needed to produce muscle contraction.

11. METHODS OF APPLICATION ELECTROTONUS:- Electrotonus means the electrical and excitability changes with occur in the nerve membrane due to its stimulation by a IDC. TYPES OF ELECTROTONUS: Catelectrotonus Anelectrotonus

12. ANELECTROTONUS: Anelectrotonus means the changes which occur at the region of anode. The RMP increase by addition of more positive charge on outer surface of membrane i.e , localized area of hyperpolarization . It is associated with decreased excitability so stronger stimuli are needed to excite the nerve fiber. CATELECTROTONUS:- Catelectrotonus means the changes which occur at region of cathode. The RMP decreases by addition of more negative charge on outer surface of membrane i.e , localized area of depolarization. It is associated with increase of excitability.

13. INDICATIONS Electrical stimulation strong enough to produce contraction. The duration of treatment should not be excessive as it will lead to muscle fatigue. Comfortable pulse duration should be used.

14. Any Question?

15. Thank you