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.
Currentamplitude
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
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.
Currentamplitude
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:
1. Catelectrotonus
2. 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