Modified galvanic current

1. Modified Galvanic Current
DR RIAZ AHMED PT
LECTURER

2. Definition
 Interruption is the most common modification of
Direct current, the flow of current commencing and
ceasing at regular intervals.

3. Production of Interrupted Direct
Current
 Production of interrupted direct current involves
following:
 Source of IDC
 Transistors: a semiconductor device with three
connections, capable of amplification in addition to
rectification.
 Potential divider
 Timer circuit (Timer device)

4. Duration & Frequency of IDC
 The duration and frequency of the impulses can be
adjusted,
 a duration of 100ms being commonly used, although it is
often an advantage to increase this to 300 to 600ms
 Frequency of the current reduces with increase in the pulse
duration.
 Pulse duration of 100ms will have frequency of 30
cycles/minute.
 The interval between the impulses should never be shorter
duration than the impulses themselves and is usually
appreciably longer.

5. Types of IDC
 Currents produced for therapeutic purposes may have
sudden or gradual fall, hence depending on this there
are several types, which are as follows:
 1) Rectangular (sudden fall of intensity)
 2)Trapezoidal (gradual)
 3)Triangular(……………)
 4)Saw-tooth (……………)
 5)Depolarized : some equipment for low intensity
reversed current between the impulses giving called
depolarized impulses.

7. Physiological Effects of IDC
 Following are the physiological effects of the
interrupted direct current:
1. Sensory Stimulation
2. Hyperemia
3. Elecrotonous
4. Pain relief
5. Acceleration of healing

8. Sensory Stimulation
 During the passage of direct currents the patient is
aware of a mild tingling or prickling sensation, which
may merge into a mild irritation or itching.

9. Hyperemia
 If sufficient current has passed for long enough an
erythema of the skin will be evident under both
electrodes, and is more marked under the negative
(cathode).
 This erythema is confined to the area of the
applied electrode.
 Since this erythema is confined it indicates a capillary
hyperemia.

10. Electrotonus
 Sub threshold nerve stimuli do not cause an action
potential but they do affect the membrane potential. This
phenomenon is known as electro tonus.
OR
 the altered sensitivity of a nerve when a constant current
of electricity passes through any part of it
 catelectrotonus. : the local depolarization and increased
irritability of a nerve in the region of the negative
electrode or cathode on the passage of a current of
electricity through it .
 anelectrotonusThe condition of decreased irritability of a
nerve in the region of the positive electrode or anode on
the passage of a current of electricity through it.

11. Pain relief
 Strong sensory stimulation blocks the pain
transmission at the level of spinal cord by pain gate
theory.
 The hyperaemia occurring may help to remove the
nociceptive substances and thus reducing pain.

12. Acceleration of healing
 Electrical stimulation by direct current enhances
healing process.
 It leads to increase bone formation and accelerate
healing when current is applied through implanted
electrodes.
 It has also got effects on healing of superficial and
open wounds

13. Therapeutic Effect
1. Stimulation of Denervated Muscle
2. Sensory Stimulation
3. Hyperemia
4. Pain relief
5. Acceleration of healing

14. Stimulation of Denervated Muscle
 Types of Denervated muscle fibers
 Neurotmesis (complete denervation)
 Axonotmesis (partial denervation)
 Neurapraxia (compression of nerve)

15. Changes in Denervated Muscles
 When the muscles are denervated the following changes
will occur.
Loss of voluntary contraction and reflex
activities
Atrophy: Resulting in fibrosis
Fibrillization: Spontaneous contraction
 There is marked wasting of the muscle fibers and if the
degeneration is of long standing they tends to become
fibrosed and to loss the properties of irritability,
contracability, extensibility and elasticity.

16. Advantage
 The purpose of such current is to maintain the
muscles in as healthy state as possible to prevent the
complication by electrically artificial contraction.
 If some of the motor units (motor end plate + motor
nerve + muscle fibers) are intact galvanic current is the
choice of treatment.
 Interrupted direct current is still recommended for the
treatment of Axonotmesis and Neurotmesis nerve
repair is to be taken.

17. Contraindications
 Skin lesions
 Impaired cognitive ability
 Pregnancy (1st trimester)
 Over Carotid sinus
 Loss of sensation.
 Cancer.
 Cardiac pacemakers.
 Superficial metals

18. Equipment preparation
 No current leaking on to the casing •
 Polarity is marked •
 Duration of impulse and frequency of impulse
controls are available desired •
 Keep all control at zero •
 Connect wire and electrode •
 Select the appropriate probe if used •
 Make appropriate size if indifferent electrode

19. METHODS OF TREATMENT
 Patient preparation • Pt position is comfortable ,the part is
adequately supported •
 Explain the patient in simple words about the treatment
(procedure and sensation) •
 Explain Pt characteristics of muscle twitches •
 Warn the patient not to touch the machine and not to
manipulate any control(when both electrode are tried to
Pt part • Report any other sensation

20. CONT;
 Expose only that area to be treated cover the rest of the
body. •
 Test skin sensation for ‘’pin –prick’’ •
 Inspect the skin , avoid stimulation when the skin has
rashes •
 Wash the area with soap and water then dry and then
soak the area with warn saline for 5 mint •
 Place the indifferent electrode to appropriate area and
secure with bandage

21. TREATMENT
 Inform Patient That You Are Going To Commence The
Treatment Obtain Content •
 Before Switching On The Mains And The Apparatus
Check To See That All Controls Are At Zero •
 Turn The Main Switch And Control Switch On. •
 Increase The Intensity Very Slowly Till You Get The
Desired Strength Of Muscle Contraction

22. Cont,…
 note the sensation reported by the patient •
 set the duration (time )of treatment •
 remain with in the calling distance from the patient a call
bell can be gives to patient •
 At the end of the treatment time turn the intensity control
slowly to zero then switch the apparatus and the mains
off •
 Remove terminals from the apparatus •
 Undo bandage to remove electrodes • Inspect the skin
and make a note of any reaction