1. LFC: Alternating Currents
Minerva Zaniebeth A. Gomez, PTRP
Department of Physical Therapy
College of Allied Medical Professions
University of the Philippines-Manila
All rights reserved. Copyright by MZAG, Use exclusively for PT 158: Physical Agents iII. Approval and consent from Minerva Zaniebeth A. Gomez and University of the Philippines-Manila required before use for other purposes.

2. Learning Objectives: Describe Alternating Currents (AC) according to:
Physical properties
Classification
Uneven (Faradic currents)
Even (Sinusoidal currents)

3. Identify the physiological effects and therapeutic effects of:
a. Uneven AC
b. Even AC

4. Differentiate the precautions/ contraindications of:
a. Uneven AC
b. Even AC

5. Select appropriate treatment parameters for indicated cases/ conditions.
a. Uneven AC
b. Even AC

6. Describe Functional Electrical Stimulation and its therapeutic uses.
Select appropriate treatment parameters when using FES for different cases/ conditions.

7. Appreciate evidence on the use of FES

8. ALTERNATING CURRENT FARADIC Uneven AC SINUSOIDAL Even AC Freq:50 Hz
PD: 1 ms
Freq: 50 Hz
PD: 10 ms
Cont.
Interrupted
Cont.
Interrupted

9. Alternating Current
Periodic changes of the direction of electron flow in a rhythmic manner  NO NET ion transfer
Frequency used medically is 50 Hz
When an AC flows in a conductor, the total number of electrons that move in one direction = the total no. of electrons that move in the reverse direction. Hence, if ions in a solution is energised by the AC, they will just move to and fro between the electrodes and no net ion transfer will occur.
Will not cause chemical burns compared to DC. Ions that move one way during one phase of current and reverse in direction during the other phase, so chemicals formed during one phase is neutralized by the next phase.

10. Alternating Current
Not possible to cause burns, unless in high intensities
Surged or unsurged
When an AC flows in a conductor, the total number of electrons that move in one direction = the total no. of electrons that move in the reverse direction. Hence, if ions in a solution is energised by the AC, they will just move to and fro between the electrodes and no net ion transfer will occur.
Will not cause chemical burns compared to DC. Ions that move one way during one phase of current and reverse in direction during the other phase, so chemicals formed during one phase is neutralized by the next phase.

11. Uneven AC/ Faradic Two phases PD: 1 ms No polarity needed Surged
Mild prickling sensation
Faradism- production of uneven alternating current through an induction coil.
Two phases: because it uses a frequency of 50 Hz followed by a damped oscillation of 1000 Hz (intensity is too low to cause excitation)
Surging: to control peak intensity to produce a near normal tetanic-like contraction and relaxation of muscle.

12. Uneven AC/ Faradic NO chemical effects
Similar to physiological effects of faradic type currents
Indication and contraindication is the same with faradic-type currents/ SIDC
Indication: Pain, swelling , facilitate muscle contraction inhibited by pain
Contraindication: BOILDS + acute inflammation, thrombus formation, psych pt, metals

13. Even AC/ Sinusoidal Sine curve PD: 10 ms Surged or unsurged
No polarity needed
Surged: to stimulate a muscle. Apply over the nerve supplying the muscle
Unsurged: to stimulate a nerve.

14. Indications and Contraindications
Indication: Swelling and pain EXCEPT referred & psychosomatic type
Contraindication: Skin lesion, Infection, Impaired sensation
Pain and swelling: except in cases of referred pain and psychosomatic pain.

15. Physiological Effects
Sensory nerves: Marked prickling sensation  longer duration
Motor nerves: Tetanizes, with a sequence of contraction followed by relaxation
NO chemical effects

16. Physiological Effects
Swelling: Absorption of exudate
Circulation: Superficial vasodilation via axon reflex (capillary vasodilation)  hyperaemia
Vasodilation occurs because of sensory nerve stimulation. Capillary vasodilation occurs if stimulation is prolonged

17. Therapeutic Effects of Even and Uneven AC
Facilitate muscle contraction
Re-educate muscle action
Train new muscle action
Exercise for paralyzed muscles
Hypertrophy
Increase strength
Improve circulation
Prevent and loosen adhesions
Give as a group activity
Facilitate muscle contraction
Re-educate muscle action
Train new muscle action
Exercise for paralyzed muscles
Hypertrophy
Increase strength
Improve circulation
Prevent and loosen adhesions
Train new muscle action: after tendon transplant/ reconstruction, the muscle may be required to perform a different action from that of before.
Exercise for paralyzed muscle: in cases of neuropraxia only since the nerve is still intact in this case. A faradic response indicates that there is nerve recovery already.

18. TECHNIQUES OF APPLICATION

19. Functional Electrical Stimulation
Functional NMES
Used for:
-disuse atrophy
- impaired ROM
- ms spasm
- ms reeducation
- spasticity
- supplement to orthotic devices

20. FES for Shoulder Subluxation
Waveform: Asymmetrical biphasic square
Modulation: Interrupted
Electrodes are placed on supraspinatus or posterior deltoid

21. FES for DF Assist in Gait Training
Waveform:
Assymetrical biphasic square
PD: µsec
Modulation:
interrupted by foot switch

23. FES for Scoliosis Management
Selection Criteria:
Curves measuring deg. (Cobb)
At least 1 year of spinal growth remaining
An idiopathic and progressive nature of the curve
Cooperative and psychologically stable
Compliant and tolerant to stimulation
Usually applied over the stretched muscles on the convex side of the curve for 7-8 hours during sleep.

24. Evidence in Practice
Can FES help improve UE motor recovery of a patient at acute-subacute phase post-stroke?
Minerva Zaniebeth A. Gomez, PTRP, PT 158 faculty AY Ma. Liezel Bumanglag, Justine Charlotte Garcia, Marinelle Rabang, Michiko Alla Uy
Pomeroy V. M., King, L., Pollock, A., Baily-Hallam, A., and Langhorne, P. (2006). Electrostimulation for promoting recovery of movement or functional ability after stroke. Cochrane Database of Systematic Reviews 2006, Issue 2. Art. No.: CD DOI: / CD pub2.

25. FES of hand extensors

26. Evidence in Practice
There is significant change in upper extremity function with the use of electrical stimulation compared to no treatment.
Low internal validity (single studies)  low power
Statistical pooling not possible because of the heterogeneous characteristics of studies included.

27. Evidence in Practice Wide confidence interval crosses zero point
Heterogenous settings of parameters used “FES” loosely used term among PTs.
Statistical pooling not possible because of the heterogeneous characteristics of studies included.

28. References:
Gersh, M. R. (1992). Electrotherapy in Rehabilitation. USA: F.A. Davis Company.
Hecox, B., Mehreteab, T. A., & Weisberg, J. (1994). Physical Agents: A Comprehensive Text for Physical Therapist. Appleton & Lange.
Wadsworth, H., & Chanmugam, A. (1988). Electrophysical Agents in Physiotherapy. Singapore: Science Press.
 Revised ACDC lecture of Ms. Jazel Ann Atienza, PTRP