Electrical Stimulation

1. Electrical Stimulation The In�s & Out�s of Getting Zapped

2. Precautions & Contraindications Current flow through the heart, carotid sinus, and pharynx MUST BE AVOIDED. It disrupts normal cardiovascular function! Sites of increased n. sensitivity must be avoided. DO NOT APPLY electrical stimulation: Over sites of infection or cancer unless prescribed by physician Cardiac disability or pacemaker Pregnant or menstruating Exposed metal implants Severe obesity

3. Therapeutic Uses for Electrical Stimulation Control acute & chronic pain Reduce edema Reduce & or inhibit muscle spasm Reduce joint contractures Minimize atrophy Facilitate tissue healing Facilitate muscle reeducation Facilitate fracture healing Strengthen muscle

4. What is Electricity? Electricity � �force� created by an imbalance in the number of electrons at two points Electromagnetic force (potential difference or voltage) � the �force� Creates a situation in which electrons flow in an attempt to equalize the difference in charges thus creating an electrical current

5. Fundamentals of Electricity Flow will be in the pathway of LEAST resistance Current flows from 2 poles � From negative pole to positive pole Negative pole � CATHODE � high electron concentration Positive pole � ANODE � low electron concentration

6. Fundamentals of Electricity A complete pathway must be established for current to flow Closed circuit � uninterrupted circuit (complete loop is formed; allows current to flow to & from the source Open circuit � interrupted circuit Example: light switch � light on = closed circuit

7. Electrical Currents Continuous Currents: Direct Current (DC) � polarity remains constant Iontophoresis Car battery Alternating Current (AC) � polarity at each end is constantly reversed Household current Pulsatile Currents: Monophasic � similar to DC (either +/-) but is not constant Biphasic � similar to AC (+/- phases) but due to interpulse intervals it can�t be AC Polyphasic

8. Direct Current DC Uninterrupted unidirectional flow of electrons Pattern � square wave recognized by continuous current flow only on one side of the baselines Electrons travel from the cathode to the anode �Galvanic� can be used to describe DC Example: Flashlight Positive pole lacks electrons, Negative pole has excess electrons Electrons leave the (-) pole, go through the wire, then the bulb & back to the (+) pole. (When electrons = at (-) & (+) poles the battery is dead!)

9. Alternating Current AC Bidirectional flow of electrons � direction & magnitude of flow reverses although magnitude may not be = on both sides of the baseline. AC possesses no true positive or negative pole. Electrons shuffle back & forth between the 2 electrodes as they take turn being (+) & (-). Household electricity uses AC.

10. Alternating Current Amplitude: (peak value) � the maximal distance to which the wave rises above or below the baseline (only one side of the baseline) Peak-to-Peak Value: measured from the peak on the (+) side of the line to the peak on the (-) side of the line. Cycle Duration: measured from the originating point on the baseline to its terminating point; the amount of time required to complete one full cycle Hertz: # of cycles per second (1 MHz = 1 million cycles/second)

11. Pulsed Currents

12. Monophasic Current Pulsed current Unidirectional flow of electrons Only one phase to a single pulse With monophasic currents, �pulse�, �phase�, & �waveform� are the same.

13. Biphasic Current Pulsed current Bidirectional flow of electrons Possesses 2 phases, each of which occurs on opposite sides of the baseline Lead phase of the pulse is the 1st area rising above or below the baseline Terminating phase occurs in the opposite direction Pulse duration = sum of the two phase durations

14. Pulsatile �Polyphasic� Current Contains three or more grouped phases in a single pulse Russian � timing-modulated AC current Interferential � interfering 2 AC of different frequencies Terminology controversy

15. Pulse Attributes � Time Dependent Characteristics Horizontal baseline (axis) represents time. Phase duration: time required for each component phase to complete its shape Pulse duration: distance a pulse covers on the horizontal axis (can�t be measured for uninterrupted DC or AC) Interpulse interval: time between the conclusion of one pulse & the initiation of the next Intrapulse interval: interruption of a single pulse or phase (can�t exceed duration of interpulse interval) Pulse period: pulse duration + pulse interval (elapsed time between initiation of 1 pulse & start of the next 1) Pulse duration & pulse periods don�t exist for AC/DC

16. Pulse Attributes A = Amplitude B = Phase Duration C = Pulse Duration D = Interpulse Interval

17. Pulse Attributes Pulse charge: # of electrons contained within a pulse Expressed in microcoulombs Pulse frequency: # of events per second Measured pulses per second (pps) or the cycle frequency of AC is cycles per second (cps) or Hz Low-frequency currents: less than 1,000 cycles or pulses per second (electrical stimulation units used for biological effects) Medium-frequency currents: 1,000-100,000 pps/cps High-frequency currents: greater than 100,000 pps/cps (used for heating effects- diathermy)

18. Pulse Attributes Pulse Rise Time: amount of time needed for the pulse to reach its peak value (nanoseconds) Rapidly rising pulses cause nerve depolarization Pulse Decay Time: amount of time required for the pulse to go from its peak back to zero Pulse Train: individual patterns of waveforms, durations &/or frequencies that are linked together (repeat @ regular intervals) Amplitude Ramp: gradual rise &/or fall in amplitude of a pulse train (causes a gradual ? in the force of m. contractions by progressive recruitment of motor units)

19. Measures of Electrical Current Flow Coulomb: (Q) # of electrons flowing in a current 1 Q = 6.25 x 1018 electrons /sec. Coulomb�s Law � relationship between like & unlike electrical charges (opposite charges attract & like charges repel) Current: (I) � net movement of electrons along a conducting medium Usually measured in milliamperes (mA; 1/1,000 of an ampere) or microamperes (�A; 1/1,000,000 of an ampere) Ampere: (A) rate @ which the electrical charge flows 1 A = 6.25 x 1018 electrons 1 A = 1 Q/sec

20. Measures of Electrical Current Flow Voltage: measure of the potential for current flow to occur; force resulting from an accumulation of electrons at one point in an electrical circuit (V) High voltage current: current in which the waveform has an amplitude of greater than 150 V with a relatively short pulse duration Low voltage current: current in which the waveform has an amplitude of less than 150 V Somewhat meaningless as electrotherapy units today modify voltages Volt: the unit of potential difference & is the amount of work required to move 1 coulomb of charge

21. Measures of Electrical Current Flow Wattage: relationship between voltage & amperage; (P); used to designate the POWER of a current Power = amount of work being performed in a unit of time 1 watt (W) = the power produced by 1 A of current flowing with the force of 1 V P = volts x amperes (VI) What is the amount of power used by a device drawing 2 A from a 120-V source? P = 120 V x 2 A = 240 W

22. Measures of Electrical Current Flow Ohm: (O) unit of measure that indicates resistance to current flow; material�s resistance to the movement of electrons 1 ohm = the amount of resistance needed to develop 0.24 calories of heat when 1 A of current is applied for 1 second Ohm�s Law: current is directly proportion to voltage & inversely proportional to resistance (I = V/R)

23. Measures of Electrical Current Flow Resistance: (R) � opposition to electron flow in a conducting material Type, length, & cross-sectional area of the material & temperature of the circuit determine the amount of resistance offered to the flow of electrons Conductors: materials allowing current to pass with relative ease Resistors/Insulators: materials that tend to oppose current flow Impedance: (Z) Alternating Current Inductance: degree that a varying current can induce voltage (H � henry) (negligible in biological systems) Capacitance: frequency-dependent ability to store a charge (C); many cell membranes are capacitors

24. Measures of Electrical Current Flow What is the current flow in a 40-V circuit possessing 10 ohms of resistance? I = V/R I = 40 V/10 O I = 4 A What is the resistance found in a 40-V circuit possessing a current flow of 10A? I = V/R 10 A = 40 V/R R = 4 O What is the voltage of a circuit providing 4 ohms of resistance when 10 A are flowing? I = V/R 10 A = V/4 O V = 40 V

25. Waveforms Graphic representation of the shape, direction, amplitude, duration, & pulse frequency of the electrical current being produced Sine, rectangular, square, or spiked AC, DC, & pulsitile (polyphasic) currents may take on any waveform shape

26. Circuit Types Series Circuit: one pathway is available for travel Current remains the same all along the circuit Total resistance (RT) = R1 + R2 + R3 Parallel Circuit: two or more routes exist for the current to pass between the two terminals Each additional resistance added decreases the total resistance 1/RT = 1/R1 + 1/R2 + 1/R3

27. Circuit Types

28. So What?

29. The Body Circuit Excitable Tissues Greater % of water content Nerve fibers Muscle fibers Blood Cells Cell Membranes Non-Excitable Tissues Low % of water content Bone Cartilage Tendons Ligaments

30. What happens in the Body? Current enters the body through a SERIES circuit. Once the current enters the tissues, it takes many different PARALLEL paths. Electical stim is applied transcutaneously except for some bone growth stimulators that may be implanted into the muscle or bone. Resting potential � potential difference between the inside & outside of the membrane Cathode � depolarization of the nerve occurs Anode � hyperpolarization of the nerve occurs

31. What happens in the Body? Cathode � pH becomes basic (greater than 7) Anode � pH becomes acidic (less than 7) Na+ move towards cathode, picks up an electron, & through reaction with H2O, liquefies proteins, causing a general softening of the tissues in the area & a decrease in nerve irritability Tissues under anode harden because chemical mediators for a coagulation of protein Effects not as pronounced when monophasic, biphasic or AC are used Na+ moves from inside the cell to the outside the cell allowing K+ to move into the cell (Sodium-potassium pump)

32. Pain Control 3 Factors that a nerve�s response to stimulation are based on: Diameter of the nerve Depth of the nerve in relation to the electrode Duration of the pulse Sensory n. are stimulated 1st & receive a greater amount of �stim� that the more deeply placed motor n. Can override pain receptors by masking the pain allowing for endogenous opiates to be released High-pulse frequency, short-duration, sensory-level currents are thought to activate the �Gate�

33. Wound Healing Low-intensity DC may reduce time needed for superficial wound healing that have poor blood flow Long pulse durations or continuous uninterrupted currents can be used Maximum pulse frequency Monophasic current is the best, but biphasic current can be used Treatment time � 2 hrs followed by 4-hr rest time, 2-3 x per day (-) electrode positioned in the wound area for 1st 3 days and then (+) electrode placed in area If infection is present then (-) electrode should be left in area until signs of infection are gone

34. Edema Control & Reduction Sensory-level stimulation attempts to stop formation of edema by preventing fluids, plasma proteins, & other solids from escaping into surrounding tissues Reduces capillary pressure & permeability Discourages plasma protein from entering extracellular tissues Monophasic current may produce a vascular spasm & prevent fluids from leaking out Motor-level stimulation attempts to assist the venous & lymphatic system in returning the substances back to the torso for filtration Muscular contractions milk the fluids out of area Electrodes placed over major vein

35. Muscle Contraction Can be used to retard muscle atrophy Can be used for muscle strengthening Can be used for muscle re-education Can be used for pumping actions Low pps

36. Basic Set-up Clean body area & electrodes Position patient comfortably Electrotherapy unit must be plugged into a GFIC Make sure electrode leads are not tangled Make sure ALL dials are off/@ zero

37. Electrodes Transcutaneous Electrical Nerve Stimulation (TENS) uses similar-sized electrodes May be placed on or around the painful area Over specific dermatomes, myotomes, or sclerotomes that correspond to the painful area May be placed close to the spinal cord segment that innervates the painful area Peripheral n. may be stimulated where it becomes superficial Over superficial vascular structures because transmission of currents may go through neural tissue as well as ionic fluids Over trigger points Crossing patterns Carbon-impregnated rubber, metal, or adhesive electrodes used with sponges or US gel

38. Monopolar, Bipolar, Quadripolar Electrode Set-up Monopolar � electrodes of 2 different sizes Active Electrode � placed where the treatment effect occurs; may be bifurcated Dispersive Electrode � completes the circuit; fastened to a body part @ a distant location (large body mass) As distance between electrodes increases, more parallel paths are formed, resulting in less specific stimulation of deep muscle nerves Little or no stimulation should occur under dispersive electrode Bipolar � electrodes equal or near-equal size Both electrodes are located in target treatment area Equal amount of current from each electrode

39. Quadripolar � Uses 2 sets of electrodes, each from own channel Current from each channel may intersect (IFC)

40. Idaho State Legislation for Use of Modalities �Rehabilitation and reconditioning of athletic injuries by administering therapeutic exercise and physical modalities including cryotherapy, thermotherapy, and intermittent compression or mechanical devices as directed by established, written athletic training service plans or protocols or upon the order of the directing physician.� www.idahoata.com - legislation

41. Types of Electrical Current 4 types of electrical current used in health care: Transcutaneous Electrical Nerve Stimulation (TENS) Iontophoresis Direct stimulation of denervated muscle Low-level current (Microcurrent)

42. Transcutaneous Electrical Neuromuscular Stimulation Pain control treatment Can cause muscle contractions, but that is not why it is used Decreases patient�s pain perception by decreasing the conductivity & transmission of noxious impulses from small pain fibers (effects large diameter fibers) Moderate caffeine levels (200 mg, approx 2-3 c. coffee) may decrease effectiveness of TENS

45. Interferential Current Stimulation Pain control; may elicit muscle contractions 2 AC on 2 separate channels 1 ch. High frequency sine wave (4000-5000Hz) 1 ch. Variable frequency sine wave Mixed = 1-100 Hz Able to penetrate tissues with little resistance Constructive vs. Destructive = Continuous IF

46. Russian Stimulation Strong muscle contractions Medium frequency (2000-10000Hz) polyphasic AC wave form Burst duty cycle (50 per second) For m. re-education, can use 3-5 x weekly (use more frequent, less intense treatments early) Place electrodes over the muscle belly, not tendon (motor points best place)

47. High-Voltage Pulsed Stimulation Application of a monophasic current ( Dynatron � High Volt) Used for m. reeducation, n. stimulation, reduction to edema, & pain control (low pps) Pulse frequency for pain control (60-150 pps) Releases opiates Change in polarity can be used: (+) polarity for acute pain; (-) polarity for chronic pain Active electrodes should be placed over painful area Acute pain is associated with acid reaction - (+) pole Chronic pain uses (-) pole � liquefying & vasodilative properties

48. Neuromuscular Electrical Stimulation (NMES) Muscle re-education, decrease spasticity, muscle strengthening, delay atrophy, decrease edema with pumping action, maintain ROM Low-frequency muscle stimulation Electrode set-up: proximal & distal ends May need to use small electrodes as larger ones may cover more than one muscle. Proximal & distal ends of muscle or quadripolar if activating agonist/antagonist or monopolar if probe is used

49. Microcurrent (MET or MENS) Subsensory or very low sensory level Doesn�t attempt to excite peripheral nerves May deliver DC, AC, or pulsed currents Effectiveness has yet to be substantiated in professional literature, yet it has been reported to: Decrease pain, ? ROM, improve wound healing Theory is based on Adenosine Triphosphate (ATP) levels Supposedly creates an imbalance in mitochondria in the # of proteins on either side of cell membrane As protons move from anode to cathode, they cross the mitochondrial membrane, causing ATP to be produced. Increased ATP production encourages amino acid transport & increased protein synthesis

50. Microcurrent Electrode placement: various set-ups are available One placed on injured site: Other placed near area One placed on site: Other placed across body One on site: Other on nerve root Four placed around site: crossing

51. Medical Galvanism Low-voltage DC Only type of current that elicits a muscle contraction from denervated muscle, but the phase duration is so long that C fibers are also stimulated, making the contraction painful Known polarity under each electrode Cathode will attract (+) charges (Na+) thus allowing for softening of the tissues & a decrease in n. irritability Anode will attract (-) charges forcing coagulation of protein in area

52. Iontophoresis Low-voltage DC Application of a medication transcutaneously; Application of a (+) or (-) charged drug molecules away from the particular electrode and into the tissues Dexamethasone is uncharged and has a poor solubility in aqueous solutions Dexamethasone Phosphate, water soluble, is generally used in iontophoretic applications. (-) charged Dexamethasone Sodium Phosphate Effects depends on the medication: anti-inflammatory, pain relief Electrode placement: Active (delivery) = placed over tissue site; Dispersive (return) = 4-6 inches away

53. Iontophoresis Dosage: Current amperage (0-5 mA) x Treatment duration = mA/min Typical treatment: 40 mA/min but can vary from 0-80 mA/min depending on the medication

54. Dynatron Interferential Premodulated Russian Biphasic High Volt Microcurrent Patented Target Feature for Interferential Microcurrent Conductance Indicator Modifiable Frequency Ranges Single, Reciprocal, Co-contraction in Russian, Biphasic Selectable On/Off Cycle & Ramp Times for High Volt, Biphasic, & Russian Modify Pulse Rate, Pulse Width in Biphasic, Russian Microcurrent & High Volt Therapy Delivered with Both Electrodes & Optional Probes Select Microcurrent & High Volt Polarity (Positive, Negative, or Bipolar)