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Electromagnetic Spectrum

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(Longwave to Shortwave) Electrical stimulating Current Commercial Radio and Television Shortwave Diathermy Microwave Diathermy Laser - Infrared Laser - Visiblie light Ultraviolet Ionizing Radiation

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Ions

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Positively and negatively charged particles contained in atoms

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Electrical Potentials

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Difference in concentration of electrons between two points Electrons will not move unless a potential difference exists

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Net movement of electrons

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Always higher to lower

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Electrical force is oriented in

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the direction of the applied force

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Rate of electrical current measured by

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Ampere (amp) Coulomb Volt (V)

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Electrons

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Particles of matter possessing a negative charge and a small mass Net movement of electrons is an electrical current Movement of electrons is like a domino reaction Electrons will move from higher to lower potential

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Ampere

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Unit of measure which indicates rate at which electrons flow 1 amp = movement of 1 coulomb or 6.25x1018 electrons /sec Current flow is in milliamps (1/1000) or microamps (1/1,000,000)

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Voltage

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Force resulting from an accumulation of electrons at one point in an electrical circuit Corresponds to a deficit of electrons at another point in the circuit Creates the potential difference Commercial current is 115 V or 220 V

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Coulomb

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Indicates the NUMBER of electrons

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Coulomb's Law

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Opposites attract/likes repel

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Conductors

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Materials that permit free movement of electrons Composed of large numbers of free electrons Offer little resistance to current flow Good conductors - Metals (copper, gold, silver, aluminum) Electrolyte solutions

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Insulators

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Materials that resist the flow of electrons Contain few free electrons Insulator materials Air, Wood, Glass

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Electrical Impedence

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Resistance or opposition to flow of electrical current Measured in ohms

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Ohm's Law

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Current Flow= Voltage/Resistance Current is directly proportional to voltage and inversely proportional to resistance

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Watt

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Measure of electrical power Rate at which electrical power is being used Power needed to produce a current flow of 1 A at a pressure of 1 V Watts = Volts x Amps Modalities use milliamps or microamps

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Electrictherapeutic Currents

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Direct current - Galvanic or DC Alternating current - AC Pulsed Currents - Period of no current flow - Monophasic - Biphasic - Polyphasic

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Direct (DC) or Monophasic

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Flow of electrons always in same direction Sometimes called galvanic Flow is always in a uniform direction Accumulation of charged ions over a period of time Creates either an acidic or alkaline environment Medical galvanism Iontophoresis

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Alternating (AC) or Biphasic

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Flow of electrons changes direction Always flows from negative to positive pole until polarity is reversed

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Monophasic Pulse

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Square Wave Twin Peaks SawTooth

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Biphasic Pulse

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Sinusoidal Asymmetrical

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Polyphasic

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Pulsed current waveforms Represents an electrical current in a series of pulses - Polyphasic sine - Polyphasic rectangle - Polyphasic Spiked

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Parts of a Biphasic Waveform

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Pulse Phase duration Interpulse interval Direction Amplitude Rate of rise Rate of decay

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Biphasic Pulse

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Individual waveform

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Biphasic Phase duration

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One + or one - amplitude arch

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Biphasic Interpulse interval

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Break between the pulse

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Biphasic Direction

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Polarity

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Biphasic Amplitude

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Height of one pulse Intensity or voltage Measured in Milliamps or microvolts Average current Determined by Interpulse interval& Current duration

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Biphasic Rate of rise

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Rising part of a + pulse How quickly the pulse reaches its maximum amplitude in each phase

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Biphasic Rate of decay

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Falling part of a + pulse Time to which the pulse goes from peak to 0 volt Accommodation

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Parts of Monophasic Waveform

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Pulse and phase duration Interpulse interval Amplitude Rate of rise Rate of decay

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Monophasic Pulse and phase duration

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Individual waveform Same base of the triangle

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Monophasic Interpulse interval

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Break between the pulse and phase

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Monophasic Amplitude

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Height of the triangle Intensity or voltage Measured in Milliamps or microvolts Average current Determined by Interpulse interval& Current duration

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Monophasic Rate of rise

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Upward slope of the triangle How quickly the pulse reaches its maximum amplitude in each phase

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Monophasic Rate of decay

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Downward slope of the triangle Time to which the pulse goes from peak to 0 volt

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Phase Duration and Action Potentials

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The longer the phase duration the less energy/current needed to generate an action potential

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Average Current

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Considered ½ of its complete cycle Taking into account the amount of time the current is flowing The total amount of charge delivered by a single cycle Useful when asymmetrical biphasic currents are used

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Accommodation Phenomenon

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A fiber which has been subjected to constant depolarization will become more excitable at the same intensity or amplitude Rise and decay times are short Nano to milliseconds The shape of waveforms is directly related to their ability to excite nervous tissue "Body gets used to the tingling and needs to be aletered to remain effective"

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Things that Prevent Accomodation

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Rate of Rise and Decay

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Law of Dubois Reymond

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Stimulus must be of adequate amplitude to reach the threshold level of excitatory tissue Rate of voltage change must be enough that tissue accommodation cannot occur Length of the stimulus or phase duration must be great enough to overcome the capacitance of the tissue to allow an action potential

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Current Modulation

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Any alteration in the magnitude or duration of pulses Continuous Interrupted Burst Ramped Amplitude Phase Duration

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Continuous

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Amplitude remains the same for several seconds/minutes Associated with direct current Used with alternating current when trying to elicit a muscle contraction

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Interrupted Modulation

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Current flow is on for a time period and off for a time period On 1-60 seconds Off 1-120 seconds Used with both monophasic and biphasic currents Sinusoidal, rectangular, and triangular waveforms Clinically used for muscle re-education and range of motion

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Burst Modulation

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Occurs when pulsed current flows for a short duration and then turned off for a short duration in a repetitive cycle Milliseconds Used with monophasic and biphasic currents "Packages" of pulses to make a burst

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Ramping Modulation

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Current amplitude increases or "ramps up" gradually to a preset maximum ~1/3 of the on time Clinically used in muscle re-education

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Phase Duration Modulation

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Typically available in TENS units Allows the phase duration to change throughout the treatment

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Current Density

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The volume of current in the tissues Highest at surface Diminishes in deeper tissue Inversely proportional to the size of the electrode 300 volts through an electrode of 10 square inches Current density = 30 V/square inch

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Electrode Size and Current Density

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Larger the electrode the more the current density is spread Smaller the electrode the greater the current density High current density close to neural structure will create the greatest stimulus with less intensity/current

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Electrode Proximity and Current Density

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Less intensity Farther away

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Circuit Types

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Series Circuit Paralell Circuit

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Series Circuit

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One path for the current to take Component placed end to end Total Resistance = Sum of Resistances Total Voltage = Sum of Voltage Decreases

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Paralell

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Component resistors placed side to side with ends connected Current chooses path of least resistance Resistors have lower resistance but higher current flow than series circuit

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Current Flow Through Tissues

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Higher water content, great conductivity Skin - Greatest concern for electrical impedance Blood - Best conductor of all the tissues, Comprised largely of water and ions Muscle - About 75% water, Depends on movement of ions for contraction, Tendons are poor conductors Fat - Poor conductor Peripheral nerves - 6 x better than muscle, But surrounded by fat and fibrous sheaths that are poor conductors Bone - About 5% water, Very poor conductor

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Methods of Reducing Skin Electrode Resistance

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Moisten electrodes with water or conductive gel Sponge or rubber electrodes Remove dirt, oil, or flaky skin Washing with soap and water, alcohol, or acetone Warm area with a moist heat pack Gently scrub area with fine emery paper Remove excess hair Saturate sponges with commercial saline solution rather than tap water Use silver electrodes

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Interferencial Current

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More comfortable than equal amplitudes delivered by other means Typical treatment goals Pain control Neuromuscular stimulation Reduction of edema The result of the interaction between the two input currents is a low frequency current

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IFC Primary physiological effect

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Depolarize sensory and motor nerve fibers

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IFC Main therapeutic effects

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Sensory nerve fibers Pain reduction Superficial never fibers receive lower amplitude stimulation than area of tissue Muscle fatigue Muscle spasm

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IFC Contraindications and Precautions

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Whirlpools Old pads Burns Pacemakers Infections Malignancies Pregnancy Musculoskeletal problems where a muscle contraction would exacerbate conditions

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IFC Frequency

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On typical interferential units Frquency = 4000-5000Hz Fixed frequency Carrier Medium-high frequency = 4000-5000Hz Variable frequency The two currents converge

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Constructive Waves

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When two sinusoidal waves that are exactly in phase or one, two, three or more wavelengths of phase, the waves supplement each other in constructive interference

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Destructive Waves

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When the two waves are different by 1/2 a wavelength the result is cancellation of both waves

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Coninuous Waves

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Constructive + destructive waves Slightly out of phase Collide and form a single wave with progressively increasing and decreasing amplitude

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Beat Frequency

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The beat frequency is what we are delivering to the target tissue Difference in carrier frequency and variable frequency = beat frequency Example 4000Hz (carrier) -4004Hz (variable) Beat frequency = 4 Hz

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IFC Currents

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When electrodes are arranged in a square interferential currents are passed through a homogeneous medium A predictable pattern of interference The body is not a homogeneous medium

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IFC Scanning and vector

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Scanning/Vector Moves force around while the treatment is taking place Enlarging effective treatment area 45º angles from center of treatment area

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IFC Pain Control Gate Control

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Beat frequency - 80-150 Hz Sweep Fast Sensory level Vector/Scan Based on treatment area and patient comfort

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IFC Pain Control Opiate Release

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Beat frequency - 1-10 Hz Sweep Slow Sensory/Motor level Vector/Scan Based on treatment area and patient comfort

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Pre-Mod

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Single alternating current Bipolar technique Mix of two channels occurring within generator instead of tissues Both output a frequency of 4,000 Hz The generator "premodulates" burst frequency within the unit Output is 1-100 bursts per second

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Hi-Volt Distinct Specifications

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Two distinct specifications - Must transmit a voltage of at least 150V, Arbitrary number determining "low" and "high" volt machines Must use a twin-peaked monophasic current

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Hi-Volt Amplitude

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Ranges from 0-500 V Determined by patient comfort and goal A high voltage means a lower average current Very safe modality Immediate pulse decay Second pulse begins before the first pulse reaches the isoelectric line Phase duration Varies between 50-120 ?s Depends on machine Can not be changed by the clinician

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Twin Peak Monophasic Wave Form

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Allows deeper penetration of energy Short phase duration Activation of sensory and type II nerve fibers Without stimulating C and A? pain fibers Long interpulse interval

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Why Polarity Matters?

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Monophasic waveform allows for choice of polarity During healing the wound emits a charge potential Depending on the stage Applying a polarity of the like charge can reinforce this physiological response Example - Leukocyte chemotaxis

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Positive Polarity

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Acute injuries Increases vascular permeability

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Negative Polarity

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Chronic injuries Decreases vascular permeability

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Hi-Volt Frequency

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Frequency ranges from 2-120 pps

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Hi-Volt Electrode Placement Monopolar

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Small active and large dispersive Goals Reduce edema Sensory pain control

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Hi-Volt Electrode Placement Bipolar

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Evoke muscle contraction from specific muscle Motor level pain control

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Hi-Volt Sensory and motor pain control

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Acute - Positive Chronic - Negative

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Hi-Volt Opiate pain control

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Monopolar Large electrode over area and hand held probe Must stimulate A? fibers

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Hi-Volt Sensory Level Edema Control

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The only current that can prevent edema If begun within 6 hours of injury Keys to success - Current flowing as long as possible - Negative electrode (cathode) over target tissue - Decreased vascular permeability - Blood cells/plasma protein repelled from cathode If setup begins too late in the healing process Can inhibit re-absorption and create further edema Combine with other treatments for best effect Post treatment care

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Hi-Volt Motory Level Edema Control

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May reduce edema once formed - Positive polarity Elicit the muscle pump/contraction Increase venous and lymphatic flow Electrode placement: Motor point, Contraction from distal to proximal Use with other treatments for best effect

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Retard Atrophy

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Not good for muscle re-education Short phase duration Not enough to produce a strong muscle contraction Strength of contraction is not sensitive to increases in frequency The muscle contractions elicited by high volt can be used to retard atrophy Denervated muscle

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Hi-Volt Limitations

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Some units do not allow duty cycle control Strength of muscle contraction is less than NMES or Russian Lacks total current needed for maximum force production Short phase duration No time for ions attracted to each electrode to dissipate Physiochemical reaction under electrode limited No significant pH changes under skin Quick accommodation

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Hi-Volt Precautions

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Stimulation of muscles: Can cause unwanted tension to be placed on muscle fibers, tendons, or bony insertion Muscle fatigue: Can rapidly develop if the duty cycle is too high Improper use: Can cause electrode burns or irritation Intense or prolonged stimulation, May result in muscle spasm and/or muscle soreness

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T.E.N.S.

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Trancutaneous Electrical Nerve Stimulation

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TENS

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Primary use is control pain TENS stimulates afferent sensory fibers Gate control theory Between 0-100% can be placebo effect Elicit production of neurohumoral substances Endorphins, enkephalins and serotonin

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TENS Indications

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Control chronic pain Manage post-surgical pain Reduction of post-traumatic and acute pain

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TENS Precautions

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Can mask underlying pain Burns or irritate skin Prolonged use may result in muscle spasm/soreness Caffeine intake (>2000mg) may reduce effectiveness Competes with adenosine, a mediator of transmission Narcotics decrease effectiveness

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TENS Contraindications

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Pacemakers Over carotid sinuses Eyes, ear, throat, mouth, etc Pregnancy Cerebral vascular disorders Stroke patients Over the chest Cardiac condition

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High Frequency TENS

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Activate AB fibers

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Low Frequency TENS

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Activate AB fibers Release of B-endorphins from pituitary

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Brief-Intense TENS

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Noxious stimulation to active C fibers

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High Frequency TENS

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Sensory TENS AB fibers are stimulated - Pure gate control theory Paresthesia is created without motor response Frequency - High Phase duration - Short Amplitude - Low to comfortable Creates the fastest relief of all techniques May stop the pain-spasms cycle

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Low Frequency TENS

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Motor Tens AB fibers and B-endorphins released Longer lasting pain relief but slower to start Frequency - Low Phase duration - Long Amplitude - Low to comfortable current

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Brief Intense TENS

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Stimulates C fibers Mono or biphasic current "bee sting" sensation Utilize motor, trigger or acupuncture points Frequency - High Phase duration - Long Amplitude - Max tolerable

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Modulated Stimulation

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Keeps tissues reactive - No accommodation Simultaneous modulation of amplitude and pulse width As amplitude decreases, pulse width is automatically increased Deliver more consistent energy per pulse Rate can also be modulated

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Russian Current

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Medium frequency - 2000Hz -10,000Hz Polyphasic, alternating current Sine wave Produced in burst mode

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Pulse Trains (Burst)

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Contain individual pulses - Pulses in the train still have time-dependent characteristics, Pulse duration, interpulse interval, etc Each train is separated by "off" times - Intertrain/interburst interval To make intensity of current tolerable Generated in 50-burst-per-second trains With a 10msec interburst interval

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Burst and Interburst Interval Effects

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Dark shaded area - Total current Light shaded area -Total current without the interburst interval When generated with burst effect

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Russian High Frequency

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Reduce resistance to current flow Wave form comfortable enough to tolerate Compared to the higher intensities of high volt As intensity increases more motor nerves are stimulated Increases magnitude of contraction Fast oscillating AC current As soon as nerve repolarizes it is stimulated again Produces a current that will maximally summate muscle contraction

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Russian On-Off Time/Duty Cycle

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Typical should be 1:5 - Recovery, Decrease fatigue AT A MINIMUM - 1:3, Even in later stages

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Russian Ramp Pulse

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Gradually increases the current Produces a more natural contraction More comfortable

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Biofeedback

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Voluntary muscle contraction Body's electrical activity is amplified by the biofeedback unit Auditory or visual feedback

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Why Biofeedback?

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Early stages Improper voluntary muscle contraction Example Post ACL surgery, VMO is not being contracted first

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Biofeedback response is designed to assist in:

answer

Developing strength of the muscle contraction Facilitate muscle relaxation Control blood pressure and heart rate Also decrease physical response to stress Basis of lie detector tests

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Electromyographic

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Measure electrical activity in skeletal muscle

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Peripheral temperature

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Measure temperature changes Increased temperature-Relaxed muscle

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Photoplethysmography

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Measure the amount of light reflected by subcutaneous tissue

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Galvanic skin response

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Measure the amount of perspiration on the skin Sweaty skin contains salt

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Not a Measure for Contraction Strength

answer

Biofeedback simply measures the conditions associated with the contraction Neurological activity - Then transfers this information into Light, sound, or meter indication

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Biofeedback Sound Indications

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Turns the neurological signals into sound Buzzing, beeping, clicking, tone, etc. Advantages Allows the patient to focus on the sound and his/her own muscle contraction rather than the machine Changes pitch according to the amount of neurological activity

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Biofeedback Electrodes

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Three electrodes within one pad - Two active: Measure the amount of electrical activity within the muscle - One reference: Filters out non-meaningful electrical activity Disposable versus non-disposable

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Iontopheresis

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Introduction of ions into the body using direct electrical current Transports ions across a membrane or into a tissue It is a painless, sterile, noninvasive technique Demonstrated to have a positive effect on the healing process

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Phonophoresis

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uses acoustic energy (ultrasound) to drive molecules into tissues

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Iontophoresis

answer

uses electrical current to transport ions into tissues

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Pharmacokinetics

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Transdermal iontophoresis delivers medication at a constant rate so that the effective plasma concentration remains within a therapeutic window for an extended period of time.

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Iontopherisis Therapeutic window

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The plasma concentrations of a drug Should fall between a minimum concentration necessary for a therapeutic effect and the maximum effective concentration above which adverse effects may possibly occur

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Advantages of taking medication via transdermal iontophoresis relative to oral medications

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Concentrated in a specific area Does not have to be absorbed within the GI tract Safer than administering a drug through injection

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Ionization

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Soluble compounds dissolve into ions suspended in solutions that are called electrolytes

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Electrophoresis

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Movement of ions in solution according to the electrically charged currents acting on them

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Cathode

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Negatively charged electrode Highest concentration of electrons Repels negatively charged ions Attracts positively charged ions Accumulation of negatively charged ions in a small area creates an acidic reaction

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Anode

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Positively charged electrode Lower concentration of electrons Repels positively charged ions Attracts negatively charged ions Accumulation of positively charged ions in a small area creates an alkaline reaction

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Current density should be reduced at the

answer

cathode (negative electrode) Alkaline reaction (+ions) is more likely to produce tissue damage than acidic reaction(- ions) Thus negative electrode should be larger (2x) to reduce current density.

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Recommended current amplitudes used for iontophoresis range between

answer

3-5 mA

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Iontopheresis Current amplitude usually set so that current density falls between

answer

0.1-0.5 mA/cm2 of the active electrode surface

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Iontopheresis Treatment duration ranges between

answer

10-20 minutes with 15 minutes being an average

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Iontopheris typical treatment dose is

answer

40 mA-min but can vary depending on the medication

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Iontophersis Indications

answer

Inflammation Analgesia Muscle spasm Ischemia Edema Calcium deposits Scar tissue Hyperhidrosis Fungi Open skin lesions Herpes Allergic rhinitis Gout Burns Reflex sympathetic dystrophy

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Iontopheresis Contraindications

answer

Skin sensitivity reactions Sensitivity to aspirin Salicylates Gastritis or active stomach ulcer Hydrocortisone Asthma Mecholyl Sensitivity to metals Zinc, copper, magnesium Sensitivity to seafood Iodine

question

Microcurrent

answer

Can be a valuable clinical resource More may not be better For electricity to produce these effects Cells must be current sensitive Correct polarity orientation may be necessary Correct amounts of current will cause cells to be more active in healing process

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