Introduction to Electrical Currents

voltage

driving force that repels like charges and attracts opposite charges

electrical current

flow of charged particles

cathode

negative electrode

anode

positive electrode

conductance

relative ease of movement of charged particles in a charged medium; if ease of movement is high, then resistance to movement is low

resistance

opposition to movement of charged particles; lower resistance provides greater comfort/tolerance by patient for higher intensity stimulation

intensity

the greater the resistance (impedence), the greater the _____ required to achieve a therapeutic goal

increased decreased

current increases as driving force (V) is _____ or as the resistance (R) to movement is ____

parallel

to decrease resistance, we want to place electrodes to that they run ______ to muscle fibers

direct curent

continuous and unidirectional flow of ions to electrons (one electrode is the anode, one is the cathode); commonly used for iontophoresis and wound care

alternating current

the uninterrupted bidirectional flow of ions or electrons and must change direction at least 1 time per second

frequency

the rate at which AC switches direction

interferential current (IFC)

type of alternating current; interference of 2 medium-frequency AC's of slightly different frequencies (at least 4 electrodes)

premodulated current (Premod)

type of alternating current; AC with medium frequency, sequentially increasing and decreasing amplitude (2 electrodes)

Russian protocol

specific parameters intended for quadriceps re-education; produces a muscle contraction

pulsed current (PC)

unidirectional OR bidirectional flow of ions or electrons that periodically CEASES for a small period of time before the next electrical eventpc)

monophasic PC

type of pulsed current; current flows in one direction - commonly used to promote tissue healing and acute edema management

biphasic PC

type of pulsed current; current flows back and forth during a pulse; can be used to induce a muscle contraction

pulse duration

how long each pulse lasta

phase duration

duration of one phase of the pulse

interpulse interval

amount of time between pulses

amplitude

magnitude of the current; "intensity" of the current

frequency distribution

number of cycles or pulses per second

modulation

change of parameters during the treatment; used to decrease the capacity of the nervous system to adapt to the settings - most commonly used for pain control (TENS)

Iontophoresis

most common example of electrochemical (ionic) effects

ionic

_____ effects include inflammation, tissue healing, and reduce edema

chemical (ionic), thermal, physical

types of effects to electrical current

heat

electrical current produces _____; dependent upon the amount of current, the resistance to the current, and the duration of the current

redness

electrical current may cause accumulation of localized heat at the skin; watch for excessive ______ beneath the electrode

action potential

electrical current cause cause the stimulation of ____ _____ in nerves (NMES); over time accomadation may occur

denervated

pulses lasting longer than 10ms can produce a _______ of a denervated muscle (direct muscle depolarization)

size location

it is important to consider the nerve _____ and _____ of the electrodes

sensory

lower current amplitudes and shorter pulse durations needed to stimulate action potentials of _____ nerves (A beta, A delta) (50-100)

motor

higher amplitudes or longer pulses are needed to stimulate action potentials in ______ nerves (C fibers) (150-350)

cellular tissue systemic

as electrical simulation moves through the body, changes occur at various levels including _____, _____, and ______ effects

cellular

effects at _____ level include excitation of nerve cells, changes in cell membrane permeability, stimulation of fibroblasts, and modification of microcirculation

tissue

effects at _____ level include skeletal muscle contraction, smooth muscle contraction, and tissue regeneration

endogenous opioid, gate control

systemic analgesic effets are best explained by the ____ ____ theory and the _____ ____ theory

pain spasms atrophy re-education circulation ROM

indications for electrical stimulation include _____, relaxation of muscle ______, prevention of disuse _____, muscle ______, stimulation of muscles to prevent deep vein thrombosis, increase local blood ______, maintaining or increasing ______

contraindications

________ for electrical stimulation include demand cardiac pacemaker, unstable arrhythmia, over carotid sinus, over venous/arterio thrombosis/thrombophlebitis, and pregnancy (over trunk)

precautions

______ for electrical simulation include cardiac disease, impaired sensation or mentation, malignancy, and skin irritation/open wound