List the goals and indications for E-Stim
List some contraindications for E-Stim
List some precautions for E-Stim
Define polarity
net charge of object
cathode = net (-)
anode = net (+)
define voltage
driving force that move electrons
force of attraction or repulsion (amplitude)
define amperage/current
rate of flow of electrons
mesaured in milliamps (mA)
what is Ohm’s Law?
I = V/R
current = voltage/resistance
(more resistance means greater voltage required to push the current through)
List some biological sources of resistance to current
what are some ways to reduce resistance at the skin?
List the different types of currents
what types of currents are unidirectional? bidirectional?
unidirectional = monophasic and direct current
bidirectional = biphasic and alternating current
pulsed can be both
What are the unique features of a pulsed current?
this type of current will periodically cease for a short time period so it has:
a frequency
a pulse duration
an amplitude
how do pulse currents influence the generation of AP differently than direct or alternating currents?
pulse currents allow for repolarization to occur (channels closing again) thus they can result in tetanic contractions
Direct and alternating currents do not allow for repolarization (the channels always remain open) thus they result in a single large contraction
the higher the current the higher the _______
heat
also the greater risk for burns
what are the effects of electrode size on stimulation?
different sizes result in different current densities
larger electrode = smaller current density/more tolerable
smaller electrode = larger current density/less tolerable
what are 2 ways to increase current density?
what is the effect of increased current density on skin?
skin burn
avoid this by:
List several electrode configurations
describe a monopolar electrode configuration
one small electrode over target area, and one large electrode placed over remote area (to complete the current)
method of choice when polarity matters
(wound healing, edema control, iontophoresis)
describe a bipolar electrode configuration
both electrodes are of similar size and are placed over the target area
current bounces between two pads
used with any waveform except DC
List some preferred uses for bipolar electrode configurations
describe a quadripolar configuration
2 electrodes from 2 separate stimulating currents are positioned so that the individual currents intersect with each other (called IFC)
how does the distance between electrodes influence current?
it influences the depth and course of current
further apart = deeper the current travels
recommended that the distance be at least one half the diameter of each electrode
List some things to keep in mind when placing electrodes for motor stimulation