E-Stim Basics Flashcards
goals and indications for E-stim
- pain modulation
- decrease muscle spasm
- improve ROM
- muscle re-ed
- improve muscle strength/reduce atrophy
- wound healing
- edema reduction
- stimulate denervated muscle
contraindications (8)
- pacemaker, insulin pump
- over cartoid artery, thrombosis, eyes, phrenic nerve, pelvis and/or low back in pregnant women
- transcerebrally
- active bleeding/infxn
- over superficial metal implants
- over malignant tumors
- over pharyngeal/laryngeal muscles
- motor-level stimulation in conditions that prohibit motion
precautions (6)
- cardiac disease
- impaired mentation
- impaired sensation
- in areas of skin irritation or open wounds
- in pt with uncontrolled hypotension or HTN
- bleeding disorders
polarity
net charge of object
cathode
net negative
anode
net positive
voltage
driving force that move electrons
amerage/current
rate of flow of electrons (mA)
ohm’s law
- more resistance, the greater the voltage needed to push the current through
- I = V/R
resistance to current flow
- skin
- hair
- fascia
- ligament
- callus
- fat
- bone
- tendon
- scar
if resistance increases…
more voltage will be required to overcome the resistance and produce the same current flow
if you have a large increase in voltage what could happen
discomfort, could lead to burns
how do you reduce skin-electrode resistance
- minimize air-electrode interface
- keep electrodes clean
- use electrodes on clean skin, minimize hair, oils, abrasions if possible
what size electrode do you typically use
- largest that you can to reduce discomfort
monophasic current
- unidirectional flow of charged particles
- electrical stim moving from one pad to the other
biphasic
- bidrectional flow of charged particles
- electrical stim bouncing back and forth btw 2 pads
direct current
- uninterrupted unidirectional flow
- one pad to the other
- type of monophasic
alternating current
- uninterrupted bidirectional flow
- bouncing back and forth btw the two pads
- biphasic
pulsed current
can either be unidirectional (monophasic) or bidirectional (biphasic) current that periodically ceases for very short period of time
- has additional parameters
frequency
pf pulses per second or beats per second
pulse duration
- width
- reported in microseconds
- how long each individual pulse lasts
amplitude
- mA
- voltage of each individual pulse
how does e-stim lead to an action potential
- influx of Na+ which causes a reduction of resting membrane potential leading to depolarization which leads to action potential
what must be great enough to cause an action potential
amplitude/intensity
what must be long enough to produce depolarization of the cell
duration of the stimulus
how is heat created with e-stim
- friction and vibration of particles moving through the material
- heat produced depends on intensity of current
is it normal to have some redness under the electrodes?
- yes bc some heat is produced
- should go away after few hours
- should not blister or break skin
if intensity is too high….
- may be at risk for burns
- important to remove resistance
large electrode pad =
current dispersed over large area = small current density = more tolerated by pt
small electrode pad =
current dispersed over small area = greater current density = less tolerated by pt
how do you increase the current density
- increase current of estim
- decrease size of electrode
- can cause skin burns
how to avoid burns
- remove resistance
- listen to pt’s perception
- use large electrodes when possible
- always maintain good contact of estim pads
- use appropriate coupling agent if appropriate
monopolar
- one small electrode over target area
- one large electrode over remote area
- polarity matters
bipolar
- both electrodes are of similar size and placed over target area
- current bounce btw 2 pads
- polarity doesn’t matter
quadripolar
- 2 electrodes from 2 seperate stimulating circuits are positioned so that the individual currents intersect with each other
monopolar configuration
- method when polarity is a concern
- wound healing (attract to area)
- edema control
- iontophoresis (drive into body)
with monopolar configuration, where are the electrodes placed
- 1 small electrode is placed directly over target area (active/treatment electrode)
- 2 larger electrode is placed away from target area (dispersive)
- pads do not need to be on same muscle
preferred use for bipolar configuration
- disuse atrophy
- neuromuscular facilitation
- ROM
- spasms
- circulatory disorders
where are electrodes for bipolar configuration
- connected in same area with target treatment site btw two pads
- same size
- any wave form except direct current
what influences the depth and course of the current
the distance btw the electrodes
if the pads are farther apart….
deeper they go
do you want the pads touching?
no, creates an arc
if youre going for sensory stimulation, put the pads where?
over that sensory pathway
if you’re going for motor point stimulation, put the pads where?
- where the motor nerve is easily excited
- muscle belly or proximal 1/3 of the muscle
common mistakes with muscle stimulation
- placing 1 electrode over a muscle belly and the other over a distal area without much muscle
- electrodes too close together when trying to stimulate a deep muscle
