Lecture 7: ESTIM (Start of Final) Flashcards
clinical applications for ESTIM
pain
muscle re-education
reduce/prevent edema
decrease inflammation
tissue healing
reduce muscle spasm
drug delivery
reinverting denervated muscle
EMG biofeedback
definition of electrotherapy or electrical stimulation
use of electrical current to induce muscle contraction, changes in sensation, reduce edema, or accelerate tissue healing
what is electrical current
flow of charged particles (can be electrons or ions)
what is cathode and anode
cathode is negative electrode that attracts positively charged ions
anode is the positive charged electrode that attracts negatively charged ions
with ESTIM current flows from anode to cathode
what does TENS stand for
transcutaneous (non invasive) electrical nerve stimulaiton
what does NMES stand for
Neuromuscular electrical stimulation
what does EMS stand for
electrical muscle stimulaiton
what does TES stand for
therapeutic electrical stimulaiton
what does FES stand for
functional electrical stimulation
what is an action potential
messaging unit of nervous system/basic unit of nerve communication
propagates down nerve’s axon until it reaches a termination point
nerve cell must have sufficient what to stimulate an action potential
amplitude and duration
what is depolarization
change in flow of ions across cell membrane
all or nothing even t
what is repolarization
return to resting membrane potential
resting is generally more neg
what is accommodation
process by which a nerve gradually becomes less responsive to stimulation of normally sufficient amplitude and duration and no longer depolarizes
what are terminating points for motor and sensory nerves
motor = muscle
sensory = spinal cord
what are nodes of ranvier
small gaps between myelin sheath from which AP jumps from one node to the next in a process called slatory conduction
time dependent characteristics of waveforms
phase
phse duration
pulse
pulse duration
interpulse
frequency
amplitude dependent characteristics of waveforms
amplitude
peak amplitude
peak to peak amplitude
phase charge
pulse charge
what are teh adjustable parameters on NMES/TENS
pulse duration (pulse width, cycle, period, duration)
frequency (rate)
burst midulation (pulse waveforms)
amplitude (intensity)
on/off time
ramp up/down time
duration
electrode size/placement
wave form (depends on unit)
what is phase
period when electrical current flows in one direction
what is pulse
period when electrical current flows in any direction
may be made up of one or more phases
what is phase duration
how long phase lasts
microseconds
what is pulse duration
aka pulse width, cycle, and period duration
how long a pulse lasts
begins at first phase of pulse and ends at last
microseconds
what is interpulse interval
amount of time between pulse
what should be the pulse diration for NMES
when using a pulsed biphasic waveform the pulse duration should be between:
small muscles = 125-200 microsec
large muscles = 200-350 microsec
if you shorten the pulse duration, what factor needs to be changed in order to achieve the same strength of muscle contraction
higher amplitude required
chatanooga continuum (LMU DPT TENS unit) has a fixed pulse width of
300 microseconds
high rate vs low rate TENS
high = 50-80 microsec to depolarize only the A beta sensory nerves
low = 200-300 microsec to depolarize motor nerves and possibly A beta
what cant you change when using interferential current with TENS
cant change pulse diration
what setting is often adjusted for pt comfort
pulse duration
usually adjustable on most portable units
what is frequency
number of cylces or pulses per sec
aka rate
inverse of cycle duration
units of frequency
PPS (pulse per sec) for pulsed currents
Hz (Hertz) for alternating currents
different frequencies and types of response for NMES
low frequency (20-30 pps) = will produce a seperate muscle twitch contraction
35-50 pps = smooth contraction
50-80 pps = stronger contractions but rapid fatigue
pulse frequencies associated with high and low rate tens and their clinical uses
high rate tens = 100-150 pps (sensory with pain gating effects)
low rate tens = <10pps with motor and endogenous effects
burst = combines high and low intermittently
why might you modulate rate of TENS
to limit adaptation/habituation and thus tolerance to tens
modulation doesnt change overall analgesic effects of stimulation if pt never adapts
what is amplitude
magnitude of current flow
amps/volts
aka strength/intensity
usually denoted by range 1-10 (weak to strong)
what is peak amplitude and peak to peak amplitude
peak = max intensoty
peak to peak = biphasic property (from top of + wave to bottom of - wave)
what setting is related to pt tolerance
amplitude
what do you want when adjusting the amplitude for high and low rate TENS
high = want strong tingling sensation
low = want to produce a muscle contraction
what is on/off time and why might it be useful
current terminated and resumed throughout treatment
stimulates voluntary contract relax phases and prevents muscle fatigue
expresses as ratio of on to off (10:50 would indicate 10 s of current and 50 s of rest)
what is ramp up/down and why is it useful
allow current to slowly reach max intensity and slowly terminate intensity
minimizes pt discomfort
ramp up = sec it takes for current to go from start to max amplitude
ramp down = from max to zero
3 types of waveforms
direct current (DC)
alternating current (AC)
pulsed current (PC)
describe direct current
continuous flow of electrons/ions in one direction
comes from battery (but not all battery powered currents are DC!)
can reverse polarity (pos to neg or neg to pos)
not used for rehab b/c of discomfort
used at low levels for iontophoresis
describe alternating current
continuous, sinusoidal, bidirectional flow of charged particles
current always flowing back and forth
type or current found in wall outlet
used clinically for pain control and muscle contraction
describe pulsed current
interrupted current flow of electrons where current flow in a series of pulses is seperated by periods when no current flows
may flow in one direction only (monophasic) or flow back and forth between polarities during each pulse (biphasic)
what is biphasic
most commonly used waveform
used in all TENS and NMES units
promote muscle contraction
control pain
what is monophasic
used clinically to promote tissue healing
manage acute edema
high volt pulsed curretn (HVPC) is most common
parameters for alternating current
always biphasic
alternating polarity between + and -
frequency for AC is measured in Hz
alternating currents sometimes referred to as what? how are they used clincally?
medium frequency
used clinically in the following protocols:
-interferential current
-premodulated current
-russian protocol
compare treatment protocols of medium frequency vs high rate vs low rate
medium = AC between 1000 and 10000 Hz
high rate = PC above 100 pps
low rate = PC below 10 pps
what is interferential current
uses 2 pairs of 2 independent circuits (quadripolar electrode placement)
they carry slightly different frequencies which cause interference at their intersecting point
electrodes are places so interference permeates the tissue at target
produces envelopes of pulses or “beats” at intersection
benefit of IFC
thought to be more comfortable and penetrate deeper than pulsed biphasic waveforms
explain beat modulation
when 2 different frequencies intersect interference pattern produces a beat frequency equal to the difference in frequency between 2 alternating current frequencies
i.e. if the 2 frequencies are 5000 Hz and 5100 Hz then beat frequency is 100 beats
what is Russian protocol
originally intended for LE quad muscle strengthening for Russian olympic athletes
only need 1 channel
cant modify preset protocol
parameters for russian protocol
medium frequency AC
2500 Hz
pulse duration of 50 bursts per sec
burst duration is 10 ms long
burst modualiton is 10 ms interburst interval
rationale for russian protocol
skin impedance decreases with decreased pulse or cylce duration thus claimed to be more comfortable
limited data
types of modulation
continuous modulaiton
burst modulation (burst modulated pulsed current or alternating current)
beat modulation
2 physiological mechanisms of pain control
gate control
endogenous opiod release
how is the gate control theory activated with tens
high rate tens
produces sensation without contracton to stimulate A Beta nerves
high frequency 100-150 pps
how is the endogenous opiod release activated with tens
low rate tens
produce brief repetitive muscle contractions to stimulate endogenous opiod production
low frequency = 2-10pps
pulse duration = 150-300 microsec
treatment time for only 20-30 min can control pain for 4-5 hours
treatmetn should not exceed 45 min to prevent DOMS
when is high rate tens recommended
when senstaion but not muscle contraction would be tolerated
post injury
inflammation present
tissues may be damaged by repeated contraction
when is low rate tens recommended
when longer duration of pain control is desired and muscle contraction is going to be tired
more chronic conditions
will have effects during an following treatment
when is burst mode TENS recommended
to apply more intensity in shorter bursts for those with higher tolerance
decreases likelihood of acommodation
equally effective as high and low rate
when might it be more comfortable to use IFC
to penetrate a larger and deeper area
