Modalities Ch. 16 Flashcards
electricity
form of energy that is produces by the accumulation and/or the movement of electrons
requirements for electron flow
electrons
path or conductor
force to push electrons
types of electricity
static
current
static
frictional
- two objects rubbing together
- electrons transferred from one object to another
currnet
electrons traveling along a conductor
-can be direct or alternating
measures of electrical charge
coulomb (Q) amperage (A) voltage (V) resistance (R) -ohm --material --length of circuit --cross sectional area --temperature
coulomb
measure of electrical charge
quantity of electrons
6.25 x 10^18
amperage
-A=
speed at which a current is flowing
-1 coulomb past a point in 1 second
voltage
-in modalities
electromotive force
difference of energy at one point to another
in modalities
-want it to be as low as possible while still achieving the desired effects
resistance
1 amp past 1 ohm
ability of a substance to oppose a current
ohn
measure of the resistance to electrons
resistance factors
material
length of circuit
cross sectional area
temperature
material in body
blood and nerves have lower resistance (more electrons)
skin and bones have higher resistance
length of circuit
the shorter the circuit, the less resistance
cross sectional area
the larger the area the less resistance
temperature
increased temperature equals increased flow of electrons
-decreases resistance
water-electricity flow analogy
table in book
Ohm’s Law
current (amps)= voltage/resistance
-A = V/R
volts = current x resistance
resistance = voltage/current
current types
direct current
alternating current
pulsed current
direct
-alternate name
continuous flow of electrons in one direction
-pulse greater than one second
galvanic current
alternating current
continuous flow of electrons in alternating directions
-IFC is a series of alternating current coming together
pulsed current
interruption in flow
pulse and cycle characteristics
pulse named by number of phases
- monophasic
- biphasic
- polyphasic
monophasic
one phase
current flows in one direction only
biphasic
two phases
current flows in both directions
polyphasic
multiple phases
quantitative characteristics
amplitude
-distance from baseline to top of wave
peak vs. average amplitude
peak
-the longest distance
average
-average of all the amplitudes
pulse duration
duration of one pulse
-made up of phases
phase duration
duration of one phase
-specific to AC
pulse period
length of on and off time of one pulse
interpulse interval
time between conclusion of one pulse and start of next
intrapulse interval
interruption in a single pulse or phase
phase shapes
sinusoidal
rectangular
spike
duty cycle
on time / (off time + on time)
russian wave form
characteristics
- polyphasic
- symmetrical
- sinusoidal
- burst
interferential wave form
characteristics
-symmetrical
-sinusoidal
-high frequency (2000-5000 Hz) AC
two channels, with different frequencies, used simultaneously
two currents cause a tissue current amplification
tissue response to electrical simulation
thermal
magnetic
chemical
kinetic
chemical response: iontophoresis
DC
used to push medication through the skin into the body
lasts 10-20 minutes
cathode vs. anode
cathode
- positive
- drives ions towards negative pole
most common iontophoresis medications
dexamethasone -corticosteriods -negatively charged lidocaine -positively charged
kinetic response
sensation
muscle contraction
muscle contraction
twitch
tetanic
-multiple contractions that fuse together into one continuous contraction
polarization and action potentials
polarized
unequal positive and negative one each side of cell -membrane
polarized
-ions lined up on each side of the membrane
depolarized
-ions move back to equilibrium
caused by sodium ion movement
mixed nerves
a fibers -largest -respond the most readily to stimulation -sensory or motor b fibers -autonomic motor nerves c fibers -smallest and slowest -sensory
knerve excitability and stimulation parameters
nerve excitability -the amount of electrical current applied to the surface necessary to elicit an action potential in a specific nerve influencing factors -nerve size and depth -tissue resistance -current density -- smaller target area, denser current -current strength -frequency of stimulation --pulses/sec. -electrode orientation -motor point
electrode orientation
longitudinal is 4x stronger than transverse
electrode size
smaller electrode = greater current density
electrode distance
increased distance = increased intensity for same result
electrode placement
-bipolar technique
electrodes from terminals are of equal size, resulting in nearly equal current density under them
both active
applied to treatment area in relative proximity to each other
electrode placement
-monopolar/unipolar technique
electrodes of unequal size, creating active and indifferent electrodes
may have multiple active electrodes
active electrode(s) applied to treatment area
indifferent electrode applied to remote location
e-stim parameters
pulse frequency pulse duration -measured in ms duty cycle amplitude -measure of intensity
types of e-stim
transcutaneous electrical nerve stimulation (TENS)
IFC
TENS - transcutaneous electrical nerve stimulation
pain control -gate control theory (sensory) -opiate theory (motor or brief intense) three types -sensory -motor -brief-intense
sensory TENS
acute pain high frequency sensory-level intensity stimulates large-diameter sensory nerves "traditional" TENS
motor TENS
chronic pain lower frequency motor-level intensity stimulates small-diameter afferent nerves produces a slight muscle twitch
brief-intense TENS (noxious tens
chronic pain stimulates C-fibers variable frequency highest possible tolerance burning, needling, twitch, tetanic contraction
IFC - interferential current
- primarily used for
- two channels
- vectors
two separate waves that meet primarily used for -pain reduction -decrease in muscle spasm two channels -carrier frequency: 4200 Hz -adjustable frequency: 4300 Hz -beat frequency: 100 Hz vectors -static -dynamic
NMES - neuromuscular electrical stimulation
- indications for use
- effects
"Russian" stim indications for use -neuromuscular re-education -atrophy prevention -muscle spasm -edema effects -depolarization of alpha motor neurons -increased proprioceptive feedback -"milking" effect for reducing edema
HVPC - high-volt pulsed current stimulation
150 V = high volt twin-peak monophasic waveform short pulse width results -wound healing -edema control
wound healing with HVPC
high-frequency, low amplitude waves
sensory-level stimulation
HVPC promotes the natural healing process
strong research
edema reduction with HVPC
stopping edema formation
resolving edema
moderate research
water application
