Modalities: Electrical Stimulation Flashcards
what are electrons
what is electrical current
negatively charged ions that are part of atoms
the flow of electrons from one area to another
electrons will only from from ___ to __ concentration
how is the rate of electron flow measured
define voltage
high to low
in amperes (A) - gives us an idea of the intensity
the magnitude of potential difference between the high and low concentration areas (the difference from high to low concentration)
what is Ohm’s law
electricity takes the path of ___ ____
the rate of current flow (I) is directly proportional to the strength of the driving force (V) and inversely proportional to the resistance (R)
least resistance
which materials give up electrons freely
which materials do not give up electrons freely
what is the resistance to electron movement measured in
materials of high conductance (metal, water)
materials of high resistance (air, wood, glass)
ohms
what are the human tissues that have high conductance (low resistance)
what are the human tissues with high resistance
if something is a good conductor of temperature, it’s also a good conductor of ____
high water content (muscle), blood, granulation tissue
skin, bone, necrotic tissue
electricity
what factors increase skin impedance
what factors decrease skin impedance
cooler skin temperature, hair and oil present, increased skin thickeness
removing excess hair, warming skin, washing skin
describe the characteristics of the anode (colour, charge, ions repelled, ions attracted, axon excitability, active/inactive, pH)
colour: red
charge: positive
repels: positive
attracts: negative
axons excitability: decreased
active/inactive: active
pH: acid
describe the characteristics of the cathode (colour, charge, ions repelled, ions attracted, axon excitability, active/inactive, pH)
colour: black
charge: negative
repels: negative
attracts: positive
axons excitability: increased
active/inactive: inactive
pH: basic
how does the cathode result in a basic reaction
how does the anode result in an acidic reaction
since the cathode is negatively charged, H+ stays and OH- bonds with NA resulting in increased NaOH in the skin
since the anode is positively charged, OH- stays and H+ bonds with Cl- resulting in increased HCl in the skin
describe direct, alternating and pulsed current
direct: an uninterrupted, unidirectional flow of electrons towards the positive pole
alternating: continuous bi-directional flow of electrons as poles constantly change polarity (electrons always flow towards positive pole)
pulsed: pulses of current flow interrupted by short periods, can be AC or DC
who was luigi galvani
he termed galvanic current (which is now termed direct current)
discovered that the NS is influenced by external electrical activity by using electrical activity and frog legs
describe the net charges of direct and alternating current
what does this mean for skin irritation
direct: net charge, has polarity (high risk of skin irritation)
alternating: no net charge/no alkaline or acidic build up because polarities always change (reduces risk of skin irritation)
describe monophasic pulsed current
T or F: this current has no net charge
isolated unit of unidirectional movement of charged particles separated by a finite period from another unit of charged particles (direct current with breaks)
F, it has a net charge and has polarity
describe biphasic pulsed current
T or F: this current has no net charge
isolated unit of bi-directional movement of charged particles separated by a finite period from another unit of charged particles (alternating current with breaks)
T
is the current in your house direct or alternating
is it the battery or the machine that determines the type of current
alternating because it’s safer
the machine, can use power from the battery to output monophasic or biphasic or alternating current
what are the 6 waveform characteristics
duration, amplitude, frequency
bursting, rate of rise and decay (ramping), waveform shape
define pulse, phase and cycle
pulse: a single waveform, may have one or more phases
phase: the portion of the pulse which rises above or below baseline and returns to baseline
cycle: includes two phases that each return to baseline (seen in alternating current)
define amplitude and duration
what is amplitude measured in
T or F: amplitude is synonymous with the amount of electricity delivered to the tissues
amplitude: the magnitude of the electromotive force driving electrons (how high up we go)
duration: how far along we go
volts, amps, current intensity
F, has to go through adipose tissue which absorbs some of it
define frequency
with sufficient amplitude, tetanic muscle contraction occurs at what frequencies
what happens if the frequency is less than that
the number of pulses or cycles per second
>50Hz
there is muscle twitching
as frequency increases, what decreases
what are bursts
what type of current uses bursts
the duration
a train of pulses followed by a short period of time with no activity
pulsatile current
what is the purpose of using bursts
decreases accommodation by nerves vs a more consistent stimulus and is more effective at eliciting contraction of muscle (summation of stimuluation)
what is ramping
what is the purpose of ramping
what is ramping important for in regards to the patient
a rise to full amplitude and then a fall gradually to 0 current
patient can feel the current start to increase so they can engage the muscle with the machine
patient comfort and patient participation
with biphasic current, what happens to the charge if the waveforms are symmetrical
with biphasic current, what happens to the charge if the waveforms are asymmetrical
T or F: in monophasic current the current flow always goes in one direction so there is always a charge
there is no charge because they are balanced
there is a charge because they aren’t balanced
T
why is it important to worry about charge
what two things are important to know about charge in regards to safety
because build up of charge can lead to acidic or basic chemical reaction/skin irritation
the type of current used (DC, AC, pulsed, non-pulsed)
if biphasic waveform are the phases balanced
what are the three key ways to bring sufficient current
the combination of these three factors can result in what 3 things
duration, amplitude, frequency
subsensory stimulation (don’t feel anything), appropriate treatment, noxious stimulation (too much)
explain accommodation
how can you decrease accommodation
over time with consistent amplitude, frequency or duration of electrical energy, a nerve will become unexcitable
modulate/change the current characteristics (intensity, frequency, duration)
what are contraindications of using electrical stimulation
pacemakers or known arrhythmia (influences beat)
over the carotid sinus or other excitable areas (chest, eyes, head)
over the pelvis, abdomen, trunk and lower back during pregnancy (can cause miscarriage and abnormal fetal tissue growth)
over areas of thrombophlebitis (blood clots may travel)
impaired sensation
severe peripheral vascular disease (influences BF)
over superficial metal implants
active cancer (propagates growth of cancer tissue)
poor communication skills or altered mental state
why is severe peripheral vascular disease a contraindication to using electrical modalities
what modalities would not affect this condition
because arterial BF to the area is already compromised
TENS or IFC because the O2 demands in these cases are low because these modalities do not contract the muscle
what are the precautions for using electrical stimulation
palliative cancer (used for pain management or increased mobility)
over skin irritations or near open wounds
what should you be aware of when adjusting amplitude
what can causes a burn when using electrical stimulation
what causes increased risk of burns when using electrical stimulation
the on:off cycles, don’t increase the amplitude during the off time
a build up of ions under the electrodes
longer treatment sessions, water/sweating, metal
what does PSS stand for
explain each letter of the acronym
pain: requires good therapist/patient communication
skin reactions: most common adverse reaction, rely on monitoring skill
risk of surge: its an electrical device and address this risk, but term selection is important (don’t use the word electrocution)
