403 Principles and Techniques of E-stim

electricity is the force generated by the imbalance of charges between

2 poles

what flow from one pole to the other to try and balance the charge?

electrons

the ____ of the flow of electrons creates the electrical current

rate

what is direct current?

continuous flow of electrons in one direction between the anode and cathode

what is alternating current?

A continuous flow of electrons that rhythmically alternates directions due to the poles changing between + and -

which current is used least often?

direct

which current is less painful?

alternating current

what is a waveform?

shape of an electrical current created when the current is graphed with amplitude on vertical axis and time on horizontal axis

what kind of waveform is dc?

monophasic

what kind of waveform is ac?

biphasic

what is a pulsed current?

current is interrupted for set periods of time

what way does electrons flow?

from negative pole to positive

what is the negative pole referred to as?

cathode

positive pole?

anode

what is a closed circuit

when pathway is completely linked and electrons are able to flow

current modulations

the outcomes can be adjusted by altering the attributes of the electrical current

what is an electrical current?

string of electrons that pass along a conductor

what is amperage?

rate or amount of current flow that's measured in units of ampere

what is voltage?

the force that moves a current measured in volts

what is wattage?

the measure of electrical power measured in watts

what is an electrical charge?

the positive or negative state of an atom, molecule, or object due to an imbalance of protons and electrons. Typically expressed in Coulomb (Q)

what is Coulomb's Law?

describes the relationship between like and unlike charges and how their interaction produces resistance on passing of an electrical current

the three parts of Coulomb's law

1. similar charges repel and opposite charges attract

2. closer the two charges are, the stronger the attraction/repulsion

3. stronger the magnitude of charge, the stronger the attraction/repulsion

what is resistance

the degree of opposition to the flow of an electrical current by the conductor

what is the conductor?

the medium the current is flowing through

so the greater the resistance the _________ the power output by the circuit

lower

what is impedence?

resistance of a tissue in the body to an electrical charge (how easily the current can move through tissue)

what is Ohm's Law used for?

used to calculate the relationship between current, voltage, and resistance in an electrical current

Current is directly proportional to _________ and inversely proportional to _______________

1. voltage

2. resistance

what is current modulation?

manipulating, regulating, and adjusting of input current to create a variety of specific output wave forms

what is the purpose of modulation?

to create action potentials in different nerves/tissues

intervention of electrical stimulation caused a nerve to

depolarize

after the action potential the nerve goes through a

refractory period

what is absolute refractory?

nerve cannot fire no matter what is done

what is relative refractory?

nerve can fire but needs increased stimulation

what is the law of Dubois Reymond?

"the law of excitation" which describes the ways in which electrical currents must interact with a nerve to cause an action potential

four components of law of Dubois Reymond

1. the intensity of the current must be strong enough to depolarize the cell membrane

2. the rampu up of the leading edge of the pulse must be rapid enough to prevent accommodation

3. the current must flow enough in one direction(phase duration) to cause the nerve to depolarize

4. sufficient time must be allotted to allow the membrane to repolarize

what is amplitude?

maximum amount that a wave rises above or drops below the baseline (also can be called intensity or output)

what is pulse?

a period of tie of charged particle movement (pulses are made up of phases)

what is phase?

an individual section of a single pulse

what is phase duration?

the time required for each component of a wave to complete its shape

why is phase duration important?

it determines the type of tissue that you stimulate. The phase duration has to be long enough to reach the threshold potential

what is pulse duration (pulse width)

the time required for a single phase to complete its route

by increasing pulse duration you stimulate ____________ nerve fibers since the current is available for a longer period of time

more

what is ramp up

the time from beginning of a phase until its peak amplitude

what is ramp down?

the time from max amplitude to end of phase

ramp up time is important in the depolarization of nerves because

if the ramp up time is too slow the nerves will accommodate to current and not generate action potential. So, a rapidly rising pulse will cause better nerve depolarization

what is a duty cycle?

the amount of time that the current is flowing relative to the amount of time the current is not flowing

what is pulse charge?

total electricity being delivered during a pulse (space within wave form)

what is phase charge?

total electricity being delivered during a phase

the higher the phase charge the ________________ the depolarization

stronger

what is pulse symmetry?

biphasic waveforms may be either symmetrical or asymmetrical

if the pulse is symmetrical

positive and negative charges are equal so there is no net residual electrical effect

if the pulse is asymmetrical

it allows for greater positive and negative effects

Asymmetrical waveforms can be either balanced or unbalanced. what is an asymmetrical balanced waveform?

the two phases carry equal electrical charges that allow for greater positive and negative charge effects but overtime the net electrical charge equals 0

what is asymmetrical unbalanced waveform?

two phases carry unequal electrical charges which allows for greater positive and negative charge effects and overtime net electrical charge is carried

what is frequency?

the rate that current changes direction per second

high frequency has to be

>10,000 Hz or pps

low frequency has to be

what is interpulse interval?

time between the end of one pulse and the start of the next which allows for repolarization of the cell membrane

high frequency pulses have ___________ interpulse intervals

lower

if the repolarization time is too short or frequency is too high than it will not be effective because the nerves can not get out of the ___________

absolute refractory period

tissues with a ______________ conduct electricity better

high water content

what are excitable tissues?

they are directly influenced by electrical currents (nerves, muscle fibers, and cell membranes)

what are nonexcitable tissues?

they are not directly influenced by the electrical currents but may be affected by the electrical fields caused by the current (bone, cartilage, tendons, adipose tissue, and ligaments)

high water content in tisues also does what?

lowers impedence and increases conductivity

what is an insulator?

a material that limits the transmission of an electrical charge to the target tissue

when going through the body, electricity follows two rules:

1. always take the path of least resistance

2. amperage and voltage must be sufficient to overcome the total resistance imposed by the circuit

some areas of the skin conduct electricity very well. What are these points called?

motor points (or trigger points)

what are motor points?

a point where a given amount of current will elicit the greatest muscle contraction because that is where the motor nerve enters the muscle

what are trigger points?

a pathological localized area of tissue injury and pain (highly sensitive to e-stim)

when resting, the inside of a nerve has a

negative charge

the outside of the nerve has a

positive charge

when those two charges switch this is called

depolarization

if the magnitude if the depolarization is strong enough to overcome the nerve's __________________________ then an action potential will ensue

threshold potential

four things that could be said about larger nerves when it comes to e-stim

1. conduct action potentials quicker

2. have lower threshold

3. have shorter duration of response

4. shorter refractory period

example:

in order to stimulate type C nerves, you need a _____ stimulus level for depolarization

higher

a nerve's response to e-stim is based on 3 things

1. diameter of nerve

2. depth of nerve in relation to electrode

3. duration of pulse or phase

a current will that is strong enough to stimulate type C fibers will also stimulate type A-delta and beta

true or false?

true

Sensory Level Stimulation

target nerves:

phase duration:

pulse freq:

intensity:

-A-beta

-60-100 u/s

-80-200 pps

-you should not see muscle contraction, they should feel tingling

Motor level stimulation

target nerves:

phase duration:

pulse freq:

intensity:

-A-alpha

-150-300 u/s

-50-70 pps

-visible contraction that's not painful

Noxious Level stimulation

target nerves:

phase duration:

pulse freq:

intensity:

-A-delta and C

-250 u/s or 1 millisecond

-1-5 pps

-as uncomfortable as can be tolerated, usually with a muscle contraction

most resistance comes from the

epithelium

As the size of an electrode increases, the current density _______________.

decreases

what is current density?

measure of quanitity of charged ions moving through a particular cross-sectional area of an electrode and the skin beneath the electrode

the higher the current density the __________ the intensity

higher

high voltages through a small electrode are more

uncomfortable

small electrodes:

-require less current to stimulate a tissue

-better target superficial nerves

large electrodes:

-better stimulate deeper nerves

-more comfortable muscle contractions

the resistance from the skin decreases as the size of the electrode

increases

how can you reduce skin impedence?

1. wash area with soap and water

2. scrub area with emery paper

3. remove excess hair

4. heat skin w/ mhp

5. ensure the most surface area contact

what is an active electrode?

the current density is great enough to elicit desired response (always the smaller one)

dispersive electrode

current density is not great enough to elicit desired response (always the larger one)

monopolar configuration

pads of unequal size coming from two terminals where the smaller pad is placed near target tissue (where pt should feel sensation) and the larger pad placed away from target tissue

if the pt is feeling sensation under larger pad what two things could you do?

1. move pads further apart

2. use larger dispersive pad

bipolar configuration

pads of equal size coming from two terminals where both pads are active

quadripolar configuration

four pads of equal size coming from two different circuits where all pads are active

electrodes that are closer together will have a more ___________ fcurrent flow

superficial

the flow of electrical current should run in the same direction as

the fibers of the tissue you are targeting

general e-stim indications:

-stimulation of select nerves

-muscle contraction

-neuromuscular reeducation

-strength augmentation

-pain control

-increase blood flow

-wound healing

-control or reduction of edema

-fx healing