Therex: E Stim Lecture Pt 1 Flashcards by Chavez Girls

electrical current

a current of electricity or flow of electrons

net movement of electrons

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Unit of measure that indicates the RATE at which electrical current flows

Ampere

rAte = Amps

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What unit of measurement is current described in?

Milliampere or microampere

net movement of electrons from higher potential to lower potential

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Volt vs Voltage

Volt - The electromotive force moving electrons

Voltage - force resulting from accumulation of electrons at one point in the electric circuit

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What is the term describing the ease at which current flows along a medium?

What term describes resistance to flow?

Conductance

Insulator

conductancE = Ease
insulatoR = Resistance

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How do you measure electrical resistance?

Ohms

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What is Ohms law?

Current is directly proportional to voltage an inversely proportional to resistance

current = voltage / resistance

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resistance of electrical flow depends on the characteristics of the ___________.

conductor

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_______ is the force

______ is the flow/rate

________ is the resistance

Volt

Amp

Ohm

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Fat and skin are a _______ conductor of electricity

Poor conductor

Great insulator (resist flow)

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Blood, nerve, and muscle are __________ conductors of electricity

Good conductors

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In the body, what is the best conductor of electricity?

Blood

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what bodily tissues provide the most resistance?

tendon, ligament, bone, fat

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what bodily tissues provide the path of least resistance?

nerves, blood, muscle

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biphasic/AC v. monophasic/DC v. pulsatile

biphasic: sine curve, crosses neutral

monophasic: stays on positive side

pulsatile: “flat line” between sine curves

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Does turning up the frequency of a current turn up the intensity?

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electrical impedance

how can you alter it?

the total resistance to the flow of electrical current through the skin, tissues, electrodes, and cables

altered by changing the distance of the electrodes and the currents frequency

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as the inter-electrode distance increases, the skin impedance ____________.

increases

theres more skin/tissue it has to go through

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As frequency increases skin impedance

decreases

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Which circuit do electrons flow in: An open circuit, or a closed circuit?

closed circuit

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which electrotherapeutic current relies on correct placement of anode and cathode?

direct current

cathode: distal
anode: proximal

Positive = Proximal

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TENS and IFC use what kind of current?

Alternating current

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T or F: Alternating current can cause chemical reactions on the skin

F because it is balanced with both positive and negative current

DC (Directional current) causes chemical reactions

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Electrons always move from _______

negative to positive

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Iontophoresis uses what kind of current?

DC (Directional current) Uninterupted flow towards the postive pole

The positive electrode is called ________ the negative electrode is called ______

Anode Cathode | PANIC

HVPG and Russian stimulation uses what kind of current?

PC (Pulsatile) aka discontinuous current

What kind of current is the most stimulating for nerves and muscles?

Pulsatile current (Hi Volt and Russian)

series vs. parallel circuits

**series**: resistors have higher resistance, lower current flow **parallel**: resistors have lower resistance and higher current flow - all get current at the same time

What is the accomadation phenomenon?

A fiber that has been subjected to constant level of e-stim will become unexcitable at that intensity (amplitude)

what is the BIGGEST difference between AC and DC

DC's ability to cause chemical changes note: With DC these will not happen until a period of time over one minute

Skin and Fat is simular to what kind of electrical circuit? Nerve/Blood/Connective tissue/muscle/bone is simular to what kind of electric circuit?

Series (high resistance and low current flow) Parallel- resistors have low resistance and high current flow

T or F: The path of least resistance is usually the shortest path

What is frequency?

How many cycles per second: Hz, CPS, PPS can determine the **type of muscle contraction** elicited

What is intensity?

the amount of amplitude/stimulation, measured in amps

higher intensity → the current reaches ________ tissues

deeper

What is pulse duration?

How wide each wave is; amount of time current is applied Can be changed to target **specific structures** (usecs, msec)

tetany is a function of ___________ of the stimulating current

frequency occurs at 50 pps

how can you increase total current

by increasing the pulse **duration** and/or **frequency**

Between frequency, Intensity, and Pulse Duration: What is the main one you increase in E-Stim?

Intensity (amps)

What is capacitance?

A tissues ability to store electricity the higher the capacitance, the longer before a response example: if you leave e-stim on there is a heat build up

capacitance in a tissue can be reduced by _______ the frequency

increasing

What kind of tissue has the highest capacitance? What has the lowest?

Highest: Muscle tissue Lowest: AB nerves (largest diameter) AB

Increased _____________ with decreased _______ is needed to stimulate tissues with higher capacitance AKA muscle

intensity pulse duration (determines type of tissue)

Pulse vs Cycle

**Pulse** applies to **DC**, it is the individual wave of a **monophasic current** (on/off/on/off) **Cycle** applies to **AC**, it is both the **positive** and **negative** wave (up+down)

Increasing the amplitude of E-Stim causes what?

1. Current to reach **deeper** tissues 2. **Additional** nerve fibers 3. **Stronger** muscle contraction

What does changing "Pulse Charge" do?

Determines the amount of chemicals formed Note: for DC/monophasic the pulse charge is the same as the phase charge (>0) For AC/biphasic, pulse charge is the sum of the positive and negative

what is the difference between the pulse charge of an symmetric and asymmetric biphasic pulse charge?

symmetric: net pulse charge = 0 asymmetric: pulse charge > 0

Pulse Rise- the time it takes for the pulse to reach maximum amplitude A slower pulse rise is usually more __________ compared to a faster pulse rise

More comfortable for the patient

decay time

the time in which a pulse goes from peak amplitude to 0V

What is duty cycle?

The ratio of time on:off within the cycles or for the total time receiving stimulation more off time → less muscle fatigue

What do these different duty cycles mean? 1:1 1:5 1:7

The first number is the time on, the second number is the time off 1:1 muscle will fatigue rapidly 1:5 less muscle fatigue 1:7 no fatigue (passive muscle exercise)

What is the definition of frequency for E-Stim? What is the unit of measurement?

Number of impulses or cycles in 1 second pps (pulse per second) or Hz

What kind of E-Stim is best for relieving pain?

IFC

Tetany occurs at approximately what Hz/pps

50 Hz

What does modulation mean?

Any change in the amplitude or frequency of the current

burst modulation

combined pulses turned on/off for a short time in a repetitive cycle

beat modulation

beat frequency produced by 2 interfering biphasic currents (AC) with different frequencies (IFC)

ramping modulation

starts low and slowing ramps up to peak amplitude according to patient comfort

Which has the highest number of electrons? The Anode or the Cathode?

Cathode

If electrodes are placed **farther** apart, what happens?

The area of highest current density is **deeper** than if they're placed superficial

Stimulus requires __________ in order to create an action potential and depolarization

Adequate intensity and duration

current density

amount of current flow per cubic volume must be high enough to facilitate depolarization

how does electrode size affect current density

if one is smaller than the other → current density under the smaller electrode is increased larger electrode → decreased current density

what size of electrodes should you place on motor points?

small electrode

When creating chemical effects using e-stim which is more alkaline, the anode or the cathode? which is more acidic?

Cathode- Alkaline effect Anode- Acidic effect

What is Rheobase? What is Chronaxie?

**Rheobase**: The **INTENSITY** of current necessary to cause **OBSERVABLE** tissue response given a long duration **Chronaxis**: The **DURATION** required for a current of twice the itensity of rheobase to produce tissue excitation

In order of stimulation, what tissues are stimulated first to last:

First: AB(Sensory fibers) Motor Nerves AD Sharp Pain Nerves C Dull Pain Nerves Last: Denervated Muscle

Therex: E Stim Lecture Pt 1 Flashcards

(68 cards)