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Caroline Summer 25 2.0 > Week 3 E Stim Lecture Pt 1 > Flashcards

Week 3 E Stim Lecture Pt 1 Flashcards

(70 cards)

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1
Q

Unit of measure that indicates the RATE OF FLOW

A

Ampere

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2
Q

What unit of measurement is current described in?

A

Milliampere or microampere

net movement of electrons from higher potential to lower potential

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3
Q

electrons will not move unless what

A

there is an electrical potential difference in the concentration

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4
Q

Volt vs Voltage

A

Volt - The electromotive force moving electrons

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

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5
Q

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

What term describes resistance to flow?

A

Conductance

Insulator

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6
Q

How do you measure electrical impedance/resistance?

A

Ohms

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7
Q

What is Ohms law?

A

Current is directly proportional to voltage an inversly proportional to resistance

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8
Q

_______ is the force

______ is the flow

________ is the resistance

A

Volt

Amp

Ohm

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9
Q

what are insulators in the body (examples)?

A

skin
fat - great one

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10
Q

bone and tendon are

A

poor conductors (bone is poorest conductor)

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11
Q

Blood, nerve, and muscle are __________ conductors of electricity

A

Good conductors

note: nerve itself is conductor but the sheath is poor (its fat)

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12
Q

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

A

Blood

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13
Q

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

A

No

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14
Q

As frequency goes up skin ______________ goes down

A

Skin Impedence goes

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15
Q

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

A

closed circuit

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16
Q

TENS and IFC use what kind of current?

A

Alternating current

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17
Q

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

A

F because it is balanced with both positive and negative current

DC (Directional current) causes chemical reactions

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18
Q

AC vs DC

A

AC: Biphasic, TENS, IFC

-bidirectional
-electrons always move - to +
-neutralizes chemical reactions if balanced

DC: galvanic current, monophasic

-unidirectional(anode)
-polarity and direction of current flow can be reversed
-chemicals accumulated at each electrode (Electrolysis)
ex: iontophoresis

BOTH ARE CONTINOUS, NOT PULSATILE

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19
Q

Electrons always move from _______

A

negative to positive

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20
Q

Iontophoresis uses what kind of current?

A

DC (Directional current)

Uninterupted flow towards the postive pole

(medical treatment that uses a small electric current to deliver medicine or other charged substances through the skin into underlying tissues.)

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21
Q

The positive electrode is called ________ and attracts _____

the negative electrode is called ______ and attracts ____

A

Anode, and attracts positive ions (anions)

Cathode, and attracts negative ions (cations)

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22
Q

HVPG (high volt) and Russian stimulation uses what kind of current?

A

PC (Pulsatile) aka discontinuous current

(chat says that Russian has burst of AC currents, but they are turned on it off so its technically pulsatile and AC, but go with pulsatile)

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23
Q

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

A

Pulsatile current (Hi Volt and Russian)

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24
Q

What is the accomadation phenomenon?

A

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

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25
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 nerve doesn't know the difference!
26
Skin and Fat are what kind of electrical circuit? Nerve/Blood/Connective tissue/muscle/bone are what kind of electric circuit?
Series (high resistance and low current flow) series make you fat Parallel- resistors have lower resistance and high current flow so as e-stim travels through the skin and fat its in series, and once it gets to muscle, bone and blood and nerve its in a parallel circuit
27
T or F: The path of least resistance is usually the shortest path
F
28
What is frequency?
How many cycles per second: Hz, PPS (pulse per sec) the number of pulses, cycles, or bursts produced by electrical stimulating device in 1 second
29
increasing frequency = inc/dec tissue impedance
decrease
30
tetanization what is it a function of?
number of twitch contractions per sec increases where single twitches can not be distinguished function of frequency! **occurs at 50 PPS (Hz)**
31
T/F tetany depends on intensity
false
32
What is intensity?
The amount of stimulation, measured in amps how STRONG
33
What is pulse duration?
How wide each wave is Can be changed to target specific structures** microseconds, msecs (if too short, there will be no AP)
34
which parameter can determine the type of muscle contraction elicited?
frequency - amount of shortening of a muscle fiber - amount of recovery
35
Between frequency, Intensity, and Pulse Duration: What is the main one you increase in E-Stim?
Intensity (amps)
36
total current can increase by
- increasing pulse duration or pulse frequency or a combo amplitude?
37
What is capacitance? How can you inc/dec capacitance?
A tissues ability to store electricity - the higher, the longer before a response capacitance in tissue can be reduced by increasing frequency or changing electrode distance EXAM QUESTION
38
What kind of tissue has the highest capacitance? What has the lowest?
Highest: Muscle tissue Lowest: AB nerves
39
how does nerve diameter affect capacitance
larger diameter = decreased capacitance AB < Agamma < C < muscle fiber < muscle tissue large nerves respond quicker than small nerves (you feel tingling before muscle contracts)
40
Increased _____________ with decreased _______ is needed to stimulate tissues with higher capacitance AKA muscle
intensity pulse duration
41
Pulse vs Cycle
**Pulse** applies to **DC**, it is the individual wave of a **monophasic current** unidirectional flow **Cycle** applies to **AC**, it is both the **positive** and **negative** wave bidirectional flow during one cycle
42
symmetric, asymmetric, balanced and unbalanced
symmetric - sam shape and size for each phase in both direction asymmetric - diff shapes an dsizes for each phase; balanced or unbalanced balanced - net charge (area under the curve) is equal in both directions (can still be asymmetric if charges are equal - diff shapes same area) unbalanced - negative charge is greater in one phase = movement of ions
43
Increasing the amplitude of E-Stim causes what?
1. Current to reach **deeper** tissues 2. **Additional** nerve fibers 3. **Stronger** muscle contraction
44
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, always > 0 (directional!) For AC/biphasic, pulse charge is the sum of the positive and negative phases - therefore if its asymmetric/they don't cancel out, the pulse charge > 0, and it acts monophasic or directional Pulse charge = amount of current w each pulse, = intensity x pulse duration
45
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
46
a fast pulse rise will ___ skin impedance
lower while a slow pulse rise will not decrease impedance (but is more comfortable)
47
ramping modulation
(aka surging mod) amplitude will increase or ramp up gradually to a preset max
48
ramp up time is usually ___ of the one on time
1/3 of on time used to elicit muscle contraction
49
What is duty cycle?
The time on:off within the cycles (msec, pt cant feel) or for the total time receiving stimulation (sec, pt does feel)
50
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) note: if you see in % form, the __% is the amount of time on
51
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
52
What kind of E-Stim is best for relieving pain?
IFC
53
What does modulation mean? What are the two types and their associated technique?
Any change in the amplitude or frequency of the current burst modulation - russian, combined pulses turned on and off in a cycle beat modulation - IFC, two interfering AC currents (think about the cross!)
54
remember the two things that affect tissue impedance. skin impedance increases as the inter-electrode distance ____
increases the farther the electrodes, the mores resistance from the skin the higher the frequency, the lower the impedance/resistance
55
Which has the highest number of electrons? The Anode or the Cathode?
Cathode
56
current density
amount of flow per cubic volume (mA/cm^2) high fat content between electrodes may prevent depolarization
57
If electrodes are placed **farther** apart, what happens?
The area of highest current density is **deeper** (nerve and muscle) than if they're placed superficial if your pt is experiencing discomfort, you can try to spread out the electrodes Decrease capacitance, increase impedance
58
if you have one electrode smaller than the other, where is the area of highest current density?
under the smallest one small electrode concentrates current over a motor point whereas the larger one disperse it over larger area
59
Stimulus requires __________ in order to create an action potential and depolarization
Adequate intensity and duration
60
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 ass is positive!
61
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
62
In order of stimulation, what is stimulated first to last: Motor Nerves, Sharp Pain nerves, Sensory Nerves , Dull pain nerves, Denervates muscle
First: AB(Sensory fibers) Motor Nerves AD Sharp Pain Nerves C Dull Pain Nerves Last: Denervated Muscle
63
Nerves always depolarize in the same order, what is that order:
Sensory Motor sharp pain dull pain Denervated Muscles so pt feels: tingling (AB) --> muscle contraction (motor) --> pain (Ad, C)
64
chronaxie for AB fibers
40 mA 100 microsec just for understanding - so your rheobase is 20mA, that's the minimum intensity you need to get a muscle response with a long duration. so if we set it to 40mA, it needs 100 microseconds to stimulate AB fibers
65
chronaxie of motor fibers
60mA 200 microsec (200-600 for motor nerves!!)
66
chronaxie of Ad fibers
80mA 300 microsec
67
chronaxie for C fibers
120mA 1 MILIsec
68
large/small diameter nerves depolarize first superficial/deep nerves depolarize first
large superficial
69
T/F: in the absence of nerve innervation, a muscle can still contract by using electrical current to depolarize the muscle membrane (vs the motor nerve)
True
70
what is the goal of using e-stim on a denervated muscle?
slow down atrophy while nerve regenerates minimize mm and contractile strength loss maintain muscle fiber size limit edema and venous stasis

Caroline Summer 25 2.0 (32 decks)

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