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Phys Agents > Intro to E-stim > Flashcards

Intro to E-stim Flashcards

1
Q

Columb’s Law

A

Forces exist between charges

Force depends on the size of the charges involved and the distance between them.

Distance has a huge impact on electrical forces

Forces can cause movement of ions

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2
Q

Electrical current (I)

A

Movement of electrons in Amperes (A) or Milliamps (mA)

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3
Q

Resistance

A

Opposition to electron flow, ohms

High Resistance = insulators (Fat, dry skin, poorly attached electrodes

Insulators create heat when current passes through

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4
Q

Conductance

A

Ease of currrent flowing in a medium, units are siemens

Neurons, Water, Muscle

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5
Q

Capacitance

A

Storage of charge

Works as an insulator, blocks direct current but allow alternating current to continue moving electrons (higher frequency = better flow)

DC = Iontophoresis

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6
Q

Impedance

A

High impedence = high resistance

Fat

Low impedance = low resistance

Regionally dependent and patient dependent

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7
Q

Ohm’s Law

A

Current Flow = Voltage/Resistance

Builds up heat and can cause burns

Resistance of tissues constantly flux

Most devices allow use to set current and keep it constant

BUT some don’t! Some keep Voltage constant so we must be aware because it could possibly cause burning if resistance drops

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8
Q

Anode

A

+, typically red

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9
Q

Cathode

A

-, typically black

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10
Q

What does a circuit contain?

A

Anode, cathode, conductor, restritors

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11
Q

To create physiologic effects we need…

A

A driving V (Battery or plug in)

A proper path for I to flow (Tissues, Nerves)

A way to overcome tissue impedance (Use pulsed or alternating current I)

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12
Q

Direct Current uses a

A

Battery

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13
Q

Alternating current uses a

A

plug in

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14
Q

DC

A

Continuous unidirectional flow of electrons; Doesn’t not flip between positive and negative

Microseconds (1 millionth of a second) or milliseconds (1 thousand of a second)

Doesn’t flow well through body tissues

May cause alkaline burn

**Used only for iontophoresis **

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15
Q

AC

A

Uninterrupted biphasic (positive to negative and back) flow of electrons

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16
Q

Pulsed Current

A

Unidirectional or bidirectional flow of electrons that periodically cease for a finite amount of time

+, -, + and -

A pulse is an isolated electrical event that repeats

17
Q

If AC or Pulsed what type of waves can we get?

A

Sinusiodal (Hump), Spiked (Triangle), Square

18
Q

If we have a pulsed current what is important about pulse duration?

A

Monophasic, biphasic and triphasic

19
Q

If we have a pulsed current what is important about symmetry?

A

Symmetry from positive and negative side

20
Q

If asymmetrical, is it balanced/unbalanced?

A

Balanced: Area below is the same as above

Unbalanced: Differing amounts of charge above and below baseline

Could irritate the skin

Will form acids and bases on skin

Monophasic can not be symmetrical nor balanced

Triphasic cannot be symmetrical BUT can be balanced **

21
Q

Phase

A

Unidirectional flow of current

22
Q

Phase duration is expressed in…

A

microseconds

23
Q

Pulse

A

isolated event seperated by finite time from next event

24
Q

Pulse duration

A

time from beginning to end of all phases within a single phase

25
Q

Pulse Duration Influences neuronal excitation

A

Sensory nerve stimulation (20-60 usec)

Motor nerve stimulation (200-400 usec)

Nociceptor Stimulation (300-500 usec)
Pain is perceived
Nociceptor is a stimulus

26
Q

Rise Time

A

Longer = More tolerable

Faster = Easier Nerve Stimulation

Decay Time (time going down)

27
Q

Frequency

A

Number of pulses/time

PPS – Pulses per seconds

Sensory stimulation for Pain relief = 80-150 PPS

Muscle re-education or strengthening = 35-50 PPS

28
Q

Amplitude

A

Magnitude of current (intensity)

Increased amplitude means increased charge

29
Q

Modulation (Change)

A

Changing a feature of the waveform

Used in pain relief applications to prevent accommodation (desesitization) of nerve

Several types of modulation may change the total charge delivered to tissue

Whatever works for patient is best

30
Q

Types of Modulation

A
  • Amplitude (aka scan)
  • Duration (change duration of pulse)
  • Frequency (aka sweep)
  • Strength-Duration (variable waveform changes)
31
Q

Bursts

A

finite series of pulses

Function very similar to pulses

32
Q

Beats

A

Another type of pulse, made out of AC

33
Q

Beats and Bursts

A

Understand frequency, amplitude, phases, symmetry and balance

Same frequency guidelines as with pulses

34
Q

Duty Cycle

A

For muscle strengthening use a duty cycle of 15% to 50%

For weak muscle: 5 sec on, 25 sec rest (5/30=17%)

Strong muscle: 10 s on, 10 sec off, (10/20 = 50%)

For muscle fatigue use a higher duty cycle

35
Q

Electrodes

A

Skin Prep:
- Clean skin with a wet paper towel not EtOH (alcohol swipes) may break down the hydrogel of electrodes (Can use EtOH wipes for iontophoresis)

Clip hair (Do not shave)
- Hair is very sensitive to electricity when shaved

Prep products
- The more treatment someone requires consider using these

36
Q

Monopolar

A

One big (dispersive) electrode and one small (active)

Active = Cathode (-)

Small concentrates it in one area

37
Q

Bipolar

A

Two electrodes of equal size

38
Q

Quadripolar

A

Four electrodes, two circuits or channels, use for large areas

39
Q

Current Density (mA/cm^2)

A

With the same current, a larger electrode will have a smaller current density than a smaller electrode

Low current density is usually more comfortable but less specific

Smaller electrode can be more specific but has a higher current density

If an electrode peels off having less area of contact (very high current density), an electrical burn may occur

Distance between electrodes influences current density in tissues
- Closer together leads to less arching, more superficial tissues
- Farther apart, hits deeper tissue

Phys Agents (10 decks)

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