Intro to E-stim

Question 1

Columb’s Law

Answer 1

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

Question 2

Electrical current (I)

Answer 2

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

Question 3

Resistance

Answer 3

Opposition to electron flow, ohms

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

Insulators create heat when current passes through

Question 4

Conductance

Answer 4

Ease of currrent flowing in a medium, units are siemens

Neurons, Water, Muscle

Question 5

Capacitance

Answer 5

Storage of charge

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

DC = Iontophoresis

Question 6

Impedance

Answer 6

High impedence = high resistance

Fat

Low impedance = low resistance

Regionally dependent and patient dependent

Question 7

Ohm’s Law

Answer 7

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

Question 8

Anode

Answer 8

+, typically red

Question 9

Cathode

Answer 9

-, typically black

Question 10

What does a circuit contain?

Answer 10

Anode, cathode, conductor, restritors

Question 11

To create physiologic effects we need…

Answer 11

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)

Question 12

Direct Current uses a

Answer 12

Battery

Question 13

Alternating current uses a

Answer 13

plug in

Question 14

DC

Answer 14

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 **

Question 15

AC

Answer 15

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

Question 16

Pulsed Current

Answer 16

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

Question 17

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

Answer 17

Sinusiodal (Hump), Spiked (Triangle), Square

Question 18

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

Answer 18

Monophasic, biphasic and triphasic

Question 19

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

Answer 19

Symmetry from positive and negative side

Question 20

If asymmetrical, is it balanced/unbalanced?

Answer 20

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 **

Question 21

Phase

Answer 21

Unidirectional flow of current

Question 22

Phase duration is expressed in…

Answer 22

microseconds

Question 23

Pulse

Answer 23

isolated event seperated by finite time from next event

Question 24

Pulse duration

Answer 24

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

Question 25

**Pulse Duration Influences neuronal excitation**

Answer 25

**Sensory nerve stimulation (20-60 usec)** **Motor nerve stimulation (200-400 usec)** **Nociceptor Stimulation (300-500 usec)** Pain is perceived Nociceptor is a stimulus

Question 26

Rise Time

Answer 26

Longer = More tolerable Faster = Easier Nerve Stimulation Decay Time (time going down)

Question 27

Frequency

Answer 27

Number of pulses/time PPS – Pulses per seconds **Sensory stimulation for Pain relief = 80-150 PPS** **Muscle re-education or strengthening = 35-50 PPS**

Question 28

Amplitude

Answer 28

Magnitude of current (intensity) Increased amplitude means increased charge

Question 29

Modulation (Change)

Answer 29

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

Question 30

Types of Modulation

Answer 30

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

Question 31

Bursts

Answer 31

finite series of pulses Function very similar to pulses

Question 32

Beats

Answer 32

Another type of pulse, made out of AC

Question 33

Beats and Bursts

Answer 33

Understand frequency, amplitude, phases, symmetry and balance Same frequency guidelines as with pulses

Question 34

Duty Cycle

Answer 34

**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

Question 35

Electrodes

Answer 35

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

Question 36

Monopolar

Answer 36

One big (dispersive) electrode and one small (active) Active = Cathode (-) Small concentrates it in one area

Question 37

Bipolar

Answer 37

Two electrodes of equal size

Question 38

Quadripolar

Answer 38

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

Question 39

Current Density (mA/cm^2)

Answer 39

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