Exam #2 For Pta 145

Front 1

Purpose of Electrical Stimulation (E-stim)

Back 1

• Strengthen muscle (Use a carbon pad w/ gel.Used for pts. who have a strength of less than 3/5)
• Decrease pain(pain management)
• Iontophoresis (distribution of medication through the use of e-stim)
• Improve motor recruitment
• Improve mobility
• Improve endurance
• Increase circulation
• Decrease spasticity (poor)

Front 2

Indications for Electrical Stimulation (E-stim)

Back 2

• Peripheral nerve injuries (wake the nerves up)
• Muscle inhibition due to joint pain
• Upper motor neuron (UMN) lesion
• Muscle atrophy
• Assist lymphatic system
  

Front 3

Contraindications for E-stim

Back 3

• Where active motion is contraindicated
• Cardiac pacemakers
• Metal implants (in the area being treated)
• Malignancies (in the area being treated)
• 1st trimester of pregnancy
  

Front 4

Precautions for E-stim

Back 4

• Decreased sensation
• Open wounds
• Extreme edema
• Extreme scarring
• Around the neck or sinus
  

Front 5

Components of E-stim

Back 5

• Electrical current is the net movement of electrons
• Therapeutic e-stim is measured in milliamperes (mA)
  

Front 6

What is an ampere?

Back 6

The rate at which electrical current flows

Front 7

What is a coulomb?

Back 7

Group of electrons; also known as charge

(like a bucket of water)

Front 8

What is voltage?

Back 8

The force at which the electrons are moving (akin to water pressure)

Front 9

What is the difference between conductors & insulators?

Back 9

Conductors allow for easy movement of electrons while an insulator does not. Metals are examples of conductors & wood is an example of an insulator.

Front 10

Describe Ohm's law

Back 10

Ohm's law states that the current (electrical flow) in an electrical circuit is directly proportional to the voltage (force of electricity) & inversely proportional to the resistance (something that is slowing down the current/flow).

As the voltage goes up or down so does the current/flow.

As the resistance goes up the current/flow goes down & vice versa.

Front 11

What is the significance of Ohm's law when using therapeutic electrical stimulation and how do we apply this to our treatment/what are we trying to accomplish/what is the goal?

Back 11

It is important to consider Ohm's law when applying the electrical stimulation to reduce the resistance to prevent burning of the tissue.

Our goal is to get the physiological response that we want to achieve with the least amount of current.

Front 12

Direct Current (D/C)

Back 12

• Can also be called monophasic current
• D/C has an uninterrupted unidirectional flow of electrons
• The interphase interval & the intrapulse interval are the same thing with D/C
• The amplitude remains the same for several seconds to minutes
  

Front 13

Alternating Current (A/C)

Back 13

• Can also be called biphasic current
• Main type of current we will use
• A/C is the continuous flow of electrons bidirectional, constantly changing its polarity (+ to -), & can be symmetrical or asymmetrical
• With a balanced symmetrical & balanced asymmetrical pulses will results in a ZNC
• With an unbalanced asymmetrical pulse will result in a positive charge (not used; primarily used for research)
  

Front 14

Pulsatile Currents

Back 14

Usually contains three or more pulses grouped together & may be unidirectional or bidirectional

Front 15

What is represented in a waveform?

Back 15

• The shape, direction (+ or -), amplitude (the vertical line on a strength-duration curve), & duration of a pulse (the horizontal line on a strength-duration curve).
• It can also represent the frequency.
• Waveform shapes are sinusoidal, rectangular, squares, or spiked. Most generators do not offer the sawtooth or trapezoid shapes.
• We will use the rectangular/square, spike, & sinusoidal waveforms.
  

Front 16

Pulse

Back 16

• An individual waveform is referred to as a pulse
• A pulse that is bidirectional (A/C) will have at least 2 phases, a positive phase & a negative phase
• Pulses and phases are the same w/ monophasic currents (D/C)
  

Front 17

Pulse Amplitude

Back 17

The amplitude of each pulse reflects the intensity of the current.

Measured in Amperes.

Front 18

What is the difference between peak current & total current?

Back 18

Peak current is the measurement of each pulse. Total current is the average current over the course of the pulse train (more than one pulse)

Front 19

Rise time (C) is...

Back 19

...how long it takes you for the pulse to go from zero to peak

Front 20

Decay time (D) is...

Back 20

...how long it takes for the pulse to go from peak to zero

Front 21

Rate of rise time is related to....

Back 21

...accommodation (loss of energy) & the excitability of nerves

Front 22

Pulse Duration (G)

Back 22

• Indicates the length of time current is following in one cycle

• With D/C, phase duration (F) & pulse duration (G) is the same.
• With A/C, the pulse duration (G) is determined by the combined phase durations (F)
  

Front 23

Pulse Frequency

Back 23

Indicates the number of pulses per second

• PPS: pulses per second
• CPS: cycles per second
• BPS: burst per second (not great abr. because it can also mean beats per second)

None of these are the same thing, it depends on the wave form you are using and what type of terminology you're using.

Front 24

What is current modulation?

Back 24

The amplitude, duration, or frequency of the current during a pulse train (more than one pulse)

• IFC: Interferential Current

Ex: 150/80 IFC means 150 pulses/sec on and then 80 pulses/sec off

Front 25

What is burst modulation?

Back 25

Occurs when pulsatile or alternating current flows for a short duration & then is turned off for a short time in a repetive cycle.

Front 26

Ramping Modulation

Back 26

Is directly related to accommodation (loss of energy)

Ramp times are a part of the total time.

• Ramp up time is how long it takes for the pulse train to go from zero to peak intensity.
• Ramp down time is how long it takes for the pulse train to go from peak intensity to zero.
  

Front 27

Ramp up time is...

Back 27

...how long it takes for the pulse train to go from zero to peak intensity

Front 28

Ramp down time is...

Back 28

...how long it takes for the pulse train to go from peak intensity to zero

Front 29

Current Flow Through Biologic Tissues

Back 29

• Electricity follows the path of least resistance
• Tissues higher in water usually are the best conductors
• Skin is considered an insulator
• The greater the resistance of the skin the higher the voltage needed to stimulate the underlying tissues
• Blood, muscle, & nerve are considered good conductors
• Fat, tendon, & bone are poor conductors
  

Front 30

Physiological Responses to Electrical Current

Back 30

• Rise in temperature in the tissue
• Electricity flowing through insulators will create the most heat
  

Front 31

Law of Exchange

Back 31

• Applies to muscles (motor units) ONLY
• The longer the phase duration of a pulse, less amplitude is required to achieve the desired physiologic response (relationship between peak amplitude & phase duration. Less current amplitude is require to achieve threshold as phase duration increases)
• As the pulse gets wider, the amount of amplitude needed will go down (200-500 microsecs ideal being ~300 microsecs)
  

Front 32

Duty Cycle

Back 32

The percent of time that the current is actually on:

on time/(on time + off time)

Front 33

What is the duty cycle for this scenario:

The total stimulation time for a specific protocol is 30 minutes. The stimulation time is 15 seconds and the one/off ration is 1:4.

How long would the total treatment time have to be?

Back 33

Duty cycle = on time/(on time + off time) =

15/(15+60) = 15/75 = 1/5 x 100 = 20%

The duty cycle is 20%

The current is only on for 1/5th of the time

To figure out total treatment time multiply the total stimulation time (30) by 5 = 150 minutes of treatment time to achieve the 30 minute total stimulation time in one treatment session.

Front 34

EMS

Back 34

Stimulation of denervated muscle to fire again

Front 35

ESTR

Back 35

Stimulation for tissue repair of wound management & edema reduction

Front 36

NMES

Back 36

Stimulation of innervated muscle to restore function (we do this the most)

Front 37

FES

Back 37

Functional Electrical Stimulation

Stimulation of muscle to do functional activity

Front 38

TENS

Back 38

Transcutaneous Electrical Nerve Stimulation

Stimulation for pain management (however, ALL e-stim is transcutaneous)

Use low impedance electrodes, they are self-sticky

Front 39

What is an electron?

Back 39

A single, individual unit of electricity (like a drop of water)

Front 40

What is current?

Back 40

The flow of electrons (similar to a stream of water)

Front 41

What is resistance?

Back 41

Also known as impedance, although refers more to A/C but also used interchangeably with resistance)

Similar to a clog in a water pipe

When electrical current is flowing and it runs into resistance, less electrons will keep traveling & all the electrons build up behind it, creating heat.

Front 42

Longitudinal resistance...

Back 42

...as the distance electricity travels increases, the more resistance builds up. When ions build up inside the conductor & attach to the insulator (capacitance) and can cause a spark and start a fire.

Front 43

Coiling a cord creates...

Back 43

...resistance

Front 44

What is a conductor?

Back 44

Conductors allow for easy movement of electrons (low resistance)

Ex: blood (best), nerves, & muscles

Front 45

What is an insulator/resistor?

Back 45

Insulators (resistors) do not allow current to pass through as easily.

Ex: skin (best), fat, bone

When someone gets hurt (burnt) it happens because of resistance.

Biggest resistor/insulator is skin. Need to decrease insulator/resistance properties of the skin.

Front 46

The flow of electricity follows the path of...

Back 46

...least resistance.

Ex: the more adipose, the more muscle someone has, the flow will not follow a straight line

Front 47

What happens to the current that is not flowing into the tissue at the point of resistance?

Back 47

The current decreases distal to the resistance, and there is a build-up on the electrode pad at the point of resistance (typically the skin) and will cause a burn.

Front 48

If a patient complains of warmth w/ e-stim?

Back 48

STOP IMMEDIATELY!!!!

You've probably already burned them

Front 49

_______ the current is the ______ the risk of burn.

Back 49

Higher; higher

Lower; lower

Front 50

How can you decrease resistance?

Back 50

• Placement (for strengthening, getting the electrode pad as close to the muscle as you can)
• Hair, is an insulator. Tell pt. to shave the area the night before to allow any abrasions to heal (abrasions significantly decrease the insulation of the skin, so if you have to shave right before e-stim, use caution)
• Oils & lotions, can be insulators/resistors. May have to ask a pt. to not use a lotion before their treatment
• Hydration (a pt.'s hydration level will have a big impact on conductivity of tissues)
• Equipment (variations from machine to machine, so be aware that some machines have more or less resistance than others)
  

Front 51

Essay Question:

Understand how to explain Ohm's law, the principles of it, the application in the clinic, and be able to give examples.

Front 52

ZNC

Back 52

Zero Net Charge

When the positive cycle is equal to the negative cycle

Front 53

What is D/C used for?

Back 53

Used for decreasing swelling, wound healing, & medication (iontophoresis)

Front 54

What is A/C used for?

Back 54

Used for pain management & strengthening

Front 55

What happens if you use a D/C that stays positive or negative?

Back 55

• You change the pH (normal pH is 7).
• The skin may appear red, bumpy, & look burned (but it's not, this reaction is due to the change in pH). The pt. will feel a itching sensation & want to scratch it.
• Be sure to explain this to the pt. BEFORE starting treatment about what to expect.
• May have to use an ice massage for five minutes after treatment of D/C to help alleviate these symptoms.

Front 56

How does A/C work?

Back 56

Through the gate theory.

For strengthening: stimulates A delta & C fibers.

For pain management: stimulation of A beta fibers, they depolarize quicker than the other fibers.

Front 57

Polyphasic

Back 57

• Means that there are many phases to 1 pulse
• On a polyphasic wave form (Russian stem), you end up with a ZNC because it will flip the current every two pulses.
  

Front 58

Interpulse/phase or intrapulse/phase interval

Back 58

With D/C only: represents the time between pulses/phases.

Front 59

Intrapulse/interphase interval

Back 59

With A/C only: represents the time between phases

Front 60

Interpulse interval

Back 60

With A/C: refers to the time between pulses

Front 61

As the phase duration increases...

Back 61

...the ability to selectively discriminate between the activation of sensory, motor, & pain nerve fibers decreases.

Front 62

At what point are all the excitatory responses (sensory, motor, pain) evoked at the same time?

Back 62

1000 microseconds; not good

Front 63

Why does heat occur with e-stim?

Back 63

Electrical current will follow the path of least resistance. Tissues in the body provide various amounts of resistance (skin being the most & blood being the least resistant). Anytime there is resistance (impedance), there is a build-up of heat (energy via accommodation).

Front 64

Important: need to have a good working understanding of the strength-duration curve in regards to e-stim to understand why parameters are set the way they are.