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06 - Functional Modalities > 06-04: Electricity > Flashcards

06-04: Electricity Flashcards

0
Q

Electrons

A

Negatively charged particles

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1
Q

Ions

A

Negatively and positively charged particles

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2
Q

Electrical current

A

Net movement of electrons

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3
Q

Ampere

A

Unit of measure = rate of electric current flow

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4
Q

Coulomb

A

Number of electrons that move

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5
Q

Volt

A
  • Electromotive force applied to cause the flow of electrons

- Electrons only move if there is a difference in concentration/charge causing an electrical potential difference

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6
Q

Conductance

A

Ease with which current flows

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7
Q

Insulators

A

Materials that resist current flow

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8
Q

Resistance

A

Electrical impedance

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9
Q

Ohm

A

Opposition to electron flow in a material

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10
Q

Watt

A

Measure of electrical power

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11
Q

Cathode

A
  • Negative electrode
  • Greater number of electrons
  • Attracts positive ions
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12
Q

Anode

A
  • Positive electrode
  • Attracts negative ions
  • Lower number of electrons
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13
Q

Direct current (DC)

A
  • Galvanic current
  • Uninterrupted, unidirectional flow of electrons towards positive pole
  • PTA may change direction of polarity which changes direction of current flow
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14
Q

Alternating current (AC)

A
  • Continuous flow
  • Bi-directional
  • Constantly changing direction
  • Reversing of polarity
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15
Q

Pulsatile current

A
  • Contains 3 or more pulses grouped together
  • May be unidirectional or bidirectional
  • Groups interrupted for periods of time.
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17
Q

TENS

A
  • Transcutaneous Electric Nerve Stimulation
  • Refers to a group of E-Stim modalities
  • Sometimes refer to specific type of pain relief E-Stim
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18
Q

Electrodes

A
  • Placed on the skin to deliver electricity
  • Self-adhesive
  • Keep electrodes specific to one pt
  • Carbon: Need moist surface or ultrasound gel to adhere to skin
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19
Q

Waveform

A

Graphic picture of an electric current

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20
Q

Waveform properties

A
  • Shape
  • Direction
  • Amplitude
  • Duration
  • Frequency
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21
Q

Wave Shapes

A
  • Sinusoidal
  • Square
  • Triangle
  • Sawtooth
  • Biphasic, Monophasic, and Pulsatile may take on any waveform shape
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22
Q

Pulse vs. Phase

A
  • Pulse = one waveform
  • Phase = part of the wave that rises above or below baseline
  • Monophasic = Waveforms with one pulse and one phase in the same direction, DC
  • Biphasic = Waveforms with two separate phases during each cycle (current reverses direction once during a cycle; symmetrical or asymmetrical)
  • Cycle = One waveform above and below baseline (refers to biphasic)
  • Pulse duration = length of time one waveform lasts
  • Interpulse interval = Short time between phases with no current flowing (seen in pulsatile current)
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23
Q

Biphasic vs. Monophasic

A
  • Monophasic: Causes chemical change if pulse duration is longer than 1 min
  • Most machines do not permit adjustment of the duration of current, so no chemical effect unless Rx more than 1 hr
  • Don’t usually do elective Rx for more than 30 min.
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24
Q

Intensity

A
  • Increasing intensity drives electrical current into deep tissue
  • More fibers are stimulated
25
Q

Hi-Volt Stimulators

A
  • Deeper penetration into tissue
  • Desirable for stimulating deep muscle tissue
  • Usually pre-set pulse duration
26
Q

Lo-Volt Stimulators

A
  • More superficial stimulation

- Usually adjustable pulse duration

27
Q

Characteristics of Pulse

A
  • Phase Duration
  • Pulse Amplitude
  • Rate of Rise
  • Rate of Decay
  • Pulse Frequency
28
Q

Phase Duration

A
  • Length of time the pulse lasts (monophasic)

- Length of time current flows in one cycle (biphasic)

29
Q

Pulse Duration

A
  • Length of time current flows in one cycle
  • Duration determines quantity of nerve fibers stimulated if intensity the same
  • Increase duration = more nerve fibers stimulated (current available for longer period of time)
30
Q

Pulse Amplitude

A
  • Height of the phase, with maximum amplitude being tip of each phase
  • Higher the peak, higher the intensity
  • Measures in amperes (amps), microamperes or milliamperes (milliamps)
  • Same as voltage and current intensity
  • Peak amplitude not same as total amount of current administered
31
Q

Rate of Rise

A

How quickly the pulse reaches max amplitude in each phase

32
Q

Rate of Decay

A

Time required for the pulse amplitude to return to 0 volts

33
Q

Accomodation

A
  • Current constantly bombards nerve fiber, nerve fiber becomes unexcitable at that intensity (gets used to it, needs more intensity to escalate to level)
  • Faster rate of rise, less likely nerve will accommodate = greater ability to excite tissue
34
Q

Pulse Frequency

A
  • Number of pulses or cycles per second
  • Each pulse = rise and fall in amplitude
  • Frequency increases = amplitude tends to increase and decrease more rapidly (rise and decay)
  • Muscle responds to frequencies of less than 50pps with twitch contractions; >50pps, a tetanic contraction occurs (muscle contracts and holds)
  • Controls amount of fiber shortening and of recovery
35
Q

Higher Frequency

A

More muscle contraction

36
Q

Lower Frequency

A

Less muscle contraction, produces muscle pumping for edema control

37
Q

Tetany

A
  • Rapid, intense and involuntary muscle fiber contractions which can cause spasms or cramping
  • Therapeutically used to fatigue muscles, reduce spasm
  • Occurs at pulse frequencies >50pps
38
Q

Modulation

A

Changes made to current amplitude, duration, frequency

39
Q

Continuous current

A
  • Amplitude constant for several seconds/minutes
  • Associated with long pulse duration, monophasic (always uniform direction)
  • DC
  • Ex: iontophoresis, medical galvanism
  • If amplitude produces contraction, only occurs when current flow turned on or off
40
Q

Burst modulation

A
  • Pulsatile or AC
  • Current on for short duration, then turned off for short time in repetitive cycles
  • Pulsatile: Sets of pulses combined into “bursts”; interruptions called “interburst intervals”
41
Q

Beat modulation

A
  • 2 different waveforms with different frequencies delivered through 2 separate electrodes through 2 separate channels - they interfere with each other
  • Total of 4 electrodes in criss-cross pattern
  • Ex: Interferential treatment
42
Q

Ramping modulation

A
  • Ramp-up and ramp-down intensity
  • Current amplitude increases gradually to preset maximum (or ramp down gradually)
  • Ramp-up is 1/3 of the on time
  • Increases comfort as it modulates “surge” of current
43
Q

Polarity

A
  • AC: Electrodes change polarity with each current cycle
  • DC: PTA designates one electrode as positive and one as negative by connecting wirt
  • General placement: Active, cathode (-) is distal, Anode (+) is proximal
44
Q

Series Circuit

A
  • One pathway for current to get from one terminal to another (Ex: Christmas lights)
  • Loss of voltage as current flows through path
45
Q

Parallel Circuit

A
  • 2 or more paths exist for current to get from one terminal to another
  • Current chooses pathway of least resistance
  • Voltage is same at beginning as at the end
46
Q

E-Stim process in human body

A
  • E-Stim modalities use combo of series/parallel circuits
  • Electrodes on skin stimulate muscle contraction
  • Series: Current passes through skin and fat
  • Parallel: Current passes through bone, connective tissue, blood, muscle; Can pass through several different pathways to reach muscle
47
Q

Best tissue conductors

A
  • Nerve
  • Blood (2nd best)
  • Muscle
  • Tissues with high water content
48
Q

Best tissue resistors

A
  • Bone
  • Skin (2nd best - resists DC more than AC)
  • Tendon
  • Fat
49
Q

E-Stim Safety

A
  • Generates heat in tissue
  • Causes chemical (ion) changes in tissues which can be acidic
  • 2 pronged devices are not grounded (use 3-pronged devices)
  • If not grounded, or cord is cut, unit can become charged and shock a person
  • Do not pull on cord to remove plug
  • Use in dry environment because water conducts
  • Burns on skin
50
Q

Therapeutic effects of E-Stim

A
  • Relaxation of muscle spasm
  • Muscle strengthening
  • Improve ROM
  • Facilitate wound healing
  • Decrease edema
  • Eliminate disuse atrophy
  • Muscle re-education
  • Increase local circulation
  • Facilitate bone repair
51
Q

Indications for E-Stim

A
  • Muscle spasm
  • Muscle weakness
  • Pain management
  • Decreased ROM
  • Idiopathic scoliosis
  • Fracture
  • Joint effusion
  • Facial neuropathy (including Bell’s Palsy)
  • Muscle atrophy
  • Open wound/ulcer
  • Labor and delivery
  • Stress incontinence
  • Shoulder subluxation
52
Q

Contraindication for E-Stim

A
  • Cardiac pacemaker
  • Cardiac arrhythmia
  • Bladder stimulator
  • Over carotid sinus
  • Seizure disorder
  • Phlebitis
  • Malignancy
  • Over pregnant uterus
  • Osteomyelitis
53
Q

Monopolar electrode configuration

A
  • Active (stimulating) electrode over target area
  • Dispersive (2nd) electrode placed away from target area (usually larger than active electrode)
  • DC
  • Wounds, iontophoresis, edema
54
Q

Bipolar electrode configuration

A
  • 2 active electrodes placed over target area (1 channel)
  • Electrodes the same size, do not intersect
  • Muscle weakness, NM facilitation, spasms, ROM, Russian, NMES
  • AC
55
Q

Quadripolar electrode configuration

A
  • 2 electrodes each from 2 separate stimulating circuits (2 channels
  • Positioned so individual currents intersect with each other
  • Interferential Current (IFC)
56
Q

Small electrodes

A
  • Increase density size
  • Increased resistance to electrical current
  • Decrease current flow
  • Concentrate electrical current
  • Pt more susceptible to pain and tissue damage
57
Q

Large electrodes

A
  • Decrease density size
  • Decreased resistance to electrical current
  • Increase current flow
58
Q

Electrode Placement

A
  • Current density is greatest under the electrode
  • Placement close to neural structure provides increased success with least amount of current
  • 2 electrodes close together = increase current density superficially
  • 2 electrodes spaced apart = increase current density in deeper tissue (nerve, muscle)
59
Q

Electrode Placement - 1 large, 1 small

A
  • Greater current density under smaller electrode; larger electrode spreads current over larger area
  • Small electrode concentrates current over motor point; larger electrode disperses over larger area

06 - Functional Modalities (21 decks)

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