Passive Care - Electrical Stimulation Terminology Flashcards
1
Q
Physiologic Effects of Electrical Stimulation
A
- Decrease Pain: gate-control theory / endorphin release
- Decrease Muscle Spasm
- Reduce Edema
- Simulate exercise by muscle contraction: increase muscle fiber recruitment and retard atrophy
- Stimulate Healing
2
Q
Capacitance
A
ability of a material to store a charge
3
Q
Ohm’s Law
A
V (volts)
I (current)
R (resistance)
V= I * R R= V/I I= V/R
4
Q
Types of Currents
A
Monophasic or Biphasic
5
Q
Monophasic Current
A
- Current flow in 1 direction
- Unique positive and negative electrodes
- direct current (DC)
- aka: Galvanic
6
Q
Biphasic Current
A
- Alternating Current (AC)
- Flow of electrons changes direction regularly (changes polarity)
- Wave form: symmetrical (same shape in both phases) / asymmetrical (different positive and negative)
- Net charge: balance - equal electrical charge in both phases / unbalanced - unequal charge
- Shape: sinusoidal, square, rectangular, triangular
7
Q
Phase Duration
A
- Time it takes current to leave the isoelectric line to when it returns to this line
- Tissues respond to phase duration not pulse duration
- Must be long enough to overcome capacitance and cause an action potential - large diameter nerves have low capacitance and reach threshold quickly
8
Q
Amplitude
A
- Intensity or Magnitude of the current
- Peak Current - maximum amplitude of the current regardless of duration
- Must be high enough to reach threshold of muscle or nerve - beta is close to skin and has lower threshold so will be stimulated first, give sensory response before motor
- High peak current is associated with greater depth of penetration
9
Q
Average Current
A
- Amount of current supplied over a period of time
- Takes into consideration peak amplitude and the phase duration
- Higher average current needed for some physiologic responses
- Too high average current can cause tissue damage
- Depending on wave form, can have high peak but low average current
10
Q
Root Mean Square (RMS)
A
- Measure of the effective current contained in the waveform
- Complex calculation
- Similar to average but more accurate
- Preferred over average
11
Q
Strength Duration Curve
A
- Describes the relationship between amplitude (strength) of the electrical current and the duration (phase duration)
- If charge is sufficient to overcome the capacitance of a nerve fiber it will depolarize
- If charge does not exceed the capacitance then no depolarization will take place
- Likewise if the amplitude is too low no depolarization will occur no matter how long the duration
- Short duration requires a higher amplitude for the nerve response
- Longer duration allows a lower intensity for the same nerve response
12
Q
Strength Duration Curves
A
Ab - tingle
Aa - muscle contraction
Ag - pain
C - a lot of pain
13
Q
Rheobase
A
- Minimum amplitude needed to depolarize a nerve fiber when phase duration is infinite
- If peak amplitude fails to exceed rehabs the nerve will not depolarize regardless of phase duration
- Rheobase will never cause depolarization
14
Q
Chronaxie
A
- The time (or phase duration) required to depolarize a nerve fiber when the peak current is twice rheobase
- When amplitude is twice rehabs and the phase duration is slightly greater than chronaxie the result will be greatest comfort for the patient
15
Q
Frequency
A
- Number of pulses or cycles generated per seconds (pos or Hz)
- Affects the number of action potentials elicited during the stimulation
- Higher frequency leads to summation (motor neuron: tetany)
- The absolute refractory period is the rate-limiting factor of the number of impulses that can be generated by a nerve
16
Q
Summation
A
- Single Twitch: contraction and then relaxation
- Summation: force from two twitches, no relaxation after first twitch
- unfused tetanus
- fused tetanus
17
Q
Wedenski’s Inhibition
A
- Stimulation at high frequency near refractory period of the sensory nerve causes inhibition
- > 1000 Hz sensory nerves
- Action Potential Failure
- Results in anesthesia between the electrodes
18
Q
Temporal Summation
A
35-50 pps / tetanic contraction
19
Q
Low Frequency Generators
A
up to 1,000 Hz contraction (rehab muscle) Produce action potential 1-10 Hz or 60-100 Hz are common treatment frequencies TYPES: EMS (electrical muscle stim) HV (low frequency) / best contract LVG (low volt galvanized - drug pusher) Sine Faradic (RD) (used with people who are paralyzed) Interference (IF and RS) / best contract TENS (milliamps) / help with pain
20
Q
Medium Frequency Generators
A
1,000 - 100,000 Hz
Russian Stim: 2,500 Hz
IF: 4,000 - 5,000 Hz
Intrinsic duty cycle of 10ms on and 10ms off creates a burst frequency of 50 Hz
It gets in with Medium Frequency but treats with Low Frequency (one side 4,200 and the other side 4,300 - the difference is 100 so it gets in with the high number and treats with the difference (100).
21
Q
High Frequency Generators
A
Greater than 100,00 Hz
used for chronic issues
Used for thermal (heat) purposes
Diathermy uses high frequency and creates minimal sensory effects
SUPERFICIAL HEAT:
IR (infrared) - mc
UV (skin and bones)
DEEP HEAT: (diathermy)
MWD (micro wave diathermy)
SWD (short wave diathermy)
US (1 MHz - 3 MHz) (continuous has heat / pulsed US removes heat and you can use for acute) / 1 MHz goes deep and 3MHz is superficial - opposite of normal electricity - increase electricity you increase the depth - opposite with US - increase electricity decrease depth / reverse piezoelectric effect
22
Q
Electrodes are attached to the current generator by wires called?
A
leads
23
Q
There must be how many leads to complete a circuit?
A
2
24
Q
Leads can be split or
A
bifurcated
25
leads usually are wired into pairs that plug into a
single channel
26
Unequal size electrodes will
concentrate the current in the smaller electrode and it will give the perception of increased intensity
27
When sizes vary greatly one may not be able to perceive current under the larger electrode. This becomes the
dispersal electrode
28
If pads are placed close together the current is most concentrated in
superficial tissues
29
When pads are far apart the current has the potential to take a
deeper path through the nerve and blood vessels that have less resistance
30
When you use one big pad and one small pad
the focus/feeling will be on the small pad
| the big pad is used for dispersement
31
Monopolar Electrode Configuration
1. Two or more unequal sized electrodes are used
2. Can be used with either biphasic (AC) or monophonic (DC) currents
3. One is the active and one is the dispersive electrode
4. Active at the target site and dispersive away from target site
5. 3 reasons for this placement: (1) leads placed far apart - deeper penetration (2) greater comfort (3) to create an electrical field with specific polarity
32
Bipolar Electrode Configuration
1. Can be used with either monophonic (DC) or biphasic (AC) currents
2. Two equal sized electrodes are placed over the treatment site
3. Most common for TENS
33
Quadripolar Configuration
1. Often used with IF
2. Two separate medium frequency currents are used with electrodes placed as cross currents
3. Current is interfered with in the center of the two currents
4. Can change this location of interference where ou feel the beat frequency
34
CURRENT: AC or DC
| AC =
Biphasic (no polarity)
35
CURRENT: AC or DC
| DC =
Monophasic (polarity)
36
AC Current types
Sine
Faradic
Interferential
37
DC Current types
Galvanic
| High Volt
38
Sine
AC - biphasic - no polarity
| symmetrical / best contractor / no charge left in patient
39
Faradic
AC - biphasic - no polarity
| asymmetrical / sporadic
40
Interferential
AC - biphasic - no polarity
| two sine waves
41
Galvanic
DC - monophasic - polarity
| make and break
42
High Volt
DC - monophasic - polarity
| Twin Pulsed Peak
43
Electrothermal
Heat
micro-vibration, electrically leads to heat
Joule's Law
44
Electrochemical
Iono and Opiods
Iontophoresis is DC current
Opiod frequency 1-10 (endorphins), 70-120 (enkephalins)
45
Electrophysical
Kinetic
| ions push other molecules around shifting Na+/K+ pump resulting in contraction
46
Increase frequency = ______ penetration
deeper penetration
47
Medium frequency = _______ skin impedance
decreased
| best to use a bigger electrode and increased voltage
48
Motor Point or Muscle Belly
isolates the muscle ( 1 pad)
49
Either side of the Muscle Belly
if the muscle is especially weak (2 pads)
50
Pad Rule
1 mA per square inch of pad size (3" square pad = 9mA)
51
Monopolar
large area or trigger / acupuncture point
Dispersal aka Indifferent - large pad (ground)
Active Pad or Pads - small pad
52
Bipolar
small muscle group
| Dispersal and Active Pads are the equal size
53
Quadripolar
Crisscross Pattern
54
mA problem
If the dispersal pad is too small or active sites are too large ( too many) = tingle
55
EMS: Continuous
Use: Pain
| Duty Cycle: None
56
EMS: Surge
Use: Exercise / Rehab
| Duty Cycle: 1:3
57
EMS: Pulsed / Tetanizing
Use: Fatigue / Spasm
| Duty Cycle: 1:1
58
EMS: Reciprocating
Use: contract agonist, then antagonist
| Duty Cycle: none
59
EMS: Modulation
Use: Avoids accommodation
| Duty Cycle: none
60
EMS: Burst / TENS
Use: Packages of stimulation
| Duty Cycle: none
61
Low Frequency: Pain
1-20 endorphins
| 70-150 enkephalin
62
Low Frequency: Edema
3-5
63
Low Frequency: Exercise
15-25
64
Low Frequency: Fatigue
50
65
Electricity: Increase mA (amps) =
Increased Muscle Contraction
66
Electro-induction
charges lie up = electrical lines of force
| one object produces electromagnetic property in another
67
Coulomb
charge
68
Waveform
pulse width
interpulse width
frequency
69
Amplitude
magnitude depth
70
Current (AMP)
electricity that flows
| number of electrons
71
Transformer
increase or decrease volts
72
Capacitance (OHM)
stores up energy
73
Resistance
property of substance to oppose current
measured in OHMs
decreased resistance = increased conduction
(shorter path, lower temp, increased diameter)
74
EMF (electromagnetic force)
measured in Volts (force behind electrons)
difference between force in two objects (whether connected or not)
greater the charge = increase EMF
greater the distance = decrease EMF
75
Impedance
slow it down (dampen)
| increased by oily skin
76
Strength Duration Curve
Chronaxie = the time necessary for contraction when the rehabs is doubled
Rheobase (threshold) = the minimum volts necessary to excite a nerve
77
Reaction of Degeneration (RD Factor)
Innervated muscle responds different than denervated muscle
| Galvanic & Faradic current are compared to determine extent of damage and prognosis
78
EMG (electromyography)
used to test muscle best
79
NCV (nerve conduction velocity)
used to test nerve best
80
Arndt-Schultz Principle
energy of modality has to be absorbed by body to stimulate physiological response
81
Law of Grotthus-Draper
inverse relationship between penetration and absorption of energy (US)
