electrical stimulation Flashcards
1
Q
matter
A
- composed of atoms, +/- charge(ions)
- have ability to move - higher concentration area to lower concentration area - electrical force propels particles - establishing electrical potentials
2
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electrical potentials
A
-more ions - high potential electrical energy
3
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electrons
A
-particles of matter possessing -negative charge & very small
4
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electrical current
A
-net movement of electrons
5
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ampere
A
- unit measurement indicates rate of electrical current flow
- 1amp =1coulomb
6
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coulombs
A
-indicate number of electrons
7
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volt
A
- electromotive force
- difference electron potential between 2 pts
8
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voltage
A
- force resulting from an accumulation of electrons at 1 point is an electrical circuit
- creates stimulation
9
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electricity
A
-electrical current flows from negative pole(cathode) to positive pole (anode)
10
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amplitude
A
-intensity
11
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duration
A
-time
12
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high volt current
A
- waveform amplitude greater than 250V
- short pulse duration
13
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low voltage current
A
-waveform amplitude less than 150V
14
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conductance
A
- ease current flows along conducting medium
- measured in siemens
15
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good conductors
A
- composed of large numbers free electrons given up readily
- metals, electrolyte solns
16
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bad conductors (insulators)
A
- contain few free electrons
- offer greater resistance to electron flow
- air, wood, glass
17
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resistance (electrical impedance)
A
- opposition to electron flow in conducting material
- measured in ohm
18
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ohms law
A
- current flow = voltage/resistance
- current flow - directionally proportional to voltage
- current flow - inversely proportional to resistance
19
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electron power
A
- voltage x amt current flowing
- watt = volts x amperes
20
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electrotherapeutic currents
A
-introduce to biologic tissue - capable of producing specific physiologic changes
21
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biphasic (AC) current
A
- continuous flow of electrons bidirectional, reverses polarity
- no net movement ions
22
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monophasic (DC) current
A
- unidirectional flow of electrons, uninterrupted, toward +pole
- glavanic current
23
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pulsatile (PC) current
A
- 3+ pulses group together
- interferential & russian currents
- unidirectional/bidirectional
- interrupted for short periods time
24
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TENS - transcutaneous electrical nerve stimulators
A
-stimulate peripheral nerves
25
NMES(neuromuscular electrical stimulator) / EMS(electrical muscle stimulator)
-electrical current used to stimulate muscle directly
26
microcurrent electrical nerve stimulator (MENS)
-uses current intensities too small to excite peripheral nerves
LIS - low intensity stimulator
27
electrical circuit
-path of current from generator power source through various components back to generating force
28
open circuit
-current flow ceases
29
closed circuit
-electrons are flowing
30
series circuit
- only 1 path for current to get from one terminal to another
- number amperes = at any point in circuit
- components placed end-end
- components -higher resistance & lower current flow
31
parallel circuit
- 2+ routes exist for current to pass between 2 terminals
- components side-side
- each pathway - same voltage
- components - lower resistance & higher current flow
32
conductivity of biological tissue is variable
-tissue highest water content & highest ion content - best conductor of electricity
33
tissue impedance
- resistance of tissue to passage of current
- high - bone, fat
- low - muscle, nerve
34
current flow through: skin
- primary resistance flow, insulator
- greater impedance -higher voltage of electrical current to stimulate underlying nerve & muscle
- impedance greater w/ DC than biphasic current
35
current flow through: blood
- best electrical conductor of all tissues
| - composition - mostly water&ions
36
current flow through: muscle
- 75% water
| - propagate electrical impulse more effectively longitudinal than transversely
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current flow through: muscle tendons
- contain relatively little water
| - poor conductors
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current flow through: fat
- 14% water
| - poor conductor
39
current flow through: peripheral nerve
- take little electricity to cause potential in nerve
| - 6x greater conductivity than muscles
40
current flow through: bone
- extremely dense
- 5% water
- poorest conductor
41
excitable tissues
- neve fibers
- muscle fibers
- blood cells
- cell membrane
42
non-excitable tissues
- bone
- cartilage
- tendons
- ligaments
43
physiologic response: thermal
- all electrical currents cause rise in temp of conducting tissue
- tissue w/higher resistance increase temp more
44
transformer
-reduce voltage from power supply
45
rectifier
-converts AC to pulsating DC current
46
filter
-changes pulsating DC to smooth DC
47
regulator
-produces specific controlled voltage output
48
amplifier
-increases amplitude of the voltage output
49
oscillator
-produces/outputs specific waveform
50
waveform
-indicates graphic representation of shape/direction/amplitude/duration/pulse frequency of electrical current
51
waveform shape
- sinusoidal, rectangular, square, spiked
| - biphasic(AC), monophasic(DC), pulsatile(PC)
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pulse
individual waveform
53
phase
-portion of pulse that rises above/below the baseline
54
monophasic (DC)
-single pulse & phase are =
55
biphasic (AC)
- waveforms have 2 separate phases during individual cycle
- symmetric - same shape & size for each phase in both directions, net pulse charge 0
- asymmetric - different shapes for each phase, net pulse charge greater than 0
- balanced-net charge in each direction equal
- unbalanced-one phase greater net charge than the other
56
polyphasic (PC)
- series of pulses of short duration (monophasic/biphasic)
| - pulse period - combined time of the pulse duration & inter pulse interval
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phase duration
-time that each pulse lasts
58
interphase interval
-interruptions between individual pulses or group of pulses
59
pulse duration
- sum of all phases plus the interphase interval
| - length of time current flowing in 1 cycle
60
interpulse interval
-short period of time when current is not flowing between 2 phases
61
pulse amplitude
- reflects intensity of the current
- max - tip/highest pt of each phase
- amplitude = voltage = current intensity
62
pulse charge
-total amt electricity being delivered to the patient during each pulse
63
rate of rise
- how quickly the pulse reaches its max amplitude in each pulse
- generally short
64
decay time
- time in which a pulse goes from peak amplitude to 0V
| - generally short
65
pulse frequency
- number of pulses or cycles per second-each individual pulse represents rise&fall in amplitude
- amplitude&frequency are inversely proportionate
- frequency increased - amplitude increase/decrease more rapidly
66
low frequency currents
- deliver 1-several hundred pps
| - muscle pumping, edema reduction
67
medium frequency currents
-2500-10000pps
68
high frequency currents
- groups pulses bursts 1-200pps
| - increase muscle tension
69
current modulation
-any alteration in the amplitude,duration,frequency of the current during a series of pulses/cycles
70
positive pole
- where negative ions go
| - cause an acid reaction
71
negative pole
- where positive ions go
| - cause alkaline reaction
72
continuous current
- amplitude of current flow remains the same for several seconds/minutes
- long pulse duration mono phasic current
- flows in uniform direction
73
burst (interrupted) modulation
- PC/biphasic current flows for short duration & turned off for short duration in repetitive cycle
- sets of pulses are combined (bursts)
- interruptions between bursts - inter burst intervals
- muscle reeducation, strengthening, improving ROM
74
beat modulation
- produced when 2 interfering wave currents w/ differing frequencies are delivered to 2 separate pairs of electrodes through separate channels w/in same generator
- electrodes set up in crisscrossed pattern - circuits interfere w/ one another
- IFC, premodulated interferential
75
ramping modulation (surge)
- current amplitude increase, ramp up/decrease gradually to preset maximum
- ramp up time - 1/3 time
- on:off time- 1-10sec
- elicit muscle contraction
76
frequency
- number of impulses/cycles produced by electrical stimulating device in 1 sec (CPS), pulses per second, hertz
- mechanical shortening of a single muscle fiber response can be influenced by stimulating again as soon as the tissue repolarizes
77
frequency determines
- type of muscle contraction elicited (amt shortening of the muscle fiber)
- amt recovery allowed to muscular fiber
78
summation of contractions (wave summation)
- process of superimposing 1 twitch contraction on another
| - number of twitch contractions per second increases - size twitch responses cannot be distinguished
79
intensity
- increasing intensity of electrical stimulus causes current to reach deeper into tissue
- higher threshold fibers - depolarized w/ increase in intensity
- lower threshold fibers - depolarized w/ increase in intensity
- high volt currents are capable of deeper penetration into the tissue than low voltage currents
- stimulate deep muscle tissue
80
duration
-increase treatment time - stimulate more nerve fibers w/same intensity
81
cathode
- negative electrode in DC
- greater number of electrons
- site of depolarization
- becomes the active electrode
82
anode
- positive electrode in DC
- low number of electrons
- makes nerve cell membrane potential more positive, increasing threshold necessary for depolarization
- become indifferent electrode (dispersive)
83
direction of current flow
- cathode positioned distally
| - anode electrode proximally
84
current density
- amt current flow per cubic volume & must be high enough to cause depolarization
- highest where electrodes meet skin
85
highest current density
- electrodes spaced closely together - superficial
| - electrodes spaced farther apart - deeper
86
electrode size
- size (relative to other) decreased - current density beneath smaller electrode increased
- larger electrode - larger area the current is spread, decrease current density
87
electrode placement
- on/around painful areas
- over specific dermatomes, myotomes, sclerotomes to painful area
- close to SC segment that innervates painful area
- peripheral nerves that innervate painful areas
- vascular structures
- over trigger points/acupuncture point locations
- muscle belly
88
electrode placement: bipolar
- electrodes same size in same general treatment area
- current density under each electrode essentially the same
- physiological effects same under each electrode
89
electrode placement: monopolar
- one or more small active electrodes over treatment area & large dispersive electrode placed somewhere else in body
- higher current density occurs under smaller active electrode
- desired physiological response likely to occur at active electrode
90
electrode placement: quadripolar
-2 sets of bipolar electrodes - each comes from separate channel on electrical stimulator
91
electrode placement: crossing patterns
- interferential & premodulated IFC
- electrical signals from each set of electrodes add together at some point in the body & intensity accumulates
- electrodes crisscrossed pattern over point to be stimulated
92
stimulating superficial areas
-electrodes should be relatively close together
93
stimulating deeper areas
-electrodes spread farther apart to give more penetration to the current
94
on/off time (duty cycle)
-lower ratio of on time to off time - less total current the patient will receive
95
thermal effects of electrical current passing through tissues
- all electrical currents cause rise in temp
| - tissues of higher resistance heat up more when electrical current passes through
96
physiologic effects of electrical current passing through tissues
-produce either muscle contractions or modification of pain impulses through effects on the motor & sensory nerves
97
type & extent of estim responses depends on:
- type of tissue & response characteristics
| - nature of current applied (AC/DC, intensity, duration, voltage, density)
98
use electrical currents for
- muscle contraction
- treat pain - sensory stimulation
- stimulate/alter healing process
- drive ions into/through skin
99
indications of electrical stimulation
- modulate pain
- muscle contraction
- muscle reeducation
- retardation of atrophy
- muscle strengthening
- increasing ROM
- tendon healing
- ligament healing
- protein syntesis
- stimulate osteoblasts & fibroblasts
- tissue regeneration
- decrease edema
- decrease muscle spasm & guarding
- stimulate healing process
- increase circulation through muscle pumping action
- wound healing
- fracture healing
- stimulate nerve regeneration
- stimulate PNS function
- change membrane permeability
100
contraindications of electrical stimulation
- pacemakers
- infection
- malignancy
- pregnancy
- musculoskeletal problems where muscle contraction would exacerbate the condition
101
cellular level of physiologic change (1st)
- excitation of nerve cells (depolarization)
- change in cell membrane permeability
- protein synthesis
- stimulation of fibroblast & osteoblast
- modification on microcirculation
102
tissue level of physiologic change (2nd)
- skeletal muscle contraction
- smooth muscle contraction
- tissue regeneration
103
segmental level of physiologic change (3rd)
- modification joint mobility
- muscle pumping action
- alters microvascular system
- movement of charged proteins into lymphatic channels
104
systematic level of physiological change (4th)
- analgesic effects through endogenous pain suppressors
| - analgesic effects from stimulation of nerves
105
excitatory physiologic responses
- patient perceives electrical sensation, muscle contraction, electrical pain
- nerves affecting these perceptions fire in that order as the stimulus intensity is increased gradually
106
electricity applied
- brain perceives stimulus
- nerves 'fire' depolarize
- strength of current increases/duration increases - more nerves fire
107
voltage sensitivity permeability
- nerve/muscle cell membrane regulates the substance between inside&outside cell
- produces unequal charge of the interior of the cell and exterior of the cell
108
resting potential
- potential difference between the inside & outside the cell
| - due to cell trying to maintain electrochemical gradient
109
electrical & chemical gradients
- greater concentration of positive ions on the outside of the membrane
- cell continually moves Na+ from inside cell to outside cell
- cell balances this positive charge movement by moving K+ to the inside
110
membrane potential develop
- membrane semipermeable
- concentration of the diffusible ions must be greater on one side of the membrane than the other side
- resting membrane potential - generated®ulated by Na+K+ pumps within cell wall
111
causing action potential
- resting membrane potential must be reduced below a threshold level
- results membrane depolarization
- created by stimulus
112
depolarization
- process of neutralizing the cell membranes resting potential
- charged ions move across the nerve fiber membrane beneath the anode & cathode
113
absolute refractory period
- following excitement & propagation of the impulse along the nerve fiber - brief period where nerve fiber is incapable of reacting to second stimulus
- excitability restored gradually as nerve cell membrane repolarizes
114
strength duration curve
- graphic illustration of the threshold & propagation & contraction of a particular fiber
- sufficient amt of electrical current delivered to make nerve depolarize
- nonlinear relationship between current duration & current intensity
115
shape of curve: strength duration curve
-relates intensity of electrical stimulus & the length of time (duration) necessary to cause tissue depolarization
116
rheobase (intensity): strength duration curve
-describes the max intensity of current necessary to cause tissue excitation when applied for max duration
117
chronaxie(time): strength duration curve
-length of time (duration)required for a current of twice the intensity of the rheobase current to produce tissue excitation
118
achieve maximum sensory/motor output
-use stimulus w/ high intensity & short duration
119
therapeutic uses of electrically stimulated muscle contraction
- muscle reeducation
- muscle pump contractions
- retardation of atrophy
- muscle strengthening
- increasing ROM
120
decrease muscle fatigue
- increase rest period during contraction
- low frequency & high intensity - keep force constant & most fatigue resistant
- rest time 60 sec for each 10 sec contraction time
121
increase strength
- increase muscle force - change intensity
- increase summating quality - high burst/pulse rates
- greater force - greater demands on muscle
- best muscle contraction - stimulate motor point
122
muscle reeducation
- after injury/surgery
- atrophy of synaptic contacts
- electrical stimulation provides an artificial use of the inactive synapses & aids in restoration of a normal balance to system
123
muscle reeducation: criteria
- intensity adequate for contraction
- pulse duration - close as possible to chronaxie
- pps: high enough for tetany (20-40)
- interrupted/surged current
- on time: 1-2 sec
- off time: 4-10 sec
- alternative voluntary contractions w/ current induced contractions
- treatment time: 15min (several x day)
- high voltage pulsed/medium frequency AC - most effective
124
muscle pump action
- duplicates regular muscle contractions
| - assists in stimulating circulation -> pumps fluids & blood through venous & lymph channels
125
muscle pump action: criteria
- intensity high - sting, comfortable contractions
- pulse duration - close as possible to chronaxie
- pps: 20
- interrupted/surged current
- on time: 5-10 sec
- off time: 5-10 sec
- treatment time: 20-30min (2-5x day)
- high voltage pulsed/medium frequency AC - most effective
- elevate, use w/ice
126
retardation of atrophy
- produces physical & chemical events associated w/ normal voluntary contraction
- helps maintain normal muscle function
127
retardation of atrophy: criteria
- intensity - high as tolerated by patient
- pulse duration -close as possible to chronaxie
pps: tetany range (65-85)
- interrupted/surge current
- on time: 6-15 sec
- off time: 1-2 min
- muscle not given resistance
- voluntary contraction with stimulation
- treatment time: 15-20 min/minimum of 10 contractions
- medium frequency AC, russian - most effective
128
muscle strengthening
-weakness/denervation of muscle group
129
muscle strengthening: protocol
- intensity - high enough to make muscle develop 60% torque developed in max isometric contraction
- pulse duration - as close to chronaxie
- pps: near top tolerable range (65-85)
- surged/interrupted current w/ gradual ramp to peak intensity
- on time: 10-15 sec
- off time: 50sec - 2min
- resistance - immobilizing limb
- patient works w/contraction
- treatment time: minimum 10 contractions
- medium frequency AC - most effective
130
increasing ROM
- pulls joint through limited range
| - continued contraction over an extended time appears to make contracted joint & muscle tissue modify/lengthen
131
increasing ROM: protocol
- intensity - sufficient to make muscle contract strongly enough to move through antigravity ROM
- pulse duration - as close to chronaxie
pps: beginning tetany (20-30)
- interrupted/surged current
- on time: 15-20 sec
- off time: =/greater than on time
- stimulated muscle group antagonistic to joint contraction
- treatment time: 90min/daily
- high voltage pulsed/medium frequency AC - most effective
132
edema movement
- ion movement w/in biologic tissue
- extended treatment times
- DC stimulation w/ polarity arranged correctly
- proper arrangement of electrodes
133
edema movement: protocol
- intensity - 30-50V/less than required for contraction
- pps: 120
- interrupted DC - most effective
- negative distal electrode
- treatment time: 30 min
- high voltage pulsed generators - most effective
134
pin control
-change patients perception of painful stimulus
135
gate control theory
- stimulating large sensory fibers
| - force CNS to make brains recognition area aware of the electrical stimuli
136
gate control theory: criteria
- intensity - adjusted to tolerance, no muscle contraction
- pulse duration: 75-150usec
- pps: 80-125
- transcutaneous electrical stimulator waveform
- treatment time: correspond to fluctuation in pain
137
central biasing theory
- intense electrical stimulation of smaller fibers at peripheral sites for short periods
- causes stimulation descending neurons - effects transmission of pain by closing the gate at SC level
- sharp, chronic pain, severe pathological pain
138
central biasing theory: protocol
- intensity - high, approaching noxious levels
- pulse duration - 10msec
- pps: 80
- on time: 30-60sec
- stimulation applied over trigger/acupuncture points
- low frequency, high intensity - best
- successful - pain relieved shortly after treatment
139
opiate pain control theory
- electrical stimulation of sensory nerves stimulate release of enkephaline from local sites throughout CNS
- point stimulation set up used
140
opiate pain control theory: protocol
- intensity - high, approaching noxious levels
- pulse duration: 200usec-10msec
- pps: 1-5
- high voltage pulsed current/low frequency, high intensity - best
- on time: 30-45 sec
- stimulation applied over trigger/acupuncture points
- successful stimulus - effects last 6-7hrs
- not successful, expand stimulation sites
141
interferential current
- using electrical stimulation in a crossing pattern
- electrical signals for each set of electrodes add together at some point in the body - intensity accumulates
- superficial area - pads close together
- large area - pads further apart
142
constructive interference
- waves combine
- both waves exactly the same
- produced in phase/originate at same time
143
destructive interference
- waves cancel out each other
- waves generated out of sync
- generator 1 - starts in positive direction
- generator 2 - starts in negative direction
144
interferential current
- muscle contraction - 20-50pps
- pain management - 50-120pps
- modulate pain
- joint sprains
- retarded callus formation following fracture
- restricted mobility
- increase venous return
- reduction of edema
145
size of electrode inversely affects density of current
-size electrode decreases - current density increases
146
smaller electrodes
-require less current to stimulate tissues than larger electrodes - due to high current intensity
147
choosing electrode size
- determined by size of body area being treated
- 'small' electrode on thigh would be 'large' electrode on forearm
- size of electrode relative to other electrodes being used
- larger electrodes produce stronger contractions w/o pain
148
bipolar
- electrodes = size
- current densities =
- stimulation occurring under each =
149
monopolar
- active electrode -where treatment occurs, high current density focuses the effect of treatment under the smaller electrodes
- dispersive electrode - completes circuit
150
sensory level stimulation
- attempts to stop formation of edema
- prevents fluids, plasma proteins, other solids from escaping into surrounding tissue
- attempts to assist venous & lymphatic system in returning the edematous substances back to care
- stimulation kept below motor threshold
- pulsed, mono phasic current produces a vascular spasm & prevents fluids from leaking out of the vessels -> causes less swelling
151
motor level stimulation
- muscular contractions encourage venous & lymphatic return
- squeezing vessels - moving fluid proximally
- voluntary contractions to encourage proximal flow
152
russian current
- stimulators deliver a medium frequency polyphasic AC current
- pulse varied 50-250usec
- phase duration - 1/2 pulse duration
- same stimulation effect as duration of stimulus decreases - increase intensity
- 50 bursts-per-second with inter burst interval 10msec
153
ground fault circuit interrupters
- compare output flow from the wall outlet to the modality with at the mat returning to the outlet
- if any leakage detected - GFCI automatically interrupt current flow
