1
Q
electrotherapy uses
A
strengthening, ROM, improved function, contraction of denervated tissue, tactile stimulation, wound healing, edema control, and pain modulation
2
Q
electricity is measured in what
A
Coulombs (C) or micro coulombs (uC)
3
Q
net gain of electrons =
A
negative charge
4
Q
net loss of electrons =
A
positive charge
5
Q
properties of electrical charge
A
like charges repel and opposite charges attract
6
Q
anode =
A
net positive pole; attracts (-) ions
7
Q
cathode =
A
net negative pole; attracts (+) ions
8
Q
voltage definition
A
- potential difference in distribution of ions
- a force that pushes charge
9
Q
voltage is also referred to as
A
electromotive force
10
Q
voltage is measured in what
A
volts (V) or millivolts (mV)
11
Q
current flow definition
A
- flow of charged particles
- moves from anode to cathode
- current flow and electron flow are opposite
12
Q
current flow is measured in what
A
- amperes (A) or microamperes (uA) or as a rate (coulombs per sec)
- measured as the number of electrons or ions that pass a certain point in a specified period of time
13
Q
resistance/capacitance/impedance defintion
A
opposition to flow of charged particles
14
Q
resistance/capacitance/impedance equation
A
I = V/R
- inverse relationship between resistance and intensity
15
Q
resistance/capacitance/impedance alternating current equation
A
I = V/Z
Z = resistance above (I = V/R) + any additional resistance found in the capacitance and inductance of an alternating current generator
16
Q
resistance/capacitance/impedance depends on what
A
- nature of material
- length of pathway
- cross-sectional area of pathway
17
Q
skin impedance
A
- a form of resistance
- resistance offered by the skin
- highly variable throughout the body
18
Q
skin impedance variables
A
- water content
- blood flow
- patient activity or position
- conducting medium
19
Q
skin impedance fixed factors
A
- distance between electrodes
- what is under electrodes
20
Q
direct current
A
- unidirectional current flow lasting for at least 1 sec
- since current flow is only in one direction will lead to an accumulation of ions under the electrodes
21
Q
direct current uses
A
- iontophoresis
- wound healing
- stimulation of denervated tissue
22
Q
direct current cathode
A
- depolarized membrane of excitable cells
- alkaline effect
- attracts hydrogen
- liquefies protein
- promotes fibroblastic migration
23
Q
direct current anode
A
- hyperpolarizes membrane of excitable cells
- acid effect
- attracts oxygen
- coagulates protein
- kills bacteria
24
Q
alternating current
A
- continuous current flow alternating direction at least once each second
- can be identified by waveform
25
alternating current uses
- stimulation of nervous and muscular tissue
- may be used for denervated tissue
26
pulsed current
unidirectional or bi-directional current flow with periodic interruptions that only lasts a few milliseconds or less
27
pulsed current uses
- most common form of e-stim used
- used in most e-stim interventions except for iontophoresis
28
constant current
- how the generator is going to act to resistance
- stays fixed even if resistance or impedance changes; voltage varies
29
constant voltage
- voltage will remain constant and current will change in proportion to resistance or impedance changes
30
amplitude
- same as intensity
- measured in Amperes more often millamperes; sometimes expressed in voltage
- peak amplitude = highest intensity reached during one stimulus
31
rise time and decay time gives shape to what
gives shape to the pulse/phase
32
rise time
elapsed time from onset of stimulus to peak amplitude of stimulus
33
decay time
elapsed time from peak amplitude to termination of stimulus
34
rise time and decay time measured in what
milliseconds or microseconds; differs from "ramp and fall" time which are modulation to an individual stimulus
35
pulse duration
- length of time one pulse lasts
- in a biphasic pulse can be broken into phase duration = length of time current flow in one phase of a pulse
36
interphase or intrapulse interval
brief interruption between phases; measured in microseconds
37
interpulse interval
elapsed time between consecutive pulses in a pulsed current; measured in microseconds
38
total current
sum of peak amperage, pulse frequency and pulse duration
39
pulse charge
based on duration and amplitude of phases in a pulsed current
40
frequency (rate)
- number of pulses or cycles per second
- measured in pps in PC
- measured in Hz in AC
41
frequency (rate) values
low 0-1,000 Hz
medium 1,000-10,000 Hz
high >10,000 Hz
42
change in frequency in AC will lead to what
will lead to an automatic change in cycle duration (inverse relationship)
43
change in frequency in PC will lead to what
no change in pulse duration due to an interpulse interval
44
does skin impedance increase or decrease with decreasing pulse or cycle duration?
decreases, therefore increasing frequency may increase current penetration
45
is higher or lower frequency more comfortable?
- higher frequency because skin impedance is reduced in AC current
- higher frequency can lead to more fatigue tho
46
relationship between frequency and recruitment of fiber type
type I: 10-20 Hz
type II: 30-60 Hz
47
modulations defintion
any parameter that is altered or varied during a series of pulses or cycles
48
modulations are usually seen in what
amplitude, frequency, phase duration or waveform
49
what are burst modes?
multiple pulses or groups of cycles carried out in bursts
50
what is the carrier frequency
number of pulses/second before burst modulation in AC current
51
what is the burst frequency
burst occurring to deliver the carrier frequency
52
what muscles are recruited in a voluntary contraction
small, slow deeper units are recruited first in an all or none fashion
53
what muscles are recruited in an electrically stimulated contraction
larger, faster motor units fire first
54
what is the biggest factor in which muscles are recruited during a contraction?
electrode placement; the closer the motor unit is to the electrodes the faster it will be recruited
55
cell type recruitment order
sensory nerves > motor nerves > deep pain nerves > muscle fibers
56
what is the strength duration curve
- need adequate total current to get a response (all or nothing)
- either have to increase amplitude or pulse duration to get the desired response
57
what does the strength duration curve show the relationship between
amplitude and phase duration
58
rheobase defintion
minimal amplitude needed to create an AP given an infinite pulse duration
59
chronaxie defintion
minimal pulse duration that will cause an AP at 2x rheobase
60
contraindications to electrotherapy
severe cardiac condition, use of demand type pacemaker, active bleeding or risk of hemorrhage, active osteomyelitis, pregnancy, carotid bodies, phrenic nerve, eyes, gonads
61
precautions to electrotherapy
sensory loss, areas of scarring, thick adipose tissue, severe edema, over malignancy/neoplasm, open wounds, severe depression, disoriented patients, superficial metal
62
do large electrodes increase or decrease skin impedance
decrease
63
electrode location
have current run longitudinally
64
unipolar or monopolar set up
- one electrode is considered active based on its function or differences in size
- use over motor point
- delivery of medication
- one small active electrode and one large dispersive electrode so current density is greater under the active one
65
unipolar or monopolar uses
used for isolating single or small muscle groups whether innervated or denervated and for training functionally after transplant or repair
66
bipolar set up
- both electrodes are of equal size with equal current density under both
- place one over the motor point and one distally over the nerve
67
bipolar uses
used primarily to stimulate larger muscle and muscle groups for functional activities
68
quadripolar uses
specific to inferential stimulation; circuits are crossed
69
electrodes with DC set up
- make the active electrode the cathode because it depolarizes excitable cells and make the anode dispersive
- place active over the motor point and dispersive on the ipsilateral side not too close to the motor point and not to distance to the anode
physical agents 2
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