Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
80 Cards in this Set
- Front
- Back
|
why do we use E stim?
|
To depolarize the nerve membrane producing an action potential (AP).
|
|
|
what are the four clinical effects of E Stim?
|
Muscle contraction
Pain modulation Tissue healing Transdermal drug delivery |
|
|
at rest, what charge does a nerve have and what is its resting membrane potential?
|
At rest, the nerve is negatively charged. It’s resting membrane potential is
-60 to -90 millivolts. |
|
|
With a stimulus of sufficient pulse duration and amplitude,what happens to a cell membrane?
|
the cell membrane depolarizes and then quickly repolarizes causing an action potential to be propagated down the nerve axon.
|
|
|
With a stimulus of sufficient amplitude and length, what element is allowed into a cell?
what is the result of this? |
sodium (Na+) is opened,
when the axon reaches approx. +30 mV it quickly repolarizes by opening the gate for potassium (Ka+) to exit the axon. Fig.8-2, p. 209 |
|
|
Increasing the amplitude or duration beyond what is sufficient to cause an AP does what?
|
it does nothing for that specific neuron. The neuron either depolarizes or does nothing.
|
|
|
what is the "strength duration curve"?
|
The amount of current required to produce an AP in a specific type of nerve
|
|
|
Amplitude
definition |
the magnitude of current. Intensity is often used interchangeably with amplitude. Measured in mA ( milliamps)
|
|
|
Pulse duration
definition |
the time from the beginning of the first phase of a pulse to the end of the last phase of a pulse. Expressed in microseconds (us) or milliseconds (ms).
|
|
|
with an actiona potential, The speed of conduction depends on what factors?
|
the diameter of the nerve and the amount of myelination of the nerve. The larger the nerve, the faster the conduction.
|
|
|
what are the small gaps in the myelin sheath called?
|
nodes of Ranvier
|
|
|
Sensory, non-nocioceptive nerves
size/ amount of amplitude required/ length of required pulse duration |
Large myelinated nerves. A beta
Require only a low amplitude And short pulse duration to depolarize. Generally less than 80 us |
|
|
Motor nerves
amount of amplitude required/ length of pulse duration |
Generally require a higher amplitude
And longer pulse duration to depolarize. 150 to 350 us. |
|
|
Pain nerve fibers
amount of amplitude required/ length of pulse duration |
Require high amplitude
And long pulse duration of 1 ms. With a long pulse duration, it is possible to stimulate all 3 nerve types. |
|
|
Denervated muscle
length of pulse duration required |
Pulse duration of greater than 10 ms is required because you must depolarize the actual muscle cell, not the motor nerve cell. Muscle cells do not accommodate, so can use a slow rise time for comfort.
|
|
|
Impedance
definition |
the opposition of tissues to the flow of current.
|
|
|
conductivity is related to what content?
|
Conductivity is related to water content
As water content increases / impedance decreases / conductance increases |
|
|
what kind of conductivity does bone, fascia, and tendon have?
|
Fascia, bone and tendon are all poor conductors
|
|
|
Tissue Impedance
what provides the greatest resistance to electrical current? |
Skin provides the greatest resistance to current
|
|
|
what effect to skin lesions have on impedance?
|
Skin lesions can significantly decrease the tissues impedance (even abrasions from shaving)
|
|
|
what are two methods to decrease tissue impedance?
|
Hydration, mild abrasion
Increase pulse frequency. |
|
|
Pulse frequency
how is this described? |
Describes the number of pulses per second and is expressed as (pps)
|
|
|
As pulse frequency increases, impedence...?
|
decreases.
|
|
|
As impedence decreases the electrical stimulation is...?
|
more comfortable
|
|
|
Terminology for Electrical Stimulation
direct current- main idea |
continuous flow of charged particles in 1 direction
|
|
|
Terminology for Electrical Stimulation
alternating current- main idea |
continuous bi-directional flow of charged particles
|
|
|
Terminology for Electrical Stimulation
pulsed current- main idea |
non-continuous flow of AC
|
|
|
Terminology
Waveform- definition |
describes the shape of an AC or pulsed current
|
|
|
Terminology
Phase- definition |
current flow in 1 direction for a definite period of time
|
|
|
Terminology
duty cycle- main idea |
percentage of time the current is on
Duty cycle = on time / total on + off |
|
|
Terminology
Ramp Time- definition |
is the time it takes to go from zero to peak or peak to zero
Primarily adjusted for patient comfort |
|
|
Electrical Stimulation
NMES meaning and main idea |
neuromuscular electrical stimulation
Stimulation of innervated muscle to restore muscle function |
|
|
Electrical Stimulation
FES meaning and main idea |
functional electrical stimulation
Activate muscle to perform functional activities |
|
|
Electrical Stimulation
TENS meaning and main idea |
transcutaneous electrical nerve stimulation
Stimulation for pain management |
|
|
Electrical Stimulation
IES meaning and main idea |
interferential electrical stimulation
Pain management, edema reduction, muscle spasm reduction |
|
|
Electrical Stimulation
HVGS meaning and main idea |
High Volt stimulation
Tissue healing |
|
|
Muscle strengthening
Electrical stimulation of sufficient pulse duration and amplitude generates... |
an AP which is conducted along the motor nerve to the muscle fiber which becomes depolarized and contracts.
|
|
|
Muscle strengthening
what kind of muscle fiber is activated with E Stim? |
With e-stim, largest diameter axons which innervate the fast twitch fibers are activated first. Normally, smaller, slow twitch fibers are activated first.
|
|
|
Fast twitch fibers
what kind of stamina do they have? |
Fatigue quickly – therefore, stimulated contractions are more fatiguing and require longer rest times between contractions than a normal contraction would require.
|
|
|
2 methods of strengthening/specificity theory
Specificity Theory- main idea |
Since e-stim causes large, high force, fast twitch fibers to contract before slow twitch fibers, we should be able to produce greater strength gains than with exercise alone.
|
|
|
how long after surgery can we expect to see strength gains from E-Stim?
|
for up to 4 weeks. By 12 weeks, there is no significant difference.
|
|
|
strengthening/overload principle
main idea |
The greater the load placed on a muscle, the greater the contraction and the greater the strength gains.
|
|
|
NMES
what amplitude should be used? |
Most are pre-set to 300 microseconds of pulse duration, if adjustable use 150-200us for small muscles and 200- 350us for large muscles. As pulse duration is shortened, greater amplitude is required for the same contraction.
|
|
|
NMES
pps/what do you want to see/duration of duty cycle/duration of treatment |
35-80 pps
Visible muscle contraction 10 sec.on / 50 sec. off. Ramping for comfort. 10-20 minutes |
|
|
NMES frequency
Frequency higher than 30 pps will cause...? |
tetany; a sustained ms contraction.
|
|
|
why do we use low frequencies (between 35-80 pps) with NMES?
|
Although a higher frequency does make e-stim more comfortable, we use a low frequency of 35 to 80 pps with NMES because a higher frequency fatigues the muscle faster.
|
|
|
Russian Protocol
main idea |
Specific protocol which uses a pre-set carrier cycle frequency
Alternating current using specific pre-set protocol. Burst method. Adjust amplitude (intensity) only to visible muscle contraction. |
|
|
DC current
use/pulse duration/length of "on time"/what do studies show/ main idea |
For denervated muscle
>10 millisecond pulse duration 3 second on time Wand stimulator Studies poor on long term effect Attempting to decrease fiber atrophy and decrease fibrosis between fibers. |
|
|
E-Stim for Pain Modulation
Release of endogenous opiates chronic pain- site specific? frequency/mechanism |
Non-specific site stimulation
Very low frequency (2-5 pps) Mechanism- release of endorphins and serotonin |
|
|
E-Stim for Pain Modulation
Release of endogenous opiates acute pain- site specific? frequency/mechanism |
Local, segmental stimulation
Higher frequency- 50-120 pps) Mechanism- release of enkephalins and Gate Theory |
|
|
E-Stim for Pain Modulation
gate theory main idea |
The use of sensory stimulation can inhibit the transmission of pain stimuli via the pain conducting fibers (“toll-booth effect”)
|
|
|
TENS
settings for "conventional" treatment |
Conventional
Short pulse duration; 50-80 micro seconds High pulse frequency for comfort, 50-150 pps Amplitude comfortable, no muscle contraction Duration: 3 hours to 24 hours/day |
|
|
TENS
settings for "low rate/ acupuncture like" treatment |
Longer pulse duration for muscle contraction; 150-350 u second
Low pulse frequency, 2-10 pps to minimize ms. soreness Duration: 20-30 minute treatment Amplitude for Motor response 4-5 hour pain relief secondary to endorphin release |
|
|
TENS
main idea for "burst mode" treatment |
Is pre set with low frequency given in bursts
Is more comfortable, gives endorphin release |
|
|
Burst Mode TENS
desired effect? target? mechanism it acts on? |
Desired effect: Immediate, lasting pain relief
Target: A and A (sensory) Mechanism: Gate Control and Endogenous opioids. |
|
|
Burst Mode TENS
settings for this treatment? |
Pulse freq: 100 pps, Burst freq: 2-5 pps
Pulse duration: ~ 250 μsec Intensity: as high as patient tolerates |
|
|
E-Stim for Reducing Protective Muscle Spasm
muscle fatigue settings |
35 to 50 pps
150 to 350 microseconds for ms. contraction Intensity to visible contraction Equal on and off times for fatigue |
|
|
E-Stim for Reducing Protective Muscle Spasm
muscle fatigue duration/main idea |
Duration 10-30 minutes
Often used with ultrasound Thought to increase blood flow and allow for max. relaxation following strong contraction |
|
|
Interferential Stim
main idea |
produced by the interference of two separate cycle frequencies producing slightly different AC currents. 4 electrodes are used and are criss-crossed across the area being treated. The interference of these current creates a higher amplitude in the tissue below. Interferential current is more comfortable than other waveforms because it allows a low amplitude current to be delivered through the skin and high amplitude to be delivered in the tissue.
|
|
|
Premodulated Stim
what does it simulate? how many electrodes? how placed? |
Simulates interferential wave form
Uses only 2 electrodes Surround the area of pain |
|
|
Theories on why E-Stim can be used for healing tissue damage
4 theories |
1.Positive potentials of injury
2.Improved circulation 3.Bactericidal effect 4. Increased lymphatic drainage |
|
|
Theories on why E-Stim can be used for healing tissue damage
bacterialcidal effect- biphasic or monophasic? what kind of polarity over the treatment area? |
Should use a monophasic type
Negative polarity over inflamed or infected wound |
|
|
High Volt Pulsed Current
Tissue healing inflammatory phase settings |
60 to 125 pps
Pre-set 40-100 us Negative polarity Comfortable tingling, 45-60 minutes |
|
|
High Volt Pulsed Current
Tissue healing proliferation phase what kind of polarity? |
Positive polarity
|
|
|
High Volt Pulsed Current
Edema control inflammatory phase settings |
120 pps
Negative polarity 30 minutes |
|
|
E-Stim for Edema Reduction
what kind of duty cycle? |
E-Stim may be used to cause muscle contraction which creates a muscle pumping effect. 1:1 duty cycle.
|
|
|
E-Stim for Edema Reduction
settings |
Frequency:35-50 pps
Pulse width:150 to 350 microseconds Intensity: Visible contraction Duration: 30 minutes |
|
|
Iontophoresis
main idea |
The use of low volt DC to move charged ions across the dermal barrier by increasing the permeability of the strateum corneum.
|
|
|
Iontophoresis
depth of penetration? dosage? amplitude? |
Studies show drug penetration from 3 to 20mm.
Dosage at 40mA.min; 2.0 mA for 20 min Amplitude to tolerance |
|
|
Electrode Placement
why shouldn't electrodes be placed over bony prominences? |
Should not be placed over bony prominences because of the high resistance to electrical current.
|
|
|
Electrode Placement
what effect does distance have between electrodes? |
The further the electrodes are apart, the deeper the current will travel.
|
|
|
Electrode Placement
general guidlines when treating for pain vs. muscle contraction? |
At least 2 finger widths apart for pain, 2 inches apart for muscle contraction.
|
|
|
There is a potential for high current concentration under the electrode
Signs of this are: |
Stinging
Biting Higher stimulation level required for the same physical response |
|
|
Applications of E-Stim
TENS |
pain relief
|
|
|
Applications of E-Stim
high volt pushed galvanic |
edema management, tissue healing
|
|
|
Applications of E-Stim
DC |
re-education for denervated muscle
Drug delivery |
|
|
Applications of E-Stim
interferential |
Pain relief, edema management
|
|
|
Applications of E-Stim
Russian / NMS |
Reeducation, edema management, relief of muscle spasm
|
|
|
E-Stim Contraindications
4 points |
Pacemaker or known arrhythmias
Over the carotid sinus Thrombosis Pregnancy |
|
|
E-Stim Precautions
4 points |
Cardiac disease
Impaired mentation or sensation Malignant tumor Skin irritation or wound |
