Lecture 3: E-STIM Flashcards
electricity is….
set of physical phenomena associated with the presence and flow of electric charge
electrical current is
current of electricity or flow of electrons
rate at which electrical current flows
ampere (unit of measure! NOT PULSE WIDTH OR FREQ)
We measure electrical currents in
milliamperes and microamperes
(net movement of e from higher to lower potential)
what is volt?
electromotive force
what is voltage?
volt is measured in voltage:
force resulting from an
accumulation of electrons at one
point in an electrical circuit,
usually corresponding to a deficit
of electrons at another point in
the circuit
conductance is
the ease with which current flows along a conducting medium
metals!
insulators are…
resist current flow; fewer free electrons and greater resistance to electron flow
-air, wood, gas
resistance or electrical impedance
unit: ohm (R)
opposition to electron flow in conducting material
Ohm’s law is….
Electrical circuit with high resistance (ohms) = less flow (amperes) than a circuit with less resistance and the same voltage
✧ Ohm’s Law – the current in a circuit is directly proportional to the voltage and inversely proportional to the resistance
current flow through SKIN
INSULATOR
greater the impedance of skin, the higher the voltage needed to stimulate
underlying nerve and muscle
What are good conductors?
JUICY THINGS
nerve
blood
muscle
what are good insulators/poor conductors?
tendon: poor conductor
fat is great cond, skin, bone is poorest cond
impedance and frequency have a
inverse relationship!
as frequency goes up, electrical skin impedance goes DOWN
closed circuit means
electrons are flowing
AC CURRENT
alternating/biphasic, TENS, IFC
continuous flow, bidirectional, constantly changing direction
negative to positive electron moving!
BALANCED!
direct current (DC)
galvanic current, monophasic
DIRECTIONAL, UNIDIRECTIONAL! towards anode (+)
-chemicals accumulated at each electrode (electrolysis)
example: iontophoresis! may be UNCOMFY
pulsatile current (PC)
current can be broken up into parts
2 or more pulses grouped together
-unidirectional or bidirectional
HI VOLT AND RUSSIAN CURRENTS (HVPG)
***most nerve/muscle stimulating currents
-discontinuous current
HVPG and Russian current
directional
*MOST NERVE/MUSCLE STIMULATING CURRENTS
accommodation phenomenon
fiber has been subjected to constant level of depolarization will become UNEXCITABLE at that same intensity (amplitude)
With continuous direct current a muscle contraction would occur only when the
current intensity rose to a stimulus threshold
Chemical effects from using direct current usually occur only when stimulus is
continuous and is applied over a period of time (> 1 minute)
electrical circuits series
resistors have
skin and fat have e-circuits in
series
nerve, blood, muscle, connective tissue, bone electrical circuits occur in
parallel
FREQUENCY IS
cycles per second (Hz) or pulses per second PPS
INTENSITY IS
VOLUME KNOB! turn up music
increasing stimulation or amplitude
PULSE DURATION IS
changing current pulse length to target specific structures
capacitance
ability of tissue to store electricity
higher capacitance=longer before a response
ramping modulation
aka surging modulation; amplitude will increase or ramp up gradually to a preset maximum
*ramp up time: 1/3 of the time
TETANY OCCURS AT APPROX
50 PPS/Hz
function of frequency!NOT INTENSITY
-complete tetanus: once the number of twitch contractions per second increases, single twitch responses cannot be distinguished
pain relieving Estem
IFC
tenz
higher intensity means current reaches
deeper into tissue!!!!
current density must be
HIGH ENOUGH to facilitate depolarization
*amount of current flow per cubic volume!
strength duration curve
threshold for depolarization of particular nerve fiber
*PULSE WIDTH
NONLINEAR RELATIONSHIP BETWEEN CURRENT DURATION AND CURRENT INTENSITY
rheobase
– intensity of current necessary to cause
observable tissue response given a long duration
chronaxie
duration required for a current of twice
the intensity of rheobase to produce tissue excitation
A-beta fibers
sensory! first, wide
A-delta fibers
sharp pain
C fibers
dull pain/crude touch
order of nerves
A-beta, motor, A delta, C, denervated muscle
what happens at cellular level with electrical current?
Excitation of nerve cells
* Changes in cell membrane permeability
* Protein synthesis
Stimulation of fibroblasts
and osteoblasts
* Modification of microcirculation
what happens at tissue level with electrical current?
Skeletal muscle contraction
* Smooth muscle contraction
* Tissue regeneration
types of e-sim
NMES
Russian
IFC
HVPC
TENS
DC
electrical stimulation (NMES, FES)
Pulsed waveform (1-500 Hz)
✧ Single or multiple-channel electrical stimulators programmed in a synergistic sequence
*MUSCLE STIMULATION FOR STRENGTHENING
IF PATIENT COMES IN WITH PAIN, WHAT DO YOU DO FIRST E-STIM WISE
IFC
interfered biphasic continuous waveform (1k-10k Hz)
*pre-mod is little brother
RUSSIAN current
Pulsatile biphasic waveform (2k-10k Hz)
where do you put electrodes to shock?
motor point
*sweet spot-mid belly of muscle
HIGH VOLT CURRENTS ARE FOR
***reducing edema!!!!
wound healing
(kinda muscle contraction but not feeling good, will not usually let u get to that point)
pain control ish…
muscle contraction
MES/russian
pain
IFC
TENS
negative polarity HVPC is most effective for
inflammatory phase of healing
positive polarity HVPC is most effective for
proliferation phase of healing
edema control
HVPC with negative polarity!!!!!
CONVENTIONAL TENS
High Rate & Low intensity (sensory level) * Best for acute pain
* Gate Control Theory – stimulate A-beta fibers
ACUPUNCTURE LIKE tens
Low Rate & High Intensity (motor level) * Usually for chronic pain
* Descending Pain control Theory – release of enkephalin
noxious level tens
hyperstimulation analgesia * Endogenous opiate pain control theory
brief intensity tens
High Rate & High Intensity
* For fast pain relief during a procedure/wound debridement
* Peripheral and central analgesia
conventional TENS
asymmetrical biphasic is most common
frequency 80-125 pps
duration 75-150 microsec
intensity: tolerable sensory stimulation
treatment time: until pain is no longer perceived (30 min up to few hrs)
theory: gate control
Gate Control Theory
Increased activity of A-beta afferents triggers the release of enkephalin from interneurons in Substantia Gelatinosa (SG), which inhibit synaptic transmission to 2nd order neurons (transmission (T) cells) and block pain message ascending to the brain
low frequency TENS
acupuncture
motor level TENS
freq: LOW below 20 pps
duration: 100-600 microsec
intensity: high enough to elicit both sensory (tingling) and motor (mm contraction)
TO MOTOR POINT
duty: 30 s-60s on, off
treat time: 15-60 min
theory: descending pain control theory
descending pain control theory
- Opiate receptors in central or peripheral terminals of nociceptive afferent fibers
- Central:
- Pituitary gland
- Hypothalamus
- Periaqueductal gray (PAG) * Raphe nucleus
- Dorsal horn
- Peripheral: * A-delta
- C fibers
noxious level TENS
hyperstim analgesia
Asymmetrical biphasic is the most common
* Hyperstimulation analgesia
* Frequency: 1-5 pps
* Duration: 100 - 1000 microseconds
* Intensity: High intensity to a noxious level (muscle contraction is acceptable)
* Applied over trigger or acupuncture points
* Duty: 30-45s, off time as needed to be tolerable
* Treatment time: until pain no longer perceived
* Theory: Endogenous opiate pain control theory
endogenous opiate pain control theory
- Peripheral blockage and extra-segmental analgesia
- Stimulation of the small afferents (A-delta and C) can stimulate the release of endorphins, beta-endorphin and dynorphin
- Beta-endorphin is released by anterior pituitary gland and hypothalamus
- Prolonged electrical stimulation on acupuncture points triggers the release of beta-endorphin and dynorphin
brief intense TENS
Asymmetrical biphasic is the most common
* Frequency: 100 pps
* Duration: 100 - 600 microseconds
* Intensity: Muscle fasciculation to sustained
muscle contraction
* Treatment time: ~ 15 minutes
* Theory: Peripheral and central analgesia
WOUND DEBRIDEMENT
IFC IS THE GO TO FOR WHAT
Pain control!
does stimulate mm but not the best…reduces mm SPASM
IFC techniques to reduce accomodation
scan mode
target mode
sweep mode
premod is how many electrodes?
two! IFC: four
Two currents are interfered within the device before delivering the current to the patient
NMES OR FES
Combining waveform characteristics makes possible to stimulate both sensory and motor nerves
✧ Muscle reeducation and strengthening (adequate intensity), pulse rate (35-55 pps), and duration (200-600 μs)
✧ Nerve stimulation
✧ Edema reduction (muscle pump contraction)
✧ Pain control
✧ Retardation of atrophy
✧ Increasing range of motion
✧ Restoring muscle tone
CONTRAINDICATIONS FOR E-STIM
- pacemakers/auto defib
- stim of current through chest, near heart, over carotid
- pts with internal stim in area
- seizure disorders, confused/disoriented
- area of venous thrombosis, occlusive vasc disease, arterial thrombosis
- infection
- Over open wounds*, osteomyelitis, scars, skin lesions, areas receiving radiation therapy, protruding metal implants EXCEPT HIGH VOLT/TENS FOR TREATING WOUNDS
- malignancies
- pregnancy
- MSK probs where contraction is bad
- high level SCI
electrode placement
Placed on or around a painful area
Over specific dermatomes, myotomes, or sclerotomes of the painful area
Close to the spinal cord segment that innervates a painful area
Peripheral nerves that innervate the painful area Electrodes placed near the superficial nerve
Vascular structures contain neural tissue and ionic fluid Trigger points or acupuncture points
Motor points of muscles or muscle belly
Combination of previously listed systems
