E-stim Flashcards
Basic concepts of electrical current
- all matter is composed of ions that posses electrical energy
- ions move from an area of higher concentration to an area of lower concentration
- the more ions an object has, the higher the electrical postential
Electrical potential
Electrical force capable of propelling particles from higher to lower energy levels
Electrical current
The net movement of electrons
- always move from higher to lower concentración
- the rate at which current flows is measured in amperes (therapeutic purposes mA or microA)
- potential difference between 2 points makes electromotive force that provides movement of electrons (volt)
Voltage
The force resulting from an accumulation of electrons at one point in the electrical circuit
- usually corresponds to the deficit at another point
Conductors
Materials that permit free movement of electrons
Watt
Amount of energy or power produced
Electrotherapeutic currents
- DC: monophasic or Direct/Galvanic unidirectional flow of charged particles
- AC biphasic or Alternating bidirectional flow of charged particles (reversing polarity)
- PC polyphasic or Pulsatile an alternating current that is modified to produce 3+ phases in a single pulse; pulses are interrupted and repeated
Pic
Pic
Continuous mode
Uninterrupted flow of current
Interrupted mode
Intermittent cessation of flow for a second or more
Surge mode
A gradual increase/decrease in intensity over a period of time
Ramped mode
A gradual rise of intensity (set time), then.a maintained intensity (for a set time), followed by either a gradual decrease or abrupt decline in intensity
Physiology
- properties of excitable cells
- electrical action of mm and nerve
- motor point
- types of mm contraction
RMP
Resting membrane potential
- the cell membrane is more permeable to K+ compared to Na+ and negatively charged proteins
- RMP is -60 to -90 mV for excitable cells
AP
Action potential
- generated when the influx of Na+ causes a deduction in RMP (depolarization)
- K+ channels fully open and Na+ channels close (repolarization)
- K+ remain open long enough to repolarization membrane to 10-20mV < RMP (hyperpolarization)
Propagation of AP
AP movement along surface of cell
Electrical actions
ES characteristic required to initiate excitable cell depolarization
- amplitude or intensity of the stimulus must be great enough to cause membrane potential to be lowered to threshold levels
- duration of stimulus must be long enough to produce depolarization
- the rate that the current rises to peak intensity should be fast enough to prevent accommodation
Motor point
Arena of greatest excitability on the skin surface
- where the smallest amount of current generates a mm response
- located at/near where the motor nerve enters the mm for an innervated mm
- located over the mm dismally, or toward the insertion, Ford enervated mm
Brief mm twitch or contraction
Each stimulus is produced by a low-frequency pulse (1-10 Hz)
Tetany
Increasing the number of stimuli (frequency) will progressively fuse the individual mm twitches to a sustained contraction
Vermicular
An asynchronous or wormlike mm response is noted in denervated mm
- or when almost on motor point but not quite
E-stim indications
Pain modulation Mm guarding/spasm decrease Mm strengthening/re-edu ROM increase Swelling/inflammation decrease Wound healing Fracture healing Transdermal drug delivery
How does e-stim work
Uses an electrical current to creat a physiological change by targeting afferent nerve pathways to include sensory, motor, and pain fibers
How does e-stim cause a change in the nerve fibers of the PNS?
Action potentials
- the flow of charged particles depolarizers nerve membranes producing an action potiential with enough simulation to cause a physiological change
E-stim precautions
Skin- irritation, wounds, sensation Cancer Cognition decrease Cardiac decrease Hypo/hypertension Pregnancy Bleeding disorders Edema Excessive adipose tissue
E-stim contras
Pacemaker Epilepsy Active bleeding/infection Donut preggy belly Dont place over: Carotid Thrombosis Eyeball Phrenic nerve Bladder stimulator Pharyngeal/laryngeal mm Superficial metal implants Transcerebral/thoracic regions
E-stim adverse reactions
- electrical burns
- skin irritation from adhesive
- pain
- sensitivity to e-stim (rash, redness)
TENS
Transcutaneous electrical nerve stimulation
Indications: pain control and modulation
Gate control theory
Stimulation of non-noxious fibers will interfere with noxious transmission to the brain to decrease the perception of pain (at the level of the spinal cord)
Endogenous opioid system
Stimulation of endorphins bind with opiate receptors to amuse an inhibitory response
- occurs with stimulation of motor nerve fibers
Amplitude
Intensity: the current strength or voltage
Pulse duration
Pulse width: the time to complete one +/- cycle in microseconds
Frequency
PPS or Hz. The number of pulses delivered by the ES to the body or number of times the nerve is stimulated in 1 second
Therapeutic frequencies of E-stim application
1-10 Hz creates a tapping effect
35-50 Hz creates smooth muscle contraction
80-150 creates a sensory effect
TENS pic
Pic
Conventional TENS
High rate - Better for ACUTE PAIN conditions. Effects last only as long as stimulation is applied; use various modes to decrease accommodation
Accommmodation phenomenon
When an unchanged, constant stimulus is applied this leads to a decrease in nerve excitability with decreased perception of a sensation after a period of time with the same sensory input
Low rate TENS
Acupuncture like - better fro CHRONIC PAIN conditions. With increased use, can lead to DOMS. Less accommodation than with high rate
Modes of TENS
- Continuous: frequency, pulse width, and intensity stay as set without change
- Burst: gradual increase in intensity which peaks, then decreases in intensity and cycles on/off
- Modulated: any pattern variation of frequency, pulse width, intensity, randomly set by the unit
Pad placement for TENS
- 2-4 pads (size of area)
- place pads on or around area of pain
- place along a nerve to assist with desensitization
- place on trigger point
- place along mm fibers (best with acupuncture TENS)
- 1 inch apart!
