Electrotherapy 1 Flashcards
Indications
Pain modulation Mm strengthening/reeducation Edema control Dec mm spasm Tissue healing (wound care) Inflammation control
Contraindications
Pacemaker Infection Malignancy Pregnancy Musculoskeletal injury specific
Current =
The flow of electrons
Voltage =
THe force resulting from an accumulation of electrons
Frequency =
the number of cycles or pulses per second (Hz = pulse per second)
Conductance
The ease at which current flows through a medium
Resistance
Opposition to current flow
Impedance
Resistance in biologic tissue
Monophasic or DC
Direct current
Most likely to cause injury
Current flows either above or below the 0 line
Times that we will use DC
Iontophoresis Noxious stim (used sometimes for management of chronic pain)
Biphasic or AC
Alternating current
Portion of the wave above the 0 and portion below
Balances the ions - safer to use because it doesnt allow for accumulation of charge that can damage tissue
Biphasic, symmetrical, balanced
Above and below the line
Sym - shape of the wave is the same above and below the line
Balanced - area under each wave is equal so no net charge
Biphasic, asymmetrical, unbalanced
Above and below the line
Asym - shapes are different
Unbalanced - different SA so there is a net charge that is building up
Biphasic, asymmetrical, balanced
Above and below
diff shape
balanced SA above and below so no net charge
Pulsed
A way to package monophasic or biphasic current (Inferential Current, Russian) - used for mm strengthening - need special machine
Current flow follows
the path of least resistance
Current flow - skin
Poor conductor
Has a lot of impedance
Skin prep we do is to dec the impedance
Current flow - blood
Excellent conductor
Current flow - mm or tendon
Poor conductor
Muscle belly is a little better because of water
Current flow - fat
Poor conductor
Current flow - nerve
Good conductor
A lot of our protocols use the nerve to stimulate whatever we are targeting
Clinical implication - skin preparation
Need to cleanse and prepare the skin to dec impedence
Need to inspect skin after taking electrodes off too
Clinical implication - target tissue (fibers)
A delta = fast pain
A beta = non-noxious fast sensory nerve endings
C fibers = chronic or slow pain
Treatment parameters
- Waveform type and shape
- Symmetrical vs. Asymmetrical
Many will be biphasic and balanced, shape doesnt impact as much - Frequency
- Pulse duration
- Phase duration
Pulse and phase duration can be used interchangeably
Relationship with pulse/phase duration and frequency
More comfortable?
Inverse
Higher frequency and lower duration is more comfortable
Why is a longer duration more uncomfortable
Building up the current and can cause injury to tissue
Current modulation or packaging (options)
Continuous
Burst
Beat
Ramping
Current modulation or packaging - Continuous
Light tingle the entire time
Current modulation or packaging - Burst
Contraction on and then rest time and then back on and rest
Current modulation or packaging - Beat
Very low frequency - has longer lasting relief when it is off - one wave though and then it is done
Current modulation or packaging - Ramping
Usually for mm protocol
Slowly ramp up and hits full contraction and then ramp back down
More comfortable for patients
Current modulation or packaging - Ramping time period
Isometric voluntary contractions - need 6 sec hold
With e-stim do 2 sec ramp up, 6 sec contraction, 2 sec ramp down so 10 total seconds and then rest time
Current direction
Usually one direction?
FILL IN
Current density
Density of the current or charge at a certain point
Inversely related to the size of your electrode
Larger electrode - lower density is preferable by patient
Electrode placement can be
Bipolar
Monopolar
Quadripolar
Bipolar electrode placement
Density is equal
Both are active
Monopolar electrode placement
Huge displacement
Iontophoresis will use this
Pad is positive and electrode is neg
Quadripolar
In picture - beign used for pain/edema
Strength/Duration Curve =
STUDY IT!
Strength/Duration Curve - Charts the
Minimal amplitude of stimulus that will depolarize tissue defined as rheobase
Strength/Duration Curve - Chronaxie
The length of time a current at twice the rheobase intensity must be applied to produce a response
Concepts of S-D curve - an extremely short duration stimuli will
NOT stimulate tissue unless the intensity is intolerable
Concept of S-D curve - different size nerves demonstrate
different S-D curves
Tetanic contraction
The higher the frequency, the more likely you will produce tetanic contraction
Single twitch is from
Single stimulus
Increase the frequency of stimulus and you will get
Successive muscle twitches and eventual reach tetany
Each mm has individual “best frequency” - usually
40-60 pps
Clinical effects of e-stim
Mm contraction
Sensory nerve stimulation to relieve pain
Creation of electrical field to promote healing
Creation of an electrical field on skin to drive ions through skin
How does estim achieve clinical effects - Cellular effects
Excitation of nerve cells
Changes in cell membrane permeability
Stimulation of fibroblast or osteoblast
Changes in microcirculation
How does estim achieve clinical effects - tissue effects
Mm contraction
Tissue regeneration
Bone healing
How does estim achieve clinical effects - segmental
Requires cellular and tissue changes
Changes in joint mobility
Mm pumping to change blood and lymph flow
Changes to automatic systems
How does estim achieve clinical effects - systemic
Endogenous pain suppressors release and control pain
Release of NT to dec pain
Fiber recruitment - Given
More motor units recruit for a muscle contraction the stronger the contraction
Fiber recruitment - CNS
Asynchronous recruitment
Fiber Recruitment - Electrical Stim
Limited nerve fibers used therefore limited motor units - synchronous recruitment
Motor unit excitability - physiologically
Gradation of small motor neurons/units excited than large fibers
Motor unit excitability - Electrically
Most excitable fibers fire first
large fibers near surface
Fibers directly under stimulation
Easily fatigued
