Electrical Stimulation Flashcards
Ampere
-rate of current flow
Current
-net mmt of electrons
-high to low
-can be increased by increasing pulse duration and frequency
Voltage
-force of current flow
Good Conductors
-nerve
-muscle
-blood**
Resistance/Impedance
-opposition to electron flow
-skin and fat are highest
-increases as electrode disease increases
-decreases as frequency increases
Ohm’s Law
I= V/R
-more resistance=less current
Good Insulators
-skin
-fat
-bone
-nerve sheath
-tendon
Current Flow: Skin
-insulator
-need more voltage to penetrate skin and layers
Current Flow: Fat
-insulator
-most resistance
Current Flow: Nerve
-conductor
-6x better than muscle, but surrunded by fat and sheath (insulator)
Current Flow: Blood
-best electrical conductor
Current Flow: Tendon
-poor conductor
-most resistance
Current Flow: Muscle
-good conductor
Current Flow: Bone
-Poorest conductor
-most resistance
Frequency vs Impedence
-increased frequencies decreases impedence
Biphasic/Alternating
-goes positive and negative
-pain relieving
-continous flow, changing directions
-no chemical reactions
ex: TENS, IFC
Monophasic/Direct Current
-uninterupted flow of electrons toward positive pole
-can be reversed
-chemical changes: electrolysis
-muscle contraction when meeting threshold
Ex: ionto
Pulsatile
-2+ pulses grouped together
-discontinuous
-most nerve/muscle stimulation
ex: Russian and High Volt
Accommodation Phenomenon
-a fiber subjected to constant depolarization will become unexcitable at the same intensity
Frequency
-cycles per second Hz
-can determine the type of muscle contraction elicited
-Tetany: 50Hz
Intensity
-amplitude/volatge/intensity
-increasing the stimulation or amplitude to reach deeper tissues, more nerves, stronger contraction
-knob on top
Pulse Duration
-pulse width
-targets specific structures
Capacitance
-ability of a tissue to store electricity
-higher capacitance= more time before a response
-capacitance can be reduced by increasing frequency
-larger diameter= smaller capacitance
Muscle: most
Nerve: least
Pulses
-individual waveforms
-monophasic current
Symmetric, asymmetric, balanced, unbalanced
Cycle: biphasic
Pulse Rise
-how quickly the pulse reaches max
-can be adjucted by ramp-up time
Slow: more comfortable, wont decrease impedance, more voltge needed
High: lowers skin impedence, less voltage needed
Duty Cycle
-on off ratio
-stimulation: break for (ms or s)
-1:7= no fatigue
-1:5= less fatigue
-1:1= repid fatigue