WK5- Electrotherapy Flashcards
What is polarity ?
when one end of a battery for example has a negative charge and the other end lacks a negative charge
What are the two poles called and what are their charges?
Cathode: negatively charged
Anode: positively charged
Define the term: Voltage
force of attraction or repulsion created by an electrical field, represents potential energy. A greater force will produce greater potential energy. The force itself is termed voltage and represents the driving force that moves electrons.
What are some conductors and insulators that are present in the human body?
conductors: water/body fluids, nerve and muscle tissue
insulators: fat
Define the term current (I) and the unit used to measure it.
movement of ions electrons in response to voltage force
measured in amps or A, miliamperes (mA)-thousandths of an ampere, microcurrent= <1mA
What does Ohm’s law state ?
I=V/R
more resistance to current, the less current there will be
Define the term capacitance.
when a current flows in an insulated area with high resistance it will slow and charges will start to store in the area where it is slowed, this is impedance.
Resistance to flow of alternating current
What body tissues will have higher resistance and impede electrical stimulation transmission ?
skin, hair, fascia, ligament, callus, fat, bone, tendon, scar
What are the different kind of currents ?
Direct Current (DC)
Alternating Current (AC)
Pulsed Current (PC)
Explain direct current (DC)
continuous unidirectional flow of electrons for at least 1 second.
can be interrupted, reversed, or both
Explain alternating current (AC)
uninterrupted bidirectional flow of electrons, must change direction at least once per second
Define the term frequency in relation to AC
rate AC current changes direction, measured in Hz or cycles per second
True or False. AC current must change direction at least one time per second. If it does not, then it is DC current.
True
Explain pulsed current (PC)
unidirectional or bidirectional flow of electrons that periodically ceases for a short time period, the interphase/interpusle interval, before the next event or pulse.
Describe how duty cycle works in terms of pulsed current.
ontime/total timex100=duty cycle
similar to US duty cycle
How does ramping amplitude help the patient.
Increases patient comfort to electrotherapy
Describe the electrochemical effects of electrotherapy on the body.
At the anode (+) negative ions will accumulate which may lead formation of HCl which could create hardened sclerotic skin
At the cathode (-) positive ions will attract Na+ which will lead to the formation of NaOH which results in a sclerolytic area which may lead to skin softening.
AAA-anode attracts acid
CAB-cathode attracts base
What are the electrothermal effects of electrotherapy on the body?
As charged particles flow through a conductor, friction occurs as they meet resistance and produce kinetic energy which produces heat
therefore it is important to ensure contact between electrode and skin, shave shair, remove oils and lotions and avoid callused skin or scars
typically redness fades within hours after treatment
What are the electrophysical effects of electrotherapy
Can have sensory, motor, or noxious responses
Describe the sensory reaction to electrotherapy
sensory perception is the first thing affected by electrotherapy
patient should feel pins and needles
stimulation of A-beta sensory fibers in the superficial dermis
Describe the motor reaction to electrotherapy
increasing stimulus from sensory reaction leads to motor response by stimulation of A-alpha fibers to depolarize, may appear as a muscle twitch
Describe the noxious reaction to electrotherapy
increasing stimulus from motor reactions to electrical stimulation leads to stimulation of pain receptors through A-delta fibers and C fibers are excited and elicit noxious sensation.
What is the strength duration curve
gives the strength and duration curves for stimulation of physiological responses from the body
Define the following type of current: Russian current ( burst modulation)
Varitation of AC used for strengthening muscles
• Medium frequency AC with carrier frequency of 2500Hz and a burst frequency of 50 bursts/sec
• Delivered in 10-ms long bursts with 50 bursts per sec, with a 10-ms interburst interval between bursts.
• Typical Russian stimulation is 10:50 for on:off time
