Week 5 Electro Therapy Flashcards
4 Principles of Electricity
- two types of charges + and -
- Like charges repel while opposites attract
- Charges are neither created nor destroyed
- Charges can be transferred from 1 object to another
Cathode=
negatively charged poll
Anode=
Positively charged poll
Voltage =
Force of attraction or repulsion created by an electrical field represents potential energy
- Greater the force the greater the potential energy
Voltage in the body is created by….
uneven distribution of charged particles
If charges are equal on each side of the membrane the will have (blank) voltage
No
Conductors of the body
water/body fluids
nerves
muscle tissue
Insulators of the body
Fat
Current =
The movement of ions/electrons in repones to voltage force
- Ampere
- Milliamperes
Microcurrent
Ohm’s Law
I= V/R
Current= Voltage/resistance
- More resistance to current the less current there will be
Capacitance
Current flowing in an insulated area with high resistance will slow and charge will start to store in that area
Impedance
Resistance to the flow of alternating current
- Clinically gels and adhesives conductive agents help decrease impedance
Areas of high fact act as insulators and will (blank) electrical stimulation trasnmissions
Impede
Waveforms
A depiction of the characteristics that describe a current
Direct Current
- Continuous unidirectional flow of electrons for at least 1 second
Types of direct current= interrupted, reversed, interrupted/reversed
- Clinical considerations= one electrode positive and one electrode negative
-Clinical uses= used less frequently in rehab than other current types, iontophoresis, wound care
Alternating Current
- Uninterrupted bidirectional flow of electrons, must change direction at least once per second
- Frequency= rate AC current changes direct
- Cycles per second= hertz (Hz)
- clinical uses= use of pure sinusoidal AC current is not common
Russian Current
Burst of modulated AC current
Interferential Current
Amplitude modulated AC current
Pulsed Current
Unidirectional or Bidirectional flow of electrons that periodically ceases for a short time period, the interphase/interpulse interval before the next event or pulse
Burst PC
2 or more pulses separated from the next series of pulses
- Burst frequency= frequency bursts are generated
- Carrier Frequency= frequency of underlying waveform
Duty Cycle
on-time/total time (on time + off time) x 100%
Examples:
on time 10 seconds, off time 40 seconds (10:40) duty cycle = 10/10+40 x100% = 20%
Phase charge
Pulse Charge
Charge within a single pulse
What are the 3 commonly used currents that result in a net + or - charge
- direct current
- monophasic pulsed current
- Asymmetrical unbalanced biphasic current
What are the electrothermal effects of electrical current in body tissue?
- As charged particles flow through a conductor friction occurs as they meet resistance and produce kinetic energy which produces heat
T/F there is more of a concern with DC than a concern for AC or pulsed current
True
What are the levels of response to Electrical Stimulation?
1st= sensory- 1st perception of electrical stimulus: stimulation of A-beta sensory fibers in the superficial dermis
2nd= motor- increased electrical stimulus causes A- alpha motor neurons to depolarize and elicit a motor response: motor response proportional to intensity of stimulus : initial motor response may appear ass a muscle twitch or fasciculation
3rd= Noxious- further increase in intensity or duration beyond that capable of eliciting a sensory or motor response stimulates pain receptors - A-delta and C fiber are excited and elicit noxious sensation : sometimes used for therapeutic purpose
Action potentials are……..
All or nothing
High Volt Pulsed Current (HVPC)
- continuous, reciprocating, or surge, monophasic
- used for pain modulation, tissue repair, wound healing
Interferential Current (IFC)
- quadripolar or bipolar set-ups available on most devices
- used primarily for pain modulation
Russian Current (Burst Modulation) is used for….
Variation of AC used for strengthening muscles
Low-Intensity DC (microcurrent) is used for
- Does not stimulate sensory/motor nerves
- Used for tissue repair, wound healing
Symmetrical/Asymmetrical Biphasic PC used for
- used for muscle stimulation, pain modulation
- Little to no difference in effectiveness for muscle stimulation using symmetrical biphasic PC vs. Russian
Voltage and current are (blank) proportional
directly
Constant Current
Maintains a constant flow of current by modulating voltage
- may be a better choice for treatment as intensity is maintained closer to the level required for therapeutic purposes
Disposable Electrodes
- many shapes and sizes, reusable for multiple applications
- 18-20 applications
Flexible electrodes
carbonized silicon rubber, reusable, pliable with good conductivity
Metal Electrodes
wet sponge between metal and tissue, great conductor, lack flexibility
Large Electrodes
- Lower current density= more comfortable
- appropriate for larger muscles and treatment areas
- may cause overflow to non-target areas if too large
Smaller Electrodes
- Higher current density
- high levels of stimulation intensity with small electrodes may cause uncomfortable burning sensation
- appropriate for smaller muscles and treatment areas
Wider electrode spacing allows….
- allows for increased current density
- allows currents to travel deeper and reach deeper tissues
- -> reach motor nerves and muscles
–> activate more motor units in NMES
–> activate more sensory fibers in TENS
Electrode Configurations
- Bipolar= 2 active electrodes
- Monopolar= 1 active
- Quadripolar= 4 active
Bipolar Electrode Configuration
- most common
- commonly used for muscle activation/ pain modulation
Quadripolar Electrode Configuration
- 4 electrodes of 2 separate circuits over target tissue
- Interferential current for pain modulation most commo application
NMES
- Neuromuscular stimulation
- for muscle strengthening
TENS
-Transcutaneous nerve stimulation
- for pain modulation
FES
- functional electrical stimulation
- Neuro re-education or functional training
CONTRAINDICATIONS for ES and Iontophoresis
- The trunk or heart region of patients with demand-type pacemakers or implantable cardioverter defibrillators
- carotid bodies
- patients with phrenic nerve or urinary bladder stimulators
- Areas of known peripheral vascular disease, including arterial or venous thrombosis or thrombophlebitis
- the phrenic nerves, eyes or gonads
- Areas of active osteomyelitis
- areas of hemorrhage
Pregnancy ES
- electrical effects of electrical stimulation on the fetus or uterus are not clearly known
–> Caution is recommended - Unknown effects of ES on fetal health should be disclosed to the patient
PRECAUTIONS for ES and Iontophoresis
- Patients without intact sensation
- unable to communicate or with compromised mental or cognitive ability
- with cardiac dysfunction
- Over neoplasms (active or previous)
- Electrodes should not be placed over: compromised skin , tissue vulnerable to hemorrhage or hematoma , cervical or craniofacial regions in patients who have a history of CVA or seizures
- do not use ES within 5 yards of diathermy units or other sources of electromagnetic radiation
What is Iontophoresis?
Using electrical current to drive medication through the skin to the target tissue
Clinical Uses for Iontophoresis
- soft tissue inflammatory conditions
- neuralgia
- edema
-ischemic skin ulcers
hyperhidrosis - plantar warts
- calcific tendonitis
- scar tissue
- other connective tissue disorders
Physiology of Iontophoresis: Electroporation
- increases in polarity of superficial skin in response to ES allows medication to enter the target tissue more easily
Physiology of Iontophoresis: Electromigration
- Using ES to move charge ions into the target tissue
- Like charges repel, opposite charges attract
Physiology of Iontophoresis: Electroosmotic flow
- when positive and negative electrodes applied to skin, ions of positive charge in the extracellular fluid attracted to the cathode and ions of negative charge attracted to the anode
- Creates bulk movement of solute in response to the electrical field and helps move ions into the tissue
- Human skin contains net negative charge, direction of electroosmotic flow is from the anode to the cathode
–> assists in delivery of positive medications
–> hinders delivery of negative medications
Two important aspects of application of Iontophoresis
- know the polarity of the ion or drug to be used
- Have a good conductivity so there is not a chemical burn under the electrode
Selecting an Ion: Inflammation
- Drug= dexamethasone
- Polarity= Negative
- Effect= anti-inflammatory
Selecting an Ion: Calcific tendonitis, myositis ossification
- Drug= Acetic acid
- Polarity= negative
- effect= increases solubility of calcium deposits
Selecting an Ion: Adhesive capsulitis/ soft tissue adhesion
- Drug= iodine
- Polarity = negative
- effect= sclerolytic effect
Selecting an Ion: Soft tissue and Inflammation
- Drug= Lidocaine
- Polarity= positive
- Effect = local anesthetic effect
Selecting an Ion: Muscle and joint pain
- Drug= salicylates
- Polarity= negative
- effect=analgesic and anti-inflammatory
Selecting an Ion: Local substance or chronic edema
- Hyaluronidase
- polarity positive
- effect= dispersion of local edema
Selecting an Ion: Skeletal Muscle Spasms
- Calcium Chloride
- polarity positive
- effect= decreased excitability of peripheral nerves and skeletal muscle
Selecting an Ion: skeletal muscle spasms /myositis
- Magnesium Sulfate
- polarity positive
- effect= muscle relaxant
Selecting an Ion: Skin ulcers
- zinc oxide
- polarity positive
- General antiseptic; increase tissue healing
Selecting an Ion: Hyperhidrosis
- Tap water
- polarity alternating
- effect= dec sweating palms, feet or axillae
Cathode conductive surface area should be
> anode up to 2x the area
Where should the active/treatment electrode go directly over?
directly over the treatment area
- Inactive electrode distant from the treatment electrode
T/F when electrodes are spaced further apart they will increase the depth of the current and drug penetration
True
Iontophoresis Dosage equation
dosage (mA min)= current (mA) x duration (min)
typical dosage ranges from 20-80 mA min
