Electrotherapy Flashcards
Therapeutic Effects of Electrotherapy
Decreased edema Decreased pain Eliminate disuse atrophy Facilitate bone repair Facilitate wound healing Improved range of motion Increased circulation Muscle re-education Muscle strengthening Relaxation of muscle spasm
Indications for Electrotherapy
Labor and Delivery Muscle spasm Spasticity/reduce hypertonicity Open wound/ulcer Pain modulation Stress incontinence Shoulder subluxation Edema reduction Decreased range of motion Denervated muscle Fracture Muscle Re-education Joint effusion Disuse atrophy (muscle weakness)
Purpose of muscle contractions via Electrotherapy
Electrically stimulated muscle contractions may be used for the following purposes:
Promote muscle strengthening & reducation
Prevent atropy, DVT’s & pressure ulcers
Reduce muscle spasm
Clinical Applications if Electrotherapy in Rehab
Pain control-acute, chronic, postsurgical Promotion of tissue healing Enhancement of transdermal drug therapy
4 FUNDAMENTAL PROPERTIES OF CHARGE
There are two types of charge-positive and negative.
Like charges repel while opposites attract
Charge is neither created nor destroyed
Charge can be transferred from one object to another
Definition of Polarity
term used to indicate the relative charge of the terminals or leads of an electrical circuit
Cathode
(-) LEAD/ATTRACTS (+) CHARGED PARTICLES (CATIONS)
Anode
(+) LEAD/ATTRACTS (-) CHARGED PARTICLES (ANIONS)
Voltage
The magnitude of the difference between the positive and negative poles is the voltage
Electromotive Force
electrical potential difference between two points in an electrical field or the force that makes charged particles move
EMF is required to depolarize a membrane and is therefore needed to force a large number of electrons through the conductive media of the body tissues
Conductor
materials which tend to give up their electrons easily and readily allow electron movement/flow within them
ex. Metal, water, copper, gel, sponges
Human body: muscle, nerve, blood
Insulator
materials in which charges are not free to move around
ex. Rubber, plastic
Human body: adipose tissue/fat
Conductance
ease with which charged particles move in a medium
higher the ___ content, the better the tissues will conduct
the higher the H20 content, the better the tissues will conduct
Current
The directed flow of free electrons from one place to another
The unit of current is the AMPERE (A)
1 A = 6.25 x 1018 electrons/second or 1A=1C/sec
Current flow is directly proportional to voltage
Current is direct or pulsatil
Ohms Law
I = V/R
Resistance
specific to the flow of direct electrical current
Impedance
Resistance to current flow when an alternating current is applied
frequency dependent
Direct Current
Continuous or uninterrupted flow of charged particles in 1 direction for greater than 1 second
Greater potential for chemical reaction under electrodes
Therapeutic Use of DC
Iontophoresis
stimulating contractions in denervated muscle
Alternating Current (AC)
Continuous bidirectional flow of charged electrons and must change direction
AC has equal ion flow in each direction, no pulse charge is retained by tissue
Therapeutic Use of AC
Pain control (Interferential premodulated) Muscle contraction (Russian protocol)
3 Types of Medium Frequency AC Current
Interferential current
Premodulated current
Russian protocol
Pulsatile Current
An interrupted flow of charged electrons
Current flows in a series of pulses which periodically ceases for a finite period of time (for less than 1 second)
Can be monophasic or biphasic
Monophasic PC
Tissue healing
Acute Edema mgt.
Biphasic PC
Pain
Current Density
The amount of current per unit area
Ratio of maximum current amplitude to electrode stimulating surface area
__ electrodes have more current density than ___ electrodes
Smaller electrodes will have more current density than larger electrodes
Current Characteristics of Small Electrodes
Increased current density
Increased impedance
Decreased current flow
Current Characteristics of Large Electrodes
Decreased current density
Decreased impedance
Increased current flow
Phase Duration
elapsed time from beginning to end of 1 phase (may be referred to as phase width)
Pulse Duration
elapsed time from beginning to end of all phases within a pulse, measured in microseconds(μsec)
Pulse Rate
(frequency)
the number of pulses per measure time
Amplitude
Magnitude of current
Intensity
T/F Increasing F will recruit more motor units
False
Tetany (definiton and frequency)
tetany occurs when tension generation doesnt have time to decrease between APs and is sustained
20-50 pps
Muscle Twitch Frequency
1-10pps
On/ Off Time
Prevent fatigue during muscle contraction
Ramp up/ Ramp down
Allows a patient to be more comfortable with muscle contraction
Rise Time
time required for a single phase to reach peak amplitude
Effects of Electrical Currents
Stimulation of APs in nerves (NMES)
AP propogation
Direct muscle depolarization (EMS)
Ionic Effects
Action Potential
achieved by rapid sequential depolarization and repolarization in response to stimulation
Strength Duration Curve
the amount of electricity needed to produce an AP is dependent on the type of nerve
Curve depicts the minimum combination of amplitude and pulse duration needed to depolarize a nerve
sensory< motor < a motor or C pain fibers < denervated muscles
Strength duration of sensory nerves
lower amplitudes and shorter pulse durations to become depolarized
<80 usec
Strength duration of motor nerves
higher amplitudes and longer pulse durations than sensory nerves
150-300 usec
Strength duration of Pain transmitting C fibers
require higher amplitudes and longer pulses than motor and sensory nerves
Rheobase
minimum current amplitude required to produce AP (w long pulse duration)
Chronaxie
the minimum duration of an electrical current at twice rheobase intensity
Accomodation
decrease in a nerve’s AP frequency over time when exposed to an unchanging depolarization stimulus
Electrical Muscle Stimulation
Application of electrical current directly to muscle to produce muscle contraction needed for stimulation of denervated muscle
Ionic Effects of Electrical Current
Treat inflammatory states
Facilitate tissue healing
Reduce formation of edem
Contraindications to Electrotherapy
demand cardiac pacemaker unstable arrythmia over carotid over venous thrombosis pregnancy
Precautions to Electrotherapy
cardiac disease
impaired sensation or mentation
malignancy
skin irritation/ open wound
