Week 2: E-stim Flashcards
What is an electric current?
A flow of charged particles. Can be electrons or ions
Electric current exert their physiological effects by ____
depolarizing nerve membranes, thereby producing action potentials.
What is an action potential?
The message unit of of the nervous system
Nerves conducting information towards the spinal cord and brain are ____ nerves
Sensory nerves
Nerves conducting information away from the spinal cord and brain are ____ nerves
Motor nerves
The positive side of an electrode is called an ___ and is electron/ion ___
- Anode
- deficient
The negative side of an electrode is called an ___ and is electron/ion ___
- Cathode
- Rich
A direct current is most commonly used for ___
Iontophoresis, high volt pulse stimulation
What is a direct current?
A continuous unidirectional flow of charged particles
Electrodes in a direct current ___ their polarity and is used to ___. Can help induce ___
- Maintain.
- transfer ions
- Chemical reactions
Direct current is ___ effective at activating denervated muscles
More effective
What is an alternating current?
A continuous bidirectional flow of charged particles
The electrodes in an alternating current ___ their polarity
Constantly change their polarity above and below the isometric line(the 0 line)
An alternating current results in ___, and ___ chemical reactions
- No net charge
- No chemical reactions being built up
Most common form of an alternating current
- Transcutaneous electric nerve stimulation
- Innerferential current for pain control
- NMES
- Russian (used for muscle contractions)
What is a phase duration?
Activity above or below the isometric line. Ends as soon as the current comes back to the isometric line.
What is a pulse?
When the current immediately moves in the opposite direction and back toward the isometric line after a phase duration
___ is seen most commonly with AC current
A pulse
What is the interpulse interval?
When there is a pause, and there is no electrical activity for any given period of time
An AC current is also called an ___ current
biphasic current
Direct current is also called a ___ current
monophasic
What is a current amplitude?
determines how strong a stimulation is going to be
Frequency of an e-stim is counted in
pulse/sec
Frequency is set up to determine ___
The type of stimulation response a patient gets
The higher the frequency the ___ stimulation a patient gets
More
A strength duration curve represents the
The amount of electricity required to produce an action potential, depending on the nerve type
The y-axis on a strength duration curve is ___
The x-axis on a strength duration curve is ___
- Current strength
- Time of pulse
What is a ramp up/ramp down time?
When the stimulation gradually increases or decreases till it gets to a certain set amplitude
What is accommodation?
The creation of variations with the form of e-stim a patient feels to help prevent them from becoming used to the machine
What are ways to prevent accommodation?
- Amplitude modulation
- Pulse duration modulation
- Frequency modulation
What is amplitude modulation?
When the machine increases and decreases the amplitude it produces based on the preset measures
What is a pulse duration modulation?
When the pulse duration over time gets shorter and longer, but stays at a set amplitude. Same as frequency modulation
What is orthodromic?
the propagation of an impulse along a conduction system (for example, nerve fiber) in the direction it normally travels
What is antidromic
the propagation of an impulse along a conduction system (for example, nerve fiber) in the direction opposite to that which it normally travels
In sensory nerves, orthodromic flow moves from __ to ___
Distal to proximal.
Peripheral tissues to the bran
In motor nerves, orthodromic flow moves from __ to ___
Proximal to distal
Brain to peripheral tissues
____ Occurs artificially during electrical stimulation based on location of stimulation on nerve
Antidromic
What is current density?
Current per size of electrode
Settings that can be manipulated/changed on an e-stim
- Frequency
- Pulse Duration (sometimes pre-programmed based on frequency)
- AC vs DC (this is often decided automatically based on machine we choose)
- If DC, which electrode is “active” (Iontophoresis / High-volt)
- Active vs Dispersive pad
- On/off time (mostly just with NMES/Russian Stim.)
- Ramp up/down (mostly just with NMES/Russian Stim.)
- Modulation
- Total treatment time
- Intensity
Reasons to use transcutaneous electrical nerve stimulation (TENS) & Interferential current (IFC)
• Control/ relieve pain
• Reduce the amount of and dependency on pain
medication
• Provide the patient a more active role in their pain
management
• Increase functional movement and mobility with less discomfort
Characteristics of a conventional TENS setting
• High frequency: 100-150 Hz (tingling response)
• Pulse Duration – 50-80 µsec
• Amplitude – “strong but comfortable”
• Treatment Duration – 20-30 minutes, up to 24 hours
• Mechanism of Action: Gate Control
• Analgesia Duration – immediate relief with little
residual effect (comes back quickly when turned off)
• Modulate to prevent accommodation
Characteristics for low-rate/acupuncture-like TENS setting
• Brief sharp pain through repetitive muscle twitches
and stimulation of A-delta fibers
• Frequency – 2-10 Hz
• Pulse Duration – 200-300 µsec
• Amplitude – strong, visible muscle contraction
• Treatment Duration – 20-30 minutes
• Mechanism of Action: Endogenous Opioids Release
(Endorphin Release)
• Analgesia Duration – up to 5 hours
Types of electrode placement for TENS
- Crisscross
- Parallel
- Bracket
- Unilateral
Where to avoid placement of electrode placement for TENS?
- Trans-cranial
* Over genitalia
What creates an interferential current?
Two medium-frequency AC currents interfering with each
other.
What is heterodyne?
Blending 2 different carrier frequencies that are out of phase. The resulting difference in the two frequencies is the treatment/beat frequency
Characteristics of IFC
- Beat Frequency can be modulated in device
- Settings mimic TENS modes
- Thought to be more comfortable and cover a larger area – Conflicting research
Ways to prevent accommodation with IFC
Sweep and scan
What is sweep in IFC accommodation prevention?
Frequency Modulation
• One carrier frequency fluctuates ±150 Hz within the same ideal treatment frequency, while the other stays the same
What is scan in IFC accommodation prevention?
Amplitude Modulation
• Can Treat a larger tissue area as the scan increases
IFC placement
Minimum of 2 leads and 4 electrodes, and always use criss-cross pattern
What is premodulated IFC?
Instead of sending currents into the tissues at higher frequencies, the machine will create interference within itself and send the it down. (avoids having to use criss cross)
Precautions of TENS or IFC
- Cardiac Disease
- Impaired Sensation
- Malignant Tumors
- Skin irritation or open wounds
Contraindications of TENS or IFC
- Pacemakers, heart conditions (unstable arrhythmias)
- Over the carotid sinus
- Venous or arterial thrombosis or thrombophlebitis
- Pelvis, abdomen, trunk, and low back during pregnancy (especially 1st trimester), can be used for pain control during delivery
