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Terms in this set (22)
Direct Current (DC)
continuous, unidirectional flow of charged particles. Most commonly used for iontophoresis and for stimulating contractions in denervated muscle
Alternating Current (AC)
A continuous bidirectional flow of charged particles, can be used for pain control (IFC) or muscle contraction (Russian). AC has equal ion flow in each direction and thus no pulse charge remains in the tissues. Most commonly, AC is delivered as a sine wave. With AC, when the frequency increases, the cycle duration decreases, and when the frequency decreases, the cycle duration increases
Pulsed Current (PC)
An interrupted flow of charged particles whereby the current flows in a series of pulses separated by periods when no current flows. The current may flow in one direction only (monophasic) or may flow back and forth during each pulse (biphasic).
What are monophasic pulsed currents used for?
Can be used for any clinical application of E-stim but most commonly used to promote tissue healing and for acute edema management. pulsed galvanic current is most common (HVPC)
symmetrical or a balanced asymmetrical biphasic = ?
charges of the phases are equal in amount and opposite in polarity resulting in NET CHARGE OF ZERO
unbalanced asymmetrical biphasic = ?
charges are not equal and there IS a net charge
What depolarizes sensory nerves?
lower amplitudes and shorter pulse durations
What depolarizes motor nerves?
higher amplitudes and longer pulse durations
What depolarizes pain-transmitting C fibers?
Even higher amps and longer pulses
process by which a nerve gradually becomes less responsive to stimulation; a stimulus of sufficient amplitude that usually produces a response no longer does so.
period when electrical current flows in one direction
how long a phase lasts and measured in microseconds
period when electrical current flows in any direction, may be made up of one or more phases
(often incorrectly labeled as pulse width): how long each pulse lasts and is the time from the beginning of the first phase of the pulse to the end of the last phase of the pulse, measured in microseconds
amount of time between pulses
Frequency (often labeled rate)
number of cycles per second (Hz for AC) or pulses per second (pps for PC)
Amplitude (strength or intensity)
magnitude of the current flow, measured in amps or volts, sometimes noted as between 1-10 on a device but actual number of amps/volts not displayed
On time/Off time
expressed as a ratio, e.g. 10 seconds on and 50 seconds off is 1:5 on:off ratio, off time allows ms time to relax and reduced muscular fatigue
to minimize the uncomfortable sensation that occurs when an electrical current suddenly turns on
on time/(on time + off time) x 100%; on 10 seconds, off 30 seconds duty cycle = 25%
How do you recruit more muscle fibers?
increasing pulse duration, inc current amplitude, inc electrode size
Indications for E-stim
•Decrease muscle spasm
•Improve muscle strength
•Soft tissue repair
•Contract denervated muscle
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