Physical Agents: Electrotherapeutics content
Exam Study Guide, Fall 2014
Introductory and Fundamental Concepts
1.
What are the contraindications and precautions to electrical stimulation, as used in physical therapy?
2.
Compare and contrast the various types of nerve fibers in the PNS that are of interest when doing e-stim; important factors are
relative size (hierarchy), threshold to depolarization (hierarchy), location in the tissues, and function.
3.
Compare and contrast (put in groups: most, least, middle) the conductivity of various biological tissues.
4.
Match drawings of electrical current with descriptors related to type of current (AC, DC, pulsed), number of phases (mono, bi,
poly), balance, and symmetry. AND, identify the quantitative characteristics of an electrical pulse and pulsed current
(frequency/rate, width, amplitude).
5.
Know the definitions and differentiate between monopolar, bipolar, and quadpolar electrode arrangements.
6.
Know the 3 excitatory responses to electrical stimulation and the expected order of occurrence with surface (transcutaneous)
electrical stimulation.
7.
Compare and contrast how the various types of current (eg AC, DC, polyphasic pulsed, biphasic pulsed, monophasic pulsed)
result in unidirectional vs bidirectional ion flow in tissues (eg. net DC effect vs no net DC effect) What is the specific
physiological cause of electrochemical tissue changes. Categorize TENS, NMES, IFC, and Ionto as having bidirectional or
unidirectional flow of ions (eg. net DC effect or not?) based on the type of current we used for each in lab.
8.
Know the terms/definitions - polarity, voltage, resistance, amperage, conductance, impedence.
9.
With bipolar arrangement of e-stim: What are the various ways in which current density can be increased and decreased when
doing e-stim on human tissue? What are the various ways in which current depth of penetration can be increased and
decreased when doing e-stim on human tissue?
10. Know the specs of the Twin-Stim regarding type of current, range & units of amplitude (intensity), range & units of pulse rate
(frequency), and range & units of pulse width (duration).
NMES:
1.
Know the 4 types of motor responses that can be elicited with NMES and how to produce each one (eg. the frequency/pulse
rate and mode [continuous vs ramp-surge] required to produce each one).
2.
Describe the decision-making approach to choosing electrode size and placement with NMES (think “motor points” and
peripheral nerves).
3.
Recognize the parameters of a NMES treatment (on time, off time, ramp up/down, on/off ratio) if given descriptions and/or
drawings of electrical currents.
4.
Describe the relationship between NMES pulse rate & muscle fatigue? Between NMES on/off ratio & ms. fatigue?
5.
Know the clinical uses of each of the 4 motor responses; keeping in mind that some can have the same clinical use.
6.
Compare/contrast ms. contractions that are electrically induced versus voluntarily induced with regard to type of muscle fiber
recruited (recruitment order), onset of fatigue, general size of A-alpha motor neuron that is recruited, and discharge rate
(asynchronous vs synchronous pattern), and specificity of exercise/function.
7.
For each clinical use of NMES - know the specific parameters for treatment using NMES (NMES Rx chart).
8.
When given a patient problem: identify the impairment to be treated with NMES, the timing mode to be used with NMES
(continuous, ramp-surge w/ 1 channel or 2 channels (synchronous or alternate), the motor response to use, and the
intensity/force of the contraction, the pulse rate & width, the on/off times and ratio and ramp (if applicable).
9.
Know the general research findings & clinical implications regarding NMES (from lecture & notes, but especially from text pgs
242-246).
10. For the Twin-Stim & EMPI Continuum:
a. Do the Ramp times cut into the On time? If so, how do (can) you compensate for this?
b. How do you avoid turning up the amplitude DURING the Off time with each of these units?
11. Know the acronyms and general definitions of NMES, FES, EMS
12. Ultrasound/E-stim will not be tested on the exam.
TENS
1.
Compare and contrast the following naturally occurring pain control theories/mechanisms: 1) Gate Control of Pain /
Presynaptic Inhibition of Pain at the Dorsal Horn, 2) Descending Inhibition of Pain via Raphe Nucleus & PAG, 4) Descending
Modulation of Pain thru Endorphin Release. How do they overlap? How do they differ?
2.
Know all the settings/parameters for Rx of acute pain (HF TENS) and chronic pain (LF TENS) using a TENS device.
3.
Recognize generic illustrations of generic types of TENS current modulations (ie. modulation of rate, modulation of width,
modulation of amplitude, modulation of a combination of 2 of these)
4.
Match the two major TENS Modes of Treatment (High Freq TENS and Low Freq TENS) with the mechanisms of pain control
(ie. theories) that may be enhanced. Key factor is the peripheral nerve fibers that are targeted with the TENS.
5.
Describe the rationales for placement of electrodes when using TENS to reduce pain.
6.
Have a general knowledge of the research evidence regarding the efficacy of TENS. Explain some challenges and deficiencies
of such research. What is generally known re: placebo effect? Why might clinical and individualized clinical research
outcomes evidence [effectiveness] and high level controlled research evidence [efficacy] differ? Much of this has to do with
you having an informed opinion rather than just knowing a bunch of facts.
Interferential Current (IFC)
1.
Know what is required to produce true, classical Interferential current. What is MFAC? Describe constructive and destructive
interference between 2 MFAC currents (in a uniform medium)?
2.
Recognize and interpret illustrations of MFAC & IFC current (resulting from constructive & destructive interference), and the
endogenously produced IFC cloverleaf pattern (all of which can occur in pure form in a uniform medium). Know the meaning
and purpose of the Carrier/Base, Variable, and Beat frequencies.
3.
Know the IFC treatment parameters (amplitude and beat frequency) for acute and chronic pain with IFC; then, relate these
parameters to the pain control theories which explain how they work to reduce pain (same concepts we used with TENS);
Additionally, know which sensory nerve fibers should be stimulated to utilize the following pain control mechanisms: Gate
Control / Presynaptic Inhibition; Descending Inhibition via Raphe Nuc. & PAG; Descending Modulation thru Endorphin. (Refer
to your TENS notes on “pain control theories”)
4.
Know the purpose(s) of using the Vector setting on IFC. Also, know the purpose(s) of Scanning the IFC beat frequency and
Balancing the amplitudes.
5.
Know the potential advantages of using IFC over TENS and vice versa. Think about issues such as patient tolerance,
impedence to current flow, cost of equipment, difficulty of setup, size & location of treatment area, amount of time available to
do the treatment, clinic vs home treatment.
Iontophoresis
1.
Define/describe Iontophoresis?
2.
What are the advantages and disadvantages of iontophoresis as compared to a corticosteroid injection and compared to oral
administration of a corticosteroid?
3.
Be thoroughly familiar with the sensory and skin injury effects of DC current (with the high current, long duration [traditional]
ionto); including what is an acceptable, normal response and what is too much.
4.
In addition to the concept of “like charges repel”, what other mechanism(s) aid the transport of an ion to the target tissue with
iontophoresis?
5.
Explain the concept of “Dosage” in Iontophoresis. When performing an iontophoresis treatment, what parameters contribute to
increasing or decreasing the dosage?
6.
Has research clearly established that there is an optimal combination of amplitude and time for delivering a dosage of
iontophoresis? Clinical opinion (and minimal research) has traditionally believed that ____ mA X ____ min = 40 mAmin may
be optimal, if tolerated by the patient’s skin.
7.
What is the maximal current density (for safety purposes) that should be produced under the cathode when using DC? Know
how to calculate current density (mA/cm2). Intensity (mA) / electrode surface area (cm2)= current density (mA/cm2).
8.
What are the general characteristics of a contemporary iontophoresis drug electrode (regarding size & control of pH, and fluid
capacity)? While pH changes in the skin are difficult to control with use of DC, pH changes in the drug electrode (and in the
drug solution) can be reasonably controlled. How? and Why is it important?
9.
Know the name, polarity and physiological effect of each chemical substances mentioned in the lecture notes that can be used
with iontophoresis.
10. According to your instructor, what is a recommended frequency of treatment for Iontophoresis (do not consider
reimbursement/insurance restrictions)? What are the risks of applying it more frequently?
11. What are the specific precautions and contraindications for Iontophoresis?
12. What does the research regarding depth of penetration of ions from Iontophoresis generally indicate?
13. Consider this statement from a published journal article about Ionto: “Several of the investigations reviewed have reported
subjective patient improvement or a faster rehabilitation recovery rate. However, none of the clinical investigations measured
the in vivo drug concentrations, and none could demonstrate any relationship between tissue or blood levels of dexamethasone
and the improvement in the clinical parameters measured.”
In clinical practice (and in the majority of iontophoresis literature), inferred results (eg. clinical outcomes like pain, ROM,
function), rather than direct measurements of ion penetration into tissue, are made about the depth of penetration of drug ions
and about the effectiveness of Iontophoresis Rx. What concerns exist about this type of evidence?