Deck 9: Foundations of Clinical Electrotherapy

Question 1

Which type of current will most likely cause changes in the tissues underlying the electrodes as a result of electrode polarity?

A) Direct current
B) Monophasic pulsed current
C) Balanced, asymmetrical biphasic pulsed current
D) Russian current

Answer 1

A

Question 2

Which of the following is the correct description of "charge"?

A) An object that has an equal number of protons and electrons
B) Movement of a current along a conductor
C) Gain or loss of protons by an atom
D) Addition or removal of electrons, creating an electromagnetic force

Answer 2

D

Question 3

Which of the following statements is true about charge?

A) There are three types of charge: positive, negative, and neutral.
B) Like charges attract, whereas opposite charges repel.
C) Charge is neither created nor destroyed.
D) Charge cannot be transferred between objects.

Answer 3

C

Question 4

Which of the following describes the typical characteristics of what is commonly known as "Russian current"?

A) Direct current interrupted every 5 seconds for 10 second intervals
B) Biphasic pulsed current, frequency greater than 100 pulses per second with 10 second interpulse intervals
C) Monophasic pulsed current, 100 μsec twin-peaked pulses and 9,900 μsec interpulse intervals
D) 2,500 Hz alternating current, burst modulated at 50 bursts per second using 10-msec bursts

Question 5

Low-intensity direct current (LIDC) is most commonly used clinically for which of the following?

A) Promotion of wound healing by augmenting the current of injury
B) Control of postoperative pain
C) Facilitation of capillary bed circulation in superficial tissues
D) Desensitization of trigger points

Question 6

Which of the following best describes interferential current (IFC)?

A) Alternating current modulated into a series of bursts
B) Superimposition of two symmetrical, asynchronous, sinusoidal alternating currents
C) Juxtaposition of four alternating currents between two circuits with four electrodes
D) Modulation of an alternating current into two interfering bipolar currents

Question 7

Why are human body tissues such as muscles, nerves, and blood good conductors of electric current?

A) These tissues have a high resistance to current flow, which allows good conduction of current.
B) These tissues have a high water content and presence of ions.
C) These tissues have a high collagen content and fat molecules.
D) Their location near the surface of the skin makes these tissues easily depolarized.

Question 8

The unidirectional or bidirectional flow of ions or electrodes that periodically ceases for a small period of time before the next electrical event is known as

A) Interrupted direct current
B) Interrupted alternating current
C) Pulsed or pulsatile current
D) Intermittent delayed current

Question 9

Why does electric current depolarize nerves more easily than it does skeletal muscles?

A) Nerves are closer to the surface of the skin than most muscles.
B) The resting membrane potential of nerves is more negative than that of muscles.
C) The resting membrane potential of nerves is less negative than that of muscles.
D) The neurolemma of nerves is thinner than the sarcolemma of muscles.

Question 10

What can be done clinically to decrease impedance between the electrode and the skin?

A) Use smaller electrodes to disperse the current over a smaller area.
B) Use electrodes with gel or adhesive conductive agents.
C) Apply a thin layer of dry gauze between the electrode and the skin.
D) Strap electrodes tightly to the skin or place a sandbag on top of the electrode.

Question 11

According to Ohm's law, an 80 volt (V) circuit passing through 4 ohms of tissue impedance (resistance) will have how many amps (A) of current?

A) 240 A
B) 160 A
C) 0.05 A
D) 20 A

Question 12

Why is the electrochemical effect negligible when using monophasic pulsed currents such as high-volt pulsed current (HVPC)?

A) Short pulse durations and long interpulse intervals prevent accumulation of charges.
B) Long pulse durations and very short interpulse intervals cause dissipation of charges.
C) Current is flowing in one direction only, therefore there is no accumulation of charges.
D) The polarity of the current is neutral, so no charges are created.

Question 13

The force of attraction or repulsion created by an electric field that represents potential energy is known as

A) Amperage
B) Impedance
C) Capacitance
D) Voltage

Question 14

The greatest amount of electrothermal heating occurs with which of the following currents?

A) Alternating current
B) Direct current
C) Monophasic pulsed current
D) Biphasic pulsed current

Question 15

Which of the following is true regarding the strength-duration curve for electrical stimulation?

A) It depicts the response of a nerve to stimulation for a given pulse amplitude and duration.
B) The area below the curve depicts the amplitudes and durations for sensory responses.
C) Values on the curve indicate the threshold for fatigue of a muscle following stimulation.
D) The area above the curve depicts the amplitudes and duration for motor responses.

Question 16

When stimulating a mixed peripheral nerve, which type of nerve fibers will be recruited first?

A) Type A alpha
B) Type A beta
C) Type A delta
D) Type C

Question 17

Which of the following is the correct description of "direct current"?

A) Flow of electrons directly from a charged object to another object
B) Bidirectional flow of electrons in opposite directions for at least 1 minute
C) Unidirectional flow of electrons for at least 1 second
D) Electrons that flow through a conductor in one direction for less than 1 second

Question 18

Which electrochemical effects match the given electrode polarity?

A) Hydrochloric acid produced under the anode results in softening of hard scar tissue.
B) The alkaline reaction under the cathode results in softening of the underlying tissues.
C) Sodium hydroxide that builds up under the anode results in sclerosis of tissues.
D) The chemical reactions that occur under the cathode are related to an increase in acidity.

Question 19

If the phase durations of a biphasic pulse are 150 μsec each and the interphase interval is 50 μsec, what is the total pulse duration?

A) 350 μsec
B) 100 μsec
C) 550 μsec
D) 300 μsec

Question 20

According to Ohm's law, when using a device that has a constant voltage, what will happen to the current when the skin resistance increases?

A) The current increases.
B) The patient will feel a short-duration shock.
C) There is no change in current.
D) The current decreases.