PAM Electrotherapy Techniques 3 — Questions and Answers
Question 1: What is the key difference between monophasic and biphasic waveforms in electrotherapy?
- Monophasic has higher amplitude than biphasic
- Monophasic deflects in one direction; biphasic deflects in both directions (Correct answer)
- Biphasic cannot produce muscle contractions
- Monophasic is always symmetrical in waveform shape
Correct answer: Monophasic deflects in one direction; biphasic deflects in both directions
Monophasic waveforms deflect to only one side of baseline, while biphasic waveforms deflect to both positive and negative sides.
Question 2: When using electrical stimulation for edema reduction, which parameter setting and electrode arrangement is most appropriate?
- High-frequency TENS with electrodes flanking the edematous area
- HVPC with negative electrode over the edema and positive proximal
- Iontophoresis with positive electrode directly over edema
- Low-frequency NMES to produce rhythmic contractions of surrounding musculature (Correct answer)
Correct answer: Low-frequency NMES to produce rhythmic contractions of surrounding musculature
Low-frequency NMES produces rhythmic muscle contractions that act as a muscle pump, facilitating lymphatic and venous return to reduce edema.
Question 3: Acupuncture-like TENS (AL-TENS) is characterized by which parameter combination?
- High frequency (80–150 Hz) and low intensity producing paresthesia
- Low frequency (1–10 Hz) and high intensity producing visible muscle twitches (Correct answer)
- Medium frequency (50 Hz) and medium intensity at sensory threshold
- Burst mode at 100 Hz bursts delivered at 2 Hz with sensory-level intensity
Correct answer: Low frequency (1–10 Hz) and high intensity producing visible muscle twitches
AL-TENS uses low frequency (1–10 Hz) at high enough intensity to produce visible muscle twitches, stimulating endorphin release.
Question 4: Which skin condition would MOST likely increase the risk of chemical burns during iontophoresis?
- Excessive hair over the electrode site
- Prior sun exposure to the treatment area
- Open skin lesions or abrasions under the electrode (Correct answer)
- Dry, callused skin on the palmar surface
Correct answer: Open skin lesions or abrasions under the electrode
Open skin lesions or abrasions bypass the skin's normal resistance, concentrating current and significantly increasing burn risk.
Question 5: A therapist treating a patient with chronic low back pain selects burst-mode TENS. How does burst-mode TENS deliver current?
- Continuous high-frequency pulses at constant amplitude
- Packets of high-frequency pulses delivered at a low repetition rate (Correct answer)
- Alternating periods of high and low amplitude at fixed frequency
- Random pulse intervals to prevent accommodation
Correct answer: Packets of high-frequency pulses delivered at a low repetition rate
Burst-mode TENS delivers trains (packets) of high-frequency pulses (e.g., 100 Hz) at a low burst rate (e.g., 2 bursts/sec).
Question 6: When performing electrical muscle stimulation (EMS) to maintain muscle mass in a denervated muscle, which waveform is most effective at depolarizing denervated muscle fibers?
- High-frequency sinusoidal AC at 2500 Hz
- Short-duration pulsed current (< 0.1 ms pulse width)
- Long-duration monophasic pulses (> 10 ms pulse width) (Correct answer)
- Microcurrent at subsensory levels
Correct answer: Long-duration monophasic pulses (> 10 ms pulse width)
Denervated muscle requires longer pulse durations (> 10 ms) because without nerve supply the higher rheobase and chronaxie of muscle tissue demand longer stimulation times.
Question 7: Which safety precaution is MOST critical when applying TENS over the anterior neck region?
- Avoiding placement near metal jewelry
- Risk of stimulating carotid sinus causing vasovagal response (Correct answer)
- Possibility of current shunting through perspiration
- Preventing accommodation by varying frequency
Correct answer: Risk of stimulating carotid sinus causing vasovagal response
Electrode placement over the carotid sinus can stimulate baroreceptors, causing a vasovagal response including bradycardia and hypotension.
PAM Electrotherapy Techniques 3
What is the key difference between monophasic and biphasic waveforms in electrotherapy?