Electrotherapy

50 Gulf Prometric Physiotherapist (DHA, DOH, MOH, SCFHS, QCHP) practice questions on Electrotherapy, part of Electrotherapy and Physical Agents. The first 25 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

1. Question 1 · Easy

   The unit of pulse frequency used in electrotherapy is:

   1. ACoulomb
   2. BVolt
   3. COhm
   4. DHertz

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   Answer: D · Hertz

   Pulse frequency is the number of pulses or cycles per second and is measured in hertz (Hz). Voltage is in volts, resistance in ohms and charge in coulombs. Setting the correct frequency is central to choosing the effect desired.

   • A: Coulomb is the unit of electrical charge.
   • B: The volt measures electrical potential.
   • C: The ohm measures resistance or impedance.

   Remember this

   Pulse frequency is measured in hertz.

2. Question 2 · Medium

   A patient develops an itchy red patch under adhesive TENS pads. What is the most appropriate next step?

   1. AContinue, but move the same pads 2 cm away from the patch
   2. BReduce the intensity and finish the session with the same pads
   3. CStop, inspect the skin and change to hypoallergenic electrodes
   4. DApply hydrocortisone cream and continue with the same pads

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   Answer: C · Stop, inspect the skin and change to hypoallergenic electrodes

   Irritation under pads is usually an allergic or chemical reaction to the adhesive or gel. Stimulation is stopped over that site, the skin is inspected and a different, hypoallergenic electrode is used. The reaction is recorded.

   • A: The same adhesive will irritate the new site as well.
   • B: Lowering the current does not stop a reaction to the adhesive.
   • D: Treating the rash does not remove its cause, the adhesive or gel.

   Remember this

   Stop and change the electrode type if the skin reacts to the pads.

3. Question 3 · Medium

   A patient with a suspected deep vein thrombosis in the calf is referred for calf muscle stimulation. What is the correct action?

   1. AUse a lower frequency and continue
   2. BProceed with high-intensity stimulation
   3. CApply to the opposite calf only without asking
   4. DWithhold stimulation and refer for medical assessment

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   Answer: D · Withhold stimulation and refer for medical assessment

   Muscle contractions may dislodge a thrombus and cause pulmonary embolism, so stimulation over a limb with suspected DVT is contraindicated. The first step is to withhold treatment and ensure medical assessment. Changing the settings does not remove the risk.

   • A: A lower frequency still produces contractions.
   • B: High intensity increases the risk.
   • C: Treating the other calf does not address the suspected DVT.

   Remember this

   Do not stimulate a limb with suspected DVT; refer for medical assessment.

4. Question 4 · Medium

   A patient after thoracotomy needs TENS for incisional pain. Where is the best placement?

   1. AOver the carotid sinus
   2. BOn the opposite lower limb
   3. CDirectly over the open wound and its dressing
   4. DOn intact skin on either side of the dressing

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   Answer: D · On intact skin on either side of the dressing

   Electrodes are placed on intact skin around the incision so that the stimulated segments cover the painful area. They must not be placed over wounds or fresh surgical dressings. Distant sites do not cover the same segments.

   • A: The carotid sinus is a prohibited site.
   • B: A distant limb does not cover the painful segments.
   • C: Open skin must not carry electrodes.

   Remember this

   Place TENS electrodes on intact skin around a surgical wound, never on the wound.

5. Question 5 · Easy

   Which implanted device is a contraindication to most forms of electrotherapy over the trunk?

   1. ADental filling
   2. BIntrauterine copper coil
   3. CDemand-type cardiac pacemaker
   4. DKnee arthroplasty

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   Answer: C · Demand-type cardiac pacemaker

   Electrical currents may inhibit or interfere with the sensing circuit of a demand pacemaker and cause dangerous arrhythmias. Electrotherapy is therefore avoided in patients with a pacemaker unless the cardiology team agrees. Other implants carry lower risks for these currents.

   • A: Dental fillings do not interfere with electrotherapy.
   • B: A copper coil is a concern for heating modalities, not low-power electrotherapy.
   • D: A knee prosthesis is not a contraindication to TENS-type currents.

   Remember this

   A demand pacemaker is a contraindication to most electrotherapy over the trunk.

6. Question 6 · Medium

   Two TENS electrodes are placed only 1 cm apart on the back. What is the likely effect?

   1. ACurrent is shunted through the skin and penetrates poorly
   2. BThe current becomes direct current
   3. CThe current penetrates much deeper than it normally would
   4. DNo current flows

   Answer and explanation in LearnFree account

7. Question 7 · Medium

   Under which electrode does a more severe chemical skin burn usually develop during direct-current iontophoresis, and why?

   1. AThe anode, because hydrochloric acid forms
   2. BNeither, because the pulses are balanced
   3. CThe cathode, because sodium hydroxide forms
   4. DBoth equally, because of heat

   Answer and explanation in LearnFree account

8. Question 8 · Medium

   A neuromuscular stimulator gives 10 seconds of contraction, then 20 seconds of rest. What is the duty cycle?

   1. A67%
   2. B50%
   3. C33%
   4. D10%

   Answer and explanation in LearnFree account

9. Question 9 · Easy

   Conventional (high-frequency) TENS for pain relief typically uses a pulse frequency of about:

   1. A1000 to 2000 Hz
   2. B2 to 4 Hz
   3. C80 to 120 Hz
   4. D0.1 to 1 Hz

   Answer and explanation in LearnFree account

10. Question 10 · Medium

    Low-dose naloxone, which blocks mainly mu-opioid receptors, is given before TENS. Analgesia from which type of TENS is expected to be reduced most?

    1. ALow-frequency, acupuncture-like TENS
    2. BHigh-frequency, conventional TENS
    3. CNeither mode, as TENS does not use opioid pathways
    4. DBoth modes to the same degree

    Answer and explanation in LearnFree account

11. Question 11 · Medium

    Two interferential carrier currents are set at 4000 Hz and 4100 Hz. What is the beat frequency in the tissues?

    1. A50 Hz
    2. B8100 Hz
    3. C4050 Hz
    4. D100 Hz

    Answer and explanation in LearnFree account

12. Question 12 · Medium

    A patient with a chronic pressure ulcer is referred for electrical stimulation to support healing. Which is the best-supported current?

    1. AInterferential at 4000 Hz
    2. BRussian stimulation at 2500 Hz
    3. CHigh-voltage pulsed current
    4. DBurst TENS at 2 Hz

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13. Question 13 · Medium

    Russian stimulation is characterised by:

    1. AA 4000 Hz carrier with two circuits
    2. BA 100 Hz continuous pulse train
    3. CA 2500 Hz carrier delivered in 50 bursts per second
    4. DA direct current with no interruption

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14. Question 14 · Medium

    Dexamethasone sodium phosphate is delivered by iontophoresis for plantar fasciitis. Which electrode should hold the drug?

    1. ABoth electrodes equally
    2. BThe positive electrode (anode)
    3. CThe negative electrode (cathode)
    4. DThe return electrode only

    Answer and explanation in LearnFree account

15. Question 15 · Medium

    A therapist at a Dubai clinic plans iontophoresis with lidocaine hydrochloride, which carries a positive charge. From which electrode should it be delivered?

    1. AThe positive electrode (anode)
    2. BEither, because the drug is neutral
    3. CA ground pad with no polarity
    4. DThe negative electrode (cathode)

    Answer and explanation in LearnFree account

16. Question 16 · Medium

    When using conventional TENS, the intensity is set to produce:

    1. AStrong, comfortable tingling with no muscle contraction
    2. BNo sensation at all
    3. CA painful stimulus that the patient can only just tolerate
    4. DA visible muscle contraction at once

    Answer and explanation in LearnFree account

17. Question 17 · Hard

    A therapist wants a 75 Hz amplitude-modulated frequency in interferential therapy. One carrier is set at 4000 Hz and the second is to be set above it. What frequency should the second carrier be?

    1. A75 Hz
    2. B4075 Hz
    3. C4150 Hz
    4. D4037.5 Hz

    Answer and explanation in LearnFree account

18. Question 18 · Hard

    For dexamethasone iontophoresis the safe current density is taken as 0.5 mA/cm2. The active cathode has an area of 4 cm2 and the prescription is 60 mA-minutes. What is the shortest session time, using the maximum current allowed for that electrode?

    1. A15 minutes
    2. B10 minutes
    3. C60 minutes
    4. D30 minutes

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19. Question 19 · Easy

    Where must electrodes never be placed?

    1. AOver the quadriceps
    2. BOver the shoulder girdle
    3. COver the lumbar paraspinal muscles
    4. DOver the carotid sinus

    Answer and explanation in LearnFree account

20. Question 20 · Medium

    Which pulse duration is needed to excite denervated muscle fibres directly?

    1. AAbout 100 microseconds
    2. BLong, in the order of tens to hundreds of milliseconds
    3. CNo pulse; only continuous alternating current
    4. DShort, below 1 millisecond

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21. Question 21 · Hard

    In four-pole interferential therapy with two crossed circuits in a uniform tissue, where is the depth of amplitude modulation greatest?

    1. AAlong the line of each individual current
    2. BAlong the diagonals, at 45 degrees between the two current paths
    3. COnly at the skin surface between adjacent electrodes
    4. DDirectly under each of the four electrodes

    Answer and explanation in LearnFree account

22. Question 22 · Medium

    At the start of a neuromuscular electrical stimulation programme for a weak quadriceps, which on:off ratio is usually advised to limit fatigue?

    1. A1:1
    2. B5:1
    3. CContinuous with no rest
    4. D1:5

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23. Question 23 · Medium

    On a strength-duration curve, chronaxie is defined as the pulse duration at:

    1. AHalf the rheobase intensity
    2. BThe rheobase intensity
    3. CTwice the rheobase intensity
    4. DThe pain threshold

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24. Question 24 · Easy

    Interferential current therapy usually uses a medium-frequency carrier of about:

    1. A100 Hz
    2. B4000 Hz
    3. C400 Hz
    4. D40 000 Hz

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25. Question 25 · Medium

    At constant amplitude, increasing the pulse duration will:

    1. AIncrease the charge per pulse and recruit more fibres
    2. BReduce the pulse frequency
    3. CSwitch the current to direct current
    4. DDecrease the charge per pulse

    Answer and explanation in LearnFree account