Electrotherapy Effects and Indications
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Questions and Answers

Which device is preferred for muscle re-education?

  • NMES (correct)
  • DC
  • TENS
  • HVPC

    • Electrotherapy can be used safely over a pregnant uterus.

    False

    What is the effect of a threshold stimulus on nerve cells?

    It evokes an action potential.

    Muscle and nerve cells exhibit __________ when the resting membrane potential is below the threshold.

    <p>depolarization</p> Signup and view all the answers

    Match the following electrotherapy devices with their indications:

    <p>TENS = Pain Relief HVPC = Wound Healing DC = Denervated Muscle NMES = Muscle Strengthening</p> Signup and view all the answers

    Which of the following is a contraindication for using electrotherapy?

    <p>Pacemaker</p> Signup and view all the answers

    The resting membrane potential (RMP) is positive at rest.

    <p>False</p> Signup and view all the answers

    What type of stimulus is required to evoke an action potential during the relative refractory period?

    <p>Suprathreshold stimulus</p> Signup and view all the answers

    Which pulse rate is typically more comfortable for muscle contraction?

    <p>50 pps</p> Signup and view all the answers

    Iontophoresis uses alternating current to deliver drugs into the body.

    <p>False</p> Signup and view all the answers

    What is the recommended range for treatment time in neuromuscular electrical stimulation?

    <p>10-20 contractions, at least 3 times a week</p> Signup and view all the answers

    In NMES, the _________ pulse duration is typically set around 300 microseconds.

    <p>high</p> Signup and view all the answers

    Match the following types of electrical stimulation with their primary applications:

    <p>NMES = Muscle strengthening or re-education Iontophoresis = Drug delivery HVPC = Wound healing and edema reduction Biofeedback = Muscle relaxation or strengthening</p> Signup and view all the answers

    What is the main goal of electronic stimulation in the context of NMES?

    <p>Muscle contraction</p> Signup and view all the answers

    An alkaline reaction occurs under the anode during iontophoresis.

    <p>False</p> Signup and view all the answers

    What should be done before applying iontophoresis to ensure patient safety?

    <p>Check for allergies to the medication used.</p> Signup and view all the answers

    The duty cycle in NMES can range from a ratio of 1:1 up to _____.

    <p>1:5</p> Signup and view all the answers

    What is a common drug used in iontophoresis for inflammation?

    <p>Dexamethasone</p> Signup and view all the answers

    What is the primary purpose of Transcutaneous Electrical Nerve Stimulation (TENS)?

    <p>Pain relief</p> Signup and view all the answers

    The amplitude control on electrical stimulation devices may be labeled as 'Intensity'.

    <p>True</p> Signup and view all the answers

    What is the recommended distance for electrodes from the same circuit for comfort?

    <p>At least one electrode width apart.</p> Signup and view all the answers

    In IFC, __________ refers to the modulation of frequency to prevent accommodation.

    <p>Sweep</p> Signup and view all the answers

    Match the TENS types with their characteristics:

    <p>Conventional TENS = High frequency, short duration pulses Acupuncture-like TENS = Low frequency, long duration pulses Brief Intense TENS = High frequency, long duration pulses</p> Signup and view all the answers

    What happens if electrodes are placed from the same channel farther apart?

    <p>Current goes deeper</p> Signup and view all the answers

    The rise time refers to how long it takes for the current to decline to zero.

    <p>False</p> Signup and view all the answers

    What is the typical frequency used for motor twitch stimulation?

    <p>1-10 pps</p> Signup and view all the answers

    The ______________ is the amount of time it takes to deliver a pulse, measured in microseconds.

    <p>pulse duration</p> Signup and view all the answers

    Match the electrical stimulation technique to its main usage:

    <p>INTERFERENTIAL CURRENT (IFC) = Pain relief NEUROMUSCULAR ELECTRICAL STIMULATION (NMES) = Activating innervated muscle for strengthening TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION (TENS) = Pain relief</p> Signup and view all the answers

    What is the purpose of modulation in electrical stimulation?

    <p>To prevent accommodation</p> Signup and view all the answers

    Gate Control Theory involves stimulating faster sensory nerve fibers to inhibit pain transmission.

    <p>True</p> Signup and view all the answers

    What is the duration range for Acupuncture-like TENS treatments to provide pain relief?

    <p>20-60 minutes</p> Signup and view all the answers

    The ___________ is referred to as the On: Off time in muscle-stimulating units.

    <p>Duty Cycle</p> Signup and view all the answers

    What is the primary function of a motor point?

    <p>The anatomical place where the nerve enters the muscle.</p> Signup and view all the answers

    Ohm's Law states that current remains the same regardless of changes in resistance.

    <p>False</p> Signup and view all the answers

    What does the strength-duration curve correlate with?

    <p>The amplitude and duration of the pulse.</p> Signup and view all the answers

    The ______ is the flow of electrically charged particles.

    <p>current</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Electromyographic (EMG) = Measures the electrical activity of muscles Direct Current (DC) = Constant flow of electrons in one direction Alternating Current (AC) = Current flow changing between positive and negative Neuromuscular Electrical Stimulation (NMES) = Stimulates muscles through electrical impulses</p> Signup and view all the answers

    Which of the following currents is capable of delivering enough charge to reach the threshold of muscle membranes?

    <p>Direct Current (DC)</p> Signup and view all the answers

    A bipolar arrangement of electrodes has unequal sizes.

    <p>False</p> Signup and view all the answers

    What is the primary disadvantage of constant current devices?

    <p>If part of the electrode loses contact, current concentrates in the part that is in contact.</p> Signup and view all the answers

    In electrotherapy, ______ refers to the ability of materials to oppose the flow of ions.

    <p>resistance</p> Signup and view all the answers

    Match the following therapeutic applications with their currents:

    <p>Iontophoresis = Direct Current (DC) Acute edema = High Voltage Pulsed Current (HVPC) Neuromuscular Electrical Stimulation (NMES) = Biphasic Current TENS = Alternating Current (AC)</p> Signup and view all the answers

    What happens when pulse duration increases while amplitude remains constant?

    <p>Sensory response becomes more intense.</p> Signup and view all the answers

    A monophasic waveform flows in two directions.

    <p>False</p> Signup and view all the answers

    What type of current produces voltage that does not vary?

    <p>Constant Voltage devices.</p> Signup and view all the answers

    With E-Stim, the sequence of activation of nerves is sensory, ______, and pain.

    <p>motor</p> Signup and view all the answers

    What does an electromotive force of 1 volt do?

    <p>Drives one amp across 1 ohm of resistance.</p> Signup and view all the answers

    What is an advantage of using a unbalanced biphasic current for NMES?

    <p>It makes one electrode more active than the other.</p> Signup and view all the answers

    Study Notes

    Effects, Indications and Contraindications of Electrotherapy

    • Pain Relief: TENS and IFC are preferred devices.
    • Muscle Re-education: NMES, Russian stimulation for disuse atrophy, muscle strengthening, relaxation of muscle spasm, increase range of motion, increase circulation, decrease chronic edema, and orthotic substitution (FES).
    • Tissue Healing: DC for drug delivery (iontophoresis) and denervated muscle stimulation. HVPC for decreasing acute edema and wound healing.
    • Contraindications: Pacemaker (potentially other implanted devices), malignancy, seizure disorder, cardiac arrhythmia, over a pregnant uterus (except during labor and delivery).
    • Safety: Avoid transcerebral, transthoracic, or anterior neck electrode placement. Refer to “Spotlight on Safety” pg. 644 for safe operation guidelines.

    Muscle and Nerve Cell Excitation

    • The resting membrane potential (RMP) is negative due to the inside of the cell being more negative at rest.
    • An impulse causes a change in ion concentration, making the inside more positive (depolarization).
    • This only occurs if the RMP is below threshold.
    • Absolute Refractory Period: No amount of stimulation will evoke an action potential.
    • Relative Refractory Period: A suprathreshold stimulation is necessary to evoke an action potential.
    • For an action potential to be evoked, the amplitude, duration, and rise time of the stimulus must be sufficient to overcome the threshold of the nerve or muscle membrane.
    • The impulse (action potential) propagates along the nerve fiber until it synapses with another nerve or the motor end plate of a muscle.
    • Action potentials are all or none based on whether the stimulus reaches threshold.
    • Conductors: Nerve, muscle, motor points, trigger points.
    • Insulators: Adipose, scar tissue.
    • Speed of conduction: Faster if fibers are myelinated (large); slower if unmyelinated.
    • Conduction slows with extreme or prolonged ice, pressure, and anoxia.
    • Motor point: The anatomic place where the nerve enters the muscle.
    • Motor unit: The motor nerve and the muscle fibers it innervates. Small units have a low ratio (e.g. 1:5) for fine motor control, while large units have a high ratio (1:100 or more) for force production.
    • Voluntary contractions: Small motor units are recruited before large units resulting in gradual contraction. The reverse happens with E-stim.

    Principles of Electricity

    • Current: The flow of electrically charged particles from one place to another. Measured in amps, milliamps, or microamps.
    • Voltage: A measure of electromotive force. Measured in volts or millivolts.
    • Resistance: The ability of a material to oppose the flow of ions. Measured in ohms.
    • Ohm's Law: Current in a conductor varies proportionally to voltage and inversely proportionally to resistance. (I = V/R)
    • Constant Current Devices: Current does not vary regardless of changes in resistance. Advantage: consistent physiological response. Disadvantage: Current concentrates in the remaining contact area if part of the electrode loses contact or dries out.
    • Constant Voltage Devices: Voltage does not vary, but current increases or decreases as resistance changes. Disadvantage: quality of the response changes with resistance changes and may not be as effective or comfortable.
    • Strength-Duration Curve: Correlates with the amplitude and duration of the pulse. The area of a pulse (S x D) = charge. Vertical axis: Strength; Horizontal axis: Pulse duration. Shortest pulse duration: HVPC; Longest pulse duration: DC.
    • Relationship between Strength and Duration: Inverse. Shorter pulses require higher amplitude to reach threshold, while longer pulses need less amplitude to reach the same nerve threshold.
    • Sequence of activation with E-stim: Sensory, motor, pain.
    • Expected response if duration remains constant and amplitude increases: Sensory: buzzing/tingling. Motor: weak contraction that becomes stronger as more motor units are recruited. Pain: Higher intensity.
    • Muscle membranes have a much higher threshold than nerve membranes.

    Waveforms of Therapeutic Current

    • Monophasic: Pulses above or below the 0 line for the entire time. Current flows in one direction. Produces a polarity effect.
    • Biphasic: Pulses above and below the 0 line. Changes direction. Produces a polarity effect only if unbalanced.
    • Polarity: Electron flow in one direction results in one electrode being (+) and the other (-). Therapeutic applications with polarity from greatest to least effect: Iontophoresis, denervated muscle (DC), acute edema (HVPC), NMES (pulsed current: biphasic asymmetrical unbalanced).
    • Balanced waveform: All electrodes are equal. No polarity effect.

    Therapeutic Currents

    • Direct Current (DC): Constant flow of electrons in one direction for more than 1 second.
    • Alternating Current (AC): Continuous flow, current changing from positive to negative. Sinusoidal.
    • Pulsatile: Non-continuous flow of electrons delivered in pulses in one direction (monophasic) or both directions (biphasic).
    • Biphasic: Can be balanced (no polarity effect) or unbalanced (mild polarity effect).

    Electrodes

    • Monopolar Arrangement: Two electrodes of unequal size. One electrode is more active (smaller) and current density is greater under the smaller electrode. Used for DC (denervated muscle, iontophoresis) and HVPC (optional).
    • Bipolar Arrangement: Paired electrodes of equal size. Current density is equally distributed.
    • Quadripolar Arrangement: Four electrodes of equal size, channels intersect to surround the painful area. Current density is equal in all electrodes.

    Other Considerations

    • Longitudinal electrode placement along a muscle increases conduction. Ideal for muscle contraction.
    • Placing electrodes from the same channel farther apart causes the current to go deeper.
    • Ideally, electrodes from the same circuit should be positioned at least one electrode width apart.
    • The patient may experience more sensation under one electrode if it is over a motor point or trigger point, not in full contact, or smaller than the others.
    • Electrode care: No bathing, sleeping with electrodes on. Store on acetate when not in use. Replace if they don't adhere to skin.

    Parameters of Electrical Stimulation

    • Amplitude: The magnitude of current. controls intensity.
    • Pulse Duration: The amount of time to deliver a pulse. Measured in microseconds.
    • Rise Time: The time it takes for current to move from zero to peak intensity within a pulse.
    • Frequency: The number of pulses per second. 1-10 pps: Motor twitch. 35-50 pps: Tetanized muscle contraction. 75-150 pps: Sensory response.
    • Modulation: Any alteration in amplitude, duration, or frequency. Used to prevent accommodation.
    • Duty Cycle: On: Off time. Longer off times for patients with neuromuscular conditions or high intensity contractions. Shorter off times for intentional fatigue or once the patient has adapted to E-stim.

    Devices

    Transcutaneous Electrical Nerve Stimulation (TENS)

    • Biphasic, balanced waveform; bipolar placement. Used for pain relief.
    • Gate Control Theory: High frequency, short duration pulses, sensory response only. Relief is fast but short-lasting.
    • Endorphin Theory: Low frequency, long duration pulses, motor twitch. Relief is slower but lasts longer.
    • Brief Intense TENS: High frequency, long duration pulses, strong paresthesia or motor response. For painful procedures.

    Interferential Current (IFC)

    • Biphasic balanced waveform, sinusoidal.
    • Used for pain relief.
    • The intersection of 2 currents with different frequencies produces beats (bps).
    • Electrode placement: Quadripolar (ALWAYS) or Bipolar (Premodulated).
    • Unique Parameters: Sweep: Modulates frequency. Scan: Modulates amplitude.

    Neuromuscular Electrical Stimulation (NMES)

    • Biphasic, symmetrical or asymmetrical waveform.
    • Used to activate innervated muscles.
    • Russian Stimulation: Biphasic balanced, AC current delivered in bursts. Often used for strengthening in a clinic setting.
    • Amplitude: F+ tetanized muscle contraction. Adjusted and progressed as tolerated.
    • Pulse Duration: Typically high (300 microseconds).
    • Frequency: 25-50 pps for smooth contraction. 50 pps is more comfortable and fatiguing than 25 pps.
    • Duty Cycle: Varying on:off times.
    • Ramp Time: Gradually increase amplitude for comfort.
    • Treatment time: 10-20 contractions, at least 3 times a week.
    • Electrodes: One over motor point, the other parallel to muscle fibers. Larger electrodes are more comfortable.

    Iontophoresis

    • Direct current (DC) to deliver drugs into the body.
    • Dosage: 40-80 mA-min.
    • Procedure: Ensure no allergy, clean skin, polarity set to drug, saturate active pad with ion solution.
    • DC is also used to stimulate denervated muscles to maintain viability.

    High Volt Pulsatile Current (HVPC)

    • Monophasic pulses of very short duration.
    • Therapeutic applications: Wound healing and reducing acute edema. Usually monopolar, but can be bipolar.

    Biofeedback

    • Not electrical stimulation, but a good substitute if E-stim is contraindicated or poorly tolerated.
    • Indications: Muscle relaxation or muscle re-education.

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    Description

    This quiz explores the various effects, indications, and contraindications of electrotherapy modalities such as TENS, NMES, and HVPC. You will learn about their applications in pain relief, muscle re-education, and tissue healing, as well as important safety considerations. Test your knowledge on the mechanisms of muscle and nerve excitation as well.

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