Podcast
Questions and Answers
Which device is preferred for muscle re-education?
Which device is preferred for muscle re-education?
Electrotherapy can be used safely over a pregnant uterus.
Electrotherapy can be used safely over a pregnant uterus.
False
What is the effect of a threshold stimulus on nerve cells?
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.
Muscle and nerve cells exhibit __________ when the resting membrane potential is below the threshold.
Signup and view all the answers
Match the following electrotherapy devices with their indications:
Match the following electrotherapy devices with their indications:
Signup and view all the answers
Which of the following is a contraindication for using electrotherapy?
Which of the following is a contraindication for using electrotherapy?
Signup and view all the answers
The resting membrane potential (RMP) is positive at rest.
The resting membrane potential (RMP) is positive at rest.
Signup and view all the answers
What type of stimulus is required to evoke an action potential during the relative refractory period?
What type of stimulus is required to evoke an action potential during the relative refractory period?
Signup and view all the answers
Which pulse rate is typically more comfortable for muscle contraction?
Which pulse rate is typically more comfortable for muscle contraction?
Signup and view all the answers
Iontophoresis uses alternating current to deliver drugs into the body.
Iontophoresis uses alternating current to deliver drugs into the body.
Signup and view all the answers
What is the recommended range for treatment time in neuromuscular electrical stimulation?
What is the recommended range for treatment time in neuromuscular electrical stimulation?
Signup and view all the answers
In NMES, the _________ pulse duration is typically set around 300 microseconds.
In NMES, the _________ pulse duration is typically set around 300 microseconds.
Signup and view all the answers
Match the following types of electrical stimulation with their primary applications:
Match the following types of electrical stimulation with their primary applications:
Signup and view all the answers
What is the main goal of electronic stimulation in the context of NMES?
What is the main goal of electronic stimulation in the context of NMES?
Signup and view all the answers
An alkaline reaction occurs under the anode during iontophoresis.
An alkaline reaction occurs under the anode during iontophoresis.
Signup and view all the answers
What should be done before applying iontophoresis to ensure patient safety?
What should be done before applying iontophoresis to ensure patient safety?
Signup and view all the answers
The duty cycle in NMES can range from a ratio of 1:1 up to _____.
The duty cycle in NMES can range from a ratio of 1:1 up to _____.
Signup and view all the answers
What is a common drug used in iontophoresis for inflammation?
What is a common drug used in iontophoresis for inflammation?
Signup and view all the answers
What is the primary purpose of Transcutaneous Electrical Nerve Stimulation (TENS)?
What is the primary purpose of Transcutaneous Electrical Nerve Stimulation (TENS)?
Signup and view all the answers
The amplitude control on electrical stimulation devices may be labeled as 'Intensity'.
The amplitude control on electrical stimulation devices may be labeled as 'Intensity'.
Signup and view all the answers
What is the recommended distance for electrodes from the same circuit for comfort?
What is the recommended distance for electrodes from the same circuit for comfort?
Signup and view all the answers
In IFC, __________ refers to the modulation of frequency to prevent accommodation.
In IFC, __________ refers to the modulation of frequency to prevent accommodation.
Signup and view all the answers
Match the TENS types with their characteristics:
Match the TENS types with their characteristics:
Signup and view all the answers
What happens if electrodes are placed from the same channel farther apart?
What happens if electrodes are placed from the same channel farther apart?
Signup and view all the answers
The rise time refers to how long it takes for the current to decline to zero.
The rise time refers to how long it takes for the current to decline to zero.
Signup and view all the answers
What is the typical frequency used for motor twitch stimulation?
What is the typical frequency used for motor twitch stimulation?
Signup and view all the answers
The ______________ is the amount of time it takes to deliver a pulse, measured in microseconds.
The ______________ is the amount of time it takes to deliver a pulse, measured in microseconds.
Signup and view all the answers
Match the electrical stimulation technique to its main usage:
Match the electrical stimulation technique to its main usage:
Signup and view all the answers
What is the purpose of modulation in electrical stimulation?
What is the purpose of modulation in electrical stimulation?
Signup and view all the answers
Gate Control Theory involves stimulating faster sensory nerve fibers to inhibit pain transmission.
Gate Control Theory involves stimulating faster sensory nerve fibers to inhibit pain transmission.
Signup and view all the answers
What is the duration range for Acupuncture-like TENS treatments to provide pain relief?
What is the duration range for Acupuncture-like TENS treatments to provide pain relief?
Signup and view all the answers
The ___________ is referred to as the On: Off time in muscle-stimulating units.
The ___________ is referred to as the On: Off time in muscle-stimulating units.
Signup and view all the answers
What is the primary function of a motor point?
What is the primary function of a motor point?
Signup and view all the answers
Ohm's Law states that current remains the same regardless of changes in resistance.
Ohm's Law states that current remains the same regardless of changes in resistance.
Signup and view all the answers
What does the strength-duration curve correlate with?
What does the strength-duration curve correlate with?
Signup and view all the answers
The ______ is the flow of electrically charged particles.
The ______ is the flow of electrically charged particles.
Signup and view all the answers
Match the following terms with their definitions:
Match the following terms with their definitions:
Signup and view all the answers
Which of the following currents is capable of delivering enough charge to reach the threshold of muscle membranes?
Which of the following currents is capable of delivering enough charge to reach the threshold of muscle membranes?
Signup and view all the answers
A bipolar arrangement of electrodes has unequal sizes.
A bipolar arrangement of electrodes has unequal sizes.
Signup and view all the answers
What is the primary disadvantage of constant current devices?
What is the primary disadvantage of constant current devices?
Signup and view all the answers
In electrotherapy, ______ refers to the ability of materials to oppose the flow of ions.
In electrotherapy, ______ refers to the ability of materials to oppose the flow of ions.
Signup and view all the answers
Match the following therapeutic applications with their currents:
Match the following therapeutic applications with their currents:
Signup and view all the answers
What happens when pulse duration increases while amplitude remains constant?
What happens when pulse duration increases while amplitude remains constant?
Signup and view all the answers
A monophasic waveform flows in two directions.
A monophasic waveform flows in two directions.
Signup and view all the answers
What type of current produces voltage that does not vary?
What type of current produces voltage that does not vary?
Signup and view all the answers
With E-Stim, the sequence of activation of nerves is sensory, ______, and pain.
With E-Stim, the sequence of activation of nerves is sensory, ______, and pain.
Signup and view all the answers
What does an electromotive force of 1 volt do?
What does an electromotive force of 1 volt do?
Signup and view all the answers
What is an advantage of using a unbalanced biphasic current for NMES?
What is an advantage of using a unbalanced biphasic current for NMES?
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.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
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.
