Electrotherapy

• Electricity


  Described by its strength (charge), rate of flow (current), driving force (voltage), and opposition (resistance/impedance)

  
• Ohm's Law


  Relationship between current, voltage, and resistance

  
• Excitable tissues


  • Nerve, skeletal muscle, smooth muscle, and cardiac muscle in which there is the ability of neurons and neurotransmitters to conduct signals
• Impedance


  The body's opposition to current flow, resulting from the combination of resistive and capacitive reactance properties of tissue
• Capacitance


  The ability to store charge in an electric field and oppose change in current flow
• Nerve and muscle membranes

  • Examples of capacitors
• Current flow


  Occurs when there is a source of energy creating a difference in electrical potential and a conducting pathway between the two potentials

  
• Therapeutic electrical stimulation


  Charge transfer occurs between the electrical generator and the biological tissue at the electrode interface
• Ionic flow


  Positive ions (cations) are repelled from the positive electrode and migrate toward the negative electrode (cathode), whereas the negative ions (anions) migrate toward the positive electrode (anode)
• Therapeutic electrical stimulation units


  • Direct current (DC)
  • Alternating current (AC)
  • Pulsatile (pulsed) current
• Direct current (DC)


  Continuous unidirectional flow of charged particles with a duration of at least 1 second
• Direct current (DC) applications


  • Dennervated muscles
  • Iontophoresis
  • Wound Healing
• Interrupted (pulsed) direct current


  • Short (<10 ms) - Innervated muscles
  • Long (>10 ms) - Dennervated muscle
• Alternating current (AC)


  Uninterrupted bidirectional flow of charged particles changing direction at least once a second. AC can also be delivered in an interrupted form, sometimes referred to as bursts.
• Pulsatile current


  Unidirectional (like DC) or bidirectional (like AC) flow of charged particles periodically ceasing for less than 1 second (milliseconds or microseconds) before the next electrical event. It is composed of individual pulses of short duration delivered in a continuous series called a pulse train
• Waveform


  Visual representation of the pulse or event, depicting the shape, amplitude (strength), and duration

  
• Waveform types


  • Monophasic - entire event takes place either above or below isoelectric zero
  • Biphasic - two phases with one above and one below isoelectric zero
  • Polyphasic - multiple phases occurring above and below isoelectric zero

  
• Criteria for depolarization


  • The stimulus must be strong enough
  • The stimulus must be fast enough
  • The stimulus must be long enough
• Peak amplitude


  Maximum current or voltage delivered in one phase of a pulse, determining strength of stimulation

  
• Rise time


  Time it takes for the amplitude of the pulse to increase from zero to peak amplitude, affecting ability to excite nervous tissue
• Decay time


  Time it takes for the peak amplitude to decrease back down to zero, defining the terminal end of the phase
• Intrapulse interval


  Time-period between the end of one phase and the beginning of the second phase of one pulse

  
• Phase duration


  Time period extending from the beginning to the end of one phase of a pulse
• Pulse duration


  Time interval between the beginning and end of all the phases of the pulse, including the intrapulse interval

  
• Phase charge


  Amount of electrical energy delivered to the tissue with each phase of each pulse, measured in micro coulombs per second (µC/sec)
• Frequency


  The body responds to the number of pulses, not the number of phases

  
• Twitch response


  At least one motor unit is responding to the stimulus, producing a non-functional muscle contraction
• Tetanic muscle contraction


  More motor units contract together in a meaningful way
• Duty cycle


  Represents the on-and-off time and the ratio between them when there is more than one channel on the electrical stimulation unit
• Ramp time


  Increase in amplitude to peak of the pulse train, how long it takes for the current to go from zero to peak amplitude and back down to zero
• Total current (average current)


  Amount of current delivered to the tissue per second, measured in milliamperes (mAmps or mA)
• Accommodation


  The ability of muscle cells to accommodate
• INDICATIONS FOR ES

  • Muscle spasm
  • Impaired ROM
  • Muscle re-education
  • Disuse Atrophy
  • Soft tissue repair
  • Edema reduction
  • Spasticity
  • Denervated muscles
• INDICATIONS FOR FES

  • disuse atrophy
  • impaired ROM
  • muscle spasm
  • muscle reeducation
  • spasticity management
  • FES on Agonist
  • FES on Antagonist
• INDICATION FOR TENS

  • Post op pain
  • During labor and delivery
  • Bone Fx
  • Chronic pain
  • Trigeminal neuralgia
  • Phantom pain
  • Antiemetic effects
  • Improved blood flow
• PRECAUTIONS

  • Unstable fracture
  • Decreased sensation
  • Impaired cognitive ability
  • Pregnancy
  • Heart problems
  • Documented evidence of epilepsy, cerebral vascular accident, or reversible ischemic neurological deficit
  • Recent surgical procedure
  • Pacemaker
• CONTRAINDICATION


  • Pregnancy
  • Over the carotid sinus
  • Malignancies
• Peak amplitude is measured in?

  current (milliamperes or microamperes) or voltage (volts) depending on the electrical stim
• Only parameters for DC is:


  Amplitude and total treatment time