electrical currents

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electrical currents
2015-03-06 11:10:23
estim NMES tens ionto ifc
PA exam 2
PA exam 2
Show Answers:

  1. flow of charged particles; may be electrons or ions and is measured in amperes
    electrical current
  2. theory of pain control and modulation stating pain is modulated at the spinal cord level by inhibitory effects of nonnoxious afferent input
    gate control theory
  3. Electrically stimulating muscle contractions may be used for what:
    • muscle strengthening and re-ed
    • prevent atrophy
    • prevent DVT formation
    • prevent pressure ulcers in pt's with spinal cord injury
  4. electrical stimulation used for:
    • production of muscle contraction
    • control of acute, chronic and post-op pain
    • promotion of tissue healing
  5. clinical implications for E-stim (5)
    • muscle strengthening and re-ed
    • pn control
    • promote healing for recalcitrant (non-responsive) wounds
    • resolve edema post-op or injury
    • enhance transdermal drug delivery
  6. which E-stim is used for transdermal drug delivery
  7. basic unit of nerve depolarization
    action potential
  8. when a nerve is at rest and the inside is more negatively charged by 60 to 90mV
    resting membrane potential
  9. reversal of resting membrane potential in excitable cell membranes; inside of cell more positive than outside
  10. no addt'l APs can be generated
    absolute refectory period
  11. greater stimulus is needed during period of hyperpolarization
    relative refractory period
  12. the amount of electricity required to produce an AP depends on what?
    type of nerve and can be represented by the strength duration curve
  13. the strength-duration curve is a minimal combination of what two things
    amplitude and pulse duration
  14. short impulses and low current amplitudes used for pain relief are what type of stimulation
    sensory stimulation
  15. longer pulses and higher amplitudes for muscle re-ed and strengthening are what type of stimulation
    motor stimulation
  16. does further increasing the current amplitude or pulse duration make the AP larger or longer?
    hells NO
  17. nerve becomes less responsive to stimulus (happens slowly)
  18. movement of an AP along a nerve axon aka conduction
  19. rapid conduction of electrical signal along a myelinated nerve axon; jumps from one node of Ranvier to another
    saltatory conducation
  20. rate in which c fibers transmit
    .5 - 2 m/sec
  21. rate at which A delta and A alpha fibers transmit:
    • A delta = 12 - 30 m/sec
    • A alpha =  60 - 120 m/sec
  22. what are the three types of waveforms
    • direct current (DC)
    • alternating current (AC)
    • pulsed current (PC)
  23. continuous unidirectional flow of charged particles that is used for into and denervated muscle only and to facilitate wound healing
    DC = direct current
  24. continuous bidirectional flow of charged particles used for pain control and muscle contraction, spasticity, and denervated muscle
    • AC = alternation current
    • frequency increases; cycle duration decreases and vice versa
  25. interrupted flow of charged particles where the current flows in a series of pulses separated by periods of no current flows
    PC = pulsed current
  26. two types of PC
    • monophasic
    • biphasic
  27. charged particle moves in one direction; stops and repeates; commonly used for tissue healing and acute edema (HVPC)
    monophasic PC
  28. series of pulses where charged particle moves in one direction and then the opposite direction; can be done asymmetrical, symmetrical, balanced or unbalanced
    biphasic PC
  29. produced by interference of two medium frequency alternating biphasic waveforms; reaches deeper tissue with higher frequency and shorter pulse widths
    IC = interferential current
  30. number of cycles or pulses per second; measured in hertz; pulses per second (pps)
  31. magnitude of current or voltage; amt of energy exerted; measured in milliamps or amperes
  32. time of current amplitude to increase from zero at the end of the off time
    ramp up
  33. time for current amplitude to decrease from max amplitude to zero during on time
    ramp down
  34. time for current to reach its peak from zero dying one phase
    rise time
  35. time for current to decrease to zero
    decay time
  36. contraindications for Estim: POOP
    • pacemaker - cardiac demand pacemaker
    • over carotid sinus
    • over venous/aterial thrombosis or thrombophlebits
    • pregancy
  37. precautions for Estim: SIC IM
    • skin irritants/open wounds
    • impaired sensation/mentation
    • cardiac disease

    • ionto after other PA
    • malignant tumors
  38. Do AP travel faster in large diameter mylinated nerves or in small diameter unmyelinated nerves
    large diameter mylinated nerves
  39. how long does a pulse have to last to produce contractions in a denervated muscle
    longer than 10ms