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Electrical Agents: Electrical Stimulation Techniques

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Once in the body it may take many different paths. Current prefers the path of least resistance ... is needed to reduce resistance between the skin and the ... – PowerPoint PPT presentation

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Title: Electrical Agents: Electrical Stimulation Techniques


1
Electrical AgentsElectrical Stimulation
Techniques
  • Body Circuit
  • As the of water in tissue increases, its
    ability to transmit electricity increases
  • Tissues are either excitable (directly influenced
    by stimulation) or nonexcitable

2
Electrical AgentsCharacteristics of Electrical
Generators
  • Excitable Tissue
  • Nerve Fibers
  • Muscle Fibers
  • Blood Cells
  • Cell Membranes
  • Nonexcitable Tissue
  • Bone
  • Cartilage
  • Tendons
  • Ligaments
  • Poor Conductor
  • Skin
  • Bone
  • Tendons
  • Fascia
  • Adipose
  • Good Conductor
  • Muscle
  • Nerve
  • Blood

3
Electrical AgentsCharacteristics of Electrical
Generators
  • The current enters the body through a series
    circuit since the skin is relatively consistent
  • Once in the body it may take many different paths
  • Current prefers the path of least resistance

4
Electrical AgentsElectrodes
  • Placement of electrodes is important for athlete
    comfort and efficiency
  • Electrodes can be of different materials
  • In most cases a medium is needed to reduce
    resistance between the skin and the electrode
  • Wet sponges
  • Conducting gels

5
Electrical AgentsElectrodes
  • Size of electrode inversely affects the density
    of the current
  • Electrode size ? current density ?
  • This affects comfort and effect of the current
  • Larger electrodes produce greater contractions,
    but, not as specific

6
Electrical AgentsElectrodes
  • Motor points, trigger points, acupuncture points
  • Closer placement of electrodes vs. electrodes
    placed farther apart
  • Closer superficial
  • Farther deeper
  • Direction of fibers is also important

7
Electrical AgentsElectrodes
  • Bipolar Technique
  • 2 leads, with equal size electrodes
  • Monopolar Technique
  • 1 or 2 active electrodes and a dispersive
    electrode
  • Dispersive pad must be much larger than active
    electrodes

8
Electrical AgentsElectrodes
  • Quadripolar Technique
  • 2 sets of electrodes each from there own channels
  • Current may intersect with each other

9
Electrical AgentsMovement of Electrical Current
  • Most forms of electrical stimulation are applied
    transcutaneously
  • When passed through the skin it has the potential
    to upset the resting potential of the axons
  • Under the cathode depolarization occurs
  • Under the anode hyperpolarization occurs

10
Electrical AgentsSelected Stimulation of Nerves
  • Nerves response is based on 3 factors
  • Relative diameter of the nerve
  • larger stimulated first
  • Depth of nerve in relation to electrode
  • sensory are closer to surface than pain/motor
  • Duration of the pulse
  • shorter durations require more current to
    stimulate a nerve type

11
Electrical AgentsSelected Stimulation of Nerves
  • Sensory nerves are stimulated first, then motor,
    then pain.
  • Pain fibers are located in between sensory and
    motor fibers, but, are smaller in diameter

12
Electrical AgentsSelected Stimulation of Nerves
  • Subsensory-level
  • From zero intensity to point athlete first feels
    the current
  • Sensory-level
  • To point of slight muscle contraction
  • Motor-level
  • Visable contraction without pain
  • Noxious-level
  • Intensity that stimulates pain fibers

13
Electrical AgentsAccommodation and Habituation
  • Accommodation
  • Over time it will take more intensity to cause
    depolarization of the nerve
  • Habituation
  • CNS filters out a continuous, non-meaningful
    stimulus
  • This can be seen when an athlete gets use to the
    current

14
Electrical AgentsMovement of Electrical Current
  • Medical Galvanism
  • Application of low voltage DC, with a known
    polarity under each electrode
  • Certain cellular and biochemical responses occur
    due to each polarity
  • Galvanic stimulation is the only form of current
    that can elicits a muscle contraction from
    denervated muscle, but the phase duration is so
    long it also activates the C fibers

15
Electrical AgentsMovement of Electrical Current
  • Medical Galvanism (Cont.)
  • Physiological effects are generally opposite
    under the cathode or anode
  • Symmetrical or balanced currents can not have any
    galvanic effects
  • Unbalanced asymmetrical current can result in
    residual chemical changes is current is high
    enough

16
Electrical AgentsElectrical Stimulation Goals
and Techniques
  • Muscular Contractions
  • Virtually any electric modality can achieve a
    contraction at a high enough intensity
  • Contractions used to
  • Retard effects of atrophy
  • Reeducate muscle
  • Reduce edema
  • Electrodes should be placed over motor points

17
Electrical AgentsMuscle Contractions
  • Muscular Contractions (cont.)
  • Large nerve closer to electrode are recruited
    first
  • If nerve is denervated, then DC or monophasic
    with a long pulse duration can be used to
    depolarize the motor unit

18
Electrical AgentsMuscle Contractions
  • Pulse Amplitude
  • As intensity increases so does the strength of
    the contraction
  • Depth of penetration increases as the peak
    current increases, thus recruiting more nerve
    fibers
  • Pain inhibits maximal contraction of fibers

19
Electrical AgentsMuscle Contractions
  • Pulse Frequency
  • Pulse rate of less than 15 pps twitch
    contraction
  • Pulse rate between 15 and 40 pps summation of
    stimuli
  • This will increase to the point of tetany
  • Further increase in frequency will promote
    fatigue of the muscle

20
Electrical AgentsMuscle Contractions
  • Pulse Frequency (cont.)
  • Strong tetanic contraction is needed to delay
    atrophy
  • Low pps decreases fatigue, but, produces less
    force
  • High pps are more comfortable

21
Electrical AgentsMuscle Contractions
  • Phase Duration
  • To recruit motor units a moderate phase duration
    should be used
  • 300 to 500 microseconds
  • Strength Augmentation
  • Voluntary contractions are better than
    electrically induced contractions

22
Electrical AgentsPain Control
  • Reduce pain by assisting in the healing process
    or affecting pain transmission
  • High pulse frequency, short duration, sensory
    level currents are thought to activate the gate
    control theory
  • Low pulse frequency, long duration, high
    intensity and noxious stimuli are thought to
    stimulate release of opiates

23
Electrical AgentsPain Control
  • During initial phases of pain control,
    electricity stimulates the dorsal horn of the
    spinal cord
  • The placebo effect of electrotherapy can not be
    overlooked

24
Electrical AgentsCirculation
  • Electrically induced contractions increase local
    blood flow the same as voluntary contractions
  • Sensory level stimulation has not been found to
    effect blood flow

25
Electrical AgentsWound Healing
  • Use of lower intensity DC may reduce the time
    needed for superficial wound healing by 1.5 to
    2.5 times
  • Depending on the polarity, certain inflammatory
    mediators can be attracted or repelled from the
    area

26
Electrical AgentsWound Healing
  • What occurs in the body
  • Increased circulation
  • Increased blood clot formation
  • Antibacterial effects
  • Influences on migration of cells
  • Presence of an injury potential (theorized to
    electrically control tissue repair)

27
Electrical AgentsControl and Reduction of Edema
  • Sensory-level stimulation
  • Attempts to stop formation of edema by preventing
    the fluids, plasma proteins, and other solids
    from escaping into surrounding tissues
  • Motor-level stimulation
  • attempts to assist the venous and lymphatic
    system in returning the edema substances back to
    the torso

28
Electrical AgentsSensory-Level Stimulation for
Edema Control
  • Used in acute trauma to attempt to decrease edema
    formation
  • Intensity is kept below motor threshold
  • Why does it work?
  • Reduction in capillary pressure and capillary
    permeability
  • Produces a vascular spasm and prevents fluid from
    leaking out of the vessels

29
Electrical AgentsMotor-Level Stimulation for
Edema Control
  • Works by squeezing the vessels and milking the
    fluids out of the area
  • Referred to as muscle milking or muscle pump
  • Use 1 pps or tonic contraction with a 50 duty
    cycle
  • Not as good as voluntary contractions
  • If used limb should be elevated

30
Electrical AgentsFracture Healing
  • Electricity has traditionally been used to heal
    nonunion fractures
  • Current research is also looking into acute
    fractures
  • Theory
  • Bone cannot differentiate between the bodys
    innate charges need for normal bone growth and
    those from outside sources

31
Electrical AgentsFracture Healing
  • Devices are known as bone growth generators
  • Generally use AC for transcutaneous use and DC
    for implanted electrodes
  • Usefulness is debatable
  • Decrease in bone growth
  • Time out due to surgical implant removal
  • M.D. is the person who prescribes the unit

32
Electrical Agents
  • General Contraindications
  • Cardiac disability (Stimulation of thorax or neck
    may effect respiration or heart)
  • Pacemakers
  • Pregnancy
  • Menstration

33
Electrical Agents
  • General Contraindications (cont.)
  • Cancerous lesions
  • Sites of infections
  • Exposed metal implants
  • Severe obesity
  • Epilepsy
  • Electronic Monitoring Equipment

34
Electrical Agents
  • Therapeutic Uses for Electricity
  • Controlling acute and chronic pain
  • Reducing edema
  • Reducing muscle spasm
  • Reducing joint contractures
  • Inhibiting muscle spasm
  • Minimizing disuse atrophy
  • Facilitating tissue healing

35
Electrical Agents
  • Therapeutic Uses (cont.)
  • Facilitating muscle re-education
  • Facilitating fracture healing
  • Strengthening muscle
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