Electrotherapy

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Electrotherapy
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Current Attributes The Effects of Changes in
Current Parameters

• Tissue Impedance
• Resistance of tissue to electrical current
• Average Current
• Describes absolute value of current per unit of
  time
• Meaningful only during monophasic and unbalanced
  biphasic currents

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Changing Current Parameters and their Effects on
Treatment Protocols

• Current Density
• Amount of flow per unit volume
• Highest where electrodes touch skin
• Electrode spacing
• Inversely proportional to electrode size

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Changing Current Parameters and their Effects on
Treatment Protocols

• Frequency
• Amount of muscle fiber shortening and recovery is
  function of frequency
• Twitch
• Summation of contractions
• Tetanization
• Frequencies commonly used in electrotherapy

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Changing Current Parameters and their Effects on
Treatment Protocols

• Intensity
• Increasing intensity cause current to reach
  deeper tissues
• Clinical application

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Changing Current Parameters and their Effects on
Treatment Protocols

• Pulse Duration
• Can stimulate more nerves with same intensity by
  increasing pulse duration

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Changing Current Parameters and their Effects on
Treatment Protocols

• Polarity
• DC Generator Polar Effect Characteristics
• Chemical
• Ease of Excitability
• Direction of Current Flow

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Changing Current Parameters and their Effects on
Treatment Protocols

• Duty Cycle
• Ratio of amount of time on to amount of time
  without current
• Expressed as a percentage

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Changing Current Parameters and their Effects on
Treatment Protocols

• Electrodes
• Size
• Placement
• Bipolar
• Monopolar
• quadripolar
• Active vs Dispersive Electrode

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Physiological Response to Electrical Currents

• Response depends on
• Type of tissue
• Response characteristics
• Nature of the current applied

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Effect of Electrical Current on Excitable Tissue

• Excitable Tissues Include
• Sensitive permeability
• Polarized cell membrane
• Resting potential
• Action potential
• Depolarization
• Absolute Refractory period
• Repolarization

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Strength-Duration Curve

• Nonlinear relationship between current duration
  and current intensity
• Shorter duration need higher intensities
• Nerve and muscle differ greatly in firing
  threshold

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Muscular Responses to Electrical Current

• All-or-none Principle
• Either stimulus causes depolarization or it does
  not
• Changing intensity of contraction influenced by
  changing parameters
• Frequency
• Intensity
• Pulse duration

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Effects of Electrical Stimulation on
Non-excitable Tissue and Cells

• Tissue Types
• Cellular Electrical Circuits
• Cell Membrane
• Intercellular Structures
• Gap Junctions
• Electropiezo Activity in Cells

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Stimulation Hierarchy of Nerves

• Occurs in an orderly manner
• Three factors dictate
• Sequence of Stimulation
• Strength-Duration Curve
• Stimulation Levels
• Accommodation
• Habituation