Electrical Agents Flashcards
1
Q
General Uses of E-Stim
A
- Most forms of e-stim can be manipulated to cause the following:
~ Sensory sensation/tingle
~ Muscle contraction
~ Pain
2
Q
Principles of Electricity: Electrical Current
A
- Electrical Current
~ Flow of electrons is an attempt to
equalize the charges between points
> Electrons are very small particles
of matter possessing a negative
charge
~ Flows from the negative pole to the
positive pole on a path of least
resistance
> Electrons are transferred from
atom to atom
3
Q
Negative Pole vs Positive Pole
A
- Negative Pole
~ Area of high electron concentration
and high electrical potential - Positive Pole
~ Area of low electron concentration
and low electrical potential
> Attracts other electrons - Current always flows from negative to positive
4
Q
Principles of Electricity: Resistance or Impedance
A
- Degree of opposition to the flow of electrical current
- All materials have some resistance
- The higher the resistance, the lower the flow
~ Conductor is material that allows for
relatively free flow of electrons
(metals, electrolyte solutions)
> Electrolytes are minerals that
dissolve in solution as electrically
charged particles (Na, K, Cl, Mg)
~ Resistor is material that oppose the
flow of electrons (air, wood)
5
Q
Principles of Electricity: Electrical Circuits
A
- Path of a current from a power source through one or more components back to the generating source
- Series Circuit
~ Only one path for the flow of
electrons; current is constant - Parallel Circuit
~ Electron flow is given alternative
pathway for travel
> Electrons will travel on the paths
of least resistance
> The current fluctuates depending
on the resistance of the paths:
less resistance = current will
always chose it
6
Q
Principles of Electricity: Current Flow Through the Body
A
- Best conductors within the body are the tissues containing high amounts of water due to high electrolyte contact
~ More water = less resistance = more
current - Electrical current enters deeper tissues as a parallel circuit due to the differences in water content between the tissue types
- Nerves are the tissues we want to reach the most
7
Q
Principles of Electricity: Good Vs. Poor Conductors
A
- Good Conductors: 70-75% Water Content
~ Muscle
~ Nerve
~ Blood - Poor Conductors: 20-30% Water Content
~ Bone
~ Tendons
~ Fascia
~ Adipose
~ Skin
8
Q
Current Types: Direct
A
- Continuous flow of electrons in one direction (negative to positive)
- Pattern Flow
~ Square wave with continuous current
flow on only one side of the baseline - Return to baseline when current is interrupted
- Not used very often
- Only current that can directly tell muscle to depolarize = bad
9
Q
Current Types: Alternating
A
- Direction and magnitude of the flow reverses
- No true positive or negative pole, electrodes take turns being the negative and positive poles
~ Vibrating back and forth - Frequency
~ Number of times the current reverses
direction in 1 sec
10
Q
Pulsed Currents
A
- Direct or Alternating currents are interrupted by periods of non-current flow
- Phase
~ Individual section of a pulse that rises
above or below the baseline - Pulse
~ An individual waveform
> Monophasic: one phase to each
pulse
• Unidirectional; Direct
> Biphasic: two phases per pulse
• One phase above and one
phase below the baseline;
Alternating - Pulse Duration/Pulse Width
~ Time from the beginning of the
phase to the conclusion of the final
phase - Pulse Frequency
~ Number of pulses per second - Interpulse Interval
~ Time between the conclusion of one
pulse and the start of the next
~ Allows for repolarization of nerve
membranes and mechanical events
(muscle relaxation)
11
Q
Physiological Effects of Electrical Current
A
- Excitatory Effects (what we want)
~ Alter Membrane Charges
> Neve
> Muscle
> Cell - Nonexciatory Effects
~ Temperature rises in a conducting
tissue
> Higher resistance gives increased
heat
~ Chemical
12
Q
Electrical Nerve Stimulation: Intensity and Phase Duration
A
- The greater the intensity the greater the ability to stimulate nervous tissue
- The greater the phase duration the greater the ability to stimulate nervous tissue
- Overall current strength is a producer of both intensity and phase duration
~ If one is decreased the other must
increase for the same effect
13
Q
Order of Stimulation
A
- Related to depth and size of nerve
~ Sensory Nerves (most superficial)
~ Motor Nerves
> Deeper than pain receptors but
are larger in diameter and
therefore stimulated first
~ Pain Receptors
> Smaller in diameter and less
myelinated
14
Q
Chemical Effects of Electrical Current
A
- Only possible with Direct Current
- Current causes migration of the charged ions within tissues towards the pole opposite of polarity
~ Negative ions to positive and negative
to the negative
15
Q
Chemical Effects of Electrical Current: Concentration
A
- Concentration of negative ions produces a more ACIDIC environment in which there’s coagulation of protein and hardening of tissues
- Concentration of positive ions produces a more ALKALINE environment causing liquefying of proteins and softening of tissues
16
Q
Accommodation and How to Combat it
A
- Accommodation is specific nerves stimulated by a constant stimulus that become less excitable or unexcitable
~ Pt. doesn’t feel anything anymore
because the nerves started to become
used to it and ignore it - Combating it
~ Intensity Changes
~ Pulse Width Changes
~ Frequency Changes
~ Burst: period of non current flow
interrupting a number of pulses
17
Q
General Uses of Electrical Stimulation
A
- Most forms of electrical stimulation can
be manipulated to cause the following:
~ Muscle Contraction
~ Sensory Sensation
~ Pain
18
Q
General Uses of Electrical Stimulation: Muscle Contraction
A
- Causes contraction by stimulating motor nerves except for denervated muscle where only DC can be used to cause direct muscle fiber depolarization
~ Muscle strengthening /
neuromuscular re-education
~ Edema removal
19
Q
General Uses of Electrical Stimulation: Sensory Stimulation
A
- Ascending pain modulation
- Edema prevention
20
Q
General Uses of Electrical Stimulation: Pain Stimulation
A
- Descending pain modulation
21
Q
Venous and Lymphatic Return Mechanisms
A
- Skeletal Muscle Contraction
~ Veins and lymph vessels have one-
way valves
> Permit flow toward the heart
and prevents back-flow
~ Vessel compression increases the
pressure which closes upstream
valves and opens downstream valves
~ Contraction forces blood and lymph
forward in the vessels - If the concentration gradient is altered, fluid will flow from tissues to vessels which is good
22
Q
Electrode Placement for Motor Level Stimulation
A
- Electrodes/Electrical Current should be placed over or through the muscle’s motor point.
~ Location where motor nerves and
blood vessels enter muscle
~ Usually located in the middle or belly
of the muscle - Current needs to cross motor point in order to contract muscle
23
Q
Motor Level Stimulation: Intensity
A
- Strength of contraction increases as amount of current increases
~ Strength of contraction is limited by
the tolerance of pt. for the current
> Maximum tolerated is usually
around 30% of maximum
contraction - Depth of penetration increases as the amount of current increases
~ Increases the number of motor nerve
fibers stimulated
24
Q
Motor Level Stimulation: Pulse/Phase Width
A
- Narrow pulse/phase widths require more intensity for muscle contraction
- Wide pulse/phase widths require less intensity for muscle contraction
~ Produce strong contraction quicker,
but run into the pain threshold
quicker - The wider the pulse width, the better
