E-stim: foundations Flashcards
1
Q
What is e-stim
A
- the electrical current as a flow of electrons
2
Q
What is e-stim used for
A
- used with other interventions
- Used to manage acute, chronic, and postoperative pain
- produce muscle contractions
- promote tissue healing
- enhance transdermal drug delivery
3
Q
Why would you use E-stim to produce muscle contractions
A
- strength and re-education
- prevent atrophy/reduce edema
- prevent DVT formation
- reduce muscle spasms
4
Q
Effects of electrical currents
Are the result of what
A
- the clinical effects of e-stim are the result of current stimulating the production of Action potentials in sensory and/or motor nerves
5
Q
What does the speed of transmission depend on within the NS
A
- diameter of nerve
- myelinated/non-myelinated
- larger diameter - fast transmission
- myleination = faster
- physiologically the AP travels in one direction but E=stim can cause AP in both directions from the site of stimulation
6
Q
Primary Afferent neurons that are associated with pain
A
- A-beta fibers: large myelinated axons (fast, discriminative touch)
- A-delta fibers: smaller than A-beta fibers, myelinated (ALST - pain)
- C-fibers: small, unmyelinated nerve fibers (ALST - pain)
all 3 work together – 1st you feel where then you fell pain
7
Q
Primary Efferent neurons
A
- large and myleinateted (fast)
- slow-twitch type 1 fibers usually smaller than fast-twist type 2
8
Q
Strength -duration curve
A
- Abeta sensory stimulated 1st
- motor neurons
- A delta - sharp pain
- C dull pain
- Denervated muscle
9
Q
Electrical current parameters/wavefroms
A
- graphic representation of wave
- generally 3 types
1. direct current (monophasic)
2. Alternating current (biphasic)
3. Pulsed current (can be mono or biphasic)
10
Q
Direct current
A
- a continuous unidirectional flow of charge electrons for at least 1 second
- commonly used for iontophoresis and stimulating contraction in denervated muscle
- Direct DC and interrupted DC are most commonly used forms
- used when the charge matters to attract or repel specific cells
11
Q
Alternating current
A
- a continous bi-directional flow of charged particles used for pain control and muscle contraction
- BUT it needs to be modulated to be effected
- modulated so that brain does not get use to it
12
Q
Biphasic pulsed current– other variables
Typesof biphasic pulsed current
A
- symmetrical: same shape, same energy within each phase
- balanced asymmetrical: different shape but that same amount of energy within each phase
- unbalanced asymmetrical: different shapes and different amount of energy within each phase; this current will have a residual net charge
13
Q
E-stim parameters
A
- pulse duration (width)
- phase duration
- interpulse interval
14
Q
pulse duration
A
- the time from the beginning of the first pulse to the end of the pulse
- measured in microseconds, miliseconds
- AKA width
15
Q
Phase duration
A
- the period when current is flowing in one direction
- if the pulsed current is symmetrical then the phase duration is 1/2 the pulse duration
- important parameter for comfort and crucial to achieve a muscle contraction
16
Q
Interpulse interval
A
- the amount of time between pulses
17
Q
Amplitude
A
- AKA intensity, strength, voltage
- units can be milliamps, microamps, volts
18
Q
Frequency
A
- numbers of cycles or pulses per second
- often referred to as the rate
- the length of the interpose interval decreases as frequency increases
19
Q
On/off time
A
- a period of cycling and a period of rest
- used commonly for muscle contraction so a muscle is not contracting for 10 minutes straight
20
Q
ramp up/ramp down
A
- the pulse comes on suddenly and goes up instead of all at once
21
Q
Adaptation
A
- a decrease in the frequency of AP’s and a decrease in the subjective sensation of stimulation in response to e-stim with unchanging parameters
- “I don’t feel it anymore”
22
Q
accommodation
A
- an increase in the threshold to nerve excitation
- need to turn it higher to get intended response
23
Q
current
A
- the directed flow of free electrons from one place to another
24
Q
modulation
A
- any parameter or variation in one or more of the stimulation parameters
- used to limit neural adaptation
25
Burst mode
- a current composed of a series of pulses in groups know as bursts
26
anode
- the positive electrode
27
cathode
- the negative electrode
28
current density
the amount of current per unit area
29
impedence
the opposition or resistance to the flow of charge
30
Describing the current requires
1. the waveform type
2. the pulse frequency (rate)
3. the pulse duration (width)
31
Contraindications fo E-stim
- demand pacemakers/implantable cardiac defibrillators
- unstable arrhythmias
- Over carotids
- venous or arterial thrombosis or thrombophlebitis
- pelvis, abdomen, trunk and low back during pregnancy
- over metal implants
32
Precautions for E-stim
- cardiac disease
- impaired sensation
- impaired cognition
- malignant tumors
- skin irritation
- open wounds
33
Adverse effects of E-stim
- burns
- skin irritation/inflammation
- some find it painful
34
Coupling medium
- required to reduce impedance and enhance conductivity between the electrode and skin
- conductive gel, cream or liquid
- sponges or gauze pads soaked in tap water
- self-adhesive conductive polymer
35
Application technique
- assess sensation to light touch
- position patient properly
- protect modesty and comfort
- clean the skin with soap and water (creams, analgesic gels etc can impede stimulation.)
- choose the correct electrodes consider type, size and shape
- electrodes should lie smoothly against the skin without wrinkles
- do not place the electrodes over bony landmarks
- space electrodes appropriately
36
What happens when the electrodes are placed close together verse far apart
- closer = superficial
- further = deep
37
With the same current which would give more current density
- smaller electrodes
38
When do you use an unbalanced stim
- when charge matters
- iontophoresis
- wound care
