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
Q
Burst mode
A
- a current composed of a series of pulses in groups know as bursts
26
Q
anode
A
- the positive electrode
27
Q
cathode
A
- the negative electrode
28
Q
current density
A
the amount of current per unit area
29
Q
impedence
A
the opposition or resistance to the flow of charge
30
Q
Describing the current requires
A
- the waveform type
- the pulse frequency (rate)
- the pulse duration (width)
31
Q
Contraindications fo E-stim
A
- 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
Q
Precautions for E-stim
A
- cardiac disease
- impaired sensation
- impaired cognition
- malignant tumors
- skin irritation
- open wounds
33
Q
Adverse effects of E-stim
A
- burns
- skin irritation/inflammation
- some find it painful
34
Q
Coupling medium
A
- 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
Q
Application technique
A
- 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
Q
What happens when the electrodes are placed close together verse far apart
A
- closer = superficial
- further = deep
37
Q
With the same current which would give more current density
A
- smaller electrodes
38
Q
When do you use an unbalanced stim
A
- when charge matters
- iontophoresis
- wound care
