Quiz 1 Prep Flashcards
1
Q
What are the contraindications to all forms of electrical stimulation?
A
-Areas where it could cause malfunction of electronic devices such as cardiac pacemakers
-Low back or abdomen of pregnant women
-Acupuncture points of pregnant women
-Regions of known or suspected malignancy
-Active DVT or thrombophlebitis
-Actively bleeding tissue or people with untreated bleeding disorders
-Infection, TB, or wounds with osteomyelitis
-Recently radiated tissues
-Chest/anterior thoracic wall in people with cardiac disease, arrhythmias, or heart failure
-Neck or head region for people with epislepsy
-Transcranially without specialized training
-Near or over eyes
-Anterior neck or carotid sinus
-Damaged or at risk skin areas that could result in uneven conduction of current
2
Q
What are the contraindications specifically for TENS?
A
-Areas with impaired sensory awareness
-People with cognitive or communication impairments
3
Q
What are the contraindications specifically for NMES?
A
-Pregnant women
-Areas with impaired circulation
-Any area unstable due to recent surgery, bone fracture, or osteoporosis
-The chest or intercostal muscles
-The lower abdomen
4
Q
What are the precautions for all forms of electrical stimulation?
A
-Active epiphysis
-Persons with skin diseases
5
Q
What are the precautions for HVPC?
A
-Person with cognition or communication problems
-Areas of impaired sensation
-Areas with impaired circulation
-Superficial regenerating nerves
-Chest wall or lower abdomen
6
Q
What are the precautions for NMES?
A
-Persons with cognition or communication impairments
-Areas of impaired sensation
7
Q
What are precautions for TENS?
A
-Areas with impaired circulation
-Anterior chest wall or lower abdomen
8
Q
What is Coulombs Law?
A
-Forces are exchanged from particle to particle by electrical fields that each particle has when the particles are approximated
-Force created by two particles is proportional to the strength and sign and inversely proportional to the distance
9
Q
What is the electrical potential difference?
A
-The stored power or the potential energy that is converted to kinetic energy when particles are approximated
-The portion of energy between any two points on a circuit
-Measured in Volts
10
Q
What is the electromotive force (EMF)?
A
-Electrical potential difference supplied by an energy source
-Autonomous with the internal resistance of the circuit
-Transfers energy through the circuit
-Measured in volts
11
Q
What is current?
A
The movement of charged particles through a conductor because of or in response to an applied electrical field of voltage
12
Q
What is required to have current?
A
-A driving force to move the particles
-A conductive pathway
-A difference in electrical potential
13
Q
What is Ohm’s Law?
A
-The amount of current induced in a conductor is directly proportional to the applied driving force (Voltage) and inversely proportional to the resistance
-Current (I)= Voltage (V)/Resistance (R)
14
Q
What is the difference between constant voltage and constant current?
A
-Constant current stimulators adjust voltage in response to impedance therefore voltage to the patient will vary in response to changes in impedance
-Constant voltage stimulators do not adjust voltage in response to impedance
15
Q
What is a conductor?
A
-A material that allows electrons to flow freely through it
-Outer ring of electrons is not full and can accept more electrons
16
Q
What is an insulator?
A
-A material that does not allow electrons to flow freely through it
-Outer ring of electrons is full
17
Q
What is resistance?
A
-The opposition to direct current flow through a conductor
-The opposition charged particles find as they move through a circuit
18
Q
What is the resistance for an in series circuit?
A
Resistance= R1+ R2+ R3
19
Q
What is the resistance for an in parallel circuit?
A
Resistance= 1/R1+ 1/R2+ 1/R3
20
Q
What is capacitance?
A
-The ability of the conductor or insulator to store an electrical charge before an action potential occurs
21
Q
What is a time constant?
A
-The product of the membranes resistance and capacitance
-The time constant determines the minimum duration that a stimulus must exist before the cell’s threshold for depolarization is reached
-The cells resistance for current flow must be overcome with a stimulus of adequate intensity
22
Q
How long does it take the voltage to reach 84% of the time constant in a muscle fiber?
A
-Typically it takes 3-5 ms to reach 84% of the time constant of mammalian muscle fibers
23
Q
What is impedance?
A
-Described the opposition to alternating current
-It is the sum of resistive, capacitive, and inductive components of the tissue which impair current flow
-Impedance is particularly effected by the frequency of the applied electrical current and is inversely proportional to the applied frequency
24
Q
What are the physiological factors that can effect current flow?
A
-Resting membrane potentials
-Action potentials
-Threshold
-Refractory periods
25
What is the resting membrane potential of a peripheral nerve?
- -70 mV
-This is due to a net negative charge on the inside of the cell compared to the outside
-More Na+ outside the cell and more K+ inside the cell
26
What is the depolarizing threshold potential for peripheral nerves?
- -55 mV
27
What is accomodation?
If a membrane remains depolarized or a membrane has been depolarized for an extended period of time an action potential will not be evoked even if you reach its threshold
28
What does threshold level depend on in regards to therapeutic electrical current?
-Amplitude
-Duration
29
How does duration relate to capacitance and resistance?
The amount of time it takes an applied current to change the cell's voltage is directly related to capacitance and resistance
30
What is absolute refractory period?
A membrane needs approximately 1-2 msec to recover its excitability after an action potential is released
31
What is relative refractory period?
During this period of time a higher stimulus may be needed for the membrane to fire and is approximately 0.5- 1 msec
32
What is chronaxie?
-The pulse duration required for excitation when the current amplitude is 2x the Rheobase intensity
-Measured in msec or µsec
33
What is Rheobase?
-The minimum stimulus intensity to initiate a response in the class of fibers at an infinite time interval
-Measured by the amplitude
34
What is chronaxie for β nerve fibers (touch)?
100 µsec
35
What is chronaxie for motor neurons?
200 µsec
36
What is chronaxie for delta fibers (pain and temp)?
300 µsec
37
What is chronaxie for C fibers (pain, temp, itching)?
1.0 msec
38
What is 2x Rheobase for β nerve fibers (touch)?
40 mA
39
What is 2x Rheobase for motor neurons?
60 mA
40
What is 2x Rheobase for delta fibers (pain and temp)?
80 mA
41
What is 2x Rheobase for C fibers (pain, temp, itching)?
120 mA
42
What are different types of waveforms?
-Balance or unbalanced
-Symmetry/asymmetric
-Shape (triangle, sawtooth, sinusoidal)
-Alternating or pulsatile (mono or biphasic)
43
What is a phase?
Current flow in one direction for a definite period of time
44
What is phase duration?
The time from the beginning to end of one phase of a pulse or cycle
45
What is pulse duration?
Total time from the beginning to end of one pulse and includes the phase duration of all phases plus the interphase interval
46
What is interphase interval?
The period of no electrical activity between two phases of a pulse
47
What is interpulse interval?
The period of no electrical activity between two successive pulses
48
What are examples of biophysical agents?
-Athermal agents: pulsed electromagnetic fields
-Biofeedback
-Compression therapies
-Cryotherapy
-E-stim
-Hydrotherapy
-Hyperbaric oxygen therapy
-Light agents: laser, infrared, etc.
-Mechanical devices: traction, tilt table
-Sound agents: ultrasound, phonophoresis
-Thermotherapy
49
What are policy and legal obligations with biophysical agents?
-Equipment check
-Calibration
-Documentation
-Repair
50
What is leakage current?
-A small amount of electricity that flows outside of a circuit
-Can increase if the system is not working properly
-Has a rest button and test button
51
What are the components of a ground fault circuit interrupter?
-White/narrow slot: neutral
-Black wide slot: hot
-Green/circle: ground
52
What should be done for skin prep?
-Assess skin: type, condition, emulsifiers, alcohol, medications
53
What are options for electrode replacement in reference to the location of pain for TENS?
-Monopolar vs bipolar
-Over the site
-Through the site (bracket)
-Around site
-Dermatomes
-Myotomes
-Peripheral nerve
-Acupuncture or motor points
54
What is a dispersive electrode?
The non-treating electrode, but it still has current passing through it
55
What are examples of electromagnetic energy modalities?
-Shortwave diathermy
-Microwave diathermy
-Infrared lamps
-UV light
-Laser therapy
56
What are examples of electrical energy modalities?
-E-stim
-Biofeedback
-Iontophoresis
57
What are examples of sound energy modalities?
-Ultrasound
-Extracorporeal shock wave therapy
58
What are factors that impede tissue healing?
-Extent of injury
-Edema
-Hemorrhage
-Poor vascular supply
-Separation of tissue
-Muscle spasm
-Atrophy
-Corticosteroids
-Keloids and hypertrophic scars
-Infection
-Humidity, climate, and oxygen tension
-Health, age, and nutrition
59
What are indications for high voltage e-stim?
-Pain modulation
-Muscle re-ed
-Muscle pumping contractions
-Retard atrophy
-Muscle strengthening
-Increase ROM
-Fracture healing (?)
-Acute injury
60
What are indications for low voltage e-stim?
-Wound healing
-Fracture healing
-Iontophoresis
61
What are indications for interferential current e-stim?
-Pain modulation
-Muscle re-ed
-Muscle pumping contractions
-Fracture healing
-Increased ROM
62
What are indications for Russian e-stim?
Muscle strengthening
63
What is current density?
-Represents the intensity per area under a stimulation pas at a fixed voltage
-The smaller the electrode, the greater the intensity of the stimulation compared to larger electrodes
64
What is the rise time?
Time for the leading edge of the phase to increase from the zero baseline to the peak amplitude of the phase
65
What is the decay/fall time?
The time for the trailing edge of a phase to fall from the peak amplitude to the zero baseline
66
What is a period?
The time from an arbitrary reference point on a pulse to the identical point on the following pulse
67
What is amplitude modulation?
Variations in the peak amplitude in a series of pulses or cycle
68
What is phase or pulse duration modulation?
Variations in phase or pulse duration in a series of pulses
69
What is frequency modulation?
Variations in frequency in a series of pulses
70
What is ramp or surge modulation?
Cyclical sequential increases or decreases in phase charge over time
71
What is duty cycle?
The ratio of the on time to the total time of the stimulation, expressed as a percentage
72
What is a burst?
-The series of pulses or cycles of alternating current delivered during a stimulator ON period
-A package of train pulses
-Delivered at a specified frequency i.e. 2 bursts/second
73
What is burst duration?
Length in time of the burst usually in msec
74
What is burst frequency?
The # of bursts per second
75
What is interburst interval?
The time the stimulator is off between bursts
76
What is a train?
A continuous, repetitive series of pulses at a fixed frequency
77
What are the basic clinical currents?
-Direct current
-Medium frequency alternating current: Russian and Interferential
-Pulsatile: mono/biphasic and HVPC
-Microcurrent
78
What does HVPC stand for?
High voltage pulsatile current
79
What is direct current?
Current that runs for one second or greater in one direction
80
What is alternating current?
-Continuous bidirectional flow of current
-2 types: symmetrical or asymmetrical
-IFC or Russian
81
What is interferential current (IFC)?
-Two sinusoidal alternating current outputs that differ in frequency
-When the 2 frequencies intersect they summate resulting in a beat
82
What is the typical root mean squared for IFC compared to biphasic currents?
-IFC: 50-90 mA
-Biphasic: 3-12 mA
83
When do you need to "cross" electrodes?
Only when doing IFC!!!
84
What is a beat?
The wave formed by the summation of two currents
85
What are the uses for IFC?
-Management of pain for larger areas such as low back or hip
-Specific TENS with clinical application such as joint mob
-Regains muscle force joint ROM if they achieve strong motor contraction
-Decrease chronic edema
86
What is IFC not good for?
-Use with small electrodes because of high RMS
-Applications where polarity is needed (wound healing, acute edema)
87
What is Russian current?
-Time modulated alternating current
-Each burst is a polyphasic pulse
-Short duration, high pulse amplitude
-The current is time modulated because it would be too much current if it wasn't
88
What are uses of Russian current?
-Regain muscle force
-Regain ROM if strong enough to produce motor contraction
-Decrease chronic edema
89
What is Russian not good for?
-Use with small electrodes because of high RMS
-Applications where polarity is needed (wound healing, acute edema)
90
What is pulsatile current?
Noncontinuous flow of direct or alternating current
91
What are the types of pulsatile current?
-Monophasic: High voltage PC
-Biphasic
-Polyphasic (AC bursts)
92
What is HVPC?
-"Twin peak" pulses
-Monophasic PC with very short pulse durations (5-20 µsec)
-Very high amplitude (2,000 to 2,500 mA)
-Because the duration is so short, the amplitude must be so high to get excitation
-RMS is low, 1.2-1.5 mA
93
What are uses of HVPC?
-Effective for exciting easily sensory, motor, and pain fibers
-Good for when polarity is needed (acute edema, wound healing)
-Disuse atrophy
-Chronic edema
94
What is HVPC not good for?
-Large muscle groups
-Deneravted muscle
-Iontophoresis
95
What is root mean squared (RMS)?
-Represents the amount of current that goes into the tissue
-Can be thought of as the amount of heat created in the tissue
-Must be kept at appropriate levels to prevent tissue damage
96
What are clinical considerations for RMS?
-There is no established RMS guideline max
-Current density is determined by dividing total current by the area of the electrode used (i.e. 10mA/cm)
97
What are currents that produce high RMS?
-Burst modulated AC or time modulated AC (Russian)
-Beat modulated AC (IFC)
-These currents should be used with larger electrodes
98
What are currents that produce low RMS?
-Monophasic PC
-Biphasic PC
-HVPC
99
What is orthodromic action potential movement?
-Physiological action potential
-AP propagate along the peripheral nerve in one direction
-Sensory from periphery to spinal cord to brain
-Motor from brain to spinal cord to muscle
100
What type of action potential movement does electric stimulation utilize? What is it?
-Antidromic movement
-Induced action potentials propagate along the peripheral nerve can move in the opposite/two directions
-Sensory away from CNS and towards
-Motor toward the CNS and towards muscle
101
How does the size principle of motor neurons differ when utilizing e-stim?
-Physiologically the smallest motor neurons are recruited first, as more tension is needed, larger ones are recruited
-When e-stim is introduced in the periphery, the oppsite will happen as the larger axons have the least internal resistance
-Physiologic recruitment order: Slow, fatigue resistance, fast fatiguable
-E-stim recruitment order: fast fatiguable, fatigue resistant, slow
102
What frequency do discharge rates for voluntary contraction not normally exceed? Why?
-30 pps
-Frequencies over this amount will fatigue the muscle very quickly
103
What is asynchronous
recruitment?
-Smooth switching between active and inactive motor units to avoid fatigue of any particular fibers
-Discharge frequencies are not the same for all motor units, some may discharge at slow steady frequencies and others discharge irregularly at even lower frequencies to create a smooth functional movement
-Physiologic volitional contraction utilizes asynchronous recruitment
104
What is synchronous contraction?
-Recruitment of the same motor units continuously
-Electrically induced contractions use synchronous contractions
105
What can affect/overpower the strength duration curve and recruitment? Why? What does this result in?
-Distance of electrode to the respective peripheral axons
-The strength duration curve assume all nerve fibers are the same distance from the stimulating electrode, but this is not true
-This results in more random stimulation of a combination of large, small, and medium fibers
106
What settings are important for smooth muscle contractions? How does it do this?
-Ramping: minimally offsets lack of rate coding
-Frequency: allows for smoother contractions at less than 30 pps
107
What setting can offset the synchronous effect and order of recruitment?
-On/off ratio: allows rest of the recruited motor units
108
What parameter can allow for more specificity of recruitment?
Electrode placement
109
What is functional electrical stimulation (FES) used for?
-Scoliosis
-Shoulder subluxations
-People who may need an AFO
-Dynamic orthosis such as during gait
110
What are contraindications to FES?
-Joint or bony instability
-Poor cognition
-Poor sensation
-Not motivated to try
-Cannot have 0 MMT
111
What are special considerations with using FES for scoliosis?
-Primary curve measures 20-45 degrees
-Spinal growth potential of at least 1 year
-Idiopathic progressive curve
-Cooperation and compliance
-Tolerant to stim
112
How can NMES be used to improve ROM?
-Utilized in absence of bony abnormality
-Results can be seen after approximately 2 weeks of treatment depending on severity
-NMES allows the patient repeatd movement of the joint through available range multiple times with the added analgesic effects
113
What are considerations for using NMES for ROM?
-To preserve ROM you need 50-100 reps through the full joint range, but more than 200 with spasticity
-Amplitude must be at levels low enough to avoid "jamming" of the joint
114
When is NMES for spasms indicated?
-Acute spasm reduction associated with orthopedic type injury
-Spasm response associated with UMN lesions
115
What is required for acute muscle spasm reduction?
-At least a grade 1 contraction
-Small stimulated muscle contraction
116
What are techniques/methods for spasticity control?
-ES to antagonist
-ES to agonist
-ES to agonist and antagonist
-ES to sensory level (dermatome)
117
How long are the effects of e-stim to the antagonist muscle for spasticity?
-Immediate effect can last up to 1 hour
-Multiple treatments can lead to a long term reduction of spasm
118
How long are the effects of e-stim to the agonist muscle for spasticity?
-Lasts for several hours
-Will not be permanent
119
What is the mechanism behind reducing spasticity via e-stim of agonist muscle?
-Muscle contraction via orthodromic movement
-Spinal level reflex via antidromic movement
-These can lead to a longer lasting modulation of the spastic tone by which simultaneous excitation of Renshaw cells cause the inhibition of alpha motor neurons of the agonist and antagonist muscles
-Affects hyperactive stretch reflexes through synaptic mechanism instead of just fatiguing the myoneural junction
120
What is very important when utilizing e-stim for spasticity?
-Making sure not to elicit hyperactivity in the process
-Requires gradual onset of e-stim and gradual ramp downs
-Use high ramp times initially
-Is the spasticity necessary for the patients function? Would taking it away be detrimental?
121
When should NMES to spastic muscles be applied?
Just before other forms of therapy
122
What are other methods for spasticity control?
-Long term NMES for spinal cord patient
-Epidural spinal cord stimulation for spasticity
-Transrectal stimulation for spasticity control
123
When is NMES for muscle re-education indicated?
-Poor force generation
-Inadequate voluntary control
-Inability to recruit
124
What are the effects of NMES for muscle re-education?
-Increase recruitment of the motor neurons
-High levels of stim are not needed, only enough to elicit a 3/5
125
How long is the effect of NMES for muscle re-education?
-In ortho problems, you can see increase in recruitment in days to a few weeks
-In case of CNS problems, a change can be seen in approximately 2 weeks
126
How can HVPC be used to reduce edema?
-HVPC can be used to elicit the pumping action of skeletal muscles, but you must have a strong rhythmic contraction
-HVPC at high sensory levels (just below contraction) using the cathodal electrode may curb the formation of edema in acute trauma; cataphoresis
127
When must HVPC be applied after an acute injury?
Within 72 hours
128
What is cataphoresis?
-The movement of colloid molecules, such as fat, albumin, starch, blood cells, bacteria, and other single cells under direct current
-Albumin is negatively charged which makes it repelled by the cathode which in turn causes a fluid shift and reduction in edema
129
What are indications for HVPC?
-Retarding acute edema formation
-Decreasing post acute to chronic edema
130
What is critical fusion frequency (CFF)?
The specific frequency required by muscle for tetanic contraction
131
What is the CFF for postural muscles?
13-15 pps
132
What is the CFF for phasic muscles?
30 pps
133
At what frequency does force produced reach a plateau?
50-80 pps
134
What are the effects of muscle adaptations for prolonged, low level activity?
-Better able to provide ATP for energy stores
-More refueling or repetitive muscle contractions
-Better capability to metabolize fats, carbohydrates, and proteins
-Metabolic enzymes are increased and are accompanied by an increase in oxygen transport protein
-A rise in the number of capillaries bringing oxygen to the muscle
135
What are the effects of muscle adaptations for intermittent, high force level activity?
-Rapid depletion of energy stores
-Muscle responds to this depletion with an increase in actin/myosin content
-Short bouts of high level NMES result in actin/myosin content
-With increased contractile proteins, the number of cross bridges increase with a proportional increase in the muscles ability to generate tension
136
What patient populations would you want to use NMES for prolonged, low level activity?
-Upper motor neuron trauma
-Cerebral vascular accidents
-CNS disorders such as MS or CP
-Spinal cord injuries where the lesion has not created a peripheral neuropathy in the FES target area
-Prosthetic joint replacements
-Post immobilization atrophy
137
What are the results of strengthening in normal individuals using intermittent, high force level activity? What about non-normal patients?
-30-40% greater strength increases from e-stim compared to voluntary exercise
-In non-normal, voluntary and e-stim combined may be more effective
138
What percentage of the maximum volitional isometric contraction (MVIC) is required to produce an increase in muscle force?
-60-70%
-For a motor unit to produce more force it must be consistently activated at a level above the usual level of activation for that muscle
139
What would the duty cycle be for rapid fatigue from tetanic contractions?
1:1
140
What would the duty cycle be that would produce minimal fatigue from tetanic contractions?
1:5
141
What duty cycle is used during sub-tetanic contractions to avoid ischemia and encourage blood flow?
1:1 or 1:2
142
What duty cycle would you use for deconditioned and atrophied muscle?
1:5
143
What duty cycle would you use for normal to somewhat weak muscle?
1:3
144
What duty cycle would you use to challenge well conditioned muscle?
1:1
145
How is the MVIC established to determine a patients baseline?
-Computer controlled dynamometer
-Hand held dynamometer
-Isometric contraction of the involved muscle
-Best of 3 reps
