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Phys Agents > High Volt > Flashcards

High Volt Flashcards

1
Q

Overview-High voltage pulsed current

A
  • Typically uses a twin-peaked monophasic waveform
  • UNBALANCED
  • Results in polarity
  • Short pulses reduce polar effects on skin (educate patient that if it gets uncomfortable to speak up)

Do short pulse durations, high voltage

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2
Q

When turning up the amplitude, what are you changing?

A

The current.

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3
Q

HVPC

A

General electrical stimulations contraindications
- Pregnancy
- Cancer
- DVT
- etc.

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4
Q

HVPC Clinical indications

A
  • Muscle contraction
  • Pain relief (provides sensory and pain options)
  • Acute edema
  • Wound healing
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5
Q

Acute edema treatment with HVPC

A

HVPC shown to delay or prevent onset of acute edema

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6
Q

Acute edema physiology

A

Tissue Injury –>
chemical and electric signals->
enhanced vessel permeability –>
proteins accumulate (pull water with it) –>
fluid follows = local tissue edema

Ex: Ankle Sprain

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7
Q

HVPC Acute edema prevention/reduction theory

A

Current theory suggests an effect on vascular smooth muscle (permeability), exact mechanism not clear

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8
Q

Acute edema Clinical Bottom Line

A

HVPC delays or prevents onset of edema, but does not reduce existing edema

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9
Q

Acute edema clinical procedures

A
  • Application within first 24 hours (sooner the better)
  • High frequency (120 pps)
  • Intensity: 10% < visible motor stimulation (See muscle twitch then back it down a little)
  • Short pulse duration (~60 µs (microseconds - pulse duration), often not programmable)
  • Cathode placed distally on extremity (near ankle/injury)
  • Treatment time approx. 30 min, combine w/ PRICE principles (Multiple 30 minutes sessions are good, give an hour off)

Waveform itself is different and has an effect on edema compared to tens

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10
Q

Chronic Wounds Types (4)

A
  • Pressure necrosis
  • Diabetic neuropathy
  • Venous insufficiency
  • Arterial insufficiency
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11
Q

Chronic Wound physiology

A
  • Epidermal and some Epithelial cells carry (-) charge
  • Wound bed carries (+) charge
    – Creates a natural voltage
    – Thought to assist in migration of skin cells across granulation tissue (red wound bed)
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12
Q

Chronic Wound healing

A

HVPC may augment (increase) skin migration
HVPC attracts other cells as well (galvanotaxis or electrotaxis)
Enhancement of natural electric signals, triggering of chemical signal pathways

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13
Q

Anode attracts:

A
  • Macrophages
  • Neutrophiles
  • Vascular fibroblasts (new blood vessels) and smooth muscle cells
  • Some endothelial cells for angiogenesis (cover skin)
  • ?? Some epidermal and some epithelial cells
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14
Q

Cathode attracts:

A
  • Fibroblasts
  • Keratinocytes
  • Microvascular endothelial cells
  • Some Epithelial cells

These cover over the wound bed

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15
Q

HVPC Stimulation in wound healing has been shown to:

A

Increase angiogenesis
Improve collagen synthesis
Release of other growth factors

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16
Q

Anode vs Cathode Over Wound

A

Anode over wounds:
* Autolysis (clean up garbage over wound)
* Angiogenesis
* Now shown to improve re-epithelialization and epidermal resurfacing too

Cathode over wounds:
* Enhance proliferative phase of wound healing (fill in with granulation and connective tissue)
* Fills in granulation tissue and re-epithelialization

Anything yellow, black, green need to get rid of that over wound

Garbage - Anode; Hole - Cathode

17
Q

Extra contraindications for wound healing with HVPC

A
  • Local skin cancer
  • Local osteomyelitis (infection of bone)
  • Silver or iodine ions in wound bed (Must be cleaned out before applying)
18
Q

Chronic Wound Care - Clinical Procedures

A
  • Usually implemented when other measures have failed
  • Irrigate wound with saline
  • Fill dead space with moist gauze (saline or hydrogel to moisten)
  • Foil or electrode over gauze
  • Other electrode over skin nearby (Is VERY large so it has very little effect there and goes to concentrate over the other electrode on gauze)
  • HVPC, 100 pps, sensory level (50-150 V), short pulse duration (usually not programmable)
  • ~60 min, 5-7 days/week
  • Polarity in wound based on needs (?)

Long term treatment

19
Q

Direct technique - HVPC Chronic Wound

A

Active electrode in wound bed, dispersive away from wound

20
Q

Straddle

A
  • Neurogenic skin - No intact peripheral N. (SCI)
  • Neuropathic skin - Nerves intact but dull sensation (DM)
  • Both electrodes have same polarity (use cable splitter), dispersive(s) placed away
  • Amplitude to just visible muscle contraction

Can turn up intensity to see muscle twitch then back off. This is a unique setup of 3 electrodes.

21
Q

HVPC wound healing outcomes

A
  • Increased capillary density 43.5% (Junger et al. 1997)
  • Antibacterial effects (Laatsch et al. 1995)
  • Improved healing rate 144% (Gardner and Frantz, 1999)
  • Best evidence to support using cathode solely. Anode and Cathode together is better than nothing.
22
Q

Electrophysiologic testing

A
  • Motor Nerve Conduction Velocity (NCV)
  • Sensory NCV
  • Reflexes
  • Needle EMG
  • Sensory evoked potentials (SEPs)
23
Q

MNCV - m wave

A

M-Wave (orthodromic conduction, motor down) - How fast you can conduct a nerve (From stimulus up the nerve down to monitoring device)

  • Compression neuropathies:
    – Prolonged distal latency
    – Velocity normal proximal to injury, but slowed across lesion
    – Wave amplitude may be diminished
    – Wave duration may be prolonged
  • Systemic neuropathy
    – Latency time and velocity may be slowed or normal
    – Wave amplitude diminished, duration prolonged
    – Diabetes Mellitus, Muscular Dystrophy Disorders

Past shoulder to fingers

24
Q

MNCV - f wave

A
  • F wave (antidromic conduction, motor up, motor down)
  • Used to evaluate proximal nerve segments
  • Latency time only useful metric
  • Normal ranges have been established

Shoulder and Neck

25
Q

SNCV

A
  • Similar to MNCV (only a single phase wave)
  • Can be ortho- or antidromic
  • Latency, velocity, amplitude, wave duration all affected by neuropathy
  • Compression or systemic disease affecting myelin will show sensory signs first
26
Q

H Reflex

A

(sensory up [tibial nerve], motor down/muscle monitoring [soleus])
Used to test integrity of S1 nerve root (essentially tests monosynaptic stretch reflex) - Most commonly effected
Commonly compromised with disc lesions

27
Q

NCV Studies

A
  • Part of comprehensive exam
  • ??? Sensitivity because partial nerve involvement is possible (the test might only stimulate the healthy part)
28
Q

EMG

A
  • Examines integrity of efferent pathways from SC to muscle, and muscle fibers
  • Useful for radiculopathies, muscle disease
  • Monitor, not stim
  • Insertional activity
  • Rest
  • Voluntary contraction
29
Q

Insertional activity - EMG

A

Normal activity with needle insertion/movement lasting 50-230 ms
Activity shorter or longer is abnormal

30
Q

Rest/Spontaneous activity - EMG

A
  • Normal muscle = no activity at rest
  • Certain types of activity can be diagnostic:
    – Positive Sharp waves (PSWs) – indicates denervation (Peripheral N injury)
    – Fibrillation potentials – random activity, single fiber - denervation (Not intact nerve)
    – Myotonic discharges – characteristic run of discharges indicative of specific neuromuscular pathology
    – Fasiculation potential – multi-fiber random activity, normal or abnormal, must be correlated with other signs (Random eye twitch)
31
Q

Voluntary muscle contraction

A
  • Small to large (light to strong contraction)
  • Shape, amplitude, duration, sound
  • Ability to achieve full, smooth muscle contraction
32
Q

Sensory Evoked Potentials

A

Monitoring electrical activity of the brain in the sensory cortex.

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