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physiotherapy > low frequency currents > Flashcards

low frequency currents Flashcards

1
Q

Gliedmaster classification of currents?

A

Low frequency-1,000hz: irritating/stimulating
Medium frequency- 10,000hz: deeper effect w/ reduced skin irritation due to lower skin resistance
High frequency- 100,000hz; analgesia

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2
Q

ypes of currents according to phases

Monophasic

A

monophasic, diphasic, pulsatile

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3
Q

describe a Monophasic current

A

Unidirectional and uninterrupted
From positive to negative electrodes
E.g. galvanic current

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4
Q

describe a galvanic current

A

constant flow and intensity
Constant voltage
Direct current= unidirectional flow of electrons
Diphasic

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5
Q

Diphasic

A

Alternating and bidirectional current flow

Reversible polarity

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6
Q

pulsatile

A

Can be mono or bi-phasic
Magnitude and intensity subject to change
Low frequency currents

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7
Q

list the Low frequency currents

A

galvanic and low frequency pulse currents

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8
Q

describe a galvanic current

A
  1. Unidirectional flow 2. Direct current 3. Constant voltage unchanged with time
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9
Q

describe low frequency pulse current

A

pulses and pauses. Each pulse has the same intensity but different shapes

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10
Q

how to generate a galvanic current

A

Apply an electric charge to stimulate molecues to become charged ions
NAOH migrates to the cathode and HCL migrates to the anode
Hydrophilic pads to protect skin from the burning/ irritative sensation at the cathode
Analgesic effect occ
Generall adults=0.02m amps/cm2 Children 0.1 m aurs at the positive anode
The dose is subjective to when the patient describes pins and needles due to the increased intensity. mps per cm2
Galvanic strucutres stimulate excitable structures e.g.
Eyes= light phenomena
Skin= sensation
muslces= contraction

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11
Q

what are the 3 zones in the skin

A
  1. polar zone
  2. peripolar zone
  3. interpolar zone
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12
Q

what happens in the polar zone:

A

DC causes charged particles to migrate
The particles have altered chem characteristics
Electro Neutralization of the opposite charged particles occurs
No therapeutic effect as they’re electrically inactive
Hcl is synthesised at the anode- site of sensation and irritation. Hydrophilic pads used to prevent skin burning
Naoh is synthesized at the cathode-site of analgesia

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13
Q

what happens in the peripolar zone:

A

The specific effects of the low frequency currents are exhibited
Tissue excitability is altered(improved)
For analgesia the anode is placed on the site of pain

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14
Q

what happens in the interperolar zone

A 
on specific reactions e.g. 
Circulation
metabolism 
Trophics-(relating to, or characterized by (such) nutrition) improving skin due to stimulating blood flow
Substance exchange
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15
Q

what is iontophoresis

A

technique of introducing ionic medicinal compounds into the body through the skin by applying a local electric current.

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16
Q

how are galvanic curretns used for iontophoresis

A

Static galvanic current used
Drug activity enhanced by increasing low current intensity
lidocain= analgesia is increased
nivalin(galantamine)= improves neuromuscular transmission in the peripheral nerves
Anode exaggerates drug effects so placed at topical drug site.
Cathode neutralizes them due to increased irritation(keep away from the cathode)

17
Q

methods to apply low frequency currents

A

Local- hydrophilic pads on body: Transverse pads, diagonal pads, longitudinal pads
Current bath
Reflex: Galvanic collar, Galvanic pants

18
Q

galvanic current indications

A

Pain
Trauma
Paravertebral spams(disc hernia)
Osteoarthritis 4Circulation disorders

19
Q

galvanic currents conraindications

A
  1. pregnancy 2. Myasthenia gravis
  2. Acute cardiac conditions
  3. Fever and inflammation
20
Q

describe low frequency pulse currents

A

For smooth and skeletal muscle stimulation

Defined as low frequency currents up to 1000hz

21
Q

what are the 6 physical parameters of low frequency pulse currents

A
  1. pulse shape
  2. pulse duration in ms
  3. pause duration in ms
  4. frequency
  5. period
  6. intensitiy in milliamps
22
Q

explain pulse shape parameter of low frequency currents

A

Shows the ability of the muscle to accommodate
Healthy muscles-short duration intense stimulation shows rectangle shape
Peripheral nerve damage = triangle. -> higher intensity and duration needed
With exponential / forefront wave shows lack of accommodation requires increased stim and longer duration

23
Q

pulse shape of healthy muscles

A

short duration intense stimulation shows rectangle shape

24
Q

pulse shape of PND

A

angle. -> higher intensity and duration needed

25
Q

what is an exponential / forefrint wave shape show

A

ack of accommodation requires increased stim and longer duration

26
Q

explain pulse duration

A

hronaxie= min time required for muscular contractions to occur if 2 rheobases are used. Used to measure the duration of the pulse which shows the conditions of the muscles
rheobase= min intensity to overcome threshold. In this case it’s overcoming the threshold to simulate the muscle
Normal chronaxie= 1-2 ms
Pain chronaxie= 0.5-100ms
Peripheral paralysis chronaxie=100-200ms

27
Q

what is chronaxie

A

in time required for muscular contractions to occur if 2 rheobases are used.
Used to measure the duration of the pulse which shows the conditions of the muscles

28
Q

what is rheobase

A

heobase= min intensity to overcome threshold. In this case it’s overcoming the threshold to simulate the muscle

29
Q

what is the normal chronaxie

A

1-2 ms

30
Q

pain chronaxie

A

0.5-100ms

31
Q

Peripheral paralysis chronaxie

A

100-200ms

32
Q

what is the Pause duration in ms-1 for

A

Responds to the refractory period-no contraction even if stimuli is applied
Pauses is needed for muscle recovery=more severe damage requires longer pause on graph

33
Q

what does the Frequency in the LFPWC

A

In hz
Shows functional mobility of muscle5.
1000ms-1/T = hz?

34
Q

what is the period in LFPWC

A

T=t(i) -time of pulse + t(p) time pf pause. A period 3-6 times larger shows PND

35
Q

what are the LFPWC parameters in a healthy muscle

A

t(i) =1-2ms
t(p)+t(i)=T eu
f= 50/100hz

36
Q

what are the LFPWC parameters in a PND

A 
t(i) 50/100/200-500ms
t(p)+t(i)=T 3-6 times increased
f=0.2/0.5hz
Therapeutic effects
Stim skin and smooth muscle
Fibroblast and osteoblast stimulation 
Modulation of microcirculation 
Tissue regeneration
37
Q

Indications of low frequency pulse currents

A

Hypotrophy? d/2 immobilization &
bone fractures-d/2 osteoblast stimulation
Muscle strengthen-Weak pelvic floor
Decrease spasticity by antagonistic muscle stim-Post stroke pt’s w/ spastic gait
Urinary incontinence

physiotherapy (17 decks)

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