Electrical Stimulation Exam

ion

particle with an electrical charge

polarity

net charge of an object

anode (+)

looses and electron and becomes positive

cathods (-)

gains electrons and becomes negative

Electrical power

measured in watts

the rate in which electrical power is being use

voltage

force resulting from the build up of electrons

electrical current

flow of electrons in response to voltage force

conductors

• water

• metal

• nerves

• blood

  • muscle

insulators

rubber

plastic

fat

myelin

bone

Ohm’s law

current is dependent on the voltage and resistance to movement of ions/electrons

I=V/R

Resistance

hair

calloused skin

excessive adipose tissue

direct current

continuous unidirectional flow of electrons for at least 1 second

alternating current

uninterrupted bidirectional flow of electrons for at least 1 second

pulsed currents

uni- or bi-directional flow of electrons that periodically ceases for defined period of time

most commonly used therapeutic current

phase

flow of current in one direction

pulse

flow of current separated from each other by interpulse duration

pulse duration (width)

time of each pulse

burst

2 or more consecutive pulses separated by an inter-burst interval

burst frequency

burst per second

frequency

the number of cycles or pulses per second

measured in Hertz (Hz)/PPS/CPS

the higher the PPS for therapeutic electrical stim

the greater the comfort level for the patient

low frequency currents

1-200 hz

medium frequency currents

between 1000 and 10,000 hz

high frequency currents

100,000 to 250,000 hz

amplitude modulation

ramp up or down

amplitude of current

Intensity of current

highest point on each phase

• higher amplitude>peak voltage or intensity

waveform

Representation of electrical current

defined by:

• shape

• direction

• amplitude

• duration

• pulse frequency

electrochemical

Na+ to cathode Cl- to anode

sclerosis

increased blood flow to restore pH

electrothermal

production of heat in response to movement of electrodes through resistance

electrophysical

nerves are depolarized first, then muscles

strength and duration of current important, a,long with nerve size and location of electrodes

cellular response

excite nerve cells

Stimulate protein synthesis, fibroblasts/osteoblasts activity

change cell membrane permeability

tissue response

skeletal and smooth muscle contraction

tissue regulation (softening)

segmental response

imporve joint mobility

increased circulatory/lymphatic activity

change in ANS responses via stimulation of sensory pathways

systemic response

analgesic effects via pain gate and endogenous opioid theory

direct effect

muscle contraction

• improves strength and function

Indirect effect

pain modulation

• sensory and motor stimulation

non-excitatory

tissue healing

medication delivery

russian current

burst modulated alternating current, commonly used for muscle strengthening

2,500 Hz AC is burst modulated at 50 bps using a 10-msec bursts

IFC

amplitude modulated alternating current, two asynchronous currents to form a current with amplitude modulation

pre mod- generated by machine

used primarily for pain modulation

HVPC

twin peaked monophasic pulsed current a high-peak intensity

short pulse duration

commonly used for tissue repair, wound healing and pain modulation

symmetrical/asymmetrical biphasic PC

used for muscle stimulation and pain modulation

no evidence to support or refute use of one over the other

low-intensity DC (microcurrent)

amplitude below threshold to stimulate sensory or motor nerves

used for tissue repair, wound healing

TENS units

home stim units used for pain modulation

used to stimulate peripheral nerves

consistutes the majority of all therapeutic electrical generators

NMES

used for innervated muscle contraction

depolarizes the motor nerve

attempts to mimic voluntary contractions and is stronger in the initial stages of rehab, preventing muscle atrophy

EMS

used for denervated muscle

depolarized the muscle

pulse duration greater than 10ms

MENS

micro current electrical nerve stimulation

intensity too small to elicit peripheral nerves

used for pain, mostly chronic pain clinics

contraindications for E-STIM

cardiac pacemakers or defibrillators

implanted stimulators; phrenic nerve or urinary bladder

Pregnancy- over abdomen or low back and pelvis

electrode placement over carotid sinus

stimulation across chest

over eyes or gonad area

over areas of active osteomyelitis

PVD

areas of venous or arterial thrombosis

acute stage of inflammation

precautions for E-STIM

history of seizures

uncontrolled hypertension/hypotension

immature or confused patients

decreased or absent sensation

obesity

osteoporosis

cancer

adverse effects of E-stim

electrical burns

skin reaction to electrodes

pain

strength duration curve

the current induced must be

Sufficient amplitude (strength)

adequate length of time (duration)

accommodation

nerve becomes progressively less response to stimulus

all receptors adapt to stimuli that are sustained or frequently repeated

modulation

variation of stimulation parameters

how does skeletal muscle contraction occur?

electrical stimulation of the alpha motor neuron

FES

Traditionally for patients with SCI

activity should be functional to patient

facilitates or improves purposeful movements

works on the agonist and antagonist muscles together

denervated muscle

maintain contractile properties while awaiting reinnervation

maintain muscle mass to prevent pressure sores/aid with circulation

requires depolarization of the muscle membrane itself

muscle contracting stimulation is through the muscle directly

biofeedback

how fast the nerve is conducted

monitoring, detection, or assessment of skeletal muscle activity

can be combined with FES

used a lot for pelvic floor and quad