10) intro to electrical stim 2

pulse characteristics

waveforms

stimulation paramaters

pulse/phase charge

pulse =

isolated electrical event

pulse duration

time to complete one pulse

phase =

unidirectional flow of a pulse

phase duration =

time to complete one phase

1 or 2 phases make up a

pulse

pulse/phase charge =

area under the curve

2 phases =

one pulse

with an AC current being used on skin, what net charge occurs

net 0 charge

strength-duration curve

shows the relationship between pulse duration and pulse amplitude

factors that effect peripheral nerve action

type of nerve/size of nerve

location

nerve fibers vary in

diameter and internal resistance

the largest diameter/lowest internal resistance are the

most easily excitable

- alpha will be recruited first

motor points

point where the motor nerve is most accessible

- usually muscle belly

motor points is where the ________ motor response is found at the _______ pulse charge

- greatest

- lowest

pulse/phase charge involves which pulse characteristics

amplitude and phase/pulse duration

Which fibers would require the lowest pulse charge to be recruited?

sensory

frequency

the number of pulses each second

carrier frequency modulation

Used only for Burst-Modulated AC currents

- Russian waveforms

- Interferential waveforms

burst frequency =

number of bursts per second (bps)

ramp up

time across successive pulses to reach peak amplitude

(usually in seconds)

ramp down

returning to baseline

duty cycle =

on time/(on time+off time) x 100

on/off times for pain/edema management

often continuous

higher intensity estim may require on/off time (1:1)

on/off times for strengthening

need on/off times to mitigate fatigue (1 min on:50 sec off)

functional electrical stimulation on/off times

on/off controlled by a trigger

modes with two channels working

continuous

synchronous

reciprocal

primary parameters

pulse duration - usually less than or equal to 400 milisec

amplitude - up to 100 mA

frequency - up to 100 pps

pulse duration and amplitude together are the most important in

how strong the electrical stimulus is and what effects it can create (pulse charge!!)

types of electrodes

single use

reusable

carbon

metal

electrode size

-Relative to muscle size

-Current Density

electrode placement

at least 2 electrodes are needed

- monopolar

- bipolar

- quadripolar

contraindications

cardiac problems - pacemaker

electronic devices

carotid sinus

pregnant

broken/damaged skin

DVT (local)

seizures

cancer (local)

Precautions

open skin lesions

skin conditions

open epiphysis

reduced sensation

allergies

metal implants

cog/communication impairments

mental status