basic principles 2
Card Set Information
basic principles 2
What type of current has 3 or more phases and contains bursts?
What is a burst?
groups together a series of pulses and delivers them as a single charge
can be called a packet, or envelope
What type of current are pts most comfortable with?
symmetrical biphasic (normal mode for TENS)
What is the magnitude of current (mA) or voltage?
What is peak amplitude?
max current or voltage delivered in one phase of a pulse
What is a peak to peak amplitude?
max current or volt amplitude over the 2 phases of biphasic or 2 phases of one cycle of AC
associated with penetration..the higher the peak the greater the penetration
What is the flow of current that ceases for a period of time?
duration and amplitude characteristics
What is a pulse duration?
time from the beginning of the first phase of a poulse, to the end of the last phase of a pulse (includes intrapulse interval)
What is the time interval from the beginning to the end of on phase of a pulse?
usually expressed in microseconds
What is an interpulse interval?
period of time between pulses during which there is no current flow
What is an intrapulse interval?
period of time within a single pulse during which there is no current flow
What is the time between the initiation of one pulse to the initiation of the subsequent pulse (includes interpulse interval)?
What is pulse frequency?
with pulsed currents
: number of pulses per second (pps)
with AC currents
: number of cycles per second
measured in hertz
What is a pulse charge?
sum of the charges from each phase in the pulse
if balanced-> no charge
What is a burst frequency?
number of bursts per second (bps)
e greater at higher frequency, since the interpulsed interval decreases
What is the ratio of on to off time?
What is the formula for duty cycle?
duty cycle= on time/ on time + off time
What is the time it takes for amplitude to increase from zero to peak amplitude?
in one phase, must have a slope
What is decay time?
time it takes for amplitude to decrease from its peak amplitude back down to zero
What is an increase in amplitude over time?
more than 1 phase -> burst
aka rate of rise, surge
What is the decrease in amplitude over time?
aka decline, rate of decline
How long do ramp up/down times normall last?
2-3 seconds is enough, but ranges from 1-8 seconds
Why would you use a ramp up/down treatment?
goal of tx is m contraction
What is modualtion?
varying 1 or more of the electrical parameters f poulse or current as a whole over time while delivering the stimulus
helps to decreased/prevemt accommodation
What are some indications for estim?
pain management (sensory, motor, noxious stimulation)
muscle strengthening (large to small->fast twitch)
stimulation of denervated mm
increase ROM (relax spasticity, decrease contracture)
replace orthotics (FES)
What are some adverse effects of estim?
electrical burns (more common than DC)
skin reactions to electrodes (contact surface)
What are some contraindications of estim?
pregnancy (over or around the abdomen or low back)
pacemakers/other electrically implanted stimulators
cardiac arrhythmic instability (cardiac conductance disturbances, avoid current flow across midline of chest area over heart)
placement of electrodes over carotid sinus or around laryngeal mm
adjacent or distal to area of venous or arterial thrombosis or thrombophlebitis
areas of adjacent hemorrhage
acute inflammation/infected areas
directly over superficial metal implants
extreme cutaneous sensitivity
cancer (may be used in advanced stages for pain relief)
close proximity to diathermy
What are some precautions for estim?
obesity (fat insulates so you have to use greater current levels)
areas of absent or diminished sensation
areas of abnormal impedance
skin conditions (worsens eczema, psoriasis, acne, dermatitis, spreads infection)
pts with fragile skin (diabetes)
peripheral neuropathies (may not be able to stimulate at a safe level for m contraction)
metal-internal or external
motor activity in area must be approved by dr
unable to follow directions or provide feedback
spinal cord injury-may worsen dysreflexia
hypotensive or hypertensive pts
recent scar tissue
What are some signs over overstimulation with estim?
rate of contraction decreases
longer period of relaxation noted
tremor like contractions
discomfort experienced by pt
stiffness reported following estim
When should you stop estim?
pain is resolved
pain increases during stimulation
pain increases after stimulation in 3-4 consecutive treatments
pain reduction plateaus for 2-3 consecutive txs
How do you prevent overstimulation with estim?
allow time for mm to recover
limit number of contractions of a single mm (need 90 contractions to retard fibrosis)