basic principles 2
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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?
- pohase duration
- 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?
- rise time
- 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?
- ramp up
- more than 1 phase -> burst
- aka rate of rise, surge
What is the decrease in amplitude over time?
- ramp down
- 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
- wound/ulcer healing
- fracture healing
- promote circulation
- edema management
- increase ROM (relax spasticity, decrease contracture)
- deliver meds
- replace orthotics (FES)
- reduce spasm
- reduce scoliosis
- electrodiagnostic testing
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
- seizure disorders
- acute inflammation/infected areas
- directly over superficial metal implants
- extreme cutaneous sensitivity
- recent fracture
- cancer (may be used in advanced stages for pain relief)
- active TB
- 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
- asymmetry noted
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)
- appropriate frequency/amplitude
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