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What type of current has 3 or more phases and contains bursts?
polyphasic
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What is a burst?
- groups together a series of pulses and delivers them as a single charge
- can be called a packet, or envelope
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What type of current are pts most comfortable with?
symmetrical biphasic (normal mode for TENS)
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What is the magnitude of current (mA) or voltage?
amplitude
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What is peak amplitude?
max current or voltage delivered in one phase of a pulse
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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
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What is the flow of current that ceases for a period of time?
- pulse
- duration and amplitude characteristics
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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)
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What is the time interval from the beginning to the end of on phase of a pulse?
- pohase duration
- usually expressed in microseconds
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What is an interpulse interval?
period of time between pulses during which there is no current flow
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What is an intrapulse interval?
period of time within a single pulse during which there is no current flow
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What is the time between the initiation of one pulse to the initiation of the subsequent pulse (includes interpulse interval)?
pulse period
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What is pulse frequency?
- with pulsed currents: number of pulses per second (pps)
- with AC currents: number of cycles per second
- measured in hertz
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What is a pulse charge?
- sum of the charges from each phase in the pulse
- if balanced-> no charge
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What is a burst frequency?
- number of bursts per second (bps)
- e greater at higher frequency, since the interpulsed interval decreases
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What is the ratio of on to off time?
duty cycle
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What is the formula for duty cycle?
duty cycle= on time/ on time + off time
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What is the time it takes for amplitude to increase from zero to peak amplitude?
- rise time
- in one phase, must have a slope
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What is decay time?
time it takes for amplitude to decrease from its peak amplitude back down to zero
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What is an increase in amplitude over time?
- ramp up
- more than 1 phase -> burst
- aka rate of rise, surge
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What is the decrease in amplitude over time?
- ramp down
- aka decline, rate of decline
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How long do ramp up/down times normall last?
2-3 seconds is enough, but ranges from 1-8 seconds
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Why would you use a ramp up/down treatment?
goal of tx is m contraction
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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
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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
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What are some adverse effects of estim?
- electrical burns (more common than DC)
- skin reactions to electrodes (contact surface)
- pain
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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
- transcerebrally
- seizure disorders
- osteomyelitis
- 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
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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
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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
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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
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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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