basic principles 2

polyphasic

• groups together a series of pulses and delivers them as a single charge
• can be called a packet, or envelope

symmetrical biphasic (normal mode for TENS)

amplitude

max current or voltage delivered in one phase of a pulse

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

• pulse
• duration and amplitude characteristics

time from the beginning of the first phase of a poulse, to the end of the last phase of a pulse (includes intrapulse interval)

• pohase duration
• usually expressed in microseconds

period of time between pulses during which there is no current flow

period of time within a single pulse during which there is no current flow

pulse period

• with pulsed currents: number of pulses per second (pps)
• with AC currents: number of cycles per second
• measured in hertz

• sum of the charges from each phase in the pulse
• if balanced-> no charge

• number of bursts per second (bps)
• e greater at higher frequency, since the interpulsed interval decreases

duty cycle

duty cycle= on time/ on time + off time

• rise time
• in one phase, must have a slope

time it takes for amplitude to decrease from its peak amplitude back down to zero

• ramp up
• more than 1 phase -> burst
• aka rate of rise, surge

• ramp down
• aka decline, rate of decline

2-3 seconds is enough, but ranges from 1-8 seconds

goal of tx is m contraction

• 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

• 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

• electrical burns (more common than DC)
• skin reactions to electrodes (contact surface)
• pain

• 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

• 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

• rate of contraction decreases
• longer period of relaxation noted
• tremor like contractions
• discomfort experienced by pt
• stiffness reported following estim
• asymmetry noted

• pain is resolved
• pain increases during stimulation
• pain increases after stimulation in 3-4 consecutive treatments
• pain reduction plateaus for 2-3 consecutive txs

• allow time for mm to recover
• limit number of contractions of a single mm (need 90 contractions to retard fibrosis)
• appropriate frequency/amplitude