ES 547- electrical stimulation techniques

electrical stimulation relies on __________ _________________

tissue depolarization

how does coloumb's law explain what is happening in the body during electrical stimulation?

-ions replace the flow of electrons

-like charges repel, opposites attract

what kind of nerves depolarize first? what is the order of stimulation from first to last?

-large, superficial nerves with longer phase durations

-sensory (a-beta), motor, pain (a-delta and c-fibers)

what are the electrical stimulation parameters for gate control theory of pain?

-high frequency (80-150 pps)

-short phase duration (<100 microseconds)

-at sensory level

what are the electrical stimulation parameters for opioid/endorphin release?

-low frequency (1-10 pps)

-longer phase duration (200-400 microseconds)

-at motor or noxious levels

how does acute sensory stimulation prevent edema formation?

tetany/"muscle pumping" clears existing edema by facilitating venous and lymphatic return

what are the safety measures taken when using stim?

-script from physician required

-avoid chemical burns under the cathode during DC application

-prepare skin to lower impedance

-adhere strictly to contraindications

__________ ______ move toward the negative pole (cathode) and _____________ _____ move toward the positive pole (anode)

-positive ions (Na+, K+)

-negative ions (Cl-)

direct current causes ____ ___ _____________ in one direction. alternating current/biphasic current moves ions ______ ____ _______

-net ion migration

-back and forth

what path do electrons follow? what in the body acts as the primary resistor?

-the path of least resistance

-the skin

how does ohm's law relate to the application of stim?

says that higher voltage or superior coupling (ge, moisture, wet sponges) is required to drive the current

conductive pathways are 4x more conductive ________ muscle fibers than _______ them

-along

-across

what is accomodation?

-peripheral nervous system response when a nerve's rate of depolarization decreases while the stimulus remains unchanged

-patients "get used to" electrical sensation

-requires intensity adjustments

what is habituation?

-central nervous system filtration of benign, continuous sensory input

what are the 3 categories that affect nerve depolarization recruitment?

diameter: large-diameter fibers depolarize before smaller ones

depth: nerves closer to the electrode depolarize first

phase duration: longer phase durations recruit deeper/smaller fibers

what is the stimulus level for depolarization for A-beta fibers? A-delta and C-fibers?

A-beta: low

A-delta and C-fibers: high

subsensory level definition

output intensity is between 0 and a the point of first discrete sensation

does the literature support the use of microcurrent?

no proven clinical/therapeutic benefits

sensory level definition

depolarizes sensory nerves (A-beta) without muscle contraction

motor level definition

produces a visible muscle contraction without causing pain

noxious level definition

stimulates pain fibers (A-delta and C-fibers) to activate descending inhibitory pathways

what are the characteristics of silicon/carbon-rubber pads?

-deliver the highest current at the lowest skin impedance

-requires a wet sponge or gel interface to protect the skin

-high risk of hot spots and chemical/electrical burns if poorly coupled

what are the characteristics of self-adhesive electrodes?

-most common in modern clinical settings

-pre-gelled

-higher resistance to current flow than carbon pads

how does size affect function of the pads?

-smaller pads have a higher current density and requires less overall current to stimulate tissue, but carries a higher risk of localized burns

-larger pads have a lower current density, more comfortable, lower impedance

what is a monopolar placement technique?

-one or more small "active" electrodes placed over target tissue

-much larger "dispersive" electrode placed elsewhere to complete the circuit

-focuses current density under the active pad