Physical Agents Exam #2 Outline

negative and black

what charge and color is the cathode?

positive and red

what charge and color is the anode?

electric current

flow of charged particles

direct current

continuous, unidirectional flow of electrons for at least 1 second

- battery-driven

- less commonly used for electrotherapy

- only modulate time and intensity

- used for ionto and stimulating contractions on denervated muscle

- parameters to adjust intensity and time (causes polarization in the tissues)

alternating current

continuous, bidirectional flow

- current is always flowing back and forth

- used for muscle contraction to strengthen (russian) or pain (IFC/premod)

pulsed current

interrupted flow of charged particles

- current flows in a series of pulses separated by periods of no current flow

- one directional flow (monophasic)

- bidirectional flow (biphasic)

true

T/F: there is usually little to no difference in effectiveness for muscle stimulation using symmetrical biphasic pulsed current vs. russian stimulation (AC)

pulse rate/frequency

measured in Hz or pps

- number of pulses of electric current that occur in a second

pulse duration/width

measured in microseconds or milliseconds

- period when current flows in one direction

amplitude/intensity

measured in Amps, mA, or Volts

- strength of estim

constant

_____ stimulation pattern

- amplitude of successive pulses (cycles) is the same

surge

_____ stimulation pattern

- pattern of variation in one or more of the stimulation parameters

- can be cyclical or random

rise time, fall, ramp up, ramp down, and plateau

what are the 5 surge characteristics?

electrochemical

______ effects

- skin like a battery, has a biometric curent which responds to external electrotherapy

- polarity of the current directs cell migration and splits them into 2 groups (one to anode and one to cathode)

- mechanism behind electrotherapy w/ ionto and wound healing

electrothermal

______ effects

- heat is a product of kinetic energy of molecules secondary to friction and vibration

- result is redness of the skin lasting a few hours

- factors: current intensity, resistance (hair, callus, dry skin) and duration

electrophysical

______ effects

- AP: message unit in NS

- to stimulate an AP, the current must have sufficient amplitude and duration

- once AP stimulated it will travel the length of the nerve

motor

stimulated AP on a _____ nerve

- brain --> motor nerve --> muscle --> muscle contraction

sensory

stimulated AP on a _____ nerve

- sensory nerve --> SC --> brain --> tingling sensation

AP

sequential depolarization and repolarization of a nerve is known as the _____

1-5 msec

how long does an AP last?

strength-duration curve

Minimum combination of amplitude & duration needed to produce an AP in that nerve

- based on averages, varies between individuals and varies in an individual based on body area and other circumstances

A beta (sensory)

what nerve is stimulated first according to strength duration curve?

motor

what is stimulated after sensory according to strength duration curve?

A delta (sharp pain)

what is stimulated after motor according to strength duration curve?

C fibers (dull pain)

what is stimulated after sharp pain according to strength duration curve?

denervated muscle

what is stimulated after dull pain (C fibers) according to strength duration curve?

sensory

low intensity and shorter pulse stimulated _____ nerves

motor

high intensity and longer pulse stimulates _____ nerves

C

an even higher intensity and longer pulse duration stimulates _____ fibers (pain)

accomodate

if current rises too slow the nerve will _____ and become less responsive to the stimulus

neuromuscular estim

occurs because AP reaches the muscle via the motor nerve

estim for denervated muscles

if the muscle is denervated, muscles contract if the electrical current is applied directly to the muscle cells

- requires pulse lasting 10 msec or longer

burns, skin irritation, and pain

what are the adverse effects of estim?

IFC, premod, TENS

what modalities treat pain?

NMES, FES, EMS

what modalities are used for muscle reeducation and motor control?

russian and biphasic pulsed current

what modalities are used for strengthening and endurance?

HVPC

what modalities are used for tissue healing?

iontophoresis

what modality is used for transdermal drug delivery?

gate control

high-rate frequency activates the _____ ____ theory and patient should feel a sensory level stimulation

EOS

low rate frequency activates the _____ and the patient should reach a motor level stimulation

increase

longer phase durations _____ the depth of penetration, recruit more motor units, and elicit stronger muscle contractions (200 microseconds or less)

stronger

pulse duration 200 microseconds or greater allows for ____ contractions with less amplitude/intensity

resistance

the ability of a material to oppose the flow of electrons through it

impedence

form of resistance dependent on frequency

- skin, fat, gels, and conducting agents' lower stimulation frequency

current density

influenced by the size of electrodes and distance apart

- same size electrodes = current density is equal

- different size electrodes = current more concentrated in smaller electrode

- electrodes close together = current is greater superficially

- electrodes farther apart = current is deeper

small electrodes

best for small areas of the body or small muscles that require low levels of stimulation

large electrodes

best for larger areas on the body or larger muscles that require higher levels of stimulation

skin prep

- clean with warm water and soap (NO ALCOHOL)

- hair should be cut, not shaved

pain

electrode placement for ____

- above/below the area

- surrounding the area

- directly on the area

- trigger point of acupuncture points

- along dermatome/myotome

strengthening

electrode placement for _____

- one on motor point on muscle belly, second on motor point near the musculotendinous junction

- farther apart = deeper

- do not place over bony prominences

TENS

transcutaneous electrical nerve stimulation

- externally applied, portable, for pain management

- biphasic pulsed current (electric tylenol)

burst mode TENS

Stimulation delivered in bursts or packages

Same mechanism as low-rate TENS

May be more effective since more current is delivered

- 100 Hz interrupted at a rate of 2-3 bursts per second

accommodation

due to prolonged subthreshold stimulation of nerve which limits the nerve's ability to reach AP

- transient increase in threshold because the prolonged subthreshold allows K+ channels to open, leaking K+ out, which prevents the nerve from depolarizing

adaptation

a decrease in response to a stimulus that remains constant over time

- decrease in firing rate of sensory receptors to constant unchanging form of stimulus

- can be rapidly adapting or slow adapting to describe the relative length of time to show an appreciable change in firing rate

habituation

a decrease in post synaptic firing rate in the dorsal horn in response to continuous repeated exposure of the sensory fibers to the same stimulus

- decrease in subjective sensation to the same stimulus

modulation

purpose of _____ with TENS

- used to prevent adaptation of sensory nerves of habituation

patients who use TENS for hours/day

who is modulation for TENS most useful for?

IFC

alternating currents

- frequency used to stimulate peripheral nerves and allows for decreased tissue impedance

- NEEDS 2 channels of differing carrier frequencies to create a "beat" frequency within the tissues

IFC sweep

frequency modulation

- helps to limit adaptation/short term habituation from occuring

IFC target

allows therapist to target beat frequency/intersection of channels to one area within the placement of the electrodes

- helps to focus on area of symptoms when it may be difficult to place electrodes/channel intersection over area of pain

indications for IFC

- pain management (acute/chronic)

- reduce muscle spasm

- muscle stimulation

- increased local blood flow

- reduced edema

advantages of IFC

Stimulates tissues deeper than a TENS unit

Larger coverage area than TENS

Possibly more comfortable than a TENS

possibly longer lasting relief

premod

single channel and only uses 2 electrodes

comfortable

simple set up

easily applied to smaller joints

HVPC and iontophoresis

what are the two main currents used by PTs for electrical current in soft tissue healing?

indications

______ for estim for soft tissue healing:

- to enhance wound healing in acute/chronic wounds

- pressure ulcers

- diabetic ulcers

- venous ulcers

- decrease edema/inflammmation

- transdermal medication delivery

applying current to the wound itself

how are wounds managed with electrical current directly?

controlling edema or delivering transdermal medication

how are wounds managed with electrical current indirectly?

galvanotaxis

the attraction of cells to an electrical charge

into

estim helps to facilitate the movement of specific cells _____ the wound

negative (cathode)

what charge is used for infected/inflamed wounds?

positive (anode)

what charge is used for wounds without inflammation or in the proliferative stage?

maximum

a range of 60-90 volts when using HVPC is when the ______ protein and DNA synthesis occurs

antimicrobial

HVPC and DC have _____ effects on wounds

circulation

estim enhances _____ even at sub-motor levels

- not only related to a muscle contraction

not

you can ____ use estim to control edema if it is due to a systemic disorder because increasing circulation can overload the system that is already failing/struggling

negative

the use of _____ polarity in HVPC slows edema formation under the theory that negative change repels serum proteins and decreases BF

motor

estim for edema due to lack of muscle contraction should be applied to a _____ stimulation level

true

T/F: NMES has been found to be more effective than IPC for venous circulation and to prevent DVTs

iontophoresis

use of electric current to promote transdermal drug penetration

- can be absorbed at sufficiently high rates and concentrations to be effective

- can be used to deliver drugs systemically

- main limitation is control of precise dosing

chronic stage III and IV ulcers that have not responded to standard treatment in 30 days

when does medicare reimburse PTs for use of estim for chronic wounds?

no

do you want to have a motor level stimulation when applying HVPC for edema due to inflammation?

physiological

______ effects of estim muscle contractions:

- strengthen muscles

- improve endurance

- slow/prevent muscle atrophy

- reduce spasticity

- help restore function

type I

physiologic contractions stimulate _____ ___ fibers

- smaller muscles activated before larger muscles

- lower force contractions (more fatigue/atrophy resistant)

- perform this type of contraction with electrical ones to optimize fiber recruitment and integrate strength gains

type II

electrical contractions stimulate ____ ___ fibers

- larger muscles activated before smaller muscles

- produce stronger and quicker contractions but fatigue rapidly (need longer rest time)

- rapid, jerky onset because all stimulated at once (use ramp up/down)

increased

physiologic contractions are increased with _____ resistance

current

electric contractions are increased with increased _____

- through pulse duration, current amplitude, and electrode size

innervated muscle

muscle has intact peripheral nerve

denervated muscle

a muscle that does not have nerve innervation

innervated

NMES is used for _____ muscles

denervated

EMS is used for _____ muscles

discontinued

occurs when EMS is _____:

- regression

- muscle atrophy returns

- decrease in muscle mass/strength

ramp time

increases muscle fiber recruitment and for it to be more comfortable for the patient