Biofeedback

concept of biofeedback

turning muscle activity into visual feedback, auditory feedback

purposes of biofeedback

muscle facilitation or relaxation

electrode

black as ground or common in the middle, red and black on outsides, 2cm apart

placement of electrodes for biofeedback

along muscle fibers - specific to muscle, or across muscle fibers - less specific but helps relax muscle

when you activate a muscle, you also activate

motor units that create voltage

more motor units activated =

more voltage

V1 =

MU activity and noise

V2 =

MU activity and noise

differential voltage measurement

V1-V2 (cancels out the noise)

order of signal processing

raw signal amplification to make larger, rectification to get the absolute value, filtering to get rid of the noise/make smooth, integration of time constant (the feedback we display to the patient)

time constant

how often we give the pt feedback

time constant for muscle facilitation

0.1sec (10x/sec)

time constant for muscle relaxation

0.5sec (2x/sec)

feedback

can be visual, auditory or via NMES activation (use arbitrary goal and use stim to meet the goal if pt cannot)

sensitivty

the ceiling/top of the graph - set at a sensitivity that would offer meaningful feedback to the patient

mode option

continuous or work/rest

application examples for muscle facilitation

TKA, gait, amputees

application examples for muscle relaxation

spasticity/tone, PROM