Week 3 Summary TI PDF

3.2 aspects of an electrical wave an uninterrupted AC vs DC bidirectional flow continuous unidirectional flow of ions or electrons for at least one second. • not synonymous w a positive current • is either positive or negative ions • electrons must change directions at least 1 time per secon...

3.2 aspects of an electrical wave an uninterrupted AC vs DC bidirectional flow continuous unidirectional flow of ions or electrons for at least one second. • not synonymous w a positive current • is either positive or negative ions • electrons must change directions at least 1 time per second. • if current doesnt change direction at least 1 time per sec.. current is aspects 1. 2. rise time 3. decay time 4. frequency 5. considered amplitude direct current. spoke about phases, cycles and poles for 4 (no phases) & 5 duration amplitude amplitude: strength of a current at any 1 point in time :magnitude of a current or voltage with respect to the isoelectric line • amplitude will also represent the magnitude of both positive and negative currents. rise and decay rate of rise: refers to how quickly phase reaches its max amplitude rate of decay: refers to how quickly the phase goes from peak amplitude to 0V (isoelectric baseline) • both rates are associated w ramp time of TES :time it takes a current to reach max intensity during each on cycle forms of rise and decay square and rectangle waveform shapes depict an instantaneous rise, a maintained peak amplitude, followed by an instantaneous decay triangular shape depicts a rapid, but not instantaneous rise & immediate rapid decay after reaching its peak amplitude phase and cycle duration phase; AC or DC position of waveform at a fraction of time period refers to the flow of a current in one direction at a set period of time • can be seen in DC and AC • duration of the phase speaks to the time it takes for the waveform to complete ONE direction of current flow, (+ or -) duration is expressed in seconds, • milliseconds, or microseconds cycle of an A/C current above is comprised of one negative phase and one positive phase cycle: AC one complete repetition of a sine wave measured in time from the beginning • point on the baseline to its terminating point pulse current is used for promoting muscle strengthening & activity bc PC is a series of pulses, muscle fibers can be stimulated frequently called tetanic contraction aka sustained muscle contraction unlike D/C currents, the cycle pattern of TES allows • for muscles to depolarize and repolarize before depolarizing again. modification of AC and DC currents in the therapeutic use of estem is periodic cessation of electron flow for a period of time before a following electrical event. • uni or bi-directional flow is called pulsatile current. • most AC or DC currents are not appropriate for therapeutic application- given pt tolerance and potential for tissue damage important application, the modif of either a A/C or • D/C waveform by intermittent determination of 1. phase duration 2. cycle duration 3. peak amplitude 4. peak to peak amplitude (bw + & -) 5. interpulse interval 6. intrapulse interval electron flow followed by another electrical event means depending on the waveform, the term pulse so sorry didnt know how to make this shorter is used instead of either a cycle or phase. pulse can be used interchangeably with phase • (sometimes) types of pulsed currents 1. 2. biphasic monophonic deviation from an isoelectric line of an electrical current in one direction for a short period of time. deviates from the isoelectric line first in one direction, so positive, then negative, up: positive down: negative 3. burst • if a pulse is one second or longer duration, it's considered to be interrupted D/C current, not a pulsed current. monophasic pulses are repeated with an interpulse interval • instant rise • maintained max amplitude • instant decay biphasic repeated with an interpulse interval • has two separate phases of negative and positive electron flow. • pulses are not interchangeable w the term cycle. burst currents when 2 or more consecutive pulses are separated from the next series of consecutive electrical bursts • primary method of delivering therapeutic electrical stimulation. frequency parameters use: pulse per second (PPS) frequency 1. non-pulsed currents: # of cycles/sec (CPS) 2. pulse current: # of pulses/sec (PPS) • how many times one cycle of a waveform is repeated per second, it is measured by the unit hertz, or Hz take-aways - direct current: continuous unidirectional flow of ions, or electrons, for at least one second. -Alternating current : uninterrupted bidirectional flow of ions that changes polarity at least one time per second. -The depiction of an alternating current is a wave superimposed over a horizontal line. horizontal line depicts an isoelectric baseline, which means there's no charge. -Anytime the waveform deviates upward from the electrical line, this indicates a current flow in the positive direction. -When the waveform moves below the line, here, this is when the current flow is negative. -The parameters of a waveform include the amplitude, rise time, decay time, frequency, and duration. -An important modification of A/C and D/C currents in the therapeutic use of electrical stimulation is the periodic cessation of electron flow for a period of time before a following electrical event occurs. -This is called a pulsed current, and it is the most common form of therapeutic electrical stimulation used.