Week 3 Summary TI PDF

3.1 intro to TES basics of electrical current charge: obtained by a net charge in concentration of the number of electrons within a system net loss of electrons = + charge collective gain = - charge ion: a molecule that has gained or lost an electron 4 fundamental properties of an electrical charge...

3.1 intro to TES basics of electrical current charge: obtained by a net charge in concentration of the number of electrons within a system net loss of electrons = + charge collective gain = - charge ion: a molecule that has gained or lost an electron 4 fundamental properties of an electrical charge 1. 2 types of charge: + & - 2. like charges repel, opposites attract 3. charge is neither created or destroyed 4. charge can be transferred from one object to another to another current: quantity or amount of ion or electrons flowing at a given time • international unit of current: amp • system of opposite charges electrons move from a negative charged pole ( higher concentration of electrons) to a positively charged system (pole w fewer electrons) cathode vs anode cathode: - charge pole anode: + charged pole electric field: force that results by separation of charges, mates whether its attraction or repulsion, creates a system of potential energy voltage accumulation of electrons at 1 point in circuit a. creates deficit at another point b. potential every voltage is a resulting electro-motive force created by difference • in potential • 2 diff charges on a battery create a concentration gradient • potential energy created in an electrical current is described by a force of attraction or repulsion voltage represents the driving force that changes the relative concentration of electrons in a closed system flow of electrons from the negative pole( excess of electrons) >> • pos pole (deficiency of electrons) >>create a current (measured as voltage) conductor vs insulators conductor: material that allows free mvmnt of electrons insulator: material that disrupts free mvmnt of electrons ex: rubber skin is a conductor of a current and fat is an insulator, skin will • mediate the flow of current while fat will disrupt it aspects of electrical wave forms; negative and positive • look at her! used to determine the physiological impact of therapeutic electrical stimulation. 1. amplitude 2. rise time 3. decay time 4. frequency 5. duration sinusoidal waveform is an AC current types two prim types of electrical current (flow or time): 1. alternating current (AC): uninterrupted bidirectional flow of ions that changes direction at least 1 time per second 2. direct current (DC): continuous unidirectional flow of ions or electrons for at least 1 sec -modes of neuromuscular stimulators a. FES: fxnal electrical stimulation b. NMES: neuromuscular stimulation c. TENS: transcutaneous electrical neurological stimulation d. EMS: electro muscular stimulation -microcurrent electrical nerve stimulation- MENS • MENS differs from NMES bc it uses a much smaller current, so it will not activate sensory or motor nerves • numerous preprogrammed parameters that offer varying physiological benefits take-aways 1. a current is the quantity or amount of ion or electrons flowing at a given time—the international unit of current is amperage. 2. voltage is a resulting electro-motive force created by differences in potential. 3. a conductor is a material that allows the free movement of electrons, while an insulator disrupts the free movement of electrons. 4. the aspects of electrical waveforms are used to determine the physiological impact of therapeutic electrical stimulation. 5. direct current is the continuous unidirectional flow of ions or electrons for at least 1 second. 6. alternating current is the uninterrupted bidirectional flow of ions that changes polarity at least one time per second. 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. 3.3 TES treatment Indications TENS indications transcutaneous electrical neuromuscular stimulation- TENS has not been found to be more or less effective in treating different types of pain, such as acute or chronic. • research assessing effects of TENS: using handheld units • underlying mechanism for pain mngmnt thru TENS is via 1. sensory nerve stimulation 2. motor nerve stimulation 3. tissue healing 4. edema management nociceptive modulation TENS does not manage pain, but the central processing of • nociception sensory nerve stimulation pain managment a. gate control theory b. descending inhibition, central mechanisms 2 prim category for TENS 1. high frequency (conventional tens): sitmulates large A beta fibers • promote local peripheral nerve or dorsal horn nociceptive modulation thru gate control theory mechanisms pts perspective: high frequency tens is better tolerated and can be used • during active mvmnt 2. low frequency (acupuncture tens): used to stimulate muscle and produce central mechanisms for nociceptive modulation due to higher intensity levels and activation of muscles, is not • recommended during mvmnt offers several hours of pain relief • -due to acting on descending methods of nociception modulation or central mechanisms motor nerve stimulation 1. muscle strengthening • a. increase force of muscle contraction motor nerve which has a lower b. overload threshold for activation than the principles of tissue overload: actual muscle states that the progressive increase in wt, frequency or # of reps of an exercise will promote tissue adaptation 2. muscle re-education a. contraction often inhibited b. not to increase force of muscle contraction using TES on innervated muscles, reflect activation of -when used in conjunction with exercise or alone later stages of healing little to no difference bw TES and exercise for strength • higher the strength of TES the greater -goal is not to increase force of muscle contraction amount of strength gained. -intensity of currents match demands of specific fxnal talks • (no overload priniciple) -only applies to tissue that is innervated • using TES for de-innervated tissue: higher intensity of current needed to directly stimulate involved muscle • increase force & muscle contraction..only if increasing intensity of TES during tx acuity & tx found to be more beneficial in initial periods of rehab when voluntary exercise may be difficult TES for strength training: special attention needed for location as well as strength of current. c. re-establish dormant motor pathways : incorporated in POC of pts w inabilities to intentionally activate their muscles • could be from stroke, head trauma or SCI 2 prim modes of TES 1. NMES 2. FES tissue healing & edema control 1. preventing and reducing inflammation a. acute management b. chronic management 2. tissue healing a lot of research for tissue healing • greatest effects of healing found in pressure ulcers (especially in later stages of progression) -use of selective polarity to promote specific biological effects tied to normal stages of healing ex: neutrophils, macrophages and lymphocytes are charged and pulled toward oppposite charge • endothelial cells orient themselves in line w fields created by electrical stimulation, and fibronectin, cyclic AMP, and protein kinase activities increase in response to the electrical stimulation field. • current is applied directly into wound and/or area around it • w consideration to polarity thought that positive charges are used to enhance early stages of healing, while negative charges are used to promote healing in later proliferations of healing. high volt pulse currents are most commonly used and supported current for tissue healing contraindications and precautions contraindications 1. pacemaker: application to trunk or heart regions: defibrillators, and/or other stimulators such as phrenic nerve and/or urinary bladder stimulator 2. carotid bodies: any replacement of electrodes at the anterior lateral aspect of the neck 3. peripheral vascular disease: including arterial and venous thrombosis, 4. pregnancy: especially suffering from miscarriages 5. phrenic nerve, eyes or gonads: direct application 6. hemorrhages Precautions 1. cardiac dysfunction: including but not limited to hypertension and tachycardia. 2. impaired cognition, communication or sensation 3. neoplasms 4. neuropathy 5. compromised skin: distinction here on the compromised skin is for tissues that are vulnerable to hemorrhaging or those with a hematoma 7. active osteomyelitis Take-Aways 1. TES has been found to offer therapeutic benefit for 3 reasons a. Sensory Nerve Stimulation for pain management. b. Motor Nerve Stimulation to promote movement and to increase muscle force generation. c. Tissue Healing and edema management 2. As with any treatment modality, there are precautions and indications for their use. Know these! 3.4 Therapeutic Eléctrical Stimulation (TES) Treatment Parameters affect muscle contraction Modes of TES 1. Neuromuscular stimulators - neuromuscular electrical stimulation (NMES) - functional electrical stimulation (FES) - transcutaneous electrical neuromuscular stimulation (TENS) 2. Microcurrent electrical nerve stimulation (MENS) does NOT affect muscle contraction TES treatment parameters therapeutic electrical stimulation • maintain/increase muscle size & overall fxn • good for OP, acute rehab for denervated muscle NMES/EMS interchangeable • promote improved efficiency in muscle contraction/activation • for loss of proprioception • weakness • coordinated muscle contraction following an injury • increase overall size/fxn of muscle • IF NOT paralyzed can be coordinated w/ or w/ active mvmt textbook: EMS stimulation of denervated muscle w/ no references others: NMES w/ parameter modification can be used for both innervated/denervated Pattern of NMES predictable/repeating pattern • FES • promote mvmt • assist in ambulating • indirectly promote CV conditioning • slow bone demineralization following neuro trauma Settings that use FES neuro rehab • - electrical stim mediated by external sensor that turns on current when requirements met - ex: heel sensor, activates when pt puts weight on it, promotes gastroc activation during ambulatory training TENS (transcutaneous electrical neural stimulation) • most common • activate sensory n to manage pain • DOES NOT activate muscles • lower intensities than NMES/EMS Microcurrent electrical stimulation • • VERY low current intensity to promote physiological response in tissue DOES NOT stimulate motor/sensory n - doesn’t manage pain or rehab muscles • mediates tissue healing Waveforms & Polarity • Monophasic • Biphasic • Alternating Current • Direct Current All characterized by ability to affect biological tissue by waveform’s polarity or average charge cumulative charge of each phase in treatment session determining waveform’s average charge charge determines magnitude of physiological • effect when stimulation to active tissue DC; positive polarity of 5 milliamps • same polar zone at same amplitude for EVERY phase (1) • average charge = +5 AC: biphasic w/ equal amplitudes in phase duration of +5 and -5 average charge = 0 (cancel each other out) • All the ones that don’t end in 0 net charge • direct current • monophasic pulsed • asymmetrical unbalanced biphasic current • symmetrical has average charge of 0 • asymmetrical not 0 Monophasic waveforms • interphase/interpulse intervals long enough to control negative side effects to net charges while being therapeutic - interpulse phase: like rest periods b/w set of exercises • healing • edema control • muscle contraction • common use: high voltage current Direct current • no net charge • DOES NOT have interphase/pulse intervals • charge builds on tissue • HARM potential: discomfort, pain, tissue damage - aka medical galvanism • DC precaution • form of treatment using electrical current to provoke muscle activation • stimulates tissues that have high thresholds for activation DOES NOT stim nerves • stimulates muscle membranes directly Preferred modalities for pain & muscle contraction biphasic & alt currents • Asymmetrical biphasic current: • dont have identical durations/amps • average charge = 0 bc both phases equal in amp and duration some more sensitive to ion mvmt b/w electrodes & skin - ex: denervated muscles • medical galvanism: any causing tissue breakdown • more popular in high charge currents 3.5 TES Treatment Parameters 2 general rule: higher freq = greater Frequency: how many times one cycle of waveform repeated per second strength of current Impulse current = # of times 1 impulse of waveform repeated per second Muscle contractions • • below 85 pulses per second = most effective activating muscle higher freq - muscle fatigue - greater muscle activation nothing over 100 bc diminishing return/poor subj tolerance strength of current Pain control: freq depends on theoretical physiological effects • Lower = 1-10 pts, lower waveform amps, shorter pulse duration • freq • intensity • pulse duration - pain management - prevents muscle contraction • Higher = 80-150 pps - gate control - central biasing/descending models of nociceptive inhibition - reduce pain after administration of therapeutic electrical stim Intensity = max amp of wave • clinically = pt tolerance - want it the highest they can handle • sub max contraction for pain management • increased to promote muscle contraction during NMES EMS • deeper penetration of electrical currents • increased effect of n and muscle depolarization leading to noxious stim/tetany in muscle = pt uncomfy Duty Cycle (on time/tot treatment time x 100%) on = pulses/burst off = nothing • on & off times of current: normally 2-5 seconds per interval • therapeutic effect/muscle reeducation = 1:5 • 10 sec on 50 sec off for 60 seconds = prevents muscle fatigue (can do smaller ratio if pt can handle) • 1:1 - edema - calm muscle spasms Ramp: increase/decrease in intensity of a series of pulses Ramp up = intensity increased Ramp down = intensity decreased Rise/Fall = time it takes for intensity in single phase to reach max amp and then from max reach isoelectric line Clinical app • long ramp - less current for pt • shorter ramp up/downtime - muscle contraction • ramp up 1-4 sec - muscle contraction, reaching appropriate intensity for muscle activity faster • ramp time 4-8 sec - comfort, calm spastic muscles • FES - max intensity immediately for fxnal mvmt NO RAMP TIME Pulse Duration • longer pulse = more tissue stim by current & motor neurons • gait control mechanisms for nociception = 50-125 microseconds • denervated muscles, depolarization of muscle membrane = long pulse duration - 200-600 microseconds or as long as 10 milliseconds - can also be helpful for descending inhibition mechanisms for nociception - normally for noxious stim Precaution • always watch pt w/ high pulse duration • can produce motor response • can perceive as painful stim help me.. feeling like diesel rn Why increase pulse duration LOL • increase amp for longer time • stimulate structures w/ higher threshold • all depends on pt discomfort Strength Duration Curve combos of stim amp & duration that elicit motor response w/ muscle activation denervated muscle • more amps/duration to active motor points in healthy/partially generated muscles • all depends on anatomy 10-20 min • avoid fatigue (normally EMS) • aim to improve muscle strength NOT neuromuscular reeducation 45-60 min 5x week • depends on injury/ device 20-30 min 30 min multiple times a day