|Modalities Study Guide
Tissue Healing (3 Phases)
1. Inflammatory: 0-6 days
-Acute: early phase
-Chronic: late phase
-Any part of the damaged area will go through an inflammatory response
2. Proliferation (repair): 4-21 days
-Granulation tissue formation
3. Remodeling: 14 days
-Everything in the proliferation phase is maturing
**Inflammatory Response – occurs in vascularized tissue and is essential for tissue healing. Response is non-specific (same pattern throughout the body). Brings phagocytes (neutrophils and monocytes to the injured tissue). Phagocytes destroy bacteria and rid of dead tissue.
0-2 weeks = Acute Phase
2-4 weeks = Sub-Acute Phase
4+ weeks = Chronic Phase
Acute Inflammatory Response – modality use to limit swelling/reduce pain
-Typically lasts 24-48 hours and is complete within 2 weeks
-Cardinal signs of response:
1. Swelling (tumor)
2. Heat (calor)
3. Redness (rubor)
4. Pain (dolor)
1. Vascular – vasoconstriction (NE) to slow blood loss, edema, formation, occlusion/”stickiness” due to endothelin, neutrophilic margination, vasodilation (remove pathogens) – filtration outward (30-40 mm Hg and a decrease in reabsorption on venule side of capillary bed <28 mm Hg)
2. Cellular – plasma, red blood cells, leukocytes – slows local BF, aid margination
3. Hemostatic – control blood loss
4. Immune – mediation by cellular and humoral factors
***Treatment of Vascular Response – offset outward filtration pressures (30-40 mm Hg)
1. Compression – adds inner pressure to offset
-Elastic wraps: 50% overlap, 50% stretch (40 mm Hg)
-Garments (18-60 mm Hg)
*Wrap distal to proximal
-Intermittent Pneumatic Compression (IPC)
*First Treatment = 40-50 mm Hg
*Never go higher than Diastolic – 10 mm Hg
*Treatment duration 45-60 minutes
2. Elevation (above 45 degrees) – above heart
Types of Pain
Acute - < 6 weeks, localized
Chronic – Difficult to localize, pain persists after healing
Referred – perceived in area of body not related to pathology
Radicular – irritation of nerve roots, cause pain over specific areas (sharp, shooting)
Trigger Points – hypersensitive areas within soft tissue
***Neurons Significant to Pain Theories
A-Beta – Fastest fibers (36-72 m/sec), target these with most modalities
A-Delta – “Fast Pain,” brief, well-localized small myelinated
C – “Slow pain,” poorly localized
Ascending Pain Theories:
**Specificity Theory – Each receptor responds to a specific stimulus.
-Each receptor propagates along specific pathway to SC
**Pattern Theory – intensity and frequency of AP interpreted by brain
-AP coding determines how sensation will be interpreted
**Gate Control Theory – A-Delta/C fibers stimulated due to tissue damage/irritation
-Substance P released, AP propagates upward to SC
-Use of modalities stimulates A-Beta fibers
-A-Beta stimulates interneurons that inhibit the closure of the T-cell, which inhibits tramission of A-Delta and C fibers.
Descending Pain Theories:
**Central Biasing Model – A delta and C stimulated.efferent fibers (from midbrain, pons, and medulla), which send impulses down. These impulses synapse with enkephalin interneurons, release enkephalin, block pain. Used during brief, intense stimuli.
**Endogenous Opioids – stimulation of A-Delta/C fibers stimulates release of endogenous opiates, releases endorphins and dynorphin from brain (pain relief lasts several hours) – BEP produced (neuroactive peptide produced in the anterior pituitary and periaqueductal grey area)
Cryotherapy – can stop bleeding/inflammatory cycle from getting too out of hand, pain threshold goes up (usually applied 10-30 min)
-Cold packs, ice massage, cold immersion, vapocoolant sprays, etc.
-Heat abstraction – heat removed or lost from an object
-PRIMARY GOALS: limit edema, reduce pain, cause muscle relaxation, reduce inflammatory response
transfer principle of heat – heat absorption heat removed or lost
**Methods of heat energy transfer
-Conduction – most methods we use – ice pack, ice massage, water immersion
*transfer of heat by direct interaction
*The more layers (even fat), the longer you have to leave it. Fat is an insulator (does not conduct heat)
*Avoid prolonged icing at areas of nerves or on bony prominences (ulnar/common peroneal) ex- ice massage
-Convection – movement of molecules across body – cold whirpool, fan
*has to be moving/flowing
*whirlpools use conduction and convection- moving around in a cool immersion bath
-Evaporation – conversion of liquid or solid into a vapor (Vapocoolant sprays)
Increased blood viscosity
Increased smooth muscle tone
Decreased vasodilator metabolites
Post-traumatic Edema & Inflammation
Cold for the first 24-48 hours after injury includes:
Vasoconstriction decreases hemorrhage which limits edema.
Less inflammation & pain.
A decrease in metabolic rate, and thus a decrease in secondary tissue hypoxia.
Peripheral Nerve Effects
Cold decreases peripheral nerve conduction velocity & synaptic activity.
Increases the pain threshold
Nerves of various diameters & degrees of myelination have different sensitivities to cold stimuli, i.e. cat studies
Ulnar nerve study
CAUTION: cold-induced nerve palsy (Peroneal Nerve at the fibular head & Ulnar or Radial Nerve at the elbow)
--Temp gradient – the bigger difference b/w temp of skin and object putting on skin, the bigger effect you will get
--Time of exposure – the depth of tissue you are going after, the longer you need
-skin temp changes occur within 1 minute (can range up to 30 minutes for tissues 1.5 inches deep)
--Thermal conductivity – higher water content a tissue has, the better the conductivity (ligament and adipose not very good conductors, but muscle and skin are)
**most efficient way to cool down is a bag of ice with wrap (must go through phase change) – lasts longer than gel pack
Effects of Cooling:
Hemodynamic – vasoconstriction, if BV decrease by half, resistance increases by 16, decrease local BF, thickens blood, slows bleeding, prevents overload by decreasing histamine and prostaglandins.
Post-traumatic Edema and Inflammation – VC decreases hemorrhage which limits edema, less inflammation/pain, lowers metabolic rate/demand for blood
Peripheral Nerve effects – decreases conduction velocity/synaptic activity, increase pain threshold, PROLONGED nerve transmission so low that it may cause permanent damage
Neuromuscular effects – decrease spasticity, tone, fiber discharge
Muscular strength effects – short duration of ice massage increased quad strength. Icing >20 minutes decreased isometric strength
Patient’s Physical Responses – CBAN
-should take about 5 minutes to go through
-coldness, burning, aching, numbness
Indications – edema, contusion, hemorrhage, immediate/acute ITIS
Studies on Vasoconstriction:
**Folkow, Fox, Krog – put an arm in cold water bath – 14 mm/min to 2 mm/min (significantly decreased BF)
**Cobold and Lewis – 10 minutes, 56% average decrease in BF, took 25 minutes to return to normal
HUNTING RESPONSE – MAINLY IN LE - our tissues think they will be damaged due to prolonged constriction, so the vessels dilate in order to warm up the tissue. Goes other way of the effect you wanted. Cutoff is below 50 degrees F (10 degrees C).
***Precautions – hypertension, CRPS (Complex Regional Pain Syndrome), decreased sensation, decreased wound healing, prolonged application, psychological response
***Contraindications to Cold
Raynaud’s – blue, black or white in distal areas of body
Buerger’s – Big toe affected first
History of frostbite to treatment area
Severe CV or respiratory problems
PRICE – Protection, rest, ice, compression, elevation
Cold Immersion Bath –
-UE – 55-65 degrees
-LE – 40-50 degrees
**COLD PRESSOR EFFECT (below 50 degrees) - for UE 55-65, LE 40-50.. can cause changes in blood pressure or
-ice bag is more aggressive than a cold pack
- ice massage conduction 10-12 minutes
do not do on bone knuckles on the fingers.. soft tissue
cold immersion 55-65 le 40-50 can do on bones
THERMAL AGENTS – applied locally to promote relaxation, reduce pain, increase BF, facilitate tissue healing, and prepare stiff joints and tight muscles for exercise.. the heat the flows through tissue varies with the type of tissue example- adipose
-physical principle of heat
- changes in surface tissue temperature
-*Stimulate A-Beta fibers, help relax muscles
*1-3 cm depth=superficial heat(moist heat pack, paraffin, fluidotherapy, infra-red)
*up to 5 cm depth = deep heat
-Conductivity = heat flowing through tissues. Adipose and air are poor conductor, water and muscle are good conductors (H20>bone>mm>adipose>air).
-Specific heat = the amount of energy to make 1 gram 1 degree Celsius warmer. The lower specific heat, the less chance of a burn.
**CONDUCTION – paraffin, moist heat pack
-Paraffin –LOWER specific heat than water (takes less energy to raise temp)- less chance of burns
*126-134 degrees F (paint on, glove method most common)
*15-20 minutes per treatment
*Superficial heat method – up to 3 cm
*Wax heats slower than water, low conductor, less chance burn
*Molten state allows even distribution of heating, treats distal extremities (RA)
dip and glove
*Disadvantages: Effective for distal extremities only. Patients are passive entire time. Heating only lasts 20 minutes
-Most Heat Pack – Canvas covered pack with hydrophilic silicate
*150-170 degrees F (reaches max temp in 6-8 minutes)
*3 sizes: standard (knee, thigh, calf), cervical (neck, shoulder, elbow, wrist), and oversized (spinal areas)
*Advantages: easy to prepare and apply, variety of sizes, treats large areas, comfortable heat, inexpensive
*Disadvantages: No method of temp control once applied, does not conform to body, hard to secure, does not retain heat for >20 minutes, pt is passive, may leak
***CONVECTION METHODS – bulk movement of cellulose particles (fluidotherapy)
*Fluidotherapy – dry heat, finely divided cellulose particles
-Conductivity and specific heat allow for higher temperatures than water
*102-106 degrees: Hypersensitive
*106-112 degrees: for LE
*112-118 degrees: for UE
- Advantages: More active than other modalities, may help desensitize patients who are hypersensitive, dry heat, temp can be controlled, comfort, pt can perform movements inside machine
-Disadvantages: expensive, claustrophobia, intolerance to dry particles, only accommodates distal limbs, open wounds must be dressed
-INDICATIONS: sub-acute or chronic conditions, CRPS (desensitization)
***RADIATION – conversion of heat into electromagnetic radiation (infra-red lamp)
*Biophysical effects of temp elevation dependent on:
-extent of temp rise, rate of tissue temp rise, volume tissue exposed, conductivity of tissue
*Tissue should elevate 104-113 degrees F for increased BF (hyperemia)
**HEAT on Metabolic Activity
-metabolic rate increases 2-3 times for each 10 degree temp increase
**Temp > 113-122 will burn tissues
-Increased O2 uptake by tissues
**HEAT on Hemodynamic Function
-VD, increased BF to area, release chemical mediators to temp elevation
-Landis-Gibbons Reflex –application of heat to one area of the body results in an increase in cutaneous BF and other reactions in another area (can appear contralaterally)
*Ex: heat low back, BF increased locally and also in distal extremities
-decreased blood viscosity, increased lymphatic drainage (venous too)
**HEAT on Neural Response
-Elevates pain threshold, increased sensory nerve conduction velocity, decrease muscle spasm, decrease in gamma activity – decreases stretch of muscle spindle which reduces afferent firing of alpha-MU…reduces muscle spasms
**HEAT on Skeletal Muscle Activity
-decreased muscle strength and endurance
-DO NOT know why, perhaps mm in relaxed state?
Biophysical effects – Temperature Elevation
The following physiologic responses are important to understand when considering a heating modality for therapeutic purposes.
These responses include alterations in:
Increased metabolic rate
Cell activity & metabolic rate increase 2 to 3 times for each 10 ˚C (50 ˚F) temperature increase
Energy output will increase with increase temperature
Temperature > 45 - 50 ˚C (113 - 122 ˚F) will burn human tissues
Increased O2 uptake by tissues
Increased metabolic rate causes increased O2 tissue demand
Increased production of CO2 & metabolic by-products
Increased blood flow to the area
Increases the delivery of substrate & O2
Skin blood flow: Core temperature
An axon reflex
Sensory afferent impulses cause the release of a vasoactive mediator
Release of chemical mediators due to temperature elevation
Heat produces a mild inflammatory reaction
Local spinal cord reflexes
Heat-activated cutaneous sympathetic afferents decrease the post ganglionic sympathetic adrenergic nerve activity
Reflex Heating (aka Landis-Gibbons Reflex)
Application of heat to one area of the body that results in an increase in cutaneous blood flow & other reactions in another area.
i.e. Heat low back: blood flow is increased locally & reflexively in the distal extremities
Decreased blood viscosity
Increased lymphatic & venous drainage
Elevates the pain threshold (Gate Theory)
Increased sensory nerve conduction velocity
Most pronounced changes in the first 1.5 - 2.0 ˚C
Decreased muscle spasm (Pain-Spasm-Pain Cycle) via gamma efferent activity
Decrease in gamma activity decreases the stretch on the muscle spindle which reduces afferent firing from the spindle
The indirect result is a decrease in firing of the alpha motoneuron reduction in muscle spasm
Skeletal Muscle Activity
Decreased muscle strength & endurance
Demonstrated in studies but no explanation as to why
Study: Quad strength/endurance reduced after immersion in a whirlpool that ranged in temperature from 104 -109 ˚F
Collagen Tissue Physical Properties
Alters viscoelastic properties
Increase elasticity, Decrease viscosity
Decrease joint stiffness
Increase muscle flexibility
Negligible heating of muscle tissue
Greatest degree of heating occurs in the skin & subcutaneous tissue within 0.5 cm of the skin surface
In areas of adequate blood supply, temperature will reach its maximum within 6 to 8 minutes
Observe for changes in vital signs
I.e. Increase HR, Decrease BP, Increase PMV
May decrease tolerance to exercise if sweating & changes in BP occur
Caution: watch for these responses in patient’s who have metabolic problems or who are generally deconditioned
Advantages/Disadvantages of each one
Sub-acute (2 weeks to 1 month) or Chronic (> 1 month to years)
Arthritis, i.e. RA/OA
Tendonitis, bursitis, tenosynovitis
Adhesive capsulitis or adhesions of superficial joints
To promote relaxation especially before traction or joint mobs
Decrease skin impedance pre-electrical stimulation
Sub-acute or Chronic Conditions (Fluidotherapy)
Desensitization (i.e. CRPS)
Combination of heat & exercise desired
Combination of heat & manual techniques desired
Treatment to a distal bony extremity
Sickle Cell Anemia
Presence of deep vein thrombophlebitis (aka thrombosis) (DVT)
Moderate to severe cases of peripheral vascular disease (PVD)
Practical check sheets
Case scenario application
**HEAT on collagen tissue: increase elasticity and flexibility, decrease joint stiffness
**HEAT on Systemic Effects: increase HR, decrease BP
-Can result in edema if applied too soon post-injury
**Indications for heat:
-sprains, strains, arthritis, spasms, tendonitis, bursitis, tenosynovitis, pain, frozen shoulder, promote relaxation,
**Precautions: DVT, PVD,
**Contraindications: areas of decreased or loss sensation, scar areas, skin infections, open wounds, cannot report heat, skin or lymphatic cancer, excessive HTN (160/90), hemophilia, steroid therapy (long term), CV or Respiratory problems,
*No difference in effects for wet vs dry heat. Dry heat elevates surface temp to a greater degree. Moist heat elevates temp to a slightly deeper level. Moist seeps deep.
*May have adverse responses in edema and superficial tissue burns
*Contrast baths – alternate VC and VD: stimulates peripheral BF and healing
-about 20 minutes, warm = 100-110 F, cold = 55-65 F
*Indications – impaired venous circulation, inflammation, sinus headaches
*Contraindications – malignancies, hemorrhage, cold hypersensitivity, PAD
*HEAT VS COLD, consider: stage of injury, area of body treated, medical status, pt preference
ULTRASOUND – acoustic energy at frequencies >20,000 Hz
*Positive molecules adjacent to the energy source (condensations) – higher density of molecules within a tissue
*Negative molecules in the same region (rarefactions)
*Conversion – converting electrical energy to sound waves via a transducer.
*Sound energy can be transmitted, absorbed, reflected, and refracted.
Piezoelectricity Effect – phenomenon in which the crystal generates an electric voltage when mechanically compressed
Reverse Piezoelectric Effect – if the crystal is expanded rather than compressed, a voltage of the opposite polarity is produced
*FREQUENCY – determined by the frequency of the alternating current
-1 MHz: target tissue up to 5 cm beneath the skin
-3 MHz: target tissue up to 2.5 cm beneath the skin
*MODE– two types (does not determine depth)
-Continuous – US waves delivered as an un-interrupted stream
-Pulsed: US waves delivered with periodic intervals in which no energy is flowing
*For acute injuries when people may have inflammation
*INTENSITY – strength of the US wave is determined by quantity of energy produced (measured in W/cm2)
-Range between 0.2-2.0 W/cm2
*FOR 3 MHz, use 1.5 W/cm2 for 3-5 minutes
*FOR 1 MHz, use 2.0 W/cm2 for 7-10 minutes
*FOR THERMAL, 1.5 – 2.00 W/cm2
*FOR PULSED – 0.5-1.0 W/cm2
Effective Radiating Area (ERA) – area of US beam as it exits the metal end plate ~ 10 cm2.
Beam Nonuniformity Ratio (BNR) – ratio at the highest intensity (special peak) compared to the average.
*Larger the BNR, the more chance of a hot spot/burning a patient. Anything above a 6:1 ratio is considered poor. Anything below a 5:1 is good.
*BNR 2-5 – 1 cm/sec
*BNR 6-9 – 4 cm/sec
Impedance – material’s ability to transmit sound; related to the molecular density and structure of the material.
*LOW – high transmission, little absorption (blood, other body fluids)
*HIGH – low transmission, high absorption (bone, collagen, tissues)
Cosine law – angle you approach the skin at should be perpendicular to ensure efficient transmission of ultrasound into layers.
-increase cell and vascular wall permeability to calcium and sodium ions.
-alter fluxes across membranes, leading to less leakage from capillaries into interstitial spaces (decrease edema)
-cavitation – changes in membrane permeability
-stimulation of tissue regeneration
-promote soft tissue/bone repair
-stimulates histamine release
-decrease inflammatory phase
-stimulate fibroblasts to secrete collagen
-accelerates wound contraction and healing of dermis
-decrease formation of hypertrophic scarring
THERMAL EFFECTS (same reasons you would pick superficial heat)
-increase peripheral BF
-increase metabolic rate
-increase O2 uptake
-elevate pain threshold
-increase tissue extensibility
-decrease muscle guarding, increase heating, skin temp, change sensory and motor nerve conduction
MUSCULAR EFFECTS – rate and magnitude of muscle heating depends on treatment intensity, duration, and frequency
CONNECTIVE TISSUE EFFECTS –
*Chan and colleague’s “window of opportunity” - >4 degrees C increase was reached half way through a 4 minute treatment and was maintained for an additional 4 minutes once treatment stopped (maximize stretching during and after treatment for 3-4 minutes)
*larger temp increases may be achieved at faster rates when using US on CT such as tendons, jt capsules, adhesions, and scars (greater than 4 degrees C needed to improve CT extensibility)
HEMODYNAMIC EFFECTS – increase BF, supply of nutrients, tissue repair
NEUROLOGIC EFFECTS – inconclusive for motor nerve velocity
INDICATIONS: subacute and chronic soft tissue inflammation, jt contractures, muscle spasm, neuroma, loosen scar tissue, trigger point areas, plantar warts, acute injuries, bone healing, tissue repair (things with a small area you may want to heat)
PRECAUTIONS – areas with sensory deficits, patients unable to clearly communicate, impaired local circulation, plastic or metal implants
CONTRAINDICATIONS – POOOP C ME
-Presence of cancer within last 5 years, pregnancy, myositis ossificans, over sites of insulin injections, over unhealing fracture sites, epiphyseal growth plates (<18 years of age), over post-laminectomy, cemented prosthesis
Advantages – target tissue specific, preferential form of deep heat.
Disadvantages – only treat small areas, constant supervision, does not conform well to irregular structures
*Effects – separation of vertebral bodies, combination of distraction and gliding of facet joints, stretching ligaments and muscles, widening of the intervertebral foramen, straightening spinal curve
Continuous (bed rest) – uses bars, pulleys, and weights in bed. Used at home or an institutional setting. Low weight, long duration, maintains immobilization during acute cervical or lumbar pain, rarely used.
Mechanical – applied while lying on a table by an electrical device
-Duration: 10-30 minutes
-Table may accommodate traction in flexion, extension, lateral flexion, or prone
Manual – applied by hands.
-Duration: 15-60 seconds or a sudden thrust
Positional – Patient positioned to cause a longitudinal pull on spinal structures. Alleviates pressure on entrapped spinal nerve and promotes paravertebral muscle relaxation
- Great for giving someone a HEP. For thoracic spine, do neural tension (slump test)
Gravity-Assisted Traction – applied to the lumbar spine. Adjustable table tilts to vertical position. Lower half of the body hangs free using gravity to provide the distraction
Inverse Traction – pt hangs in an inverted position by boots/scraps. Duration: 5-15 min.
*Separate bony structures, vertebral bodies/facets.
*Decompress impingement of peripheral nerve root. Decrease or centralize intradiscal pressure, decompress articular cartilage, decrease muscle hypertonicity, transient, not-segment specific
PHYSICS OF SPINAL TRACTION:
-Force is applied longitudinally. The resistive forces that oppose the motion of traction cause friction. Direction of friction forces parallel and opposite to the distractive forces
-Coefficient of friction: the constant frictional forces present when applying traction (0.5 for the human body lying on a mattress). It will require ½ the patient’s BW to move horizontally in a bed. ½ the BW is below L3. It will cause greater than 1/4th BW to cause distraction of lumbar spine
*Nerve root impingement, stenosis, hypomobility or impingement of facet joints, subacute or chronic joint pain, any condition relieved by widening disc spaces or vertebral foramen, DJD.
*Can use traction to nourish the joint. Would never want to use traction on someone with an acute injury with muscle spasm
*Hypertension (over 160/90), claustrophobia, traction anxiety, pregnancy, obesity, acute neck or back pain, mental disorientation, history of spine surgery, exaggerated symptoms
*Known joint instability, osteoporosis, spinal infection, spinal malignancy, cord compression, acute sprain, strain or inflammation of joints, RA, aortic aneurysm, signs and symptoms, cardiac or respiratory problems,
*Measurable degree of pull, greater intensity than manual, requires limited attendance, may perform with hot or cold pack
*Not segment specific, may be cumbersome to apply and adjust, may aggravate condition
POSITIONING: Supine is preferred (greater posterior intervertebral separation, increased relaxation, decreased muscle guarding, increased stability, and less force needed to overcome weight of the head).
FORCE (First treatment session low poundage, alter with symptom response):
*C1-C2 = 10 pounds
*C3-C4 = 10-15 pounds
*C5-C7 = 15-40 pounds
ANGLE OF PULL:
*C1-C2 (10 pounds) = 0-5 degrees
*C3-4 (10-15 pounds) = 10-20 degrees
*C5-C7 (15-40 pounds) = 25-30 degrees
*HNP or muscle hypertonicity
-Static: 5-8 minutes
-Prolonged Intermittent: <10 minutes, hold 60 seconds, rest 20 seconds (3:1 ratio)
*Stenosis, DDD, facet hypomobility, any joint condition, DJD
-Intermittent: 10-20 minutes, hold 20 seconds, rest 20 seconds (1:1 ratio)
**Pt must rest 2-3 minutes before getting up. Observe for dizziness and or headaches
*Supine most common, hips/knees flexed or extended, can do prone
*FORCE: Generally 30-50% of pt’s BW
-Initial treatment: 1/3 BW, Goal is ½ BW
*HNP or muscle hypertonicity
-Static: 5-8 minutes
-Prolonged intermittent: <10 minutes hold 60 seconds, rest 20 seconds (3:1 ratio)
*Stenosis, DDD, facet hypomobility, any joint condition, DDD
-Intermittent: 10-20 minutes, hold 20 seconds, rest 20 seconds (1:1 ratio)
LATERAL AND MEDIAL DISC HERNIATION
-If someone has a disc bulge that is irritating a nerve, must shift one way another to get off the nerve.
-Right trunk shift (in direction of shoulder)
-Name scoliosis curve by direction of convexity
*Dextra – right
*Levo – left
***If a patient leans AWAY from the painful side, LATERAL herniation.
***If a patient leans TOWARD the painful side, MEDIAL herniation
-Traction pulls on opposite side of symptoms.
**Most common disc bulge is posterolateral
*Muscle spasm – pull on concave side
*HNP – pull on convex side.
ELECTROTHERAPY – used for pain control, muscle strengthening, edema reduction, promotion of tissue repair, muscle spasm reduction, pain (TENS/IFC)
*Principles of Electricity:
-Atom – smallest particle of an element that retains the properties of the element
-Electron – a subatomic particle that carries a one-unit negative charge
-Ion – a particle made up of an atom or group of atoms that possesses either a positive or negative charge
*alike charges repel and unlike charges attract one another.
*Conductor – substances that readily allow movement of charged particles (muscles, nerves)
*Insulator – substances that limit the movement of charged particles (skin, fat). IMPEDE CONDUCTION
*Anode – in voltage, the positive pole or point with a deficiency of electrons
-Cathode – in voltage, the negative pole or point with an excess of electrons
-Current – the movement of charged particles
-Resistance – opposition of current
-Voltage – potential for electrons to flow from a high to low concentration. Higher the voltage, higher the potential.
-Ohm’s law – current in a conductor will vary in proportion to the voltage and will vary inversely to the resistance (I=V/R)
****Must have two electrodes on the body. These electrodes must be opposite in charge (polarity) so current can flow through biological tissues. Must be at least one anode (positive) and one cathode (negative) on the body at all times to ensure flow.
Types of Electrical Currents:
*Direct – continuous unidirectional flow of charged particles for at least 1 second (Iontophoresis, DENERVATED MUSCLE)
*Alternating Current – the continuous bidirectional flow of charged particles. The change in direction of flow (positive or negative) occurs at least once every second (PAIN CONTROL) – balanced (0 charge)
*Pulsatile – better suited for short-duration applications of electrical current. Brief unidirectional or bidirectional flow of electrons separated by a brief period of NO flow.
-Uses: pain control, edema, muscle spasm, re-education, FES, microcurrent
-TENS, Russian Stim, HVPC
-MONOPHASIC Pulsed – waveform either positive or negative. May result in polarity effect: Any physiological effect on tissues that occurs when the flow of electric current through those tissues is only one polarity for a given period of time
-BIPHASIC Pulsed – Two phases, one is negative, other is positive. Can be Symmetric of Assymetric.
*PC waveform – polyphasic. Bidirectional (usually symmetrical) – IFC, Russian stim (many different sin waves)
*Frequency (rate) – number of pulses per second (pps)
*Amplitude (intensity) – measure of the magnitude of current or voltage. Higher the amplitude, higher the area (area under the curve)
*Pulse Duration (width) – time elapsed from beginning to end of all phases
*Phase Charge – charge within each phase (area under curve)
*Pulse Charge – charge per pulse (cycle). Monophasic waveforms – phase and pulse charges are equal. For Biphasic – sum of two phases.
-Quantity of charge delivered to the tissues influences the type of nerve fiber that will be excited and the response (sensory, motor, pain) that will be elicited.
*Can modulate frequency, duration, and amplitude. We do this to prevent accommodation and habituation.
-Accommodation: cell membrane adapts to stimuli by requiring an increased stimulation to depolarize the nerve
-Habituation: CNS filters out continuous, non-meaningful stimuli (white noise)
Ramp – cyclical, sequential increases or decreases in phase charge over time
Train – a continuous repetitive sequence of pulses or cycles
Burst – a pulsatile current in which a finite interval of AC is delivered at a specified frequency for a specified length of time, in the form of a series of pulses called “bursts”
Duty Cycle – Percentage of on time to the total time the pulsatile current is on
-Over high adipose areas when a motor response is desired (uncomfortable)
-Over areas of poor skin integrity, unless wound healing is desired
-In an area of any condition that can be exacerbated by increased circulation
-Patients with demand pacemakers
-Patients with indwelling stimulators (urinary bladder and phrenic nerve)
-Application over transthoracic region or carotid sinus
-Application over areas of severe vascular compromise such as thrombosis
*Excitable – tissues diretctly influenced by an electric current. Go after these first.
-nerve and muscle fibers and cell membrane
-causes movement of charged particles in the tissues (electrolytes Na/K), results in depolarization of peripheral nerves resulting in sensory/motor responses
-Membrane potential of -75 mV for peripheral nerves (MUSCLES RMP = -90 mV, usually secondary to motor neuron depolarization)
*Non-excitable – tissues influenced by electrical fields created by the current
-bone, fascia, tendons, ligaments
RESPONSES: subsensory, sensory, motor, noxious response
*Different tissues have differing potentials for excitation. Sensory nerves will depolarize before motor nerves and motor nerves before pain
*Strength-Duration Curve – Can either increase amplitude and feel it or increase pulse width and feel it
Factors affecting tissue excitation – tissue impedance, axon size, nerve tissue depth
Tissue Impedance – ability of tissue or fluid to conduct an electrical current is dependent upon its water and ion content. Greater the water and ion content, the greater the electrical conductivity. Good conductors are poor insulators.
-Blood>nerve>muscle>tendon>adipose>epidermis>bone (best to worst)
Axon Size – Larger axon diameter, the more easily the nerve will depolarize due to less internal resistance. Larger the axon, easier it is to depolarize
-Motor nerve (Alpha MN)>Sensory Nerve (A beta)>Pain nerve (C)
Nerve Tissue Depth – closer nerve is to surface electrode, the greater the current density it receives/the sooner.
-Sensory then Motor then Pain nerves
Current Density – amount of current or charge flow per unit area. Highest where electrodes interface with the skin and decreases as current travels into deeper tissues. Smaller size of electrode you use, higher amount of current density
Electrode Size – inversely related to current density. If one electrode is larger than other, there is less current density in the larger electrode. If same size, current density is equal.
Electrode Distance – Closer electrodes are together, the more likely you are to hit Sensory/superficial. Farther apart = deeper tissue/motor.
Electrode Impedance – rubber electrodes with self-stick demonstrate lowest electrical resistance at point where tip of pin from the lead wire inserts into the electrode. Creates unequal current densities under electrode. Reduced or non-conductive areas can create HOT SPOTS and burn patient.
Electrode Placement – use areas of body where skin has less electrical impedance than other areas (stimulation points), because they require less current to excite a tissue…motor points, trigger points, acupuncture points.
-Motor Points – over muscle belly where alpha MN enters muscle and results in decreased electrical impedance
-Trigger Points – palpable bands or nodules within the soft tissue such as muscle, ligament, fascia, or joint capsule that refers pain (DECREASED electrical impedance)
-Acupuncture Points – specific sites on skin that have decreased impedance (stimulate to alleviate pain)
Electrode Position – Muscle conducts current about 4x better in the longitudinal direction of fibers vs transversely. Keep electrodes going PARALLEL to fibers.
MONOPOLAR – one or more ACTIVE electrodes placed over tx area, with one larger NON-active placed at a distance to tx area. Current density is lower in the large dispersive pad and should be subthreshold.
BIPOLAR – all electrodes are of equal or near equal size and are placed over tx area
-current densities should be very similar and result in excitation of the target tissues
QUADRIPOLAR – electrodes from two circuits are positioned so that currents intersect or interfere with each other in the boddy tissue (IFC)
<10 pps = twitch (not enough to get full contraction)
>20 pps = tetany (full contraction)
80-150 pps (SENSORY ONLY) = acute (A-beta fibers, pain)
*Electrodes closer = superficial
*Electrodes further = deeper
*Depolarization order: sensorymotorpain10>10>10>18>28>