Modalities
3 types of physical agents
Thermal, Mechanical, Electromagnatic
Cryotherapy will
Decrease tissue temp, circualtion, tissue extensibility, pain
Thermotherapy will
increase tissue temp, circualtion, metabolism, tissue extensibility, decrease pain
Mechanical Agents Are:
Traction, compression, water, sound
Traction will
decrease pressure, decrease inflammation and helps to normalize sensation
compression will
counteract fluid pressure and control or decrease edema
Hydrotherapy will
increase pressure on the body
Continuous US
Heats deep tissue, increase circulation, metabolic rate, tissue extensibility, decreases pain
Non-thermal US
helps with tissue healing, assists with phonophoresis
electromagnetic agents
UV radiation, infared radiation, laser, diathermy, electric current
reflection
some energy bounces off interface
refraction
some energy changes direction as it passes through interface
absorption
some energy absorbed by interface
wavelength
distance from peak to peak
frequency
# of oscillations per second
longer wavelength =
lower frequency
shorter wavelenght =
higher frquency
precautions
treatment should be applied but with limitations or with caution
contraindication
treatment should not be applied
water is a type of ____ agent
mechanical
deep heat is a contraindication for pregnancy if it affects and can reach the fetus
true
what type of ice pack is most efficient
ice chips in a wet thick towel
put in order from most efficient to least officient cooling agent
- ice chips in a dry thin towel
- ice chips in a wet towel
- ice chips in a dry thick towel
- gel pack in a wet towel
1. ice chips in a wet towel
2. gel pack in a wet towel
3. ice chips in a dry thin towel
4. ice chips in a dry thick towel
poor sensation is always a contraindication for cryotherapy
false
hot packs are usually stored in water that is
70-75 degrees celcius
protein in your body begings to denature at
45 degreec celcius
conduction
heat gain or loss by direct contact between materials with different temperatures
convection
transfer of heat to a body by the movement of air, matter or liquid around or past the body
the ___ the temperature difference the ___ the rate of transfer
greater, faster
rate of heat transfer
area of contact x thermal conductivity x temperature difference / tissue thickeness
specific heat
the amount of energy required to raise the temperature of a given weight of a material by a given # of degrees
thermal conductivity
the rate of heat tranfer by conduction (in or out of the body) depends on:
- temperature difference
- area of contact
metals =
high TC
Water =
moderate TC
Air =
low TC
cell death occurs if
43 degrees is maintained for 60 min
does convection or conduction transfer more heat?
convection
agents in motion transfer energy more quickly, why?
because the molcules are moving faster it is going to transfer heat faster (e.g whirlpool)
radiation
energy transfer from a warmed source to a cooler source (usually through air) e.g. infared lamps transfer heat by irridation
conversion
temperature change resulting from energy changing from one form to another (e.g. US vibration causes cells to move around faster, increasing metabolism, increasing temperature) - dont need direct contact but do need conducting element such as gel or water - vibration being conducted to heat
evaporation
transformation of liquid to gas or vapour, giving off heat (e.g. vapo-coolant spray absorbs heat, sweating)
effects of cold and heat
- hemodynamic (circulatory) effects
- neuromuscular (nerve conduction) effects
- metabolic (cellular) effects
* these apply to all the modalities*
hemodynamic effetcs of cold
- initial decrease in blood flow to the area
- later increase in blood flow may occur
- increase blood viscosity
- decreases release of histamine and prostoglandins
- cutaneous blood vessels affected (constricted = smaller)
hunting response
temperature cycling with alternating vasoconstriction and vasodialiation in response to prolonged cold exposure
- usually seen with distal extremities or fingers
cold application should be how long
15-20 min
CIVD
cold induced vasodialiation
neuromuscular effects of cold
- decreased nerve conduction velocity
- increased pain threshold, decreasing pain sensation
- altered muscle strength
- decreased spasticity - prolonged cooling
- facilitation of muscle contraction
- decreased muscle spindle response
neuromuscluar effects of heat
- increased nerve conduction velocity
- gait control theory* sensory messages inhibit pain messages at the spinal cord
- increased pain threshold, decreasing pain sensation
- altered muscle strength
heat decreases muscle strength and endurance
initial 30 min post
prolonged cooling
Decreased strength for about an hour and then after 1.5 hours the person will get stronger
hemodynamic effects of heat
- initial and ongoing increase in blood flow (vasodilation)
- cutaneous blood vessels affected (relax)
- increase release of histamine and prostoglandins
- local and distal heating can occur
- protective response of the body
muscle spindle
is a sensory organ that detects velocity and duration of a stretch
metabolism effects of cold
- decreased cell permeability (decreased local swelling)
- decreased metabolic activity (good for acute inflammation, important with acute RA and OA and trauma but bad for chronic inflammation) - don't want to ice with chronic inflammation because it slows chemical reactions and slows circulation which would further slow down the healing process
- viscoelastic effects (tissues become less elastic (not relaxed))
Metabolic effects of heat
- increased cell permeability (increased local swelling)
- increased metabolic rate
- viscoelastic effects - tissues become more elastic due to increased collagen extensibility (more stretchable)
- caution - acute inflammatory conditions - RA, etc.
indications for cryotheryapy
- during the first 72 hours ICE should be repeated frequently (hourly reccommended) after injury
R - rest
I - ice
C - Compress
E - elevate (above the heart)
contraindications for cryotherapy
1. cold hypersensitivity (cold induced urticaria)- blood is going to clot due to the cold
2. cold intolerance
3. cryoglobulinemia - blood turns to gel
4. paroxysmal cold hemoglobinuria - blood cells break down and hemoglobin is released into the urine
5. raynaud's disease - causes some areas of the body to feel numb and cold in response to cold temperatures
6. over regenerating peripheral nerves
7. don't apply cryotherapy to an area with circulatory compromise or peripheral vascular disease
precautions for cryotherapy
- Over a superficial main branch of a nerve
- Over an open wound
- Hypertension - high blood pressure
- Poor sensation or poor mentation
- Very young and very old patients
freezing or frostbite at
-4 to -15 degrees celcius
maximum time for cryotherapy in an athlete should be
45 minutes
as long as the tissue temp stays above 15 degrees celcius
cryotherapy sensation progression
progression usually occurs within 5-15 minutes (to achieve extreme analgesia, 15 minutes is often necessary since it takes longer to trigger hunting response, if it happens at all)
intense cold
burning
aching
analgesia (no pain)
numbness
variables for cryotherapy
- application temperature (straight ice, ice pack in a towel, ice pack in plastic, gel ice pack, frozen peas in plastic)
- temperature of the body part
- ability of the tissues to recover from the cold
- quality of circulation
- duration of the application
- density of skin, fat or muscle
- size of area treated, location on the body
- existing pathophysiology
indications for thermotherapy
- Inflammation (post acute)
- Muscle spasm
- Swelling (post acute)
- Adhesions
- Soft tissue stiffness
Precautions for Thermotherapy
- Acute injury or inflammation
- Pregnancy - can apply heat just as long as it is not around the belly or can affect the fetus
- Impaired circulation
- Poor thermal regulation
- Edema
- Cardiac insufficiency
- Metal in the area
- Over an open wound
- Over areas where topical counterirritants have recently been applied (apply A535 and then apply a heat pack - will burn the person)
- Demyelinated nerves - multiple sclerosis is an example of this
contraindications for thermotherapy
- Recent or potential hemorrhage
- Thrombophlebitis - inflammatory process that causes a blood clot to form and block one or more veins, usually in the legs.
- Impaired sensation
- Impaired mentation - mental abillity/cognitive impairment
- Malignant tumour - (sometimes will be applied to patients who are in the end stages in their life - as they do not care about their cancer sperading)
- Infarred irradiation of the eyes
adverse effects of thermotherapy
burns, fainting, bleeding, skin/eye damage from IR
documentation should include
- area treated
- cooling/heating agent
- treatment duration
- patient positioning
- reponse to intervention
cardinal signs of inflammation
- heat
- redness
- swelling/edema
- pain
- loss of function
what would you do if the skin has not achieved numbness after 15-20 minutes of a patients first treatment?
end treatment, chart it and report to PT
when would the application of cold be preferred over heat for muscle stretching?
swelling and inflammation
how long should a warm pack be applied to a patient for?
20-45 min
the expected sensation for a person receiving thermotherapy is
warm
paraffin wax is appropriate for a patient with RA during an exacerbation of symptoms
false - it can only be used when a patient is not in a flare up
how long does a heat pack need to be in the hydrocollator for between patients?
30 minutes
true or false a warm pack requires at least 6 layers of towels/cover between the pack and skin?
true
how often should you perform skin checks?
every 5-10 minutes
Why is it safe to put your hand in wax at 52 degrees celsius but not water?
Wax has lower specific heat and thermal conductivity
for US the optimal patient position (as related to the body part being treated) is
perpendicualr to gravity
true or false feeling hot under the treatment area for continuous US is normal
false
true or false for US to reach deeper tissues (3-5cm) using a frequncy of 1MHz is required
true
what benefits does continuous US offer that pulsed does not
increased blood flow, decreased joint stiffness
during US treatment how do you check if a patient is beign burnt?
ongoing communication with the patient
when is it okay to remove the transducer head off the patient?
when the machine has been correctly turned off
contraindications to US are
malignancy, joint cement
ultrasound frequency is
high frequency sound wave higher than 20,000 Hz
humans can hear approx
16,000-20,000Hz
therapeutic US range
0.7-3.3 MHz
most common frequencies used in therapy 1MHz and 3MHz
also way above the level of hearing for humans and dogs
diagnostic US
2-18MHz (much higher intensity)
- sound wave travels in, wav returns, and energy is converted to produce image
intensity
W/cm2 (0.15-2)
frequency
MHz (1 or 3)
duty cycle
10-90% of 100% continuous
ERA
effective radiating area - cm2
area that is covered by the sound head
(these are characteristics of the specific machine or transducer head and cannot be changed)
BNR
beam nonuniformity ratio
can't alter this
intensity can be displayed as two things
Watts/cm2 or watts
intensity shown on the screen is an average based on the space occupied by the beam
SATP
spatial average temporal peak
spatial average - the actual energy in the beam is not evenly distributed and therefore the intensity recieved by the patient my be very high or low in some parts of the beam, compared to the average displayed
Using a transducer with a maximum BNR of 6:1, when the spatial average intensity is set at 1.5 W/cm2, the spatial peak intensity within the field could be as high as
9 W/cm2.
temporal peak
max intensity during the "on time"
3MHz
13 waves occuring in 1 seccond
- will penetrate tissue up to 2cm deep
- will heat the skin faster
- doesn't penetrate as far but adds more energy to the tissues it affects (epiderms, dermis)
1MHz
5.25 waves occuring in 1 second
- penetrates tissue up to 3-5cm
- will go deeper into the skin
- penetrates farther but adds less energy to the tissues it affects
- penetrates through the epidermis, dermis, hypodermis (fat=adipose tissue), muscle
- fat - low absorption/high penetration
- muscle - high absorption/low penetration
acoustic impedance
The relative resistance of a medium to wave energy
attenuation
gradual decrease in intensity as it travels through space happens in part because of impedance
what is the tranducer of the US machine made of
- crystal - made of P2T plubium zirconium titanate
- crystal expands and contracts in response to the electric current
- causes compression and rarefraction
compression
increasing density of material as the wave passes through it
rarefaction
decreasing density of material as the wave passes through it
ultrasound wave
alternating compression and rarfaction
attenuation
- As sound wave travels attenuation occurs
- Gradually decreases in intensity as it travels through material, just like sound we hear gets quieter the further away it goes from the speaker
non-thermal physiological effects of US
the vibration caused by the sound waves causes three related things to occur:
1. cavitation
2. microstreaming
3. acoustic streaming
it can alter the cell membrane permeability
cavitation
- US makes tiny gas filled bubbles present in the bodies, vibrate
- sound waves make these bubbles shrink and grow
microstreaming
- microscale eddying that occurs around the gas bubbles
- vibrating bubbles make fluid around it move
acoustic streaming
circular flow of cellular materials, moving materials from one part of the US field to another
** cellular fluids are made to move because of the action of microsreaming (vibrating) and acoustic streaming (circular movements)
how is heat produced in the tissues? (thermal US)
- by conversion of kinetic energy to radiant energy (e.g. movement to heat)
- faster movement (higher frequency) = more heat
absorption coefficient
higher absorption coefficient (more heat)
- sacr
- tendon
- joint capsule
- ligament
- periosteum
- bone
- bursa
- cartilage
Lower absorption coeficient (less heat)
- skin
- fat
- blood
standing waves
if the sound heat is stationary these waves can reinforce each other, creating intense peaks of energy known as standing waves
- Sound waves usually bounce back (reflection) but there is no reflection in standing waves
refraction in US
US can be scattered when it encounters tissues of different densities
- this means less US is delivered to the target tissue
dangers of standing waves
- increased risk of burns
- blood cell stasis
- permanent damage to endothelial lining
risks of US
- pain
- burns - starionary transducer - standing waves
- fragile crystal - poor technique can damage the crystal and change the emission pattern from the sound head or destroy it
- cross contamination/infection - bottle tips, transducer head disinfect
contraindications of US
- Malignant tumor
- Pregnancy
- Central nervous system (CNS) tissue
- Pacemaker
- Thrombophlebitis/ DVT
- Eyes
- Reproductive organs
- Lack of sensation
- Joint Cement and Plastic Components
precautions of US
- Acute inflammation: heat can make acute inflammation worse, causing bleeding, pain, swelling and impair healing
- Epiphyseal plates: low does safe
- Fractures: low dose US can help # healing vs. high dose causes pain and impair healing
- Breast implants: can increase pressure and rupture
- Metal -US MAYBE used over Metal. Although US penetrates most metal easily, metal creates an interface and can set up standing waves, with increased heating if not applied correctly
Equipment safety for US
If an US sound head is exposed to air:
- almost all US energy is reflected to the sound head
- sound head may be damaged or destroyed
- sound heads of different compositions may tolerate air for a few seconds or slightly longer before being damaged BUT some can be destroyed VERY quickly
**Never expose a sound head to air when it is turned on
**Always use sufficient conducting medium (gel or water) to prevent an air interface
technique for making intensity safe US
- keep the sound head moving whenever the machine is turned on to compensate for spatial averaging and to avoid standing waves
- some overlap is okay
- use a coupling agent such as gel or water
- kee the sound head in contact at all times
- good quality US gel will remain in place during the treatment
- don't scoop gel as you will expose the sound head to air
- sound head must be on patient before starting machine, machine must be turned off before the sound head is removed
- moving the head too fast, especially over bony prominences, makes it difficult to maintain proper contact
- movement is crucial to safely compensate for the effects of beam nonuniformity (BNR)
- standing waves can form under a stationary sound head
- burns can result from standing waves, even at non-thermal settings
area to be treated (US)
- 2x the ERA (effective radiating area) per 5-10 minutes of treatment is commonly suggested
must move far enough to ensur that he area under the hottest part of the sound head is not over treated, or you risk burning the patient
speed of the movement (US)
- must move fast enough that the tissues recover, but slow enoguh to get accumulated effects
- speeds between 2 and 8 cm/sec will have equal heating effects AS LONG AS the correct area is covered - beware of fast circles giving you the impression you're covering more area that you really are
approx 3-4cm/second (up to 8cm/second) is commonly reccomended
setting up the environment (US)
- good body mechanics for you and the patient
- plan (US on the cart and what side it should be on)
- get close (short lever arms)
- LOG within BOS
- keep your COG close to objects COG
- avoid trunk flexion and rotation
- ensure you can see the US screen as well as where you are applying the US too
documentation - include all parameters
- area treated
- US freq
- US intensity
- US duty cycle
- treatment duration
- if underwater
- response to intervention