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Thermal Agents

Terms in this set (100)

Goals for using thermal agents
1. create a therapeutic change in the temperature of the target tissue without creating an adverse effect
2. enhance the healing process
3. improve ability to tolerate activity
4 mechanisms of heat transfer
1. Conduction
2. Convection
3. Conversion
4. Evaporation
Conduction
transfer of heat through direct contact
What does the amount of temperature change depend on with conduction?
1. difference in temperature between the 2 surfaces
2. the length of time
3. the area of contact
Heat flows from _________ to ________
higher to lower energy areas (hot to cold)
Examples of conduction
1. hot pack
2. cold pack
3. paraffin
Convection
transfer of heat through motion of a circulating medium
Why use convection instead of conduction?
convection speeds the process of energy exchange
Examples of convection
1. whirlpool
2. fluidotherapy
Conversion
converts one form of energy into another
T/F conversion requires direct contact with skin
false
Examples of conversion
1. ultrasound
2. diathermy
3. cold pack you break up
Evaporation
heat exchange that occurs when a liquid changes to a gas or vapor state
Evaporation results in (heating or cooling)
cooling
Example of evaporation
vapocoolant spray
Core body temperature
~98.6 degrees F
37 degrees C
Skin temperature is how much lower than core energy?
3-4 degrees F lower
Therapeutic range for heating
106-113 degrees F
Therapeutic range for cooling
68-50 degrees F
How deep do superficial heating agents go?
greatest tissue temperature rise is within 1 cm of surface/contact interface
What is the skin temperature increase in 8-10 minutes when using a superficial heating agent?
18 degrees F
What is the temperature increase 1 cm deep after 15-20 minutes when using a superficial heating agent?
5-9 degrees F
How deep do deep heating agents go?
greatest tissue temperature rise is seen between 3-5 cm
How much do skin temperatures drop in 10 minutes when using a cooling agent?
13-24 degrees C
23-43 degrees F
After ten minutes, how much does the temperature drop 2 cm deep when using a cooling agent?
4-5 degrees C
7-9 degrees F
After 30 minutes, how much does the temperature drop 4 cm deep when using a cooling agent?
5-9 degrees F
What is the depth of heat transfer affected by?
1. compression
2. type of barrier used
3. adipose layer
Thermal conductivity
the ability of a substance to transmit or conduct heat
Describe the relationship between thermal conductivity and heat transfer
increase thermal conductivity = increased heat transfer in faster times
Specific heat capacity
the ability of a substance to hold or store heat at a given temperature
Which is a greater specific heat capacity?
a. water
b. paraffin
a (water)
What does it mean that paraffin has a lower specific heat capacity than water?
it means that when you place your hand in paraffin at a given temperature it is perceived as cooler than if you were to place your hand in water of the same temperature
Mild intensity of heating/cooling
-small temperature change is obtained in tissues at the site of the lesion (1 degree C)
-temperature maintained for a short time
-rate of change of temperature is slow
Vigorous intensity of heating/cooling
-highest/lowest temperature is produce at the site of the lesion
-tissue temperature is close to tolerance level
-rapid rate of rise/fall of tissue temperature
What is the tolerance level for heat? cold?
-heat: 45 C/113 F

-cold: 10 C/50 F
Vascular effects of heat
1. vasodilation
2. increased circulation
3. hyperemia
4. max vasodilation in 20-30 minutes
Vascular effects of cold
1. vasoconstriction
2. decrease blood flow
3. effect within 10 minutes
4. Possible "hunting response"
What is the "hunting response"?
-cold induced vasodilation that occurs after 8-10 minutes. thought to alternate between vasoconstriction, vasodilation
-occurs more consistently distally
Metabolic Effects of heat
1. increase metabolic rate 2-3x with each 10 degrees C
2. increased O2 uptake
3. acceleration of protein synthesis
Metabolic Effects of cold
1. decrease local metabolic activity
2. limit inflammation
Tissue effects of heat
1. improve electrical conductivity of skin
2. increase extensibility with stretch
3. decrease joint viscosity
Tissue effects of cold
1. decrease extensibility of non-contractile tissue
2. increase joint viscosity
Theoretically, when should you perform manual therapy/stretching?
a. before heat
b. before cold
c. after heat
d. after cold
c (after heat)
Neuromuscular effects of cold
1. slows nerve conduction velocity
2. facilitate muscle contraction if brief application
3. decrease in muscle contraction if prolonged application
4. decrease spasticity temporarily
5. elevate pain threshold
In what ways does cold elevate pain threshold?
1. gate control theory
2. decrease muscle spasm
3. decrease edema
Neuromuscular effects of heat
1. increase nerve conduction velocity
2. decrease conduction latency
3. elevate pain theshold
4. decrease muscle strength for 30 mins
In what ways does heat elevate pain threshold?
1. gate control theory
2. increase blood flow can reduce pain from ischemia
3. decrease muscle spasm
Performance effects of cold
1. diminished performance of rapid movements
2. diminished force generation for 30 mins after application
3. diminished proprioception for 20 mins after application
Performance effects of heat
muscle strength and endurance may decrease for 30 mins after application
Phases of healing
1. inflammatory (day 1-6)
2. proliferative (day 3-20)
3. maturation (day 9 and on)
Goal of inflammatory phase
prepare the wound for healing
Characteristics of inflammation
redness (rubor)
heat (calor)
swelling (tumor)
pain (dolor)
loss of function (functio lasso)
Goal of the proliferative phase
rebuild damaged structures and strengthen the injury site
Goal of the maturation phase
restore the prior function of the injured tissue
Use heat or cold for early inflammatory phase? why?
cold
-decrease edema, tissue injury, and pain via vasoconstriction and decreased metabolic rate

avoid heat
Use heat or cold for late inflammatory phase? why?
after 48 hours you can use either
-both provide pain relief and decrease muscle spasm
When might it be ideal to provide heat during the late inflammatory phase?
when no swelling is present heat could be used to increase rate of metabolite clearing via vasodilation
What other modality could be used during the late inflammatory phase?
nonthermal ultrasound
Use heat or cold during the proliferative phase? why?
deep heating agents
-increase circulation, metabolic rate, and analgesia
Use heat or cold during maturation phase? why?
superficial and deep heat
-stretching, relaxation, pain relief
Temperature range for paraffin
125-127 degrees F
How many times should you dip for paraffin?
8-10 times allowing wax to dull between each
Treatment time for paraffin
15-20 minutes
T/F hand should be placed in lap during treatment with paraffin
false, elevate
Method of heat transfer for paraffin?
conduction
Method of heat transfer for vapocoolant spray?
evaporation
What should the patient do after vapocoolant spray treatment?
perform active motion after spraying
Method of heat transfer for hot packs?
conduction
Why use moist heat?
-feels warmer
-increases heat transfer
How many layers of towel should be placed between the skin and the heat pack?
6-8 layers
Treatment time for hot packs
15-30 minutes
Method of heat transfer for air activated heat wraps
conduction/conversion
Method of heat transfer for cold packs
conduction
Treatment time for cold packs
-pain, inflammation, edema
-spasticity
-10-15 minutes for pain, inflammation, edema
-30 minutes for spasticity
Treatment time for ice massage
3-10 minutes (or until numb)
Order of sensation for ice massage/cold agents
1. cold
2. burning
3. aching
4. numbness
What is a contrast bath?
alternating hot and cold water
Temperature for contrast bath:
-cold
-hot
-cold: 55-65 degrees F
-hot: 100-104 degrees F
Describe the process for using a contrast bath
-usually start in hot for 3 minutes
-cold for 1 minute
-alternate 5-7 times for total of 20-30 minutes
What type of heat transfer is a contrast bath?
-conduction
-convection if water is moving
Advantages of a contrast bath
1. can move affected part in water
2. maybe stimulate vascular pump
Disadvantages of a contrast bath
limb is in a dependent position
What is one thing you must do if a patient is doing a contrast bath?
monitor blood pressure
Method of heat transfer for fluidotherapy
convection
Treatment time for fluidotherapy
20-30 minutes
T/F fluidotherapy actually uses dry heat
true
Temperature range for fluidotherapy
105-125 degrees F
What is diathermy?
delivers moderate heat directly to pathologic lesions in the deeper tissues in the body
Method of heat transfer for diathermy
conversion
T/F ultrasound is a form of diathermy
true
Method of heat transfer for ultrasound
conversion
Heat contraindications
1. sensory impaired
2. any disease process that should not receive the effect of increased metabolic rate (cancer, hemophilia, fever, active bleeding, cardiac insufficiency, PVD, thrombosis, acute inflammation, acute infection)
3. pregnancy (total body)
4. gonads
5. acute injury
Heat precautions
1. pregnancy (limbs)
2. impaired circulation
3. poor thermal regulation
4. edema
5. cardiac insufficiency
6. metal in area
7. over open wound
8. over areas with topical counter irritants
Cold contraindications
1. sensory impaired
2. conditions that are hypersensitive to cold
3. gonads
4. developing fetus
5. any situation that should not receive effects of vasoconstriction (arterial insufficiency, PVD, cardiac dysfunction, open wounds after 48-72 hours)
6. regenerating peripheral nerves
Cold precautions
1. over superficial main nerve branch
2. over open wound
3. patients with hypertension
4. poor sensation
5. elderly or young
1st degree burn
stinging redness
2nd degree burn
blister
Frost nip
blanched skin, tingling pain
Frost bit
blister
How long into the treatment should you check the patient using either hot or cold?
5 minutes
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