1. Heat and Cold Modalities
Chapter 3

2. Physical Mechanisms of heat exchange
The extent of temp change results from:
Temp differences between the thermal agent & treatment tissue
Time of exposure to the thermal agent
Thermal conductivity of the Rx tissue
Adipose tissue: acts as insulator
Blood & muscle: absorb & conduct heat
Intensity of the thermal agent

3. 4 ways which therapeutic heat or cold is delivered to the target tissue
Conduction:
Heat loss or gain through direct contact between materials with different temps
Convection:
Transference of heat to a body by the movement of air, matter, or liquid around or past the body
Radiation:
Transfers heat (usually through air) from a warmer source to a cooler source. Does not come in contact with body.
Conversion:
Temp changes that results when energy is transformed from one form to another
Evaporation
Transformation from a liquid state to a gas state, requires an energy exchange ( ex. Sweating)

4. Physiologic effects of heat
Heating levels categorized as mild or vigorous
Mild = tissue temp below 40 C (104 F)
Vigorous = tissue temp between C ( F)
Temps above 45 C may result in thermal pain & irreversible tissue damage
Heat accumulation is affected by intensity & duration of stimulus & rate of heat absorption by tissue
Local heat application has both direct & indirect heating effects

5. Treatment Goals for therapeutic heat
Therapeutic heating agents are used as adjunctive Rx techniques for achieving functional goals
Pain reduction: facilitated by gate control theory
Reduction of muscle guarding or spasm
Tissue extensibility:
Shortening of connective tissue may result from injury or immobilization
Heat decreases viscosity & increases elastic properties
40-45 C is temp needed for residual length changes
Apply stretch during heating process or immediately after
Low-load prolonged stretch preferred over high-load brief stretch

6. Heat & exercise
Studies show that there is a greater increase in blood flow with heat & exercise together, than with either alone.

7. General indications for superficial heat modalities
Before active exercise
Before passive ROM exercises
Before electrical stim: reduces skin impedance
Before traction: relaxation & decreases muscle tension
Before massage: increases local blood flow & relax
In presence of muscle spasms
Before ultrasound: relax & warm tissue
Before joint mobilization: relax & improve extensibility of soft tissue

8. General Contraindications for superficial heat modalities
Injury where bleeding & edema still present
Deep vein thrombophlebitis
Areas with poor circulation
Area where sensation is reduced
If patient is very young or old
If patient can’t report heat sensation accurately
In presence of skin or lymphatic cancer

9. General procedures to follow before applying superficial heat
Remove heavy clothing
Explain purpose of Rx & what to expect
Position & drape patient properly
Inspect area to be treated (discolorations, open wounds, ect)
Cleanse area (no lotion, oils, ect)
Make certain pt can respond normally to changes

10. Methods of superficial heat application
Generally penetrates to depths of less than 1 cm from the surface of the skin
Subcutaneous tissues reach maximum temp increase within 6-8 min after application
Skin & subcutaneous tissue increase 5-6 C after 6 min & maintained up to 30 min

11. Hot packs
Transmit heat by conduction; Pt should experience sensation of pleasant warmth
Duration: min
Equipment:
Consists of silica gel in canvas cover; immersed in stainless steel tank with water between 165 & 175 F; Packs should be left in tank 20 – 30 min between Rx

12. Hot packs cont. Application: Indications: Precautions:
Remove hot pack with metal tongs; Place in hot pack cover with 6-8 layers place pack on body part & secure firmly; inspect skin after 5 min
Indications:
Before or in conjunction with other Rx for relaxation; when moist heat is more comfortable than dry heat
Precautions:
Be careful about pt falling asleep on it

13. Paraffin Used to Rx chronic joint disorders; Duration: 15-20 min
Transfers heat by conduction
Will experience hot, but not painful heat sensation (pleasant warmth after 3-5 min.)
Duration: min
Equipment:
Mixture of paraffin wax & mineral oil in ratio of about 6 to 1 is melted in tank
Temp at F for UE
Temp at F for LE
Insulated wrapping material (ex. Plastic bag, aluminum foil, towels)

14. Paraffin cont.
Application: Instruct patient not to move part to avoid cracking; inspect pts skin; remove all jewelry & wash and dry part to be treated
“Glove” technique
Most common; dip part in paraffin 8-10 times; keep fingers separated; immediately
Dip-immersion technique:
Place part in tank & leave there for 15 min
Brush method
For difficult to reach parts (ex. Elbow); paint part with multiple layers of paraffin and wrap

15. Paraffin cont. Post treatment: Advantages: Disadvantages
Remove wax over tank; peel wax off like glove
Advantages:
Heats difficult to reach areas;
softens skin & prepares part for massage
Disadvantages
Can’t use with open wounds;
can be messy

16. Fluidotherapy Heat by convection;
extremely small solid particles are heated & suspended by circulating air, thus producing effect similar to circulating warm liquid
Duration: 20 min
Equipment:
Machine stands 3 ft high & contains heating element, air compressor, tiny silicon or corn cob particles, timer, temp gauge, & mesh sleeve

17. Fluidotherapy cont. Application: Advantages Disadvantages
Wash & dry part; Remove jewelry; check & cover open wounds
Insert part into sleeve & close snugly
Set thermostat between F
Turn timer on
Instruct pt how to exercise or stretch
Advantages
Circulating particles give patient feeling of lightness 7 warmth (like WP)
Can exercise while heating
Disadvantages
Limb units to small to accommodate more than distal limb
Open wounds must be covered

18. Diathermy
A deep heat, that causes increase in tissue temp at depths of 3 to 5 cm, without overheating skin.
Means “to heat through”
Biophysics: As electromagnetic radiation waves pass into the body, internal kinetic energy of tissue is increased; heat is generated from conversion of electromagnetic energy to mechanical energy
Benefits: Increases blood flow; decreases pain; increases tissue extensibility

19. Diathermy Cont. Types of diathermy:
Microwave (MWD): Frequency = 2450 MHz; not used in US often
Shortwave (SWD): Frequency = MHz;
Capacitance (electrical field): body part being treated is placed between 2 electrodes & becomes part of circuit; More heat generated into tissues of low conductivity, such as fat, ligament, tendon, & cartilage
Inductance (magnetic field): body not part of circuit; Heat generated as eddy currents generated by magnetic field pass into tissue; more heat generated into tissue with high conductivity, such as blood, muscle, & sweat
Contraindications: Metal implants or any metal within Rx area (zippers); Cardiac Pacemakers

20. Cryotherapy Heat always travels from hot to cold
Tissues are cooled because they transfer their heat to the cold modality

21. Cryotherapy Cont. General indications
Reduction of acute pain: numbs area
Reduction of local bleeding & swelling
Reduction of spasm
Reduction of Spasticity
Facilitation of motor responses (quick icing)
Rx of acute burns
In conjunction with other Rx’s

22. Cryotherapy cont. General contraindications
If frostbite has been in area
Pt has Raynaud’s disease
Circulation to part is compromised
Pt very old or young
Pt extremely sensitive to cold

23. Cryotherapy cont. Before applying cryotherapy Inspect skin
Test small area of skin, to determine if hypersensitive
Verify good circulatory status
Make certain patient never had frostbite in area to be treated
Make certain pt never experienced a lot of spasticity when used
Position & drape pt comfortably

24. Ice massage Stroking of ice on body part to numb skin Equipment:
Ice that is frozen in insulated cup
“Lollipop”: Ice in cup with small tongue depressor frozen in middle
Ice cube wrapped in paper towels or washcloth

25. Ice massage cont. Technique: Duration: 3-10 min Advantages
Sensation = cold, burning, aching, numbness
Part being Rx’d may become pale & eventually red
Ice should be applied in circular, smooth, rhythmical strokes
Duration: 3-10 min
Advantages
Numbs skin easily in short time
Ice colder than chemical cold packs
Ice readily available
Disadvantages: ice may cause frostbite

26. Chemical Cold Packs 3 types:
Clinical type: durable plastic cover around silica gel & stored in refrigerator tank
Home type: similar but smaller than clinical type; purchased in pharmacies & stored in freezer
Disposable type: activated by breaking inner seal that mixes chemicals within
Equipment: stored in refrigeration tank like one used for hot packs with temp about 10 – 15 F

27. Chemical Cold Packs cont.
Technique:
Use wet, well wrung out towel next to skin (wet towel hastens cooling of part being Rx’d, because moisture increases rate of thermal conductivity)
Duration: min
Advantages:
reusable
Can be used immediately after injuries such a as sprains or fractures

28. Ice Towels Towels containing ice shavings Technique:
Towels thoroughly soaked in water & ice mixture
Towel wrung out & applied to part; Procedure repeated every few min
Duration: min
Advantages:
Equipment required is available almost anywhere
Disadvantages:
Therapist must keep changing towels

29. Ice packs Equipment: Technique: Duration: 5-15 min Advantages:
Plastic bag filled with ice cubes or crushed ice
Technique:
Fill bag with ice & seal well to prevent leakage
Duration: 5-15 min
Advantages:
Can mold to part being Rx’d
Disadvantages: Bag can leak

30. Vapocoolant spray
Method of cooling the skin by the evaporation of a substance sprayed on the skin
Equipment: Fluori-Methane
Liquid begins to evaporate & continues to evaporate when contacts skin, thus cooling skin briefly
Technique
Expose area to be Rx’s
Eyes should be protected
Hold bottle in an inverted position at a 30 angle, 18 inches away at a rate of 4 inches per sec.

31. Vapocoolant spray cont.
Duration Spraying should not exceed 6 sec
Advantages:
Immediate reduction of pain
Can use on joint sprains to relieve pain & swelling
Can use on thermal burns to decrease pain, erythema, & blistering

32. Quick icing Used primarily with patients with CNS disorders Equipment:
Ice cubes held in paper towel or gauze
Technique:
3-5 quick swipes with ice cube over belly of muscle
Response may occur immediately or up to 45 minutes after application
Advantages:
Motor response may be seen once patient past flaccid stage
Disadvantage:
Response may not be seen immediately