Heat and Cold Modalities Chapter 3

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

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)

Physiologic effects of heat Heating levels categorized as mild or vigorous Mild = tissue temp below 40 C (104 F) Vigorous = tissue temp between 40-45 C (104-113F) 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

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

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

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

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

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

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

Hot packs Transmit heat by conduction; Pt should experience sensation of pleasant warmth Duration: 15-30 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

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

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: 15-20 min Equipment: Mixture of paraffin wax & mineral oil in ratio of about 6 to 1 is melted in tank Temp at 126-135 F for UE Temp at 113-126 F for LE Insulated wrapping material (ex. Plastic bag, aluminum foil, towels)

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

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

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

Fluidotherapy cont. Application: Advantages Disadvantages Wash & dry part; Remove jewelry; check & cover open wounds Insert part into sleeve & close snugly Set thermostat between 115-123 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

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

Diathermy Cont. Types of diathermy: Microwave (MWD): Frequency = 2450 MHz; not used in US often Shortwave (SWD): Frequency = 27.12 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

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

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

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

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

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

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

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

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: 10-15 min Advantages: reusable Can be used immediately after injuries such a as sprains or fractures

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: 10-15 min Advantages: Equipment required is available almost anywhere Disadvantages: Therapist must keep changing towels

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

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.

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

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