Foundation of Therapeutic Modalities: Thermotherapy

What is conduction?

Direct collision of molecules from 2 different materials at 2 different

temperatures - heat transfer is by direct contact

What are examples of conduction?

heat and ice packs

What does the rate of transfer depend on?

• Material thermal conductivity

• Temperature difference between materials (↑ difference → ↑ transfer rate)

• Area of contact

What is the thermal conductivity from high to low?

Metals, Water, Air

↑ temperature difference =

↑ risk of burn or frostbite

Small area =

↑ risk of burn or frostbite

More Pressure =

↑ risk of burn or frostbite

How does ↑ area affect total energy transfer

↑ A greater total transfer

How does ↑ the distance from the source, relating to thickness, impact transfer?

↓ heat or cold

What is convection?

Heat transfer from direct contact with a circulating

medium; the thermal agent is in motion, and the body part is "stationary."

What are examples of convection?

• Whirlpool- moving water

• Fluidotherapy- moving cellulose particles and warm air

• "Game-ready" type device

What is conversion?

nonthermal energy to heat

• Mechanical, electrical, or chemical

What are examples of conversion?

• US- mechanical

• Diathermy- electrical

Does not require that the _________ is in

contact with the body, but does require a

_________ that will transfer the energy

Heat source; Medium

What is radiation?

Heat transfer between materials without

intervening medium or contact

• No longer used in PT, but seeing a resurgence

in the form of an infrared sauna for health and

wellness

What are examples of radiation?

• Infrared lamps

• Body bakers

What is evaporation?

Cooling occurs as liquid changes to gas

• No longer used in PT

What are examples of evaporation?

• vapocoolant spray

• Flouromethane spray replaced with Ethyl Chloride spray

• Spray and stretch

• Used for injections, IVs, etc.

What is superficial thermotherapy?

very shallow penetration (millimeters)

• Will not heat to the depth of most muscles

What are superficial thermotherapy examples?

• Hot packs

• Paraffin

• Fluidotherapy

What is deep thermotherapy?

deep penetration- centimeters

What is an example of deep thermotherapy?

ultrasound

What are the temporary hemodynamic effects of thermotherapy?

• Vasodilation

- SUPERFICIAL NOT in muscle

• Increased venous and lymphatic drainage

• Increased capillary permeability

- Edema

What are the temporary neuromuscular effects of thermotherapy?

• Increased nerve conduction velocity

• Decreased pain - mechanisms

• Increased pain threshold

• Muscle strength and endurance: Unclear impact on muscle

strength and hypertrophy

• detrimental to endurance athletes

• Decreased DOMs when a hot pack is applied within 1hr lasting for 24

hours.

What are the metabolic effects of thermotherapy?

• Increased metabolic rate

• Increased O2 uptake in tissues

• Can increase acute inflammation

How does superficial heat increase collagen extensibility?

Must raise the tissue temperature by 4 °C (5.6° F)

Where does superficial heat increase collagen extensibility?

• Only very superficial tissues

• Hands and dorsum of feet, maybe

• Surgical or traumatic scars, yes

What are the indications of superficial heat?

• Pain control

• Increased ROM and Decreased Joint Stiffness

- Direct - not likely related to ↑ tissue extensibility

-Indirect - likely a neurologic response

• Muscle spasm- indirect response

What are contraindications for superficial heat?

• Recent hemorrhage

• Thrombophlebitis- swollen or inflamed vein due to a blood clot

• *Impaired sensation*

• *Impaired mentation*

• Malignancies- in the region

• Acute inflammation (unless associated with acute superficial infection

i.e. cellulitis)

What are the precautions for superficial heat?

• Pregnancy*

• Impaired circulation

• Poor thermoregulation

• Edema (acute don't, chronic ok)

• Cardiac insufficiency

• Metal- if it is superficial

• Open wounds

• Demyelinated nerves

• Over areas where counterirritants have recently been applied

What are the adverse effects of superficial heat?

• Burns

• Fainting- *think about vasodilation!

• Bleeding

• Negative CV responses

• Edema, increased inflammation (acute)

What do you look for during thermotherapy screening?

• Heat tolerance?

• Cardiac problems?

• Circulation problems? Blood clots?

• Hx malignancies?

• Numbness in the region?

• Pregnancy*

• Superficial metal?

• Test sensation

• Inspect skin and document before and after

• Extremity pulses

What do you look for when inspecting skin for thermotherapy screening?

• Color

• Ecchymosis

• Open wounds

• Temperature

What is a hydrocollator?

The heat source for hot packs

• Hot water absorbed by hydrophilic silica gel in the canvas cover

• Kept in a thermostatically controlled water bath

What is the mechanism of heat transfer from the hot pack?

conduction

Ideally, how long should you wait to use a hydrocollator hot pack between uses?

30 minutes

What should the water temperature be for a hydrocollator?

158°-167°F

What is the hydrocollator hot pack application?

Silica Gel Packs: 6-8 layers of towels

- cover = 2 layers

How long should you put an ice pack on for?

15 to 20 min

- check skin after 5 minutes

What should the water temperature be for a Hydatherm?

120°-140°F

What is the Hydratherm hot pack application?

Gel Packs: 1 towel or pillowcase

What are the advantages of hot packs?

• Inexpensive

• Easy to setup

• Cover large areas

• Pack cools during treatment

• Reusable

What are the disadvantages of hot packs?

• Have to remove to check skin

• Weight

• Potential cross-contamination

• Burns

• "Can't exercise during application."

• Packs must stay wet

• Evaporation

• Cleaning heating unit

What is Paraffin?

warm wax mixed with mineral oil

What is the temperature a paraffin bath should be?

126- 134 °F

What is the mechanism of heat transfer with paraffin?

conduction

What are the different paraffin application methods?

• Dip and wrap

• Dip and immersion

• Paint

What is the paraffin application during dip and wrap?

• Dip in paraffin

• Pull out, wait for paraffin to harden

• Dip in paraffin, pull out, repeat 6 to 10 times

• Wrap in plastic wrap and then in toweling

• Avoid movement so paraffin doesn't crack and cool faster

What is the paraffin application during dip and immersion?

• Dip in paraffin, pull out and let harden

• Put back in bath and keep it there for 15- 20 min

• Bath should be off so heating element won't burn patient

What is the paraffin application during paint?

paint 6 to 10 layers, cover with plastic and towels (messy)

What are the advantages of paraffin?

• Maintains good contact

• Contours to skin

• Easy to use

• Inexpensive

• Oil conditions skin

What are the disadvantages of paraffin?

• Mess

• Floors and slippage

• Cross-contamination risk

• Dip and wrap and paint methods lose heat quickly

• Dip immersion hard to stay still

• Bath collects a lot of funk

What is fluidtherapy?

Cabinet with heated cellulose particles from ground corn cobs

• Patient puts the extremity in the sleeve in the cabinet

• Can perform ROM during treatment

What should the temperature be in the fluidotherapy?

100 and 118° F

What are the advantages of fluidotherapy?

• Patient can move during heating

• Minimal pressure applied to the area

• Temperature control

• Easy

What are the disadvantages of fluidotherapy?

• MESSY!

• Expensive

• Cross-contamination

What are the desired effects of heat?

- decreased pain

- increased tissue extensibility

- decreased stiffness

What are the undesired effects of heat?

- can increase edema

- increase acute inflammation