Thermal Agents

Chapter 6

• Heat Energy can be transferred to, from, or within the body through different modes of heat transfer.

MODES OF HEAT TRANSFER

MODES OF HEAT TRANSFER

Conduction

energy is exchange by direct contact between molecules of two materials at different temperatures

PAs transfer thru Conduction

• Hot pack

• Cold Pack

• Paraffin

Guidelines for Heat Transfer By Conduction

1. The greater the temp difference between the PA and the body part it is applied to, the faster the rate of heat transfer.

2. Materials with high thermal conductivity transfer heat faster than those with low thermal conductivity.

Guidelines for Heat Transfer By Conduction

3. The area of contact

4. The Temperature Rate.

Convection Heat Transfer

• Result of direct contact between circulating medium and another material of different temperature.

• Examples: whirlpool, fluidotherapy

Conversion Heat TransferA non-thermal form of energy is converted to

heat .

No Direct contact

i.e. US – mechanical energyDiathermy – electromagnetic energy

Radiation Heat Transfer

Example – infrared lamp

Heat Transfer Thru Evaporation

A material must absorb energy to evaporate.

i.e vapocoolant spray, sweat

Physiological Affects of Thermal Agents

Heat vs Cold

• Blood flow – vasodilation

• Neuromuscular - ↑nerve conduction, ↓pain, strength changes

• Metabolic - ↑ metabolism

• ↑tissue extensibility

• Blood flow – vasconstriction

• Neuromuscular - ↓ nerve conduction, ↓pain, strength changes, ↓spasticity

• Metabolic - ↓metabolism

• ↓ tissue extensibility

Use of Cold

Controls

• Pain

• Inflammation

• Edema

• Modification of spasticity

Cryokinetics

• Technique that combines the use of cold and exercise in the treatment of pathology or disease.

Cryostretch

• Application of a cooling agent before stretching.

Contraindications For Cryotherapy (p. 140)

• Cold hypersensitivity

• Cold intolerance

• Cryoglobulinemia

• Paroxysmal cold hemoglobinuria

• Raynaud’s disease or phenomenon

• Over regenerating peripheral nerves

• Over an area with circulatory compromise or peripheral vascular disease

Precautions For Cryotherapy (p. 141)

• Over a superficial main branch of a nerve

• Over an open wound

• Hypertension

• Poor sensation

• Poor mentation

• Very young or old

Application Techniques

Page 143, 144, 145, 149

Use of Heat

• Pain control

• Increase tissue extensibility

• Increase healing

Examples: HP, Paraffin, and Fluidotherapy

Contraindications for Use of Thermotherapy (page 157)

• Recent or potential hemorrhage

• Thrombophlebitis

• Impaired Sensation

• Impaired Mentation

• Malignant Tumor

• IR irradiation of the eyes

Precautions for Use of Thermotherapy (page 158)

• Acute injury or inflammation• Pregnancy• Impaired circulation• Poor thermal regulation• Edema• Cardiac insufficiency• Metal in area• Over an open wound• Demyelinated nerves

Adverse Effects of Thermotherapy (page 160)

• Burns

• Fainting

• Bleeding

• Skin and eye damage from infrared irradiation

Superficial Thermotherapy

Hot Packs

• Commercial HP are made of a hydrophilic silicate gel covered in canvas.

• Come in various shapes and sizes

• HP are stored in hot water.

• They are stored in a thermostatically controlled water cabinet called a hydrocollator.

Application Technique - HP

Page 162

Paraffin

• Warm, melted wax mixed with mineral oil is used as a superficial thermal agent.

• 6:1 Ratio

• Paraffin is heated to 126-134 degrees.

Application of Paraffin (page 164)

Two Techniques:

Dip-Wrap Method

Dip-Immersion Method

Fluidotherapy

• Fluidotherapy is a dry agent that transfers heat by convection.

• Finely ground corn cob particles are housed in a cabinet. Heated air circulated thru the particles acting to superficially heat the immersed body part.

Infrared Lamps

What is infrared?• IR is the portion of the electromagnetic spectrum

that is just beyond red visible light.

• Heat and electromagnetic rays in IR ranges are emitted due to vibration of electrons.

• IR is a source of superficial heat that will absorb about 3 mm.

• Currently being utilized as “Anodyne” to treat diabetic peripheral neuropathy.

Application Techniques for IR

Page 167

Documentation

Documentation of Cryotherapy(page 149)

• The following should be documented:– Area of body being treated– Type of cooling agent used– Treatment duration– Patient positioning– Response to intervention

Review Examples – page 149

Documentation of Thermotherapy (page 168)

• The following should be documented:– Area of body being treated– Type of heating agent used– Treatment parameters:

• Temp or power of agent• # and type of insulation layers used• Distance of agent from patient• Patient’s position or activity

– Treatment duration– Patient positioning– Response to intervention