ByB. Nelson

Definition of IR radiation

Radiation: the process of emitting energy in waves from a source

Portion of the electromagnetic spectrum with wavelength of 780 nm – 100,000 nm

Physiological effectsCutaneous vasodilationIncrease nerve conduction velocity

50% of the IR radiation of 1200nm wavelength penetrates beyond 0.8mm and interact with subcutaneous capillaries and cutaneous nerve endings.

Types of IR generators2 types of generators:1) Luminous generator

2) non luminous generator

Infrared Lamp

Infrared lamp

Therapeutic effects

Decreases painIncrease joint flexibility– increase joint ROMDuration of treatment application ranges

from 15 – 30 minutes

IndicationsUsed when patient cannot tolerate pressure

from another type of modality

ContraindicationsWhere is decreased sensationPeripheral Vascular Disease with

compromised circulationOver a tumor

Increase in tissue temperatureIs influenced by the amount of radiation that

penetrate the tissueThe power and wave length of the radiationThe distance of the radiation source from the

tissueThe angle of incidence of the radiation to the

tissueThe absorption coefficient of the tissue

Absorption of IRIntensity reaching the skin is greatest when :1) the source of radiation is closest to the

skin

2)the radiation beam is perpendicular to the skin surface (optimal absorption occurs when the rays strike perpendicularly)

Absorption coefficient

IR absorption coefficient are mainly affected by skin colour ( darker skin will absorb more)

Absorption of IRAbsorption is affected by:1) the amount of melanin in the skin ( darker

skin absorbs more radiation than lighter skin)2)skin texture3) dryness, smoothness

Adverse effects of IR radiation

Dries the skin more than other modalities

Does not treat uneven body parts well due to uneven heating

Laws governing the effects of electromagnetic radiation1)Arndt-Schultz principle : no reaction or

changes can occur in the body tissues if the amount of energy absorbed is insufficient to stimulate the absorbing tissues

2) Law Grotthus –Draper:if the energy is not absorbed by the superficial tissue, it will penetrate to the deeper tissues

Cosine LawThe cosine law states that the smaller the

angle between the propagating ray and the right angle ,the less radiation reflected and the greater absorbed

Inverse square lawStates that the intensity of the radiation

striking the particular surface varies inversely with the square of the distance from the source

noteThe modalities that emit radiations with

relatively longer wavelength have the ability to transmit energy through the superficial tissue layers ,thus penetrating to the deeper tissues where it is absorbed

Method of application

Contrast packs/bathAre applied by alternately immersing an area

first in warm water/hot and then in cool/cold water

Published data on this modality is lacking

Indications Chronic oedemaSubacute traumaSprains , strains, or tendinitisChanging a modality from cold to hot to

facilitate a mild temperature increase

Therapeutic effectsIncrease blood flow to the injured area

without the accumulation of additional oedema

Oedema is decreased

Method of application3:1 or4:1 ratio of hot to cold for 20 minutes

Physiologic responseVasoconstriction and vasodilation

ReferencesPhysical Agents in Rehabilitation: From

Research to Practice: Michelle H. Cameron

Physical Agents: Theory And Practice: Barbara J. Behrens, Susan L. Michlovitz

Therapeutic Modalities in Rehabilitation by William Prentice