Infrared Radiation Prof.Dr. Gehan Mosaad

At the end of the lecture the student should be able to Know classification of IRR. Understand the mechanism of IRR production. Identify and differentiate between the different sources of IRR. Discus the physiological effects of IRR. Determine indications and contraindications of IRR.

Infrared Radiations Infrared radiations (IRR) are electromagnetic radiation that lies within that part of electromagnetic spectrum between visible light and microwave radiation. The radiation is characterized by wavelength extended from 760 nm to 1 mm. IRR can be subdivided into 3 regions (A,B &C) according to their absorption and their effect upon the tissue.

Infrared Radiation 760nm to 1 mm

Classification of infrared radiation Penetration Wavelength Type 5 mm reach to dermis 760 - 1400 nm IRA(short or near IR) Up to 1 mm to epidermis 1400 – 3000 nm IRB(long or far IR) Not used therapeutically 3000nm – 1 mm IRC

Production of Infrared Infrared is produced as a result of molecular motion within heated materials. All hot bodies emit IR, as increase the temperature of any material above absolute zero result in vibration and rotation of molecule within the material . The wavelength of the emitted IR are determined by the temperature of the material. The higher the temperature of the body, the higher the frequency, and the shorter the wavelength.

Sources of Infrared Natural sources: The sun Artificial sources: 1- Luminous sources 2- Non-luminous sources

Artificial sources Luminous sources Electrically heated filament made of tungsten filament within a glass bulb which contain an inert gas at low pressure. Part of the glass bulb is silvered to provide a reflector. Luminous sources emit mainly: - Short or near IR (IRA) - Visible light - Ultraviolet

Non-luminous sources Non-luminous sources are those which produce infrared radiation from a non-glowing source, such as moist heat packs and non-luminous IR lamps Non-luminous infrared lamp consists of a coiled resistance wire which embedded within a ceramic insulating material Non - luminous sources emit mainly long or far IR radiation.

Absorption and penetration of IRR IRR is strongly absorbed near the skin surface and the heat is carried to deeper tissues by conduction and by the circulating fluids. The absorption and penetration of IRR rays depend on: 1- Wavelength of the rays 2- Angle of incidence of the rays. 3- The intensity of the emitting source. 4-The distance of the radiating source from the tissue.

Physiological Effects of Infrared IRR is considered as superficial heating modality Cutaneous vasodilatation Increase metabolism Neurological effect (Pain control) Effect on connective tissue

1- Cutaneous vasodilatation Heating with IRR leads to vasodilatation of the blood vessels as a result of: release of chemical mediator histamine like substance axon reflex mechanism. Vasodilatation causes increase blood flow in the cutaneous circulation

Vasodilatation starts after short period of exposure to IRR and leads to redness of the skin that appears as irregular patchy erythema and its intensity depends on the degree of heating. This local erythema appears immediately after exposure to IRR and lasts 30 minutes after treatment has stopped.

2-Increase metabolism Increase temperature by IRR leads to increase metabolic activities within the superficial tissue due to direct effect of heat on chemical process in the cell Increase metabolic activities lead to improve cell function and improve tissue healing.

3- Neurological effect The heat production by IRR leads to relief pain by: Stimulation of sensory nerves (A-Beta nerve fibers) lead to inhibition of pain at the level of the spinal cord. Decrease activity of muscle spindle leading to relaxation of muscle Removal of waste products as the result of improving circulation and increase venous return thus removing the source of pain stimulation.

Effect on connective tissue The heat effect of IR leads to increase the extensibility of connective tissue and therefore is used prior to exercise to increase range of motion (stretching and mobilization exercises). N.B. Increasing tissue extensibility by heating through IRR will not decrease soft tissue shortening. So infrared must be used in conjunction with stretching and ROM exercises.

Therapeutic Uses of Infrared Pain Muscle spasm Incisional wound (Acceleration of healing) Subacute and chronic inflammation of musculoskeletal system Chronic mild to moderate edema Prior to stretching &mobilizing exercises Some skin conditions (fungal infection)

Contraindications Acute inflammation Acute infection Open wounds Impaired sensation Impaired circulation Over pregnant uterus Eyes Metal

Burns: The main danger of IR treatment is the burn. It occurs if Hazards and Dangers Burns: The main danger of IR treatment is the burn. It occurs if 1- heat is too intense. 2- the patient is not fully aware of the level of heating. 3-the patient is unable to communicate with physiotherapist. Eye damage : The eye should be covered with a light towel or head turned away during the application of IRR to avoid eye surface dryness or possible irritation.

Thank you