Electrotherapy 1 Lecture 04 Infrared Radiation PDF

Electrotherapy 1 Lecture 04 INFRARED RADIATION (IR) Dr. Mohamed M. ElMeligie, PT, MSc. , Ph.D Lecturer of Physical Therapy, Department of Basic Sciences, Facult...

Electrotherapy 1 Lecture 04 INFRARED RADIATION (IR) Dr. Mohamed M. ElMeligie, PT, MSc. , Ph.D Lecturer of Physical Therapy, Department of Basic Sciences, Faculty of Physical Therapy, Ahram Canadian University Objectives Define Infrared radiations (IRR).  Distinguish between different types of (IRR).  Describe production of (IRR).  Mention source of (IRR).  Recognize physiological effects of (IRR).  Describe indication and contraindication of (IRR).  Apply (IRR) to patients. Definition Infrared radiation (IR) is a superficial thermal agent used therapeutically for the relief of pain and stiffness, to increase joint motion and to enhance the healing of soft tissue lesions and skin conditions. Infrared radiations The infrared rays are electromagnetic waves with the wavelengths of 750 to 400000 nm and frequency 4 × 1014 Hz and 7.5 × 1011 Hz. It lies beyond the red boundary of visible spectrum. (Infra=below, red= red visible light). Any hot body can produce infrared rays like the sun, electric bulb, coal fire, gas fire, etc. Infrared radiatio n IR radiation has a wavelength of 770 to 10 6 nm, lying between visible light and microwaves on the electromagnetic spectrum Heat vs. Temperature TEMPERATURE IS THE MEASURE OF AN HEAT IS A FORM OF ENERGY PRODUCED BY OBJECT’S ABILITY TO SPONTANEOUSLY THE MOVEMENT OF ATOMS AND MOLECULES. GIVE UP ENERGY. (SCALE) (JOULES) The heat energy of a substance depends on three elements: The speed of its particles (its The number of particles (its The capacity of its particles to kinetic energy) mass) store heat (its specific heat capacity). Notes All substances with a temperature above absolute zero (−273°C) possess heat. Notes (Cont’d) Most of the heat and cold modalities, such as: 1. Hydrocollator packs 2. Paraffi n baths 3. Hot and cold whirlpools 4. Ice packs 5. Infrared lamps Produce forms of radiant energy that have wavelengths and frequencies that fall into the infrared region , so called infrared modalities Infrared energy is emitted from any object having a temperature greater than absolute zero  Infrared (thermal changes) Ultraviolet (chemical changes) Classification of IRR IRR Classification By International commission on illumination (CIE) Type Wavelength Frequency IR-A (near or short 700 nm – 1400 nm 215 THz – 430 THz IR) IR-B (Mid IR) 1400 nm – 3000 100 THz – 215 THz nm IR-C (Far or long IR) 3000 nm – 1 mm 300 GHz – 100 THz Physical Characteristics of IR 01 02 03 04 IR produced by Increase in Higher body Most bodies emit molecular motion temperature → temperature → multiple IR ♻️ vibration/rotation higher frequency wavelengths owing of molecules → IR output → shorter to emission 🔥 wavelength 🤒 emission/absorptio n effects on molecules 💡 Infrared lamps IR lamps emit electromagnetic radiation within the frequency range that gives rise to heat when absorbed by matter Sources of Infrared radiation Natural Artificial Sources Sources Non- Luminous The sun Luminous Sources Sources  Luminous vs. Non-Luminous Point of Luminous Generators Non-Luminous Generators Comparison Tungsten filament enclosed in glass Coiled resistance wire embedded in Composition bulb containing inert gas at low ceramic insulating material pressure Emit infrared, visible light, and Light Emission Emit only infrared rays ultraviolet rays Wavelength Range 350 - 4000 nm 750 - 15000 nm Peak Wavelength Around 1000 nm N/A Require 5-7 minutes heat-up time Heat-up Time Low heat-up time before use Can penetrate into dermis and Depth of Penetration Can penetrate only superficial dermis epidermis Counter-irritant effect good for Sedative effect good for su-acute Therapeutic Effects chronic lesions inflammation and injuries Coiled elements mounted on Examples Incandescent lamps, bulbs Luminous Generator Luminous generators of infrared include incandescent lamps or bulbs The electromagnetic waves emitted range from 350 to 4000 nm, with the majority around 1000 nm The front of these bulbs is typically red to filter out shorter visible and ultraviolet rays. What are Incandescent Bulbs? An incandescent lamp consists of a wire filament enclosed in a glass bulb The filament is a coil of fine wire, usually made of tungsten The bulb may contain an inert gas at low pressure Why Tungsten? Tungsten is a metal that can It's used as the filament in these tolerate repeated heating and lamps due to this property cooling How do Incandescent Bulbs Work? The bulb is mounted at the center of a parabolic reflector The reflector is on an adjustable stand The exclusion of air prevents oxidation of the filament, avoiding an opaque deposit forming on the inside of the bulb Range of Emitted Waves Luminous generators emit a The maximum proportion of Shorter visible and range of electromagnetic these rays have a ultraviolet rays are filtered waves wavelength in the region of out by the red front of the 1000 nm bulb Non-Luminous Generator Nonluminous generators consist of an element or coil wound on an insulating cylinder Instruments like fireclay or porcelain are commonly used as insulating materials An electric current is passed through the wire, generating heat and therefore infrared rays Working Mechanism of Nonluminous Generators The heat from the wire is transmitted through the porcelain or fireclay The coil is often embedded in or placed behind the fireclay or porcelain to minimize visible rays The coil is typically placed at the focal point of a parabolic or spherical reflector The Role of the Reflector The reflector is mounted on a stand and its position can be adjusted as needed The construction of the apparatus ensures that the reflectors don't become excessively hot A wire mesh typically surrounds the element for safety An Alternative Nonluminous Generator In another type of nonluminous generator, a steel tube is used An electric coil embedded in a heat-conducting, electrically insulating material is installed inside the tube When electric current is passed through the coil, heat is produced, causing the steel tube to emit infrared rays Preparing Nonluminous Generators Nonluminous To ensure readiness, generators take some they should be time to heat up for switched on 5–7 the production of minutes before infrared radiations treatment begins Physical Characteristics of IR IR can be: Reflected Absorbed Transmitted Refracted Diffracted Reflection and absorption most significant biologically and clinically Penetration of IR Intensity of the source Wavelength/frequency Angle of incidence Absorption coefficient Intensity of the source The brighter the infrared source, the more energy it emits and the deeper the penetration into a material. For example, a 100W infrared lamp will penetrate deeper than a 50W lamp. Wavelength/frequency Shorter infrared For example, near- wavelengths have infrared (700- higher frequencies 1400nm) penetrates and more energy, deeper than far- allowing deeper infrared (1400- penetration. 3000nm). Angle of incidence Infrared hitting a surface at a For example, infrared from an perpendicular angle penetrates overhead lamp penetrates deeper deeper than at an angled or glancing than a lamp off to the side. angle. Absorption coefficient Outer skin layers (epidermis, dermis) have lower absorption, allowing IR to reach sensory nerves. Pigmentation affects absorption - darker skin absorbs IR more superficially than lighter skin. Most soft tissues exhibit moderate absorption, so IR penetrates to shallow depths. Deep heating still occurs through conduction from superficial tissues.  Longer IR wavelengths: Penetrate 0.1 mm depth (Harlen 1980) Shorter IR wavelengths: Penetratio Penetrate up to 3 mm depth (Harlen 1980) n of IR Penetration decreases exponentially with depth Greatest heating most superficial Penetration of IR Deeper heating by: Conductio Convectio n between Increased n via tissue blood flow circulation layers Evidence for Clinical Efficacy Pain Joint Stiffness Skin Diseases Pain IR applied to ulnar nerve → analgesic effect distal to application (Lehmann et al 1958) IR increased ulnar nerve conduction velocity, with 0.8°C temp increase (Kramer 1984) IR can increase nerve conduction velocity in normal humans (Halle et al 1981, Currier & Kramer 1982) Joint Stiffness IR increased hand joint temp to 45°C → 20% drop in joint stiffness (Wright & Johns 1961) Limited evidence with only 2 subjects May be effective for small joints like hands Skin Lesions IR dries skin → beneficial for some lesions like psoriasis and fungal infections 80% psoriasis remission with 42°C IR (Westerhof et al 1987) But IR damages and inhibits healing of open wounds Indications Wound Decreased Joint Pain healing Circulation stiffness Neuropath Rheumato Sleep y id Arthritis Deficits Contra-indications Acute Injuries Deep vein thrombosis (DVT) Lack of local thermal sensitivity Recent local bleeding/hemorrhaging Devitalized skin after deep X-ray Certain skin conditions: Skin carcinomas Acute dermatitis with wax Precautions Acute febrile illness/ infection Analgesic & narcotic drugs Patients not follow command well Defective blood pressure regulation Pregnancy: for large irradiated area Physiological 1. Metabolic effects Effects of Thermotherapy 2. Vascular effects 3. Neuromuscular effects 4. Connective tissue effects Metabolic effects ↑ 10°C in temperature = ↑ Cell activity and metabolic rate by 2-3 times. (Van Hoff’s Law) PROMOTE HEALING Vascular effects Axon reflex Vasodilatation Release of ↑ Tissue Chemical temperature mediators Local Spinal cord reflexes Axon Reflex (Direct effect) V.D Blood Thermorecepto vessel rs Heat Modality Spinal Cord Axon Reflex Heat applied to skin will stimulate cutaneous thermoreceptors Thermoreceptors Vasodilati will carry on impulses to the spinal cord Some of these Release of afferent impulses vasoactive transfer mediators (Nitric antidromically oxide) toward skin blood vessels Release of Chemical mediators (Indirect effect) Histamine Mild Inflammator Vasodilatatio y reaction n Prostaglandi Heat ns Kallikrein ↑ Sweat Release ↑ Vascular enzyme is secretion bradykinin permeability released Local Spinal cord reflexes (Indirect effect) Stimulation of cutaneous thermoreceptors ↓ postganglionic sympathetic nerve activity to smooth muscles of blood vessels Vasodilatation  Neuromuscular effect Effect of heat application on Neural system 1. ↑ Nerve conduction velocity By 1-2 meters/sec for every ↑ 1°C 2. ↓ Latency of motor and sensory nerve fibers 3. Pain relief + Increased Pain threshold Activation of cutaneous thermoreceptors has direct inhibitory gating effect on pain impulses travelling to spinal cord. 4. ↓ Gamma firing rate + ↓ Alpha motor neuron activity Change in muscle spindle firing rate  Decrease sensitivity of muscle Neuromuscular effect Effect of heat application on Muscular system 1. Relaxation Increased blood supply to muscle helps to remove lactic acids and metabolic wastes  decrease pressure on nerve and blood vessels  Muscle relaxation. 2. ↓ Muscle Spasm Heat application can help break pain-spasm cycle mechanism. Connective tissue effects Increase collagen extensibility Stretching the soft tissue without heating  elastic deformation Stretching the soft tissue with heating  plastic deformation Plastic deformation is due to the change in the viscoelasticity of collagen fibers + the organization of collagen fibers Thermotherapy temperature benchmarks 50 C Burn 45 C 44 C ↑ Plastic 43 Enzymati deformation of C c activity collagen rich 42 ↑ C structures Release 41 of O2 C 40 (Doubled C ) 39 C 38 C Laws Governing the Effects of Electromagnetic Energy Arndt-Schultz Principle Law of Grotthus-Draper Cosine Law Inverse Square Law Arndt-Schultz Principle Arndt-Schultz principle states that no reactions or changes can occur in the body tissues if the amount of energy absorbed is insufficient to stimulate the absorbing tissues. The purpose of using therapeutic modalities is to stimulate body tissue. This stimulation will only occur if energy produced is absorbed by the tissue. What does it mean ? impaired normal Too function and There is an optimal much irreparable amount of energy energy damage absorption per unit Less of time that is energy will not cause a beneficial than reaction. require d Law of Grotthus-Draper Waves must be absorbed in order to be beneficial. Also known as the principle of photochemical activation and the Draper law. This law was proposed in the 19th century to define the effect of photons in stimulating photochemical reactions in a substance. What does it mean ? There is an inverse relationship between the amount of energy absorption and the depth of penetration of the energy. Energy that is absorbed by superficial layers is no longer available to deeper-lying tissues. This law explains why the effects of laser and infrared radiation are only superficial. Cosine Law The optimum radiation occurs when the source of the radiation is perpendicular to the center of the surface of the area to be radiated. When the source is at an angle, some of it is reflected to the side rather than moving into the tissue. Cosine Law The amount of transmission is a function of the angle of application: full effects are achieved at 90°; 86% at 60°, and only 50% when radiation is applied at 30°. Inverse Square Law The intensity of the radiation striking a particular surface is known to vary inversely with the square of the distance from the source. For example, when using an infrared heating lamp to heat the low back region, the intensity of the heat energy at the skin surface will be four times greater if the lamp is positioned at a distance of 25 cm (10 inches) compared to if the lamp is placed at a distance of 50 cm (20 inches). Inverse Square Law Practical Application Practical application Equipment needed Treatment parameters Safety Considerations Advantages Disadvantages Equipment Infrared lamp, Anodyne unit, etc Choice of lamp: non-lumnious or luminous Non-luminous: around 10 minutes to warm-up needed - Large lamps (3-6 bulbs) for large area - Smaller lamps for smaller areas and home use Protective goggles Alcohol wipes Towel Sheets, pillows Treatment table/chair  Treatment/Parameters Confirm patient does not have contraindications to treatment. Determine optimal patient position—supine, prone, or seated. Remove clothing and jewelry from area. Prepare skin area before treatment—clean and wipe dry area. Establish correct parameters, including distance of lamp (~ 20 inches [51 cm]), and angle of lamp to tissues (ideally perpendicular). Make sure you and patient are wearing safety goggles. Drape nontreatment areas with dry towels. Begin treatment; provide patient a call light/bell. Check on patient 5 min after treatment begins. Patient can receive treatment for 15 to 30 min. Check patient’s skin and ask for feedback after treatment Safety Considerations Monitor patient’s response (verbally and visually) during treatment session. Make sure you and patient are wearing goggles and other tissue is protected by dry towels. May need to move lamp farther away if patient becomes too warm.  Dry toweling: This is to be used for Infrared lamp draping the parts of the body not Equipme being treated. nt Moist toweling: A GFI should be Needed Moist towels are used with an used to cover the infrared lamp. area to be treated. Dosage 01 02 03 Lamp intensity Distance from Treatment (watts) patient duration Hazards & Detrimental Effects Burns (superficial) Inadequate equipment testing Devitalized tissue Impaired skin sensation Electrical burns if faulty equipment  Chronic tissue damage Prolonged high temperature exposure Hazards & Epidermal hyperplasia Increased ground substance Detriment Permanent pigmentation al Effects Infection in open wounds Increased adhesions in surgical wounds Hazards and Detrimental Effects Apnea in infants Optical damage Corneal burns Retinal injury Lenticular injury Dehydration, dizziness, low BP in susceptible subjects