Light Modalities

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Light Modalities

  1. 1. Light Modalities Chapter 19
  2. 2. Description  Light modalities are found on the electromagnetic spectrum  Most abundant form of energy in the universe  Drying superficial tissues or via superficial photochemical effects  Some mild superficial thermal effects
  3. 3. Types of Therapeutic Lamps  Infrared  Superficial dry heat  Ultraviolet  Heats the body’s tissues for either tissue destruction or therapeutic effects  Laser  Combination of homogenous ultraviolet and/or infrared energy
  4. 4. Infrared Lamp  Used to dry seeping open wounds or sedate superficial sensory nerves  Radiant modality: An electrical current passes through a carbon or tungsten filament  Intensity controlled by adjusting current flow or distance between lamp and tissue  Constant temperature, increased risk of burns  Heating skin depends on the amount of radiation absorbed  Pigmented, darker skin will absorb more energy and will heat more rapidly than lighter skin
  5. 5. Types of Infrared Lamps  Near-Infrared  Luminous Infrared Lamp  Wavelength: 780 to 1,500 nm (near visible light)  Thermal Effects: 5 to 10 mm deep  Energy formed by carbon and tungsten filament  Light bulb  Some energy is reflected by the surface of the skin
  6. 6. Types of Infrared Lamps  Far-Infrared  Nonluminous Infrared Radiation  Wavelength: 1,500 to 12,500 nm  Thermal Effects: < 2mm  Less penetrating than Near-Infrared  Skin feels warmer  Energy formed by metal coil  i.e. electric stove or space heater  Invisible to human eye
  7. 7. Effects of Infrared Lamps  Constant, dry heat to assist with superficial tissue  Dermatological conditions  Increase cell metabolism  Blood flow  Muscle Relaxation  Contraindications  Any conditions in which other forms of superficial heat are contraindicated
  8. 8. Clinical Application  Turn On and warm if necessary  Treatment Duration: 20 to 30 minutes  Intensity: adjust wattage or distance of lamp  Luminous = 24 inches  Nonluminous = 32 inches  Inverse Square Law  Cosine Law  Clean sweat and dirt, remove jewelry, and fit infrared goggles (if applicable) for patient
  9. 9. Ultraviolet Therapy  Used to produce photochemical reactions in the skin  Wavelength: 180 to 400 nm  3 UV bands (A, B, and C) produce unique effects Ultraviolet A & B Lamp Ultraviolet C Lamp
  10. 10. Types of UV  UV-A  AKA: near UV  Effect:  Erythema without pigmentation  UV-B  AKA: middle UV  Effects:  Erythema without pigmentation  Formation of vitamin D  Skin tanning (blister/burn)  UV-C  AKA: far UV  Effects:  Kills bacteria  Formation of vitamin D  Skin tanning
  11. 11. Types of UV Lamps  ‘Hot’ UV Lamps  Low Volt (30-110V) High-Amp (5A)  Electrical current passes through tube, argon gas heats, vaporizing and polarizing mercury to produce UV light in ALL 3 bands and visible violet light  ‘Cold’ UV Lamps  High Volt (3000V) Low-Amp (15mA)  Energy is cooler than ‘Hot’ and produce UV-C
  12. 12. Biophysical Effects  Energy absorbed at a depth between 0.20 to 0.22 mm  Damages cell proteins, DNA, & RNA to initiate local inflammatory responses  Effects:  Vitamin D synthesis  Enhances melanin production  Thickens epidermis  Superficial vasodilatation  Bactericide
  13. 13. Effects of UV Lamps  Wound Healing  Activates inflammatory response  Use: Cold Lamps at intensity of E3  Treat Skin Disorders  i.e. psoriasis  Exfoliates tissue and damage DNA that produces the excess skin growth associated with psoriasis  Use: UV-B
  14. 14. UV Contraindications  Sunlight sensitivity  Fair skin (precaution)  Medications or food that increase sunlight sensitivity  Examples:  Tetracycline  Shellfish  Hyperthyroidism
  15. 15. UV Dosage  Determined by Minimal Erythema Dose  Least amount of UV exposure time to produce redness within 1-6 hrs and disappear within 24 hours  “Hot” Lamps  Determined by each patient and each lamp  Standard distance = 30 in., not closer than 15 in.  “Cold” Lamps  Standard MED value  12-15 seconds at a distance = 1 in.
  16. 16. Determining MED for UV Lamp  Cardboard Test Strips  1. 6 different shapes cut out  2. Use to cover shapes  UV Lamp 30 in. away
  17. 17. MED (Cont.)  Expose 1 cut out, open the shutters for 30- sec., expose the 2nd cut out and leave the 1st uncover for the 30-sec.  Repeat the steps above for the remaining 4 cut outs, but expose them at 15-sec intervals  Instruct patient to check area every hour and record changes
  18. 18. UV Treatment Dosage  SED  No erythema  MED  Smallest dose that produces erythema within 1-6 hr  E1  Erythema lasts for 1-3 days, some scaling of skin present, approximately 2.5x MED  E2  Erythema with edema, peeling, and pigmentation, approximately 5x MED  E3  Severe erythema and burning, blistering, peeling, edema, approximately, 10x MED
  19. 19. Clinical Application  Calculate treatment dose and duration  Clean area and remove jewelry  Cover skin not being treated (sunscreen if applicable)  Fit UV-resistant goggles to patient and clinician  Position lamp at right angle using the correct distance and duration for each type of lamp  Clean machine and check periodically for maintenance of bulbs
  20. 20. Adjusting the Treatment Dose  Biophysical changes occur with light exposure causing changes in treatment  Duration  30 to 50% increase for each subsequent treatment  If 3 to 5 minutes, then distance is reduced  5 to 10 sec is decreased when missing a treatment  Be aware of patients skin color and the lamps distance, duration, and angle
  21. 21. Therapeutic Lasers  L=Light  A=Amplification by  S=Stimulated  E=Emission of  R=Radiation  Classified by the FDA’s Center for Devices and Radiological Health
  22. 22. Types of Lasers  High-Power Laser  “Hot Laser”  Effect:  Causes thermal changes in tissues (cause tissues to be destroyed, evaporated, or dehydrated)  Uses:  Surgery  Capsular shrinkage  Wrinkle and tattoo removal  Low-Power Laser  “Cold Laser”  Effect  Causes photochemical changes in tissue  Uses:  Wound healing  Arthritis  Burn care
  23. 23. Production of Laser Energy  Lasers are referred to by the type of active medium (gas, liquid, solid)  HeNe: visible red light penetrating 0.8 to 15mm  GaAs: invisible penetrating up to 2 cm  Energy is introduced into the active medium  An orbiting electron briefly elevates into a higher or ‘excited’ state  The electron spontaneously returns and releases another photon
  24. 24. Effects of Lasers  Photons are absorbed by tissues to alter molecular-level activity  Theorized to affect pain-producing tissue (muscle spasm), by increasing ATP synthesis that increases cell metabolism and encourages the release of free radicals
  25. 25. Wound Healing  Superficial wounds  Ulcers, surgical insicison, burns  Lasers alter cell membrane permeability and increase in fibroblast, lymphocyte, and macrophage activity occurs  Blood and lymph improve to promote the growth of granulation tissue  Increase collagen and tensile strength of healing wounds
  26. 26. Pain Reduction  Decrease acute and chronic pain  Reduce the rate and velocity of sensory nerve impulses  Similar to cryotherapy but without thermal changes
  27. 27. Fracture Healing  May enhance fracture healing and bone remodeling by increasing capillary formation, calcium deposition, increase callus formation, and reducing hematomas  Photons striking the tissue create acoustic waves that affect bone healing similar to ultrasonic bone growth stimulators

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