Transcript Light Modalities

Light Modalities
Chapter 19
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
Types of Therapeutic Lamps
• Infrared
– Superficial dry heat
• Ultraviolet
– Heats the body’s tissues for either tissue
destruction or therapeutic effects
• Visible
– Combination of ultraviolet and infrared known
as Lasers
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
Types of Infrared Lamps
• Near-Infrared
– Luminous Infrared Lamp
– Wavelength: 780 to 1,500 nm (closest to 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
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
Effects of Infrared Lamps
• Constant, dry heat to assist with superficial
tissue
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Dermatological conditions
Increase cell metabolism
Blood flow
Muscle Relaxation
• Contraindications
– Any conditions in which other forms of
superficial heat are contraindicated
Clinical Applications
• Turn On and warm if necessary
• Treatment Duration: 20 to 30 minutes
• Intensity: adjust wattage or distance of lamp
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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
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
Types of UV
• UV-A
– AKA: near UV
– Effects: Erythema without pigmentation
• UV-B
– AKA: middle UV
– Effects: Erythema without pigmentation,
formation of vit D, skin tanning (blister/burn)
• UV-C
– AKA: far UV
– Kills bacteria, formation of vit D, skin tanning
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
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:
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Vitamin D synthesis
Enhances melanin production
Thickens epidermis
Superficial vasodilatation
Bactericide
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
UV Contraindications
• Sunlight sensitivity
• Fair skin (precaution)
• Medications or food that increase sunlight
sensitivity
• Hyperthyroidism
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.
Determining MED for UV Lamp
• Cardboard Test Strips
1. 6 different shapes cut out
2. Use to cover shapes
• UV Lamp 30 in. away
• Exposes 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
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
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
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
Therapeutic Lasers
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L=Light
A=Amplification by
S=Stimulated
E=Emission of
R=Radiation
Classified by the FDA’s Center for Devices
and Radiological Health
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
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
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
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
Pain Reduction
• Decrease acute and chronic pain
• Reduce the rate and velocity of sensory
nerve impulses
– Similar to cryotherapy but without thermal
changes
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
Clinical Application
• Because of the investigational status of
therapeutic lasers, the clinical application is
not described.