Phototherapy



Phototherapy


Cynthia Rena Heaton

Margaret Hirsch

Angela Hamilton






I. OVERVIEW

Phototherapy is the exposure of nonionizing radiation for therapeutic benefit; ultraviolet light (UVL) is not visible and is classified by wavelength—UVC, UVB, and UVA; UVB and UVA are used in treating dermatologic diseases. Phototherapy is the use of UVL to clear skin diseases. This is also referred to as photomedicine. Phototherapy is prescribed by dermatologists and other physicians, nurse practitioners, and/or physician assistants.

A. Evolution of phototherapy

1. Broadband (BB) UVB—first used in the 1920s (290 to 320 nm).

2. Full-body cabinets—first used in the 1970s.

3. Narrowband (NB) UVB—first used in the 1980s (311 to 313 nm).

4. Psoralen plus UVA (PUVA) gets Food and Drug Administration (FDA) approval in 1982 (320 to 400 nm).

5. Ultraviolet A1 (UA1), the long-wavelength band of UVA—first used in the 2000s (340 to 400 nm).

B. Ultraviolet light (Figure 6-1)

1. Phototherapy terms

a. Wavelength—the distance measured along the wave from any given point to the next similar point, as from crest to crest (peaks).

b. Nanometer (nm)—the unit of measurement used to describe the distance between wavelengths. One billion nanometers equals 1 m or 39.37 inches.

c. Photons—the energy emitted from the UVL wavelength.

d. Joules (J)—the dosing unit for UVA. One joule equals 1,000 millijoules.

e. Millijoules (mJ)—the dosing unit for UVB.

C. Facts about UVL

1. Longer wavelengths produce fewer photons, resulting in less energy.

2. Shorter wavelengths produce more photons, resulting in more energy.

3. UVL can do one of three things. It can be reflected, transmitted, or absorbed. When UVL is absorbed, photons activate specific cells in the dermis and epidermis called chromophores, resulting in a biological response.

4. Most natural sunlight exposure occurs in the first 18 to 20 years of life, and phototherapy adds to total lifetime accumulation. Overexposure to UVL increases the risk of skin damage. Therefore, risks versus benefits of therapy must be considered.







FIGURE 6-1. UVL spectrum.

5. UVL’s therapeutic physiological effects are immune function manipulation, decreased DNA synthesis, and selective cytotoxicity.

D. Common diseases treated with phototherapy

The most common dermatological diseases treated with phototherapy are psoriasis, vitiligo, various types of dermatitis, and cutaneous T-cell lymphoma (CTCL). The goals of phototherapy are different depending on the disease being treated (Table 6-1).

1. Psoriasis: goal is to depress the immune system and slow down T-cell activity, which will then result in thinning of plaques, decreased pruritus, decreased scaling, and induction of remission.








TABLE 6-1 Photoresponsive Diseases



































































































































Photoresponsive Diseases


BB-UVB


NB-UVB


UVA


UVA-1


PUVA


Alopecia






X


Atopic dermatitis/other eczemas


X


X


X


X


X


Folliculitis


X


X


X



X


Graft vs. host disease





X


X


Granuloma annulare



X



X


X


IRBD (“itchy red bump disease”)


X


X


X



X


Lichen planus



X




X


Localized scleroderma





X



Mycosis fungoides (CTCL)


X


X



X


X


Parapsoriasis


X


X


X



X


Photosensitivity


X


X


X



X


Pityriasis rosea


X


X





Prurigo, pruritus





X



Psoriasis


X


X


X



X


Uremic pruritus


X


X


X




Urticaria pigmentosa





X



Vitiligo



X




X


BB, broadband; NB, narrowband; UVA, ultraviolet A; UVB, ultraviolet B; PUVA, methoxsalen + ultraviolet A.


2. Vitiligo: goal is repigmentation, which will occur in 50% to 80% of patients.

3. Dermatitis: goal is to depress the immune system resulting in elimination or reduction of pruritus. Improvement of the rash is secondary. This group includes atopic dermatitis, eczema, folliculitis, IRBD or papular dermatitis, and lichen planus.

4. CTCL: goal is to slow the systemic progression of the disease as evidenced by flattening of plaques and normalization of skin pigmentation.


II. PHOTOTHERAPY

UVL waves found in sunlight have a therapeutic effect. The types of UVL used to treat skin diseases are UVB and UVA (Figure 6-2).

A. UVB

UVB is referred to as the sunburn ray. It is 1,000 times more capable of producing erythema than UVA and is dosed in millijoules (mJ). It has shallow penetration into the epidermis, takes a short time to develop erythema (4 to 6 hours), and the erythema resolves quickly (18 to 24 hours). Skin protection against UVB is referred to as hyperplasia, thickening of the top layer of skin.

1. Broadband UVB (BB-UVB) wavelength 290 to 320 nm

a. Must wear goggles, as corneal burns can occur (Figure 6-3).

b. Sunburning spectrum of light, therefore potentially the most damaging.

c. Potential carcinogenesis following long-term exposure.

d. No medications needed as epidermis has sufficient chromophores to absorb UVB. When phototherapy truly indicated in pregnant women, UVB is frequently the type chosen because no additional medications are used with this treatment.

2. Excimer laser UVB-wave length of 308 nm.

a. Treatment twice a week.

b. Emits light that is monochromatic and coherent.

c. Handheld device with a fiber-optic arm allows for targeted application of light while avoiding unaffected skin.

d. Uses a spot diameter of 14 to 30 mm.






FIGURE 6-2. Energy of UVL.







FIGURE 6-3. Eye light absorption.

3. Narrowband UVB (NB-UVB) wavelength of 311 to 313 nm.

a. Clears lesions faster than BB-UVB.

b. Fewer treatments necessary.

c. Treatment Schedule.

(1) Clearing phase: three to five treatments per week until disease clears.

(2) Maintenance phase: every 9 to 11 days to maintain clearance.

4. Indications (BB-UVB and NB-UVB).

a. Treatment of photosensitive dermatoses.

b. Pregnant women and children may be treated since there are no drugs needed for UVB to be effective.

c. Used for patients with UVA contraindications, such as previous arsenic or x-ray therapy.

5. Absolute contraindications (BB-UVB and NB-UVB).

a. Xeroderma pigmentosum

b. Albinism

c. Porphyria

6. Relative contraindications (BB-UVB and NB-UVB).

a. Can exacerbate photodermatoses.

b. Previous nonmelanoma skin cancers or family history of melanoma.

c. Inability of patient to stand due to physical limitations.








TABLE 6-2 Skin Typing

































Type*


Characteristic


Example


I


Always burns, never tans


Celtic or Irish, often blue eyes, red hair, freckles


II


Burns easily, tans slightly


Fair skin, often blonde hair; many whites


III


Sometimes burns, then tans gradually, and moderately


Mediterranean’s and some Hispanics


IV


Burns minimally, always tans well


Asians and darker Hispanics


V


Burns rarely, tans deeply


Middle Easterners, Asians, dark brown-black skin, African American


VI


Almost never burns, deeply pigmented


Black skin, African American


* Reflects color of unexposed buttock skin. Skin types I to III are white, type IV is white or faint brown, type V is brown, and type VI have dark brown or black buttock skin.









TABLE 6-3 Comparison of Ultraviolet B Narrowband and Broadband Protocols































Skin Type


Broadband


Narrowband (NBC protocol)


I


10 mJ


120 mJ


II


20 mJ


220 mJ


III


30 mJ


260 mJ


IV


40 mJ


330 mJ


V


50 mJ


350 mJ


VI


60 mJ


400 mJ


d. Noncompliance with regular treatment schedule.

e. Physically or mentally unstable, debilitated, or intoxicated patients.

7. Dosing (BB-UVB and NB-UVB).

a. Skin type—estimate of patient’s ability to tolerate UVL (Table 6-2).

b. Intensity and dosage length are increased as tolerated per a specific protocol designated by the prescribing provider (Tables 6-3, 6-4 and 6-5; Boxes 6-1 through 6-2).

c. Minimal erythema dose (MED)—smallest amount of UVL needed to produce mild erythema.

(1) Small sections of the patient’s skin are exposed to increasing doses of UVB.

(2) Results are read within 18 to 24 hours.

8. Nursing considerations (BB-UVB and NB-UVB).

a. Always evaluate extent of erythema prior to each treatment.

b. Arms and legs may require extra dosing; if so, all other areas must be shielded.

c. Always question the patient regarding new medications as they may be photosensitizing.

d. Protective goggles must be worn during treatment, genital shields for males.

e. Do not increase dose if it has been 7 days since last treatment (or per facility protocol).

B. UVA

UVA is referred to as the suntanning ray. It is 1,000 times less effective in producing erythema than UVB and is dosed in joules (J). UVA penetrates deep into the dermis, takes a longer time for erythema to develop (12 to 36 hours) and can take days to resolve. Skin protection against UVA is referred to as melanogenesis, which leads to hyperpigmentation (tanning).








TABLE 6-4 Narrowband Treatment Protocol































Skin Type


Initial Dose


Subsequent Dose


I


120 mJ


15-25 mJ


II


220 mJ


25-40 mJ


III


260 mJ


40-45 mJ


IV


330 mJ


45-60 mJ


V


350 mJ


60-65 mJ


VI


400 mJ


65-100 mJ










TABLE 6-5 Broadband Treatment Protocol































Skin Type


Initial Dose


Subsequent Dose


I


10 mJ


5-10 mJ


II


20 mJ


5-20 mJ


III


30 mJ


5-30 mJ


IV


40 mJ


5-40 mJ


V


50 mJ


5-50 mJ


VI


60 mJ


5-60 mJ

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Mar 9, 2021 | Posted by in NURSING | Comments Off on Phototherapy
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