PATIENT EDUCATION GUIDELINES

Patch Testing

Patch testing is a process used to determine what substances may be causing allergic reactions in your skin. Your dermatologist will decide which substances to test. The goal of patch testing is to reproduce the skin rash on a small, controlled area of the skin. The patch test will identify materials, such as preservatives, fragrances, dyes, and chemicals that cause an allergic reaction upon contact with your skin. Because patch testing does not break the skin barriers, allergies to food, inhalants, and oral medication cannot be identified by this method.

WHAT TO EXPECT

During your initial visit, which lasts approximately 30 minutes, the nurse will apply one or more small aluminum disks to an area on your upper back (used as the test site because the strongest responses are seen in this area). These disks, or patch test kits, contain small amounts of each suspected chemical or allergen; the substances to be tested are determined by your dermatologist or other health care provider. A visible reaction in the skin in contact with a disk indicates allergy to the substance contained in that disk. This redness or rash may itch and persist for several days to several weeks.

You will be advised to return 48 hours later. At this time, the nurse will remove the patches, mark your skin, and do the first reading; you will be expected to remain at the office for 30 minutes so that the nurse can complete the reading.

A final reading will be done on your next visit, which will take place 96 hours after the disks have been removed. A copy of your test results will be provided and explained to you at this visit.

DO'S AND DON'TS

DO wear loose or high-necked clothing throughout the day. Hint: Wear a T-shirt to bed to avoid catching the edges of the tape on the bed sheets.

DO apply tape to the patch edges if they become loose.

DO contact your health care provider immediately if a patch test area burns severely or if you are unable to carry out normal daily activities. Note: Some itching will occur if you are having a positive reaction; you do not need to call your dermatologist.

DO NOT wet the patches during the testing periodfor example, do not take showers. Sponge baths are allowed as long as care is taken to keep the patches completely dry.

DO NOT engage in strenuous activities. Exercise may result in excess sweating, thereby causing the tape to loosen.

DO NOT expose your back to the sun for 2 weeks before patch testing.

DO NOT discontinue antihistamine therapy (these agents do not affect test results).

DO NOT use nonmedicated creams and lotions on your back for at least 24 hours before testing (lotions and creams prevent patches from sticking).

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OTHER TESTS

Patch Testing

Patch testing is an office procedure done in dermatology to determine if patients are allergic to contact materials. Materials are applied in patches to the skin and checked for reaction 48 hours after application and possibly again later. Erythema, swelling, papules, and vesicles indicate an allergic contact dermatitis rather than an irritant contact dermatitis or no reaction.

See Patient Education Guidelines and Procedure Guidelines 33-1.

GENERAL PROCEDURES AND TREATMENT MODALITIES

BATHS AND WET DRESSINGS

A therapeutic bath is used to apply medication to the entire skin surface and is useful in treating widespread eruptions and general pruritus. Baths soothe, soften, and reduce inflammation, and relieve itching and dryness. See Table 33-1, page 1098, for types and desired effects. Wet dressings and soaks are damp compresses that contain water, normal saline solution, aluminum acetate solution, or magnesium sulfate solution. They may be sterile or clean, or warm or cool, depending on the skin condition and the area to which they are applied.

TABLE 33-1 Therapeutic Baths

BATH SOLUTION AND MEDICATION

DESIRED EFFECT

Water

Removes crusts and relieves inflammation

Saline

Used for widely disseminated lesions

Colloidal

Oatmeal or Aveeno

Antipruritic and demulcent

Sodium bicarbonate

Cooling

Starch

Soothing

Tar baths

(follow package directions) Alma-Tar, Balnetar, Lavatar, Polytar

Used for psoriasis and chronic eczematous conditions

Bath oils

Alpha Keri, Lubath, Nutraderm

Used for antipruritic and emollient soothing properties

Used for acute and subacute eczematous eruptions

THERAPEUTIC BATHS

Indications

Vesicular disorders, eczema, atopic dermatitis

Acute inflammatory conditions.

Erosions and exudative, crusted surfaces.

Nursing and Patient Care Considerations

Prepare the bath or teach the patient to prepare a lukewarm bath at 90 to 100 F (32.2 to 37.8 C); with the tub half full, add the prescribed quantity of medication, and mix thoroughly to prevent sensitivity reaction. Add Aveeno, Alpha Keri oils to emulsifying baths

Do not rub the skin. Soaking for at least 5 to 10 minutes will promote removal of loosened scales.

Keep the room and water at comfortable temperatures and limit bathing to 20 to 30 minutes; the bath area should be well ventilated if tars are used because they are volatile.

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Tell the patient to use a bath mat inside the tub and to use a rug outside the tub when bathing at home because medication may make the tub and wet surfaces slippery.

Blot skin dry with a towel and apply emollient or topical medication to moist skin, if prescribed. While skin is wet, apply steroid to inflamed areas if prescribed.

PROCEDURE GUIDELINES 33-1

Patch Testing

PURPOSE

Patch testing is an essential diagnostic tool used to differentiate irritant versus allergic contact dermatitis. Patients who present with dermatitis or eczema are potential candidates for patch testing.

EQUIPMENT

Finn chambers (strips of 10 shallow aluminum cups or chambers 3 inches [8 cm] wide)

Allergens (2-inch [5-cm] ribbons of petrolatum-base allergen or disks with filter paper dampened with aqueous solution). Standard tray includes:

Benzocaine 5%

Meraptobensothiasole 1%

Colophony 20%

p-Phenylenediamine 1%

Imidazolidinyl urea 2%

Cinnamic aldehyde 1%

Lanolin alcohol 30%

Carba mix 3%

Neomycin sulfate 20%

Thiuram mix 1%

Formaldehyde 1%

Ethylenediamine dihydrochloride 1%

Epoxy resin 1%

Quaternium-15 2%

P-tert-Butylphenol formaldehyde resin 1%

Mercapto mix 1%

Black rubber mix 0.6%

Potassium dichromate 0.25%

Balsam of Peru

Nickel sulfate

DRUG ALERT

Patients should not be taking oral corticosteroids at the time of the test; topical corticosteroids should be discontinued 1 to 2 weeks before testing to prevent a weak reaction or false-negative results. Make sure the patient has followed the health care provider's instructions.

PROCEDURE

Nursing Action

Rationale

1.

Prepare Finn chambers with allergen. Aqueous allergens come in prefilled syringes that should be kept refrigerated.

1.

2.

Apply strip to patient's back.

2.

a.

Avoid hairy areas and areas affected by dermatitis and sunburn.

a.

Should be a large area of skin unaffected by friction and free from interfering skin lesions so that results will be clear. Hair may interfere with tape adhesion.

b.

Preferred area is upper back.

b.

Skin on upper back is most sensitive to reaction.

3.

Number the disks 1 through 10 to match the allergen placed on the disk. If the patient is having several strips applied, draw a diagram on the patient's file to record which tray is placed in which location.

3.

To ensure that results are interpreted correctly.

4.

Apply additional tape as required to keep patches secure.

4.

Sweating and activity may reduce adherence in some people.

5.

Instruct the patient to keep area dry, not to scratch or remove the patches unless they become unbearable (severe burning, stinging, or pruritus).

5.

Area may become uncomfortable with positive reaction, but removal or disruption of patch will invalidate results.

6.

When patient returns in 48 hours for the first reading, mark the outline of the patch strip on the patient's back, then remove the strip. A skin marker or an ultraviolet skin pen marker may be used.

6.

Outline serves as a reference point to interpret results.

7.

Wait 30 minutes, then do the first reading. Document as follows:

7.

The skin may be red from the application of the tape and a false reading may occur if read too soon.

1 + Weak reaction. Nonvesicular, but with erythema, induration, and possible papules

2 + Strong reaction. Edematous and vesicular, with erythema, edema, papules, and vesicles

3 + Extreme reaction. Spreading, bullous, ulcerative

IR Irritant reaction

Negative reaction

Not tested

Patches fell off

8.

Instruct patient to keep the area dry after removal of the patches and return again in 24 to 72 hours (usually 48 hours) for additional reading.

8.

Though the initial 48-hour reading may be negative, positive results may be seen at the 96-hour reading because of delayed reaction.

9.

A final reading is done on the last visit, results are recorded, and counseling is given on negative or positive results.

10.

If the results are positive, the nurse discusses avoidance of allergens and gives the patient written information regarding the allergens to be avoided.