skin patch test

The skin patch test is one of the experimental methods for studying the toxicity of poisons to the skin. Fold a few layers of gauze into a certain size (1cm on each side of the square, 1cm in diameter), wet the gauze of the test substance or dilution and stick it to the skin, cover with a layer of oil paper or plastic film, and fix it with a bandage. . Usually unwind after 12 hours or 24 hours, observe the local reaction. Basic Information Specialist classification: skin examination classification: immune examination Applicable gender: whether men and women apply fasting: not fasting Analysis results: Below normal: Normal value: no Above normal: negative: normal. Positive: Very light edema (almost undetectable) is 1 point; mild (edge ​​is significantly higher than the skin) is 2 points; moderate (edema is 1cm higher than the leather surface) is 3 points; severe cases (edema is higher than the skin) The surface is 1 cm or more, and the area exceeds the patch area) is 4 points. Tips: During the spot test, it is not advisable to bathe, drink and sputum test sites, and avoid intense exercise. Normal value Normal person is negative (-). ±, for suspicious, itching or mild redness. +, weakly positive, simple erythema, itching. ++, positive, redness, papules. +++, strong positive, marked redness, papules, small blisters. ++++, very strong positive, marked redness, blisters, necrosis. Clinical significance Score according to the size of erythema and eschar and edema. A very light erythema (almost undetectable) is 1 point, a clear boundary is 2 points, a moderately severe one is 3 points extremely severe with a slight eschar is 4 points. Very light edema (almost undetectable) is 1 point, mild (edge ​​is significantly higher than the leather surface) is 2 points, moderate (edema is 1cm higher than the leather surface) is 3 points, severe cases (edema is higher than the skin) The surface is 1 cm or more, and the area exceeds the patch area) is 4 points. According to the total score obtained, the skin local reaction was determined. Observation and recording were performed twice at 24 hours and 72 hours, respectively. Some people take the average value, called the "primary stimulation index." <2 is divided into mild stimuli, 2-5 is divided into moderate stimuli, and >6 is divided into strong stimuli. A positive result of an abnormal result indicates that the patient is allergic to the test substance, and an enhanced reaction generally occurs 24 to 48 hours after the test article is removed. Patients who need to be examined for eczema, contact dermatitis, occupational skin diseases, etc. Precautions Pre-inspection contraindications: The meaning and possible reactions should be explained to the subject before the spot test in order to achieve full cooperation. Requirements for examination: 1. The subject must be paralyzed, and the spot test should be removed immediately if a strong reaction occurs. 2. During the spot test, it is not advisable to bathe, drink alcohol and plaque test sites, and avoid intense exercise. 3. In the determination of the degree of reaction, the false positive or false negative results should be excluded. 4. Excipients should be used as controls. Necessary fashion needs to be compared with normal people. Inspection process 1. Test site: normal skin on both sides of the upper back. 2. Strip the strip test strip and place the chamber up on the test bench. The plaque samples are arranged in a top-down order from left to right and marked. The test substance, such as a solid or semi-solid, may be directly added to the drug chamber in an amount slightly exceeding half the volume of the drug chamber (about 0.02 g); the liquid test article may be wetted (about 0.02 ml) into the drug chamber. Be careful not to get on the edge of the spot tester when adding the test sample. 3. The plaque test tape with the plaque test is applied longitudinally from the lower part to the normal skin on both sides of the spine, while gently pressing the drug chamber one by one to drive off the air and evenly distribute the test object. 4. Mark the test site for observation. 5. Patch test time: 48 hours. 6. Observation time: 48 hours after the application, first remove the spot tester, remove the residual plaque sample with wet soft paper or cotton swab, observe for 30 minutes at the first time, and make the second time at 72 and 96 hours respectively. With the third observation. If necessary, continue observation on the 7th day, pay attention to whether there is a late reaction. Not suitable for the crowd Inappropriate people: 1. It is not suitable for patch test in the acute phase of dermatitis. 2. The tester should not apply corticosteroids for 2 weeks before the test and during the test period. Antihistamines should be discontinued 3 days before the test and during the test. 3. Pregnant women avoid this experiment. Adverse reactions and risks There are no related complications and hazards.