Patch testing with Finn Chambers® on Scanpor®
Instructions for use
Finn Chambers on Scanpor are intended for use by or under the supervision of a physician.
Allergic reactions to aluminium and Scanpor tape are rare. However, occasional cases
of contact sensitivity to aluminium e.g. due to vaccination or hyposensitization
of hay fever patients with aluminium precipitated antigens have been reported.
The skin may react to the removal of the tests with a slight mechanical irritation,
indicated by erythema on the area covered by the tape.
Patch test substances are usually applied in petrolatum. In general the concentrations of allergens in
commercially available test series are suitable for Finn Chambers.
Due to the incompatibility of aqueous mercuric solutions with aluminium, polypropylene coated Finn
Chambers should be used when testing aqueous mercuric solutions. Mercuric compounds incorporated in
petrolatum do not react with aluminium. Aluminium may enhance the polymerization of acrylate monomers
and false negative reactions have been noticed with acetone solutions of ethyl cyanoacrylate glue.
Application of the test substances
Mark identification on the top of each tape to show the order of the test substances throughout the
testing procedure. Remove the protective paper and place the tape on the desk or the tray with the
chambers up. Keep a narrow strip of the protective paper on the tape until the tape has been attached
onto the skin.
Tips
1. If you put the tapes with the marked end to the left, you
can fill the chambers in the normal reading order from left to right.
2. In order to provide non-sticky handling of the tape keep the narrow strip of
the protective paper on the tape until the tape has been attached onto the skin.
The removed protective paper can also be reattached on the edge of the tape.
Semisolids (e.g. petrolatum as the vehicle) are applied directly into the chamber, filling more than half the chamber volume (a bar of 5 mm if the diameter is 2 mm). Do not use filter paper discs with semisolids.
Tip - A toothpick is useful for removing excess of test substance
from the chamber.
For liquids, place a filter paper disc in the chamber. Moisten the disc thoroughly without surplus. Excess liquid should be removed e.g. with porous paper. Place the test onto the skin within a few minutes. Do not let the filter paper disc dry, because this may result in weak or false negative reactions and the discs tends to slip out during application onto the back.
Tip - The last chambers are preferably reserved for liquid test
solutions (e.g. formaldehyde in water), because this minimizes drying.
Placing the tests onto the skin
The patient shall stand or sit in a relaxed normal position, the back slightly bent forwards. The tests are applied to healthy skin on the back, which is to be free of ointments and excessive sebum. It is recommended that the patient takes a shower or bath in the morning before testing. If necessary, the skin can be cleaned e.g. by alcohol. Allow alcohol to evaporate completely.
The preferred test area is the upper back leaving out the middle line. Apply the tape starting with the lower part pressing the chambers from below to let air escape. After having applied the tape this way, press each chamber containing a semisolid gently with the finger to get an even distribution of the test substance. Rub the tape gently but firmly with the palm against the skin, especially on the corner, to ensure good adherence. The patient should refrain from vigorous activities and taking showers during the first day after application of the tests.
The position of the tapes on the skin can be marked e.g. with nontoxic ink or tape. If the patient can come to the clinic for removal of the tests, the physician has the advantage of using the marked tape for locating the test sites. If the test sites have been marked with ink remarking is advisable.
Removing the tests
The tests are removed after one (24 hours) or two (48 hours) days’ exposure. Before removing the tests the position of the tapes should be (re)marked. Whenever possible the patient should return to the clinic for removal of the tests. If the patient removes the tests himself, he should be advised to destroy the remnants properly.
Check test sited immediately after removal of the tests. A ring-shaped depression around each test verifies the occlusion and validates the test, especially in the case of negative reactions.
Reading the test reactions
The tests should be read not less than 20 minutes after removal. The subsequent reading should be done 3-7 days after application of the tests. Observing the course of the reactions helps differentiating the allergic reactions from irritant ones.
To locate and identify the reactions align the Reading Plate with the ink mark(s) on the skin. The Reading Plate serves as a template with the holes indicating the test sites.
Storage
Storage at room temperature, cold tape adheres less well.
Download: Package insert