SKIN TEST KIT

Abstract: Skin test kit which greatly facilitates the testing of patients for detecting allergen hypersensitivity. The kit comprises a multiplicity of sachets (50) containing various allergens in the form of bubbles (49). The sachets (50) are capable of being connected together in any desired combination of allergens. The kit furthercomprises a needle assembly (57, 58) for piercing the sachets and the skin and a roller (61) or other means for applying pressure to the needle assembly to effect piercing. A guide or aligner may be used to guide the pressure applying and limit the penetration of the needles.

Description: "Skin Test Kit" THIS INVENTION relates to a test kit for administering prick skin tests for detecting allergen hypersensitivity. The current method of administering prick skin tests for detecting allergen hypersensitivity is to apply a drop of allergen extract to a marked spot on the volvar surface of the extended forearm, and to just break the skin surface with a sterile needle, thus administering a minute amount of extract into the dermal layer. The extract then binds to IgE antibody attached to the surface of mast cells and induces histamine release manifested by a wheel and flare reaction in the skin if the subject has produced, afore- hand, IgE antibodies with specificity for that particular allergen i.e. he/she has been sensitized. A positive reaction is taken to mean that the individual is allergic to that allergen. Subcutaneous skin tests are performed by administering via hyperdermic syringe approximately 50 ul of allergen ex¬ tract beneath the dermal layers. Subcutaneous skin tests employ in general more dilute allergen extracts than do prick skin tests. Positive reactions are read as for prick skin tests and the magnitude of the reaction in both instances is measured by the diameter in mm of the wheal produced. There are 4 major limitations to both procedures: (1) Both require repeated access to stock allergen ex¬ tracts stored hopefully at 4°C but often at room tem¬ perature, particularly under field conditions. Allergen extracts are notoriously unstable hence long-term storage of relatively large volumes (5-10 mis) of allergen extracts may lead to considerable loss in potency - a property which is difficult to monitor. In addition, repeated access to the ex¬ tracts over a period of up to 12 months, whether by the agency of droppers or syringes, involves the risk of introducing microbiological contaminants. (2) A new needle is required every time the skin is breached - this requires large stocks of relatively expensive items of equipment. Similarly large num¬ bers of syringes are required if subcutaneous skin testing is to be employed or if the allergen is to be applied to the surface of the skin by syringe instead of dropper in the prick test method. (3) Since the introduction of each allergen requires a separate procedure, accurate reproducibility is dif icult. (4) The location of each allergen on the skin must be marked and identified by assigning a number, a time-consuming exercise. Moreover, since all aller¬ gen extracts of a given group are identical in colour, e.g. pollen extracts are colourless, moulds brown, etc. , incorrect application of an extract cannot be readily monitored. This may lead to an incorrect diagnosis of the allergen triggering aller¬ gic disease. The object of the present invention is to provide a sim¬ plified precedure for accurate, safer administration of prick skin tests under conditions of high reproductivity yet sufficiently simple to be operable with no additional reagents, e.g. pollen extracts, syringe, needles and the like. In one form the invention resides in a skin test kit comprising a number of pre-packaged sachets of sterile allergens which can be clipped together end to end to provide a chain of selected allergens, aligners adapted to be connected to each end of the sachet chain incorporating means for marking the skin, a solid strip having a plura¬ lity of projecting needles spaced to correspond to the spacing of the sachets, and means for applying pressure to the needle strip to force each of the needles through the bubble of the corresponding sachet and into the skin. The invention will be better, understood by reference to the following description of several embodiments shown in the accompanying drawings wherein:- First Embodiment Fig. 1 is a plan view " of a sachet; Fig. 2 is a plan view of an aligner; Fig. 3 is a plan view of a needle strip; Fig. 3A is a side elevation of the needle strip; Fig. 4A is a side elevation of a roller for applying pressure to the needle strip; Fig. 5 shows a series of sachets clipped together; Second Embodiment Fig. 6 is a perspective view of a modified form of sachet; Fig. 7 is a section on line 2-2 of Fig. 6; Fig. 8 is an exploded perspective view of a modified needle assembly; Fig. 9 is a perspective view of a modified form of aligner or guide; Third Embodiment Fig. 10 is a plan view of a chain of sachets; Figs. 11, 12 and 13 are side elevations of various groups of sachets included in the chain; Fig. 14 is a perspective view of an aligner or guide; Fig. 15 is a section on line 15-15 of Fig. 14; Fig. 16 is a sectional view showing a needle assembly positioned in the aligner or guide; and Fig. 17 is a view of a tongue to be used for applying pressure to the needle assembly. Description of First Embodiment A. COMPONENTS OF THE TEST KIT 1. Allergen sachets. The allergen sachets contain a small quantity of sterile allergen sealed as a bubble 49 in sealed soft plastic sachets 50 (see Fig. * 1). The allergen is preferably made viscous by the addition of a suitable solvent such as glycerine to ensure that the allergen will adhere to the needle and to prevent the allergen spreading over the surface of the skin. Each individual allergen extract is identified by a suitable coding stamped on the sachet, e.g. gl = rye grass pollen Lolium perenne g2 = canary grass pollen ml = alternaria mould el = cat dander (epidermal) hi = histamine control Each sachet 50 carries on one edge a male plastic clip 51 and on the opposite edge a female plastic clip 52 (see Fig. 1) to allow sachets containing different allergen extracts to be clipped together to form a continuous allergen sachet chain. They also contain a small female plastic clip 53 on adjacent sides to the chain connectors which are used to attachment oC a needle strip. These small clips are located on the same axis as the allergen bubble. 2 . Aligners. Aligners 54 (see Fig. 2) are attached to each end of the sachet chain. These aligners 6 carry on adhesive surface covered by a removable tear-off backing 55. One set of aligners, to attach to the head of the sachet chain, carries connectors 56 in the form of female plastic clips, and the adhesive surface contains an alcohol soluble green dye. The other set of aligners, to attach to the tail of the sachet chain, carry connectors 56 in the form of male plastic clips, and the adhesive sur¬ face contains an alcohol soluble red dye. 3. Needles. Sterile stainless steel needles 57 for puncturing the sachets are attached to a solid plastic strip 58 with the points covered by a tear-off. soft plas¬ tic backing. Each strip contains 10 needles spaced at a distance exactly equal to the mid-point of the allergen bubble on the allergen sachet chain (Fig. 3). Each nee¬ dles trip carries small male plastic clips 59 on the minor axis of the needle strip and in line with the stainless steel needle points, thus coinciding with the appropriate small female plastic clips 53 (Figs. 1 and 3) on the allergen sachet chain. 4. Roller. The stainless steel, or good quality plas¬ tic, roller 61 is mounted into the frame 62 via a spring loaded axle 63. The bracket of the frame carries a wide runner 64 to ensure that the roller can only be applied at a fixed maximum pressure (Fig. 4). B . PROCEDURE Step 1. The operator selects from the various allergen sachets those deemed by case history to be appropriate for the given patient. The sachets are clipped together as illustrated (Fig. 5) and it is preferable to include both a histamine and solvent control sachet. The order of in¬ dividual allergen sachets forming the chain is irrelevant as each sachet is clearly identifiable. Aligners are then clipped to the ends of the sachet chain to provide the green aligner at the head and the red aligner at the tail of the sachet chain. The allergen sachet chain is then sterilized by wiping with a sterile swab. Step 2. The appropriate length of the needle strip is prepared, the tear off sterile cover removed, and the needle strip is then clipped on to the allergen sachet chain via the small plastic clips 53 and 59. It should be noted that this attachment must not puncture the allergen sachets. Step 3. Wipe the surface of the skin with a sterile swab. Tear off the backing strips covering the adhesive surface and attach the sachet chains (with attached needle strip) to the cleaned volvar surface of the arm pressing firmly over the area of the adhesive surfaces of the aligners. Step 4. Apply the roller to the head of the sachet chain, exert the maximum pressure and run the roller down the entire length of the sachet chain. This action will force the sterile needle points through the allergen sachet and to the required depth in the skin surface transferring in so doing, a fixed and predetermined amount of allergen, adhering to the needle surface through its viscosity, into the skin. Step 5. Remove the sachet strip from the forearm and confirm that the green and red dyes have marked the skin. Pull off needle strip and discard, but do not dismantle allergen sachet chain which is temporarily attached to the patient's file. Step 6. After 15-20 minutes, realign allergen sachet chain with the green and red dye marks on the arm and read the magnitude of the skin reactions, including that of the histamine and solvent controls, for each coded allergen. Step 7. Record data in patient's chart, remove coloured dye with alcohol swab and discard sachet chain. If more than one allergen sachet chain is to be applied to the patient's forearm, identify each chain with a numeral, applied with a marker pen to the top surface of the green aligner and to the corresponding point of attachment to the skin. Description of Second Embodiment Sachet As shown in Figs. 6 and 7 of the drawings the sachet com¬ prises a lower layer 11 of heat deformable plastic in which a semispherical bubble 12 has been formed. After the desired allergen has been placed in the bubble an upper layer 10 of the plastic is placed over the lower layer and the two layers heat sealed together over the area designated 13 in the drawings. The layers are cut so that the upper layer has an extension flap 14 at one end of the sachet and the lower layer has an extension flap 15 at the opposite end of the sachet. The extension flaps are coated with a pressure sensitive adhesive so that a number of sachets can be linked together in a chain. It is preferable that the sachets at each end of the chain be provided with a longer flap provided with an opening through which it is possible to mark the skin of the patient being tested with a marking pen or the like. With this arrangement it is possible for a nurse or the like to make up strings of sachets containing the most appropriate allergens and/or control substances for each patient. Needle Assembly As shown in Fig. 8 of the drawings the needle assembly comprises a strip of plastic 16 having a series of hydro- dermic needles 17 projecting from one thereof. The nee¬ dles are very fine and project approximately 2 -3 mms from the plastic strip. A cover strip 18 having a slot 19 is provided to protect the needles during transport or storage. Aligner or Guide As shown in Fig. 9 of the drawings the aligner or guide comprises a strip of plastic 20 corresponding approxima¬ tely to the length of the chain and provided with a longi¬ tudinal slot 21 and transverse slots 22 and 23 at each end to align with one of the slots in the extended flap on each of the each sachets in the chain. Procedure The chain of sachets is placed in position on the patients arm with the bubbles uppermost and the aligner or guide positioned with its transverse slots aligned with the slots in each sachets. If desired the aligner may be held in position with adhesive tape or adhesive applied to each end of the aligner. The needle assembly is then posi¬ tioned in the slot 21 with the needles facing towards the patients skin. A roller is then run along the upper surface of the aligner so that the needles pierce the bubble and enter the patients skin carrying sufficient allergen to produce a reaction. Description of Third Embodiment In this embodiment the chain of sachets may be assembled to provide a sachet 31 containing several global aller¬ gens, a single sachet 32 containing a selected local allergen and a sachet 33 containing several regional allergens. The end sachets are provided on each face with adhesive strips 34 and 35 so that the sachets can be fastened to the patients skin. Preferably the adhesive strips at each end are provided with a different colour which will mark the patients skin and make relocation straight forward. In this embodiment the aligner 36 is provided with a longitudinal slot 37 which is provided with a ledge 38 on each side. A needle assembly 39 is placed in the slot as shown in Fig. 16 and pressure app¬ lied thereto by running tongue 40 along the slot. The ledges 38 ensure that the penetration of the needles into the skin is substantially the same. Advantages The skin test procedure kit of the present invention eliminates most, if not all, of the limitations referred to above by:- (1) Providing pre-packaged aliquots of sterile allergen which eliminates the need for sampling by the opera¬ tor. It also eliminates the requirement for long-term storage of large volumes of allergen which may have a limited life time. The operator is only required to purchase exactly the number of tests required. (2) No additional equipment, e.g. syringes, needles, etc., are required - a distinct advantage in develop¬ ing countires and where the tests are to be under¬ taken under 'field' conditions. (3) Since all allergen extracts are introduced by one simple operation, reproducibility is assured. (4) The location of each allergen on the skin is readily identifiable by a permanent record. It is not neces¬ sary to identify the application of each allergen by marking the skin with numbers. By this method errors of transcription are avoided.

Claims: THE CLAIMS defining the invention are as follows:- 1. A skin test kit comprising a number of pre-packaged sachets of sterile allergens which can be clipped together end to end to provide a chain of selected allergens, aligners adapted to be connected to each end of the sachet chain incorporating means for marking the skin, a solid strip having a plurality of projecting needles spaced to correspond to the spacing of the sachets, and means for applying pressure to the needle strip to force each of the needles through the bubble of the corresponding sachet and into the skin. 2. A skin test kit as claimed in claim 1 wherein the means for applying pressure to the needle strip is a roller. 3. A skin test kit as claimed in claim 1 wherein the pressure applying means is a manually held tongue with one end bearing against the needle strip. 4. A skin test kit as claimed in claim 1, 2 or 3 in¬ cluding aligner or guide provided with a longitudinal slot to receive the needle strip. 5. A skin test kit as claimed in claim 3 wherein the longitudinal slot is provided with flanges to regulate the degree of penetration of the needles. 6. A skin test kit as claimed in any one of the pre¬ ceding claims wherein the end sachets in the chain are provided with means for marking the skin of a patient. 7. A skin test kit substantially as herein described with reference to Figs. 1 to 5, 6 to 9 or 10 to 17 of the accompanying drawings.

Inventors: SIEMENSMA NICHOLAS P, TURNER KEVIN J, SIEMENSMA, NICHOLAS, P., TURNER, KEVIN, J.
Applicants: WRAY REGINALD CHARLES, WRAY, REGINALD, CHARLES
Application year: 1987
Main classification: A61B10
IPC codes: A61B5, A61B17