GB2450152A

GB2450152A - Allergy Testing Device

Info

Publication number: GB2450152A
Application number: GB0711594A
Authority: GB
Inventors: Roger Peter Matthams; Amolak Bansal
Original assignee: OAKLEAF INVEST Ltd
Current assignee: OAKLEAF INVEST Ltd
Priority date: 2007-06-15
Filing date: 2007-06-15
Publication date: 2008-12-17
Also published as: GB0711594D0

Abstract

An allergy testing device 10 for effecting simultaneous multiple skin tests comprises an applicator 11 having an array of tines 13 and a base plate 12 having a first surface 16 for engaging the skin of a patient and an opposed second surface 15 having an array of openings 17 corresponding to the array of tines. The base plate 12 also has an array of wells 18 which correspond to the array of openings 17. In use, as the applicator 11 is brought into engagement with the base plate 12, co-operating guide parts 23, 24 guide the tines 13 into and out of the wells 18, which are loaded with allergen, and into the openings and into a skin-pricking position.

Description

Allergy Testing Device This invention relates to a testing device for

effecting simultaneous multiple allergy skin tests on a patient.

Approximately 15 to 20% of the UK adult population has an allergic disease of sufficient magnitude to warrant medical attention. A much larger proportion of people believe they have an allergy. There is thus a clinical need for an effective, fast and easy to use allergy testing device.

Blood-based allergy tests can be expensive. This method of allergy testing requires the user to have a blood sample taken which is then sent away for analysis and the patient has to wait, usually days, for the results. Skin prick testing (SPT) has become the generally favoured method of allergy testing over blood-based methods, as it is faster and easier to perform. In SPT the point of a sharp needle is loaded with an allergen for testing. The skin of the patient is pricked with the needle, causing the allergen to enter the pricked area of skin, and that area is then observed for a reaction to the allergen. The testing is usually repeatedly performed with a plurality of allergens in order to identify a particular allergy. Sequential testing with allergens in this way is both demanding on the time of medical personnel and is often stressful for the patient, especially if the patient is a child or has a phobia of needles.

Furthermore, in order to save time, procedures such as reusing a needle but wiping it between successive tests are sometimes employed. This can produce erroneous results, as an allergen may be carried forward from one test to the next.

A solution to the above identified problem has been provided by multiple allergy testing devices. Existing multiple allergy testing devices generally comprise an applicator with a plurality of needles for simultaneously pricking a patient's skin. Each needle can be loaded with a different allergen and then the testing performed by placing the applicator on the patient's skin and applying pressure. Whilst this method enables multiple allergens to be tested simultaneously, such devices carry an increased risk of needle-stick injury to the operator. Ideally the depth of penetration of each needle into the patient's skin should be consistent. Furthermore, there is. difficulty in loading the allergens onto all of the needle points, whilst avoiding inadvertently losing allergen droplets when transporting the applicator to the patient's skin. This can lead to a risk of cross contamination of allergens on the patient's skin.

It is a principal aim of the present invention to provide a device for performing multiple skin tests, and which addresses the problems of the known devices discussed above.

According to this invention, there is provided an allergy testing device for effecting simultaneous multiple skin tests, comprising: -an applicator having an array of tines and a handle portion; -a base plate having a first surface for engaging the skin of a patient and an opposed second surface, there being a like array of openings through the base plate; -a guide arrangement having co-operating guide parts on the applicator and base plate to guide the tines of the applicator into the corresponding array of openings in the base plate as the applicator is moved into engagement with the base plate and -attachment means to hold the first surface of the base plate at a chosen location against a patient's skin.

The device of this invention has a base plate which may be secured to a chosen area of a patient's skin, where the testing is to be performed. Then the multiple tests may be effected by bringing the applicator into engagement with the base plate, so minimising the risks to the operator and also of cross-contamination. The base plate also serves to flatten the skin when it is attached to a patient and therefore provides a uniform area for testing.

Preferably, an annular protrusion is provided around each opening, projecting from the second surface of the base plate, which is arranged to limit the maximum projection of the tines beyond the first surface of the base plate when the applicator is fully engaged with the base plate in a skin-pricking position. This thus limits the depth of penetration of the tines into the patient's skin. In this way uniform testing for the allergens can be achieved.

A raised annular bead may also be provided around each opening through the base plate, projecting from the first surface thereof -that is, the surface which contacts the patient's skin. The beads will serve to isolate each site where a test is performed from the others, when the base plate is attached to the patient, such that the likelihood of cross-contamination of the testing substances from one test site to another is reduced. The beads also serve slightly to desensitise the skin of the patient when the base plate is attached to the patient's skin with sufficient pressure. Furthermore, in this arrangement, each annular bead leaves a witness mark on the patient's skin when the base plate is removed, which remains visible for a short while. This assists in the subsequent identification of each site where a test substance was pricked into the skin.

Preferably, the applicator tines are formed in an array of two rows, the base plate having a corresponding array of openings. In this arrangement multiple testing can be effected over a relatively small area on the patient's skin.

In a preferred form of this invention there is an array of wells in the second surface of the base plate, projecting upwardly therefrom, for holding allergy testing substances, which array of wells corresponds to the array of openings, with each well spaced from the corresponding opening. The wells may be preloaded with testing substances and a seal provided over each well to retain the substance therein. In this arrangement when testing is to take place, the seal may be removed by hand or access to the testing substances may be provided by piercing the seal with the tines of the applicator.

Alternatively, testing substances may be loaded into the wells manually by the operator when the device is to be used.

Preferably each tine of the applicator comprises a cylindrical base part from which projects a sharp point. In this arrangement, the cylindrical base part may be arranged to limit the maximum projection of each tine into the corresponding well, when the testing device is in an allergen-loading position, by engaging a tapered side wall of the well.

In this form, the guide arrangement may be configured also to guide each tine of the applicator into the corresponding well of the base plate, to allow loading of the tines with allergens pre-loaded into the wells. The guide arrangement thus prevents the sharp point of the tines of the applicator coming into contact with the base plate as the applicator is moved to the position where the tines protrude into the wells by a sufficient distance to become loaded with allergy testing substances.

The guide arrangement may comprise a camming surface on one of the base plate and applicator and a cam follower on the other of the base plate and applicator, the camming surface and cam follower being arranged to guide the tines of the applicator into and out of the corresponding openings in the base plate. This arrangement provides a smooth entry for the tines into and out of the openings, such that the risk of inadvertently losing testing droplets, that might otherwise occur if the tines are subject to sharp sudden movements, is reduced. In this configuration, the camming surface and cam follower may be arranged to also guide the tines of the applicator into and out of the corresponding wells in the base plate so as to prevent the sharp point of the tines from contacting the base plate.

The guide arrangement may comprise a camming surface on the base plate and a cam follower on the applicator. Preferably, however, the guide arrangement comprises a pair of camming surfaces spaced along the length of the base plate and a pair of corresponding cam followers spaced along the length of the applicator. The handle portion of the applicator may be hollow, with the cam followers located therein. In this case, the camming surface on the base plate may locate within the hollow handle portion when the applicator and base plate are engaged. This arrangement provides lateral location for the applicator with respect to the base plate.

The camming surface may be provided with end stops projecting substantially normal to the second surface of the base plate. These end stops may serve to guide the cam follower onto the camming surface in a smooth fashion without inadvertently damaging the tines of the applicator.

A protruding peg may be provided within the hollow handle portion of the applicator for co-operation with the base plate to restrict engagement of the applicator to the base plate to one orientation only, thus ensuring that the applicator is used the right way round with respect to the base plate. Further visual or tactile signs may also be provided to indicate the correct orientation.

The base plate attachment means should enable secure attachment of the base plate of the testing device to the skin of a patient. Preferably the base plate attachment means includes a pair of slots on opposed edges of the base plate for receiving an elastic or an adjustable strap, such as a hook and loop fastening strap. This latter form of strap is ideal as it can readily be adjusted to suit limbs of different sizes.

Advantageously, the applicator comprises a one piece plastics material moulding with integrally formed tines. Similarly, the base plate may also be a one-piece plastics material moulding.

By way of example only, one specific embodiment of allergy testing device of this invention will now be described in detail, reference being made to the accompanying drawings in which:-Figure 1 is a perspective view of the embodiment of allergy testing device; Figure 2 is a perspective view of the underside of the applicator of the allergy testing device of Figure 1; Figure 3 is a plan view of the second surface of the base plate of the allergy testing device of Figure 1; Figure 4 is a perspective view of the first surface of the base plate of the allergy testing device of Figure 1; Figure 5 is a side view of the allergy testing device in an allergen-loading position; Figure 6 is a detailed side view on an enlarged scale showing the position of a tine of the applicator with respect to the base plate when in a loading position as shown in Figure 5; Figure 7 is a detailed side view on an enlarged scale illustrating the connection between the camming surface and follower when the device is in a loading position as shown in Figure 5; Figure 8 is a side view of the allergy testing device in a skin-pricking position; Figure 9 is a detailed side view on an enlarged scale showing the position of a tine of the applicator with respect to the base plate when in a skin-pricking position as shown in Figure 8; and Figure 10 is a detailed side view on an enlarged scale illustrating the connection between the camming surface and follower when the device is in a skin pricking position as shown in Figure 8.

Referring initially to Figure 1, there is shown an allergy testing device, generally indicated 10, according to the present invention. The device 10 comprises an applicator 11 and a base plate 12. The applicator 11 has an array of twelve tines 13, formed in two rows of six, one to each side of a handle portion 14 enabling the applicator to be held safely by an operator. Each tine 13 has a cylindrical protrusion 27 from which projects a sharp point. The applicator 11 is a one-piece plastics moulding with the tines 13 being integrally formed.

The base plate 12 has a first surface 15 for engaging the skin of a patient and an opposed second surface 16. The base plate 12 has an array of openings 17 therethrough which array corresponds to the array of tines 13 of the applicator 11. The base plate 12 also has an array of wells 18 which correspond to the array of openings 17, with each well 18 spaced from the corresponding opening 17. A pair of fastener slots 21 are provided on opposed edges of the base plate 12, for receiving the ends of a hook and loop fastening strap 22 to hold the first surface 15 of the base plate 12 at a chosen location against a patient's skin, such as on the forearm of a patient.

The applicator 11 and base plate 12 have co-operating guide parts for guiding the tines 13 of the applicator 11 into and out of the corresponding openings 17, as well as into and out of the corresponding wells 18, when required. The co-operating guide plates also serve to guide the tines 13 from the wells 18 to the corresponding openings 17 in the base plate 12. These guide parts comprise a pair of spaced camming surfaces 23 on the second surface 16 of the base plate and co-operating cam followers 24 on the applicator. As can be seen in Figure 2, the handle portion 14 of the applicator is hollow and the cam followers 24 are located within that handle portion 14.

Figure 7 illustrates one position of the cam follower 24 with respect to the associated camming surface 23, when the allergy testing device 10 is in an allergen-loading position as shown in Figures 5 and 6. The camming surfaces 23 are disposed within the hollow handle portion 14 of the applicator 11 when the base plate and applicator are engaged, thus limiting lateral movement of the tines 13 of the applicator 11 with respect to the base plate 12. The camming surfaces 23 are provided with end stops 30 which project from the second surface 16 of the base plate 12 to guide the cam followers 24 onto the camming surfaces 23.

Figure 5 shows the allergy testing device 10 of Figure 1 in an allergen-loading position with Figure 6 showing on an enlarged scale the applicator 11 in a corresponding well 18 of the base plate 12. The fastener slots 21 are not visible in this diagram for clarity. As can be seen, cylindrical base parts 27 engage with the walls of the wells 18, which limits the projection of the tines 13 into the wells 18.

Figure 10 shows a detailed view of the position of the cam follower 24 on the applicator 11 with respect to the camming surface 23 on the base plate 12 when the allergy testing device 10 is in a skin- pricking position. In this position camming surfaces 23 again serve to limit lateral movement of the tines 13 by engaging the internal side walls of the handle portion 14.

Also within the hollow handle portion 14 of the applicator 11 is a protruding peg 26 which serves to prevent the applicator 11 from being used -10-the wrong way round, by interfering with the camming surfaces 23 when presented in the wrong orientation. The applicator 11 and base plate 12 are further provided with arrows 20, as shown in Figure 1, to indicate the correct orientation of the applicator 11 to the base plate 12.

Figure 3 shows the base plate 12 attached to the forearm 28 of a patient, the second surface 16 of the base plate 12 and the relative positions of the openings 17 and wells 18. A raised annular bead 29 is provided around each opening 17 on the base plate 11 protruding from the first surface 15, as shown in Figure 4. The annular bead 29 serves to isolate each site where a test is performed from the others and thus restricts allergen cross-over between test sites. Additionally, the annular bead 29 leaves a witness mark on the patient's skin when the base plate has been removed which assists in identifying each site where a test substance was pricked into the skin.

Referring now to Figure 8, there is shown the allergy testing device 10 of Figure 1 in a skin-pricking position, in which the tines 13 of the applicator 11 are in the openings 17 of the base plate 12. The projection of a tine 13 of the applicator 11 is illustrated in detail in Figure 9, and the maximum projection of a tine 13 beyond the first surface 15 is limited by an annular protrusion 25 projecting from the second surface 16 of the base plate 12, as shown.

When the allergy testing device 10 is to be used, the base plate 12 is attached to a patient's arm 28 (or leg) as shown in Figure 3. The wells 18 of the base plate 12 are either preloaded with allergen or allergen is manually loaded into the wells at the time of use. The applicator 11 is then guided by the operator using the handle portion 14 onto the base plate 12, into an allergen-loading position in which the tines 13 of the applicator 11 are in the allergen loaded wells 18 as illustrated in Figure 5. In this position the tines 13 of the applicator 11 protrude into the wells 18 a sufficient distance to pick up a small amount of allergen that hangs as a small droplet on each tine. The applicator 11 is then guided, again by the operator using the handle portion 14, from the allergen-loading position to a skin-pricking position, in which the tines 13 of the applicator 11 are in the openings 17 of the base plate 12, as illustrated in Figure 8. Pressure is applied by the operator to the applicator 11 to enable the tips of the tines 13 to pierce the skin of the patient's arm 28. The applicator 11 is then guided away from the base plate 12 and discarded. The base plate 12 is usually left for a short period on the patient's arm 28 before being removed and also discarded. The annular beads 29 on the first surface 15 of the base plate 12 leaves witness marks on the patient's skin on removal of the base plate 12 to aid in identification of test areas. -12-

Claims

1. An allergy testing device for effecting simultaneous multiple skin tests, comprising: -an applicator having an array of tines and a handle portion; -a base plate having a first surface for engaging the skin of a patient and an opposed second surface, there being a like array of openings through the base plate; -a guide arrangement having co-operating guide parts on the applicator and base plate to guide the tines of the applicator into the corresponding array of openings in the base plate as the applicator is moved into engagement with the base plate; and -attachment means to hold the first surface of the base plate at a chosen location against a patient's skin.

2. An allergy testing device as claimed in claim 1, wherein there is a respective annular protrusion projecting from the second surface of the base plate around each opening through the base plate, which protrusion limits the maximum projection of the respective tine beyond the first surface of the base plate when the applicator is fully engaged therewith in a skin-pricking position.

3. An allergy testing device as claimed in claim 2, wherein there is a respective annular bead projecting from the first surface of the base plate around each opening through the base plate.

4. An allergy testing device as claimed in any of the preceding claims, wherein the applicator tines are formed in an array of two rows, the base plate having a corresponding array of openings. -13-

5. An allergy testing device as claimed in any of the preceding claims, wherein there is an array of wells in the second surface of the base plate for holding testing substances, which array of wells corresponds to the array of openings, with each well spaced from the corresponding opening.

6. An allergy testing device as claimed in claim 5, wherein the guide arrangement is configured also to guide each tine of the applicator into the corresponding well of the base plate, to allow loading of the tines with allergens pre-loaded into the wells.

7. An allergy testing device as claimed in claim 5, wherein each tine comprises a cylindrical base part from which extends a sharp point, the cylindrical base part limiting the maximum projection of the associated tine into the corresponding well by engaging the walls of the well.

8. An allergy testing device as claimed in any of the preceding claims, wherein the guide arrangement comprises a camming surface on one of the base plate and applicator and a cam follower on the other of the base plate and applicator, the camming surface and cam follower being arranged to guide the tines of the applicator into and out of the corresponding openings in the base plate.

9. An allergy testing device as claimed in any of claims 5 to 7, wherein the guide arrangement comprises a camming surface on one of the base plate and applicator and a cam follower on the other of the base plate and applicator, the camming surface and cam follower being arranged to guide the tines of the applicator into and out of the corresponding wells in the base plate.

-14 -

10. An allergy testing device as claimed in claim 8 or claim 9, wherein the guide arrangement comprises a camming surface on the base plate and a cam follower on the applicator.

11. An allergy testing device as claimed in claim 10, wherein the guide arrangement comprises a pair of camming surfaces spaced along the length of the base plate and a pair of corresponding cam followers spaced along the length of the applicator.

12. An allergy testing device as claimed in claim 11, wherein the handle portion of the applicator is hollow and the cam followers are disposed therein.

13. An allergy testing device as claimed in claim 11, wherein the camming surfaces on the base plate are located within the hollow handle portion of the applicator when the base plate and applicator are engaged, thus providing lateral location for the applicator with respect to the base plate.

14. An allergy testing device as claimed in any one of claims 8 to 13, wherein the camming surface is provided with end stops projecting substantially normal to the second surface of the base plate, to guide the cam follower onto the cam ming surface.

15. An allergy testing device as claimed in claim 5 or any claims dependant thereon, wherein each well contains a testing substance and a seal is provided over each well to retain the respective substance therein.

16. An allergy testing device as claimed in any of the preceding claims, wherein there is a protruding peg provided on the applicator arranged to co-operate with the base plate to restrict the engagement of the base plate with the applicator to only one orientation. -15-

17. An allergy testing device as claimed in any of the preceding claims, wherein the base plate attachment means includes a pair of openings on opposed edges of the base plate for engagement with a strap.

18. An allergy testing device as claimed in claim 17, wherein the attachment means includes a hook and loop fastening strap.

19. An allergy testing device as claimed in any of the preceding claims, wherein the applicator comprises a one-piece plastics material moulding with the tines of the applicator being integrally formed therewith.

20. An allergy testing device as claimed in any of the preceding claims, wherein the base plate comprises a one-piece plastics material moulding.

21. An allergy testing device substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.