WO2016070265A1

WO2016070265A1 - Medical and dental safety syringe

Info

Publication number: WO2016070265A1
Application number: PCT/CA2015/000567
Authority: WO
Inventors: Khurrum Masood ASHRAF
Original assignee: Ashraf Khurrum Masood
Priority date: 2014-11-05
Filing date: 2015-11-05
Publication date: 2016-05-12

Abstract

A housing unit for a syringe is provided. The housing unit includes a barrel adapted to receive a carpule. The barrel has a front end comprising a needle mounting means, and a rear end comprising an opening to receive a carpule and releasable engagement means to engage a plunger unit. The engagement means are aperture-free. The housing unit also includes a sheath, having a front end and a rear end, which is slidably mounted onto the barrel. The sheath is moveable between a first extended position to cover a needle mounted on the barrel and a second retracted position which exposes a needle mounted on the barrel. A plunging unit for a syringe is also provided. The plunging unit includes a plunger head, a thumb rest which is in the shape of an open- ended pocket and functions to hold the thumb of a user, a shaft connecting the plunger head to the thumb rest and barrel receiving means to releasably receive a barrel for a carpule, wherein the shaft is slideable through said receiving means.

Description

MEDICAL AND DENTAL SAFETY SYRINGE

Field of the Invention

[0001] The present invention relates to a medical device and more particularly to a medical and dental safety syringe.

Background Art

[0002] Syringes are used in the fields of medicine and dentistry to dispense medicine to patients. One specialized class of syringes is especially adapted for use in dentistry, particularly for desensitizing or anaesthetizing the patient's intraoral tissues with an anesthetic prior to having dental work performed.

[0003] This class of syringes is constructed so that they can be loaded with cartridges pre-filled with medication, also called carpules. A typical carpule has: (i) a barrel containing the medication; (ii) a seal or stopper at the rear end of the barrel; and (iii) a penetrable membrane at the front end of the barrel. Carpules are loaded into a hollow housing of the syringe.

[0004] Dental syringes generally include a plunger unit attached to the rear end of the hollow housing of the syringe. The plunger unit includes: (i) a plunger for engaging the seal of the carpule; (ii) a circular thumb ring for driving and retracting the plunger; and (iii) a shaft connecting the plunger to the circular thumb ring. The circular thumb ring provides some additional control of the plunger over the conventional T- shaped finger flange present on most medical syringes, particularly for retracting the plunger. The plunger unit may also include a finger rest for the index finger and middle finger situated between the circular thumb ring and the plunger and a round lever or button situated above the finger rest which activates the syringe to aspirate fluid from the injection site. One would use his or her thumb to push this lever. This is important in the field of dentistry because after an initial stick, the dentist needs to determine if a blood vessel has been hit. It is not desirable to inject an anesthetic into a blood vessel because epinephrine in the anesthetic can have a detrimental effect on the heart rate. Furthermore, the anesthetic would be carried away from the injection site and into the bloodstream, and the operating site would not be sufficiently anesthetized. By pushing the lever or button, the dentist can determine if a blood vessel has been hit by whether blood has been pulled into the carpule by aspiration. If a blood vessel has been hit, the dentist will need to find another injection site.

[0005] A double-ended hypodermic needle is attached to the front end of the hollow housing of the syringe. The rear end of the needle penetrates the membrane on the front end of the carpule. The front end of the needle is used to stick into the injection site of the patient. When not in use, a plastic cover is placed over the front end of the needle. Prior to use, the plastic cover is manually removed, thus exposing the front end of the needle.

[0006] When in use, the dentist uses the circular thumb ring to depress the plunger. The plunger engages and moves the carpule seal into the interior of the barrel of carpule, which drives the medication out the front end of the carpule and into the needle. The medication is delivered to the patient through the front end of the needle.

[0007] The circular thumb ring provides better control of depression and retraction of the plunger than the conventional T-shaped finger flange. However, dentists and dental assistants still find that the circular thumb ring does not fit their thumb tips very well and during the course of a work day, develop fatigue because of this awkward fit. Many times, the user's thumb can get caught in the thumb ring and due to loss of control, the patient or user is at risk of accident. Improvements are desired to increase control of the plunger and reduce fatigue.

[0008] Furthermore, the manual removal and replacement of the plastic cover over the needle leads to many accidental needle sticks which injure dentists, dental assistants, patients and others. This danger is magnified by the risk of the needle being contaminated with bacteria and/or viruses, thus leading to the spread of communicable diseases. It is desired to provide an improved system for uncovering and covering the needle and preventing accidental needle sticks to dental personnel. Summary of the Invention

[0009] A novel syringe has now been developed, including novel housing and plunging units.

[0010] Thus, in one aspect, the present invention provides a housing unit for a syringe comprising: i) a barrel adapted to receive a carpule, said barrel having a front end comprising a needle mounting means or an affixed needle, and a rear end comprising an opening to receive a carpule and engagement means to releasably engage a plunger unit, wherein said engagement means is aperture-free;

ii) a sheath having a front end and a rear end, said sheath being slidably mounted onto the barrel, said sheath being moveable between a first extended position to cover a needle mounted on the barrel and a second retracted position which exposes a needle mounted on the barrel.

[0011] In another aspect, a plunging unit for a syringe is provided comprising:

(i) a plunger head;

(ii) a thumb rest which functions to hold the thumb of a user;

(iii) a shaft connecting the plunger head to the thumb rest; and iv) barrel receiving means to releasably receive a barrel for a carpule, wherein the shaft is slideable through said receiving means.

[0012] In a further aspect, a kit is provided comprising a plunging unit for a syringe and at least one housing unit for a syringe as above-described.

[0013] These and other aspects of the invention are described by reference to the detailed description and the following figures. Brief Description of the Drawings

[0014] Figure 1 illustrates a syringe in accordance with an embodiment of the present invention.

[0015] Figure 2 illustrates a cut-away view of the syringe of Figure 1.

[0016] Figure 3 illustrates a housing unit for a syringe in an embodiment.

[0017] Figure 4 illustrates an expanded view of a barrel of the housing unit of

Figure 3.

[0018] Figure 5 illustrates a plunger unit for a syringe in an embodiment.

[0019] Figure 6 illustrates the interior of a finger rest of a plunger unit in an embodiment.

Detailed Description of the Invention

[0020] A medical/dental syringe is herein provided. A preferred embodiment of the medical and dental syringe 10 of the present invention is illustrated in Figures 1 and 2. The syringe comprises a tubular housing unit 20 and a plunger unit 40 for use with a needle unit.

[0021] As shown in Figs. 3 and 4, the tubular housing unit 20 comprises a barrel

12 adapted and sized to receive a medication-containing carpule 18. The front end 14 of the barrel 12 comprises a needle mounting means 22 onto which a needle unit can be securely and removably mounted. The needle mounting means 22 may be any means useful to stably attach a needle unit, including a threaded protrusion as shown. Alternatively, the barrel may be provided with a needle affixed thereto which is not removable. The needle mounting means 22 includes a passage 23 therethrough to receive the end of a needle, thereby permitting contact of the end of the needle with a penetrable membrane at the needle-contacting end of a carpule within the barrel 12. The passage 23 extends or protrudes into the barrel 12 beyond the front end 14 of the barrel 12 in the form of projection 24 to provide a space (e.g. at least about 1 mm, and preferably at least 2-3 mm) between the carpule and the front end 14 of the barrel 12 that permits some forward movement of a carpule within the barrel 12 which is important following injection when the syringe is used to aspirate.

[0022] The rear end 16 of the barrel 12 has an opening 25 through which a carpule can be loaded into the barrel 12. The rear end 16 and rear end opening 25 is also adapted to receive and releasably engage the plunger unit 40. In this regard, to provide attachment to the plunger unit 40 that is secure and does not release unexpectedly, the rigidity of the rear end 16 of the barrel 12 is not compromised with any apertures or cutouts, i.e. the rear end 16 retains a solid, aperture-free composition, and instead incorporates attachment means 26 that securely engages within a barrel receiving means formed in the plunger unit 40, and which may require a pulling force to release the engagement of the housing unit 20 and the plunger unit 40, e.g. a pulling force of the housing unit from the plunger unit, a pulling force of the plunger unit 40 from the housing unit 20, or a pulling force in both directions to separate the housing and plunger units. The pulling force will generally be a force which is greater than any force imposed during use of the syringe to inject or aspirate. In one embodiment, the rear end 16 incorporates one or more projections as attachment means 26 which securely engage corresponding aperature(s) formed within the barrel receiving means of the plunger unit 38, and which permit release of the barrel 12 from the plunger unit 40 when a pulling force is applied. To provide a more secure attachment, the rear end 16 of the barrel 12 may optionally incorporate a flange 28 to provide the rear end 16 with a circumference that is larger than that of barrel 12. In another embodiment, the barrel receiving means in the plunger unit 40 may include an L-shaped channel 45 that receives the attachment means 26. On entry of the attachment means 26 into the channel (a first arm of the "L"), a twisting motion of the housing unit 20 relative to the plunging unit 40 moves the attachment means 26 to the end of the channel (along the second arm of the "L") securely engaging the attachment means within the channel 45. This channel prevents removal of the housing unit 12 from the plunging unit by a pulling force alone. In this case, engagement of the housing unit 12 and the plunger unit 40 is released by twisting the housing unit 12 relative to the plunger unit 40 to move the attachment means 26 along the channel (the second arm of the "L") to the point of release (first arm of the "L"), and a pulling force to remove the attachment means 26 from the channel. [0023] The barrel 12 may include cut outs or openings 29 formed in the sides thereof (as shown in Fig. 1) for ready visibility of a carpule situated within the barrel 12, and to assist with the insertion and removal of the carpule from the barrel 12. In this regard, such openings permit a user to grip a carpule within the barrel 12 by squeezing the barrel at an opening with their fingertips to grip the carpule, and then removing the carpule by pulling the carpule towards rear end 16 of the barrel.

[0024] The housing unit 20 also comprises a hollow protective sheath 30, having a front end 32 and a rear end 33, which functions to cover or expose the needle, when desired. The sheath 30 is slideably mounted onto the barrel 12 and is slidable between a first extended position which extends past the front injection end of a needle and a second retracted position in which the needle is exposed for use. In the absence of a needle, the needle-mounting means 22 is exposed when the sheath 30 is in the retracted position to permit mounting of a needle thereon. The barrel 12 and/or the sheath 30 incorporates position retaining means that releasably retain the sheath 30 in either its first extended position or its second retracted position. As one of skill in the art will appreciate, a variety of mechanisms may be employed as retaining means to releasably retain the sheath 30 in a desired position, including a twist and lock mechanism, a groove and ridge mechanism, threading, a tight (press) fit, or the like. For example, to retain the sheath 30 in the extended position (in which the sheath 30 covers the end of a needle attached to the barrel 12), the interior of the rear end 33 of the sheath 30 may incorporate threading to engage with corresponding threading formed on the exterior of the front end 14 of the barrel 12, or the interior of the rear end 33 of the sheath 30 and/or the exterior of the front end 14 of the barrel 12 may incorporate one or more ridge(s) and/or groove(s) to maintain the sheath 30 in the extended position. Likewise, the retracted position of the sheath 30 may be retained by threading or ridges/grooves formed in the interior of the rear end 33 of the sheath 30 to engage with corresponding threading or ridges/grooves on the front end of the barrel 12.

[0025] In one embodiment, the exterior of the front end of the barrel 12 incorporates a groove with a ridge on either side (partially or wholly about its circumference) which function to engage the interior of the rear end 33 of sheath 30 (which may optionally also include a ridge to fit within the groove) when a pulling force of the sheath 30 relative to the barrel is applied in opposing directions (e.g. away from one another), and retains the sheath in an extended position. The extended position of the sheath 30 may be released by applying a pushing force of the sheath 30 relative to the barrel 12 in opposing directions (e.g. towards one another). To maintain the sheath in a retracted position, the rear end 33 of the sheath 30 incorporates a flange 38 that tightly fits onto the flange 28 of barrel 12 (i.e. the circumference of flange 38 with respect to flange 28 is only somewhat larger such that the retracted position of sheath 30 is retained by a tight or press fit.). The retracted position of the sheath 30 is released by applying a pulling force of the sheath 30 relative to the barrel 12 in opposing directions). The width of flange 38 of sheath 30 will be smaller than the width of flange 28 of barrel 12, e.g. about ½ the width such that it does not interfere with attachment means 26 on flange 28.

[0026] The sheath 30 may include cut-outs or openings 39 formed in the sides thereof which may generally line up with the cut-outs or openings 29 formed in the sides of the barrel 12 when the sheath 30 is in its retracted position. The cut-outs permit viewing of the carpule within the barrel 12 during use of the syringe, and may also provide access to the carpule for removal.

[0027] To prevent rotation of the barrel 12 within the sheath 30, the barrel and/or sheath may include means to maintain the position of the sheath 30 relative to the barrel 12. In one embodiment, the barrel 12 is provided with one or more ridges formed along the length of the exterior of barrel 12 which engage with corresponding grooves formed along the length of the interior of sheath 30.

[0028] The housing unit may optionally include a cap 34 that fits onto the front end 32 of the sheath 30 to provide further protection from the injection end of a needle secured to the syringe. The cap may be held in place in the usual manner, including, but not limited to, a twist lock mechanism, engagement with a dimple or depression, threading, or a tight fit.

[0029] The housing unit 20, including the barrel 12, sheath 30 and cap 34 may be made of any suitable material, preferably a disposable material such as a polymeric material, e.g. plastic and the like. In one embodiment, the material used to make the barrel 12 and sheath 30 is transparent to permit viewing of the carpule contents, and particularly to determine the presence of any blood on aspiration (i.e. indicative that a blood vessel has been hit on injection).

[0030] The syringe further comprises a plunger unit 40, an embodiment of which is shown in Figure 5. The plunger unit 40 comprises: (i) a plunger head 42; (ii) a thumb rest 44; (iii) a shaft 46 connecting the plunger head 42 to the thumb rest 44; and iv) barrel receiving means to releasably receive a barrel end of a housing unit 20. The thumb rest 44 may be any suitable thumb rest, including a thumb ring. In a preferred embodiment, the thumb rest 44 is ergonomically designed, preferably in the general shape of a thumb tip, e.g. an open-ended thumb pocket or pouch, which functions to engage and hold the thumb of a user in position. The user can comfortably insert his or her thumb tip into the thumb rest 44 and readily depress or retract the plunger head 42. The pocket advantageously holds the thumb in position as opposed to a thumb ring which requires the user to hold the thumb in position which results in fatigue in the thumb.

[0031] In further embodiments, the plunger unit 40 may also comprise a cylindrical finger rest 48 for the index finger and middle finger, which includes a concave middle section within which the fingers rest. Additionally, situated above the finger rest 48, the plunger unit 40 may further include a spring-loaded actuator 49, e.g. lever or button, which functions to permit the syringe to aspirate. The finger rest 48 and actuator 49 are slideably mounted on shaft 46 to permit the shaft to slide therethrough in a channel or the like formed therein.

[0032] The plunger unit 40 includes a barrel receiving means to receive the attachment means 26 of the housing unit 20 for releasable attachment of the barrel 12 of the housing unit 20 to the plunger unit 40. The barrel receiving means is slideably mounted on the shaft 46 of the plunger unit 40 and comprises a housing which includes an outer wall 47a, an inner wall 47b, and an internal channel 43 therebetween to receive the barrel 12 of a housing unit 20. If the plunger unit 40 is formed with a finger rest 48, then the barrel receiving means is appropriately incorporated within the finger rest 48 as illustrated in Fig. 6, e.g. generally in an internal region of the finger rest 48 comprising a channel 43 to receive the rear end 16 of the barrel 12 formed between outer and internal walls 47a/b within the finger rest 48 and further adapted to receive attachment means 26. The barrel receiving means is formed to releasably engage the attachment means 26 of the barrel 12 such that a pulling force, or a twisting and pulling force, of one of or both of the housing unit 20 and/or the plunger unit 40 in opposing directions may be applied to release the engagement therebetween. In one embodiment, the receiving means comprises one or more apertures formed within the outer wall 47a which correspond to and securely engage one or more projections 26 in the rear end 16 of the barrel 12 and which release the engagement of projections 26 from the receiving means when a pulling force is applied to release the housing unit 20 from the plunger unit 40. If a pulling force may be solely used to release the attachment means 26 from a receiving aperture, then the pulling force will generally be a force which is greater than any force employed during use of the syringe to inject or aspirate. In another embodiment, the receiving means comprises one or more hooked channels 45 formed within wall 47a which receive projection(s) 26 and engage the projections 26 when a twisting motion of the barrel 12 relative to the plunging unit 40 is applied. As described above, a twisting and pulling force (opposite to that used to for engagement) is applied to release the housing unit 20 from the plunging unit 40.

[0033] The plunger head 42 is adapted to engage with the seal of a carpule situated within the barrel 12 of the housing unit 20 such that when a force is applied to the shaft 46 of the plunging unit 40, the plunger head 42 will move the carpule seal within the carpule. Accordingly, the plunger head 42 is designed to engage the end of the carpule, and may include a harpoon, protrusion to be received by the carpule seal, an aperture to be engaged by the carpule seal, or a blunt end.

[0034] The plunger unit 40 made be made of any suitable material, including a disposable or non-disposable material. Preferably, the plunger unit 40 is made of an autoclavable material to permit re-use. Examples of suitable autoclavable materials include, but are not limited to, metals such as stainless steel, aluminum, metal alloys and the like. [0035] The syringe 10 is for use with a needle unit which includes a needle, such as a double-ended hypodermic needle (e.g. ½ inch, 1 inch or 1 ¾ inch needle) of varying gauges (e.g. 27 or 30 gauge). The needle includes a front injection end and a rear end, as well as an attachment means to connect the needle to the housing unit 20 via the mounting means 22 on the barrel 12 of the syringe 10. Alternatively, the syringe may be provided with a needle already affixed thereto. The rear end of the needle extends through the channel 23 formed in the front end of the barrel 12 and penetrates the membrane at the front end of a carpule within the barrel. Thus, once the rear end of the needle penetrates the carpule membrane, the needle is in fluid communication with the liquid medicine inside the carpule. The channel 23 is preferably of a circumference that tightly fits the selected needle to retain the needle in position and does not allow side to side movement of the needle within the syringe.

[0036] In use, a carpule 18 is loaded into the barrel 12 of the housing unit 20 through the rear end opening 25 of barrel 12. The sheath 30 of the housing unit 20 may either be in the extended or retracted position for carpule loading. However, if the housing unit 20 is provided with a needle already affixed thereto, the sheath will be in the extended position to cover the end of the needle. The barrel 12 is then attached to the plunger unit 40. The flange 28 of the barrel 12 with attachment means 26 is slid into the barrel receiving means of the plunger unit 40 to engage the housing unit 20 with the plunger unit 40. In one embodiment, as shown in the figures, the attachment means 26 fit into corresponding channels 45 provided in the receiving means and retain the housing unit 20 within the plunging unit when twisted. Attachment is confirmed by applying a pulling force of the housing unit 20 relative to the plunger unit 40 in opposing directions.

[0037] Once the housing unit 20 and plunger unit 40 are attached, and a needle is not already affixed but requires mounting, the sheath is put into its retracted position, and a needle unit may be attached to the housing unit 20 by inserting the end of the needle into channel 23 and into the penetrable membrane of the carpule 18. The needle is then connected to the housing unit 20 via the needle mounting means 22. If the syringe is not to be used immediately, the sheath 30 is moved into its extended position to cover the front end of the needle, and a cap 34 may be put on the front end of the sheath 30 for greater protection from unintentional needle sticks.

[0038] To prepare the syringe for delivering an injection to a patient, the cap 34 is removed from the front end of the sheath 30. To expose the needle, the sheath 30 is moved from the extended position to the retracted position by sliding the sheath along the barrel 12 of the housing unit 20 to engage the rear end 33 of sheath 30 with the rear end 16 of the barrel 12 via retaining means.

[0039] A user will then position the syringe appropriately for an injection, placing index and middle finger on the finger rest 48 and thumb in the thumb rest 44, and applying pressure with the thumb, depresses the shaft 46 of the plunger unit 40. The plunger head 42 pushes against the carpule seal/stopper, which results in fluid from the carpule being expelled from the needle. Once an initial testing of the syringe is complete, the syringe may then be used for injection into a patient. Following the initial stick, the user may engage the spring-loaded actuator 49 to aspirate, viewing the carpule for aspiration of blood, and in the absence of blood continue with the injection by depressing the shaft 46 of the plunger unit 40 with the thumb.

[0040] On completing the injection, the syringe is then prepared for safe disposal, and the front end of the needle is covered again. The sheath 30 is slid back into the extended position to cover the end of the needle by gripping the sheath 30 at its rear end 33, which is advantageously safely distanced from the injection end of the needle, thereby minimizing the risk of an accidental needle stick. An appropriate pulling/pushing force is applied to disengage retaining means and the sheath is moved from the retracted position to the extended position. Retaining retaining means at the front end of the barrel 12 are engaged to retain the sheath 30 in the extended position. The cap 34, if used, may then be placed onto the front end of the sheath 30. The plunger unit 40, if re-useable, may be detached from the rear end 16 of the barrel 12 by disengaging the attachment means from the barrel receiving means for re-use following proper sterilization protocol. The housing, carpule and needle unit are then safely disposed without incident. [0041] The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.

Claims

1. A housing unit for a syringe comprising:

i) a barrel adapted to receive a carpule, said barrel having a front end comprising a needle mounting means, and a rear end comprising an opening to receive a carpule and attachment means to releasably engage a plunger unit, wherein said attachment means are aperture-free;

2. The housing unit as defined in claim 1, wherein the needle-mounting means comprises a threaded protrusion which includes a channel therethrough for receiving a needle end into the barrel.

3. The housing unit as defined in claim 2, wherein the channel forms a protrusion within the barrel to provide a space between the carpule and the front end of the barrel.

4. The housing unit as defined in claim 1 , wherein the attachment means requires at least a pulling force to release engagement of the barrel with a plunger unit.

5. The housing unit as defined in claim 4, wherein the attachment means is one or more projections.

6. The housing unit as defined in claim 1 , wherein the rear end of the barrel comprises a flange.

7. The housing unit as defined in claim 1, wherein at least one of the barrel and sheath incorporates position retaining means that releasably retain the sheath in its first extended position or second retracted position.

8. The housing unit as defined in claim 7, wherein the position retaining means comprises a mechanism selected from the group consisting of a twist and lock mechanism, a groove and ridge mechanism, threading and a tight fit.

9. The housing unit as defined in claim 8, wherein the front end of the barrel incorporates a groove with a ridge on either side at least partially about its circumference to retain the sheath in its extended position.

10. The housing unit as defined in claim 8, wherein the rear end of the sheath incorporates a flange that fits onto a flange at the rear end of the barrel to retain the sheath in a retracted position.

11. The housing unit as defined in claim 1 , wherein the barrel and/or the sheath include openings for viewing a carpule within the barrel.

12. The housing unit as defined in claim 1 , wherein the barrel and/or sheath include means to prevent rotation of the sheath relative to the barrel.

13. The housing unit as defined in claim 12, wherein the barrel incorporates one or more ridges or grooves along its length to engage with one or more corresponding grooves or ridges formed in the sheath along its length.

14. The housing unit as defined in claim 1 , which is transparent.

15. The housing unit as defined in claim 1 , which is disposable.

16. A plunging unit for a syringe comprising: (i) a plunger head; (ii) a thumb rest which is in the shape of an open-ended pocket and functions to hold the thumb of a user;

(iii) a shaft connecting the plunger head to the thumb rest; and iv) barrel receiving means to releasably receive a syringe barrel for a carpule, wherein the shaft is slideable through said receiving means.

17. The plunger unit of claim 16, additionally comprising a cylindrical finger rest slidably mounted on the shaft, wherein said finger rest incorporates a concave section within which an index and middle finger can rest.

18. The plunger unit of claim 16, additionally comprising a spring-loaded actuator slidably mounted on the shaft to aspirate.

19. The plunger unit of claim 16, wherein the barrel receiving means is incorporated within the finger rest.

20. The plunger unit of claim 16, wherein the barrel receiving means require a pulling force, or a twisting and pulling force, to release the barrel from the plunging unit.

21. The plunger unit of claim 16, wherein the barrel receiving means comprises a housing including an outer wall and an internal channel to receive the barrel of a syringe, wherein one or more apertures or channels are formed in the wall and are adapted to receive one or more attachment means formed in the barrel.

22. The plunger unit of claim 16, wherein the barrel receiving comprises one or more channels adapted to receive and retain corresponding projections in the barrel.

23. The plunger unit of claim 16, wherein the plunger head is adapted to engage the end of a carpule.

24. The plunger unit of claim 16, which is made of a disposable or non-disposable material.

25. The plunger unit of claim 24, made of a non-disposable autoclavable material.

26. A kit comprising a plunging unit as defined in claim 16 and one or more housing units as defined in claim 1.