NEEDLE PROTECTION DEVICE

Abstract: The present invention relates to a device for protecting a needle (6) in medical equipment. It has a rigid front part (10) connected to a flexible rear part (12). The front and rear parts surround the needle (6) circumferentially. A locking means (36) is accommodated in a chamber (24) provided in the front part (10). In a position of preparedness, the locking means allows the needle (6) to pass through a hole or a channel (14) in the front part (10) and, in an activated position, prevents the needle (6) from passing through. In the position of preparedness, the parts (10, 12) are spaced from the tip of the needle (6). The novelty of the invention is that the locking means (36) is a resilient member which in the position of preparedness is maintained under tension, exerting a force substantially at right angles to the longitudinal direction of the needle (6), that at least the tip of the needle (6) in the position of preparedness is supported by the hole or the channel (14), the resilient member (36) being thus maintained under tension, and that the resilient member (36), after passing from the position of preparedness to the activated position when the needle (6) is moved rearwards relative to the front part (10), prevents the needle (6) from passing through the hole or the channel (14).

Description: NEEDLE PROTECTION DEVICE The present invention generally relates to a device for use in infusion cannulas, and more specifically to a device for protecting a needle or the tip of a needle used in such contexts. The existence of contagious or infectious diseases, such as Aids and hepatitis B, which via the blood, other body fluids or tissue parts can infect the nursing staff, makes the treatment/care of patients extremely hazardous, since each patient must be regarded as a potential infec¬ tion source. Since the discovery of HIV, many people in the health service, ambulance personnel, nurses, doctors and others have been infected, e.g. by body contact with or acciden¬ tal pricking by infected needles which have been used in the treatment of blood-infected patients. To protect the nursing staff who is directly involved in the care of such highly infectious patients, extensive efforts have been used for developing syringes and infu¬ sion cannulas, as well as protection devices for use in such syringes and infusion cannulas, with a view to pre¬ venting direct contact with infected needles and safe¬ guarding against accidental needle pricking. One example of such a device is disclosed in US-A- 4,725,267, in which a spring-biased needle tip protection means is moved forwards over the needle tip after the needle has been used. The spring actuating the protection device may be integrated with a flexible tube which pre- vents direct contact with the end of the needle remote from the needle tip. Another example of a protection device of the above- mentioned type is disclosed in DE-A1-38 08 688. A needle tip protection means connected to a flexible tube is moved forwards over the needle after this has been used, and is so angled as to bring the needle tip into a clamped posi¬ tion inside the protection device. The flexible tube is then pulled over the end portion of the needle remote from the needle tip. Further,, protection devices are known in the art which have no flexible tube, but yet cover, that is sur- round, the entire needle. One example of such a device is illustrated in US-A-4,850,994, in which a rigid sleeve- shaped member, which is movable in the longitudinal direc¬ tion of the needle, is moved, after the needle has been used, over the needle, which then is completely surrounded by the sleeve-shaped member in spaced-apart relationship thereto. US-A-4,955,866 discloses a needle tip protection means which is in the form of a cylindrical part surround¬ ing the needle. The cylindrical part is fixed, e.g. by a thread, to the end of the needle remote from the needle tip. This part may be formed with a chamber provided with a washer having a hole through which the needle passes in the position of use. After the needle has been used, the cylindrical part is manually moved over the needle tip, the needle being retracted from the hole in the washer which thus descends, obstructing the passage in the cylin¬ drical part. Further, it is known from 090/08564 to replace the washer traversed by the needle, with a gravity-actuated ball provided in a chamber and serving to prevent exposure of the needle after use. In addition to sleeve-shaped members which are applied in some suitable manner over the needle tip for protecting it after the needle has been used, it is also known to act on the end of the needle remote from the needle tip, i.e. the mounting end of the needle, such that the needle is made, after use, to form an angle with the axis of the sleeve-shaped member. Examples of this type of approach are given in US-A-4,770,655, where the needle is also deformed, and in US-A-4,838,863, US-A-4,908,022, US- A-4,932,939, US-A-4,978,343, and US-A-4,986,813. Present-day techniques thus offer a large number of more or less complex solutions for protecting nursing staff and others from used, sometimes contaminated needles. However, since all the known solutions suffer from more or less serious drawbacks, further technical development in this field is indeed called for. Above all, it is the risk of unintentional or deliberate exposure of the used needle after actuation of the needle protection means that should be minimised by developing technically efficient, viable solutions, automatically implemented in connection with the normal handling of the needle and the infusion cannula. Common to all protection means using a flexible, extensible tube, hose or the like, or a rigid, movable sleeve element is that they are pulled or pushed over the entire needle from the needle end opposite the needle tip. For this reason, the protection means of the above-related type have channels or holes allowing the needle to pass through before the needle is used. One of the most serious problems encountered in most of the known devices is that the protection means must be applied manually, that is be pushed or pulled forwards along the needle, after this has been withdrawn from the blood vessel or tissue of the patient, where it may have become contaminated, the user holding the needle support¬ ing member in one hand while applying the protection device with the other. It will be appreciated that the risk of injuries from the sharp needle tip or contagion by direct contact with infected blood or infected tissue, by inadvertence, carelessness or even malfunction of the pro¬ tection device is at a maximum if the protection device must be made operative by an active intervention with the free hand, falling outside the normal handling of the device, after the needle has been removed. Another problem inherent in the prior-art devices is that the protection device in some cases is so designed that the needle protection means can be unintentionally or deliberately retracted so as to expose the, possibly, con¬ taminated needle. This problem has been encountered in protection devices with actuated as well as unactuated needle connection. A considerable drawback is that most of the prior-art solutions are complex and of impractical design, entailing relatively high production costs. A first object of the present invention therefore is to provide a device which is adapted to protect the entire needle and which is automatically made operative in normal handling when the needle is retracted from a blood vessel or tissue of a patient. A second object of the present invention is to pro¬ vide a device for protecting the entire needle so as to prevent direct contact with the needle once it has been retracted from a blood vessel or tissue of a patient. A third object of the invention is to design the needle protection means so as to provide safety against unintentional or deliberate exposure of, primarily, the needle tip, once the protection device has been activated. A fourth object of the invention is to design the needle protection device so as to prevent the needle, in cases of incorrect use, from being unintentionally removed or the needle tip from being exposed. Moreover, the device according to the invention should be usable in different types of infusion cannulas, and have a simple and cost-effective design. These and other objects are achieved by a device for protecting a needle according to the characterising clause of claim 1. Other features and alternative embodiments will appear from the dependent claims. Embodiments of the present invention will be describ¬ ed in more detail hereinbelow with reference to the accom- panying drawings. Fig. 1 is a sectional view of a schematically illu¬ strated infusion cannula with an inventive protection device in a .position of preparedness. Fig. 2 is a sectional view, similar to Fig. 1, of the schematically illustrated infusion cannula after it has been used, with the inventive protection device in acti¬ vated position. Fig. 3 is a sectional view, similar to Fig. 1, of a schematically illustrated infusion cannula, with a pre- ferred embodiment of the inventive protection device in a position of preparedness. Fig. 4 is a sectional view, similar to Fig. 2, of the preferred embodiment shown in Fig. 3, after the schema¬ tically illustrated infusion cannula has been used, with the inventive protection device in activated position. Figs 5 and 6 illustrate other embodiments of a lock¬ ing means according to the invention. Fig. 7 illustrates an alternative way of designing the front part of the infusion cannula. Fig. 8 is a sectional view, similar to Fig. 7, where the front part of the infusion cannula is provided with a chamber in which blood that may adhere to the needle is collected. Figs 1 and 2 illustrate a first embodiment of an inventive protection device arranged in an infusion can¬ nula 2, schematically illustrated. Within the infusion cannula 2 there is a mount or anchorage 4 for a needle 6 having a pointed tip 8. It is understood that the needle can be used with different types of syringes, such as infusion cannulas. The protection device according to this first embo¬ diment comprises a rigid front part 10 and a rear, flex¬ ible part 12 which individually and jointly surround the needle 6 circumferentially. Both the front and the rear part 10 and 12, respectively, are movable in the longitu¬ dinal direction of the needle 6. To this end, the front part 10 has a channel 14 (see Fig. 2) extending through the front part 10, coaxially with the longitudinal axis of the needle 6. Preferably, the channel 14 has a cir¬ cular cross-.sectional profile with an inner diameter equal to or slightly exceeding the outer diameter of the needle 6. The front part 10 is formed with a chamber 16 through which the needle 6 passes. A locking means is disposed in a pocket or recess 24. In the illustrated embodiment, the locking means is an elastic, axially compressible body 26 which in the posi¬ tion of preparedness of the device is in a compressed state in the recess 24 (see Fig. 4). The front part 10 is connected in conventional manner to the rear, flexible part 12 through a socket or tubular extension 30, whose length is adapted to the length of the needle 6 and the casing 18. In the illustrated embodiment, the rear, flexible part 12 consists of a thin, film-like flexible material which is in the form of a tube or a hose, both ends of which are open. The ends are fixed to the front part 10 and to the needle mount 4. In the position of prepared¬ ness, the flexible hose 12 is located inside the casing 18, the thin hose material allowing tight compaction, thus minimising the extent of the hose in the longitudinal direction of the needle in the position of preparedness of the protection device. Further compaction can be achieved if the hose 12 is given a conical or cornet-shaped form, as indicated in Fig. 2, in which case the hose can be com¬ pressed like a spiral into a thin, discoid body. The same effect is attained if the hose 12 is bulging, preferably in its central region. The hose 12 has such a length that, in the activated state of the protection device, the needle tip 8 is located, when in its retracted position, inwardly of the channel 14, i.e. in the chamber 16 or inside the socket or tubular extension 30. In this manner, the entire needle 6 will be effi¬ ciently protected, both by the hose 12 surrounding the needle and by the front part 10 enclosing the needle tip 8. Figs 3 and 4 illustrate a second, preferred embodi¬ ment of the inventive protection device. The difference between this embodiment and that shown in Figs 1 and 2 is the design of the locking means, here designated 36, which is disposed in the front part 10. The remaining components are essentially similar and therefore have been given the same reference numerals. For a detailed description of these components, reference is made to the foregoing description of the first embodiment. The locking means 26 and 36 operate in substantially the same manner, as will appear from the following description. As appears from Figs 1-4, the recess 24, in which the locking means 26 or 36 is located, is provided in the vicinity of the end of the channel 14 which is remote from the channel mouth. When the needle tip 8, by a relative movement between the needle 6 and the front part 10, is moved to a location behind the end of the channel 14 remote from the channel mouth, the tip end of the needle is no longer supported by the channel 14, but the front end portion of the needle 6 is acted on in a region in the immediate proximity of the needle tip 8, and the force exerted by the locking means 26 or 36 essentially at right angles to the longitudinal axis of the needle results in a deflection of the needle 6 away from the lon¬ gitudinal direction of the device, thus preventing the needle from passing into the channel 14. It is then pre¬ ferred to limit the relative movement between the needle 6 and the front part 10, such that the needle tip 8 oncup.ies a position in the chamber 16 or the tubular extension 30 immediately below the recess 24 accommodating the locking means 26 or 36. This limitation of the path of movement of the needle is suitably brought about by giving the hose 12 such a length that the needle tip 8 can be retracted just out of the end of the channel 14 remote from the channel mouth. Figs 5 . and 6 illustrate variants of the embodiment, described with reference to Figs 1-4, of the front part 10 of the protection device when in activated position. Also in this embodiment, the front part 10 has a chamber 16 communicating with the recess 24 accommodating a locking means 26, described with reference to Figs 1 and 2, or a locking means 46 (see Fig. 6), which will be described in more detail hereinbelow. The chamber 16 passes into a tubular extension 34 extended in the longitudinal direc¬ tion of the device and having a diameter equalling or but slightly exceeding the outer diameter of the needle 6. While perfectly guiding the needle 6, the narrow, tubular extension 34 at the same time excludes the possibility of deflecting the needle 6 away from the longitudinal axis of the device, as described by way of introduction. There¬ fore, the rear, flexible part 12 is given such a length that the needle tip 8, after completed rearward movement in relation to the front part 10, is brought to a position within the tubular extension 34. Once the needle tip 8 has passed backwards through the chamber 16, which in normal handling occurs by retraction of the needle 6, after the front part of the infusion cannula has been fixed, the locking means 26 or 46 expands substantially in its lon¬ gitudinal direction and extends between the bottom of the recess 24 and the portion of the chamber 16 opposite the recess bottom, so as to obstruct the channel 14, thus pre¬ venting the needle 6 from passing into the channel 14. In Fig. 5, the locking means consists of the elastic body 26, described with reference to Figs 1 and 2, which is compressible in its longitudinal direction. It is made of any suitable material, such as silicone. It is under¬ stood that the needle 6, by the exertion of a sufficient- ly great force in the axial direction, can be caused to pass through the elastic body 26 and into the channel 14. In this embodiment of the front part 10, it is therefore preferred to use the locking element 46 of Fig. 6. The locking element 46 has at least one compressible, elastic portion 46' and one rigid, impenetrable portion 46". These portions are so arranged in relation to each other that the rigid portion 46", in the activated position of the protection device, is brought into such a position that at least the opening of the channel 14 is obstruct¬ ed, thus preventing the needle from passing into the channel 14 after the protection device has been activat- ed. The elastic portion 46' may then be a silicone body, a spring or any other suitable element. Fig. 7 shows yet another alternative embodiment of the front part 10. The channel 14 described above is here replaced by a through hole in an end wall 48, facing the needle tip 8, of an elongate chamber 50 which, as in the previous embodiments, communicates with the recess 24 accommodating the locking means, in this case a locking means 26 of the type described by way of introduction, and with the tubular extension. The advantage conferred by the embodiment of Fig. 7 appears clearly. As a major part of the needle 6 is surrounded by, here, the more extended front part Ϊ0 1 and the rear part 12 already in the posi¬ tion of preparedness of the device, the distance through which the needle 6 must be moved rearwards relative to the front part 10' will be considerably shorter than in the embodiments described above. This means that the protec¬ tion device is made operative earlier in connection with the normal handling of the cannula. Although the force exerted by the locking means on the needle 6 no longer affects the area in the immediate proximity of the needle tip 8, it has been found that this force is sufficient for deflecting the needle away from the longitudinal direction of the device, or deflecting the front part 10, 10' away from the longitudinal direction of the needle, whereby to, again, prevent the needle from passing through the hole in the end wall 48 of the front part 10' . Fig. 8 illustrates a variant of the embodiment in Fig. 7. The features of the embodiment in Fig. 8 are how¬ ever also applicable to other embodiments. In this case, the elongate chamber 50 is slightly shorter as compared with the embodiment of Fig. 7. At the side of the wall 48 facing the needle tip 8, there is provided a chamber 58 circumferentially surrounding the needle 6 which passes through the chamber. In the chamber 58 there is disposed an absorbent material, here a felt 60. The advantage of this arrangement is that any blood that may adhere to the needle 6 is efficiently intercepted and absorbed by the felt 60 in the chamber 58 in connection with the relative movement between the needle and the cannula. In activated position, the needle tip 8 thus is located at the side of the wall 48 facing away from the chamber 58. Any blood adhering to the needle has been efficiently taken up by the absorbent material 60 in the chamber 58 and, hence, does not constitute any hazard. As appears from Figs 1-8, the bottom of the recess 24 consists in all the cases of a seal or a cover 38, for instance a snap cover, to facilitate the mounting of the locking means (the spring 36 or the body 26 or 46), which is suitably mounted after the needle 6 has been inserted in the channel 14, after which the cover 38 is applied on the outside of the device, such that the locking means will be mounted under tension between the needle 6 and the cover forming the bottom of the recess. For engaging, e.g. a catheter unit, the front part 10 has resilient, circumferentially spaced fingers 54 provid- ed with a bead or a lug 52 (see e.g. Fig. 4) and extended in the longitudinal direction of the device. The lugs 52 which in the position of preparedness of the infusion cannula have been moved over an annular flange 56 of the cannula unit will thus lock this unit to the front part 10. The front part 10 being made of a plastic material, the fingers 54 have a certain flexural elasticity and can thus be disengaged from the annular flange of the cannula unit. When the front part 10 is engaging the cannula unit, the casing 18 can be retracted until the rear, flexible part 12 is stretched, without disengaging the device from the cannula unit. Before the rear part 12 comes to its fully stretched position, in which it can transmit trac¬ tive forces, the needle protection device has been acti¬ vated. When an additional tractive force is applied to the casing 18, the front part 10 is thus disengaged from the cannula unit. The casing 18 has such an inner diameter and such an extent in the longitudinal direction that, in the position of preparedness of the infusion cannula, i.e. before use, it encloses the front part 10. In this manner, the risk of incorrect use is minimised in the normal handling of the infusion cannula. Designing the means for mutual locking of the cannula unit and the front part 10 as individual, cantilevered fingers 54 confers increased safety against incorrect use. If the front part is exposed by moving the casing 18 rearwards only a short distance, the front part 10 might be disconnected from the cannula unit before the needle protection device is activated, i.e. before the needle 6 is located in the chamber 16 or 50 or in the tubular extension 34. However, if the user grips the front part 10 in the area of the fingers 54, a pressure is exerted on each finger, so as to further in- crease the locking effect. In this manner, the needle is efficiently prevented from being exposed by incorrect use. The invention has thus provided an infusion cannula in which the protection device is automatically activated during normal handling, i.e. when the needle is withdrawn from a blood vessel or tissue of the patient. Hence, the first object has been met. In the activated position of the protection device, the entire needle is covered by the rear, flexible part and by the front part, the needle tip being safely kept within the rigid, front part, thus preventing direct con¬ tact between the needle, which may be contaminated, and exposed body parts of the nursing staff. The deflection of the needle or the channel in the front part away from the longitudinal axis of the device, or obstruction of the channel opening, together with the other constructional features affords good safety against unintentional or deliberate exposure of the needle tip, once the protection device is activated. Designing the means for mutual locking of the front part and the cannula unit as cantilevered fingers in¬ creases safety against exposure of, primarily, the needle tip, also in case of incorrect use of the infusion can¬ nula. It is understood that a person skilled in the art may find alternative embodiments and carry out modifications within the scope of the basic inventive concept. Thus, the compressible body or the helical spring can be replaced by a leaf spring applied e.g. in the tubular extension, or by a helical spring through which the needle passes. All such modifications and alterations are therefore intended to be covered by the scope of protection of this invention.

Claims: CLAIMS 1. A device for protecting a needle (6) in medical equipment (2), especially after using this equipment, having a rigid front part (10) with a chamber (16, 24) provided therein and accommodating a locking means (26; 36; 46) which in a position of preparedness allows the needle (6) to pass through a hole or a channel (14) in said front part (10) and which in an activated position prevents the needle (6) from passing through, said front part being connected to a flexible rear part (12), said front and rear parts, when in said position of prepared¬ ness, being spaced from the tip (8) of the needle (6) and surrounding the needle circumferentially, c h a r a c ¬ t e r i s e d in that the locking means accommodated in the chamber (16, 24) is a resilient member (26; 36; 46) which in said position of preparedness is under tension, exerting a force substantially at right angles to the longitudinal direction of the needle (6), that at least the tip (8) of the needle in said position of prepared¬ ness is supported by said hole or channel (14) in the front part (10), the resilient member (26; 36; 46) thus being maintained under tension, and that the resilient member (26; 36; 46), after passing from the position of preparedness to the activated position when the needle (6) is moved rearwards relative to the front part (10), prevents the needle (6) from passing through said hole or channel (14). 2. Device as claimed in claim 1, c h a r a c t e r ¬ i s e d in that the front part (10) at the side facing away from said hole or the mouth of said channel (14) passes into a tubular extension (30), the interior of which forms a portion of said chamber (16), that the tubu- lar extension (30) has an inner diameter considerably exceeding the outer diameter of the needle (6), that the recess or chamber (24) is provided beside the tubular extension (30) with which it communicates, and that the force exerted by the resilient member (26; 36; 46) on the needle (6) in activated position, in which the needle is no longer supported by the channel (14), brings about an angle between the front part (10) or the needle (6) and the longitudinal axis of the device. 3. Device as claimed in claim 1, c h a r a c t e r ¬ i s e d in that the front part (10) at the side facing away from said hole or the mouth of said channel (14) passes into a tubular extension (34), that the tubular extension (34) has an inner diameter which but slightly exceeds the outer diameter of the needle (6), that the tubular extension (34) supports the needle (6) both in the position of preparedness and in activated position, and that the resilient member (26; 46) in activated position extends transversely of the longitudinal direction of the device between opposing side walls of the chamber (16) or the recess or chamber (24), so as to cover the passage to the hole or channel (14). 4. Device as claimed in any one of claims 1-3, c h a r a c t e r i s e d in that the rear, flexible part (12) is connected to the tubular extension (30; 34) and to a casing (18) enclosing an attachment or mount (4) for the needle (6), and that the rear part (12) has such a length that the tip (8) of the needle is located within the front part (10) when the rear part (12) is stretched. 5. Device as claimed in any one of claims 1-4, c h a r a c t e r i s e d in that the recess or chamber (24) is closed from the outside of the device by a cover (38), so that the resilient member (26; 36; 46) can be easily mounted in the recess or chamber (24). 6. Device as claimed in any one of claims 1-5, c h a r a c t e r i s e d in that the hole or channel (14) is provided in a wall (48) spaced from the locking means (26; 36; 46), a chamber (50) being formed between said wall (48) and the tubular extension (30; 34). 7. Device as claimed in any one of claims 1-6, c h a r a c t e r i s e d in that a chamber (58) is pro¬ vided at the. mouth of the channel (14) which faces the tip (8) of the needle and which in the position of pre- paredness surrounds the needle (6) circumferentially, and that an absorbent material (60) is disposed in the cham¬ ber (58) for sucking up any blood that may adhere to the needle (6). 8. Device as claimed in any one of claims 1-7, c h a r a c t e r i s e d in that the front part (10) at the side remote from the tubular extension (30; 34) is provided with fingers (54) extended in the longitudinal direction of the device and circumferentially spaced apart, that each finger (54) has a lug or bead (52) extended substantially inwards towards the axis of the device and adapted to engage an annular flange (56) of the cannula unit, and that the front part (10) is detach¬ able from the cannula unit by the application of a suffi¬ ciently great tractive force on the casing (18). 9. Device as claimed in any one of claims 1-8, c h a r a c t e r i s e d iri that the resilient member is a body (26) of silicone rubber or the like, which is compressible in its longitudinal direction. 10. Device as claimed in any one of claims 1-2 or 5-8, c h a r a c t e r i s e d in that the resilient member is a spring (36) which is compressible in its longitudinal direction. 11. Device as claimed in any one of claims 1-8, c h a r a c t e r i s e d in that the resilient member comprises at least one part (46') which is compressible in its longitudinal direction, and one rigid, impenetrable part (46"), the length of the compressible part (46') in activated position being such that the rigid part (46") obturates the passage of the needle (6) to the hole or channel (14).

Inventors: BRANDT WERNER, KARLSSON JOERGEN, BRANDT, WERNER, KARLSSON, JOERGEN
Applicants: VIGGO SPECTRAMED AB, VIGGO-SPECTRAMED AB
Application year: 1992
Main classification: A61M5
IPC codes: A61M5, A61M25