Medical devices

Abstract: A medical device includes a hollow needle 6 for piercing the skin of a patient. Prior to use, the needle 6 is located in a housing 22. Means 14 is provided for moving the needle tip 8 outwardly from the housing 22 ready for piercing the patient's skin. After use the means 14 is employed to retract the needle 6 back within the housing 22 to a needle protected position. Further means 28, 28 ' 42 is provided outside the housing 22 which is movable between a first position to allow longitudinal movement of the needle 6 relative to the housing 22 and a second position for preventing such movement.

Description: The present invention relates to medical devices and in particular to medical devices such as intravenous catheters which include a hollow needle having a sharp distal end for piercing the skin of a patient. The existence of infectious diseases such as AIDS and Hepatitis has highlighted the danger to which medical personnel may be exposed when treating patients by means of catheter devices where a sharp needle point is used to pierce the skin of a patient. Medical personnel have been infected by physical contact with or accidental prick by an infected needle (needle-stick). In order to protect medical personnel against inadvertent needle-stick a number of solutions have been developed whereby a protective means incorporated within the catheter prevents physical contact with the needle after use and hence against inadvertent needle-stick. A known device for protecting a needle both before and after use is described in European Patent Publication No. 0599564, in which a needle is arranged within a housing and is displaceable between a retracted position and a second extended position. Means is provided for displacing the needle between said first and second positions. A sealing means for sealing the initially open distal end of the housing is connected to the displacing means, at least initially. The sealing means during displacement of the needle from said first retracted position to said second position, is moved in the direction towards the open distal end of the housing to a sealing position and is then fixed in said sealing position substantially sealing the interior of the housing. The structure described in European Patent Publication 0599564 although effective to prevent inadvertent needle-stick is complicated and relatively expensive to manufacture. Furthermore, the structure does not give any clear visible sign to show the user that the needle is locked in the protected position. WO 93/08865, which is used as a basis for the preamble of claim 1, describes a needle catheter particularly for endovasal use, including a needle-guide or metallic mandrel fitted with an end grip, and a catheter with end casing. Between the end grip of the metallic needle and the casing of the catheter, there is an extensible element acting as a cover for the metallic needle after its extraction and with at least one means of blockage of interception and/or of needle blockage being foreseen in the casing of the catheter, movable from a position where it does not obstruct the lumen of the catheter, to a position where it occludes the lumen. It is an aim of the present invention to provide a simple but effective means for protecting the point of a needle forming part of a medical device such as an intravenous catheter, in order to minimise the possibility of inadvertent needle-stick. According to the present invention, there is provided a medical device comprising a hollow needle having a sharpened distal end for piercing the skin of a patient, the needle in a first needle protected position being located in a housing, means for moving the needle from the first position to a second position in which the sharpened distal end of the needle extends from the distal end of the housing ready for piercing the skin of a patient, said moving means being employed to retract the needle after use back within the housing to said first needle protected position and further means movable between a first position to allow movement of the needle between its first and its second position and a second position for preventing movement of the needle from said first needle protected position, said further means being a door mounted for sliding movement between the first position in which the needle can pass from the interior of the housing and a second position in which the door blocks the exit of the needle from the interior of the housing, characterised in that the door has an aperture through which the needle can pass when the door is in its first position, the door is located outside the housing and immediately adjacent the distal end of the housing, and the door includes two resilient arms which in the first position of the door engage opposite sides of the housing to latch the door in said first position. Preferably, at least one arm has an enlarged free end which in the second position of the door engages an aperture formed in the housing adjacent its distal end. Preferably, the door is slidably mounted along tracks formed immediately adjacent the distal end of the housing. Preferably, the needle is fixedly mounted to and extends from the distal end of a body positioned within the housing, at least one web extending from the body through a slot in the housing, a gripper fixed to said web at a position outside the housing whereby the body and the needle may be moved longitudinally through the housing between said first and said second positions. Embodiments of the invention will now be described by way of example, reference being made to the Figures of the accompanying diagrammatic drawings in which:- Figure 1 is a perspective view of a needle assembly forming part of an infusion cannula as illustrated in Figure 3; Figure 2 is a perspective view similar to Figure 1 but illustrating a catheter assembly mounted on the needle assembly of Figure 1; Figure 3 is a perspective view of an infusion cannula; Figure 4 is an end view of the infusion cannula illustrated in Figure 3; and Figure 5 is a detail partly in cross-section of the end view illustrated in Figure 4. As shown particularly with reference to Figure 1, a needle assembly 2 forming part of an infusion cannula 4 (See Figure 3) includes a hollow needle 6 having a sharpened distal end 8. The proximal end of the needle 6 is fixably mounted in a body 10 from which extends from each side thereof webs 12. As shown, each web 12 supports a serrated gripper 14. The body 10 at its distal end is formed with a boss 11. Referring also to Figure 2, mounted on the needle assembly 2 is a catheter assembly 16 including a hollow catheter 18 extending from a hollow catheter hub 20. Prior to use and as illustrated in Figure 2 the needle 6 extends through the catheter hub 20 and the catheter 18 such that the sharpened distal end 8 extends outwardly from the free distal end of the catheter 18. The proximal open end of the catheter hub 20 is supported by the boss 11 of the body 10. Referring also to Figure 3, the sub-assembly of the needle-assembly 2 and the catheter assembly 16 is mounted in an elongate tubular housing 22 having elongate slots 24 in each side through which the webs 12 extend thereby to position each gripper 14 on the outside of the housing 22 for engagement by a nurse or doctor in a manner known per se . The proximal end of the housing 22 may be open or closed. The distal end of the housing 22 is open and is formed at upper and lower (as shown) surfaces with a track 26 which slidably supports a door 28 having a central aperture 29. In the middle of the upper (as shown) track 26 is an aperture 27. The door 28 is provided on its upper (as shown) edge with two resilient arms 30. Each arm 30 is formed at its free end 32 with an enlarged portion which has a chamfered upper surface. In the position of the door 28 as illustrated in Figure 4 the end 32 of each arm 30 engages co-operating sides of the housing 22 and the aperture 29 is substantially aligned with the centre of the open distal end of the housing 22. Protuberances 36 are formed on the upper (as shown) of the housing 22. in the ready-for-use position illustrated in Figures 3 and 4, the sub-assembly of the needle assembly 2 and the catheter assembly 16 is located within the housing 22 with the grippers 14 located adjacent the proximal end of the housing 22 such that the sharpened distal end 8 of the needle 6 is spaced inwardly of the door 28. Further, the door 28 is positioned so that the aperture 29 is substantially central of the open distal end of the housing 22 with the champered free ends 32 of the arms 30 engaging opposite sides of the housing 22. To displace the needle 6 and the catheter assembly 16 from the ready-for-use position to a patient penetrating position, the grippers 14 are engaged and the sub-assembly is slid along the interior of the housing 22 in a manner known per se . Once penetration has been effected and the needle 6 withdrawn through the catheter 18 and the catheter hub 20, the grippers 14 are used to withdraw or retract the needle 6 back into the interior of the housing 22. Once the sharpened distal end 8 of the needle 6 is located within the housing 22 pressure is then applied to one side of the door 28 such that the arm 30 adjacent said one side is deflected downwardly as shown in Figures 4 and 5 to allow the door to slide along the tracks 26 until the enlarged chamfered end 32 engages in the aperture 27 as illustrated in Figure 5. In this position, the open distal end of the housing 22 is shut or blocked by the door 28 and there is thus no possibility of the sharpened end 8 of the needle 6 inadvertently pricking the skin of a nurse, doctor or other user of the infusion cannula 4. The protuberances 36 are used in a manner known per se to assist in the relative movement of the housing 22 and the sub-assembly of the needle assembly 2 and the catheter assembly 16. The embodiment described hereinbefore provides protection for the needle 6 and in particular the sharpened distal end 8 of the needle 6 before and after use. Furthermore, the means located outside the housing for preventing movement of the needle from its retracted position within the housing substantially eliminate the possibility of accidental needle-stick in an economically effective manner. It will be apparent that the means for preventing accidental needle-stick are simple to manufacture and to operate.

Claims: A medical device comprising a hollow needle (6) having a sharpened distal end (8) for piercing the skin of a patient, the needle (6) in a first needle protected position being located in a housing (22), means (14) for moving the needle (6) from the first position to a second position in which the sharpened distal end (8) of the needle (6) extends from the distal end of the housing (22) ready for piercing the skin of a patient, said moving means (14) being employed to retract the needle (6) after use back within the housing (22) to said first needle protected position and further means (28, 28' 42) movable between a first position to allow movement of the needle (6) between its first and its second position and a second position for preventing movement of the needle (6) from said first needle protected position, said further means being a door (28) mounted for sliding movement between the first position in which the needle can pass from the interior of the housing (22) and a second position in which the door (28) blocks the exit of the needle (6) from the interior of the housing (22), characterised in that the door (28) has an aperture (29) through which the needle (6) can pass when the door is in its first position, the door (28) is located outside the housing (22) and immediately adjacent the distal end of the housing (22), and the door (28) includes two resilient arms (30) which in the first position of the door (28) engage opposite sides of the housing (22) to latch the door (28) in said first position. A device as claimed in Claim 1, in which at least one arm (30) has an enlarged free end (32) which in the second position of the door (28) engages an aperture (27) formed in the housing (22) adjacent with its distal end. A device as claimed in Claim 1, in which the door (28) is slidably mounted along tracks (26) formed immediately adjacent the distal end of the housing (22). A device as claimed in any one of claims 1 to 3, in which the needle (6) is fixedly mounted to and extends from the distal end of a body (10) positioned within the housing (22), at least one web (12) extending from the body (10) through a slot (24) in the housing (22), a gripper (14) fixed to said web (12) at a position outside the housing (22) whereby the body (10) and the needle (6) may be moved longitudinally through the housing (22) between said first and said second positions.

Inventors: OESTERLIND ROLAND JOERGEN, WAHLBERG ULF HARRY, OESTERLIND, ROLAND JOERGEN, WAHLBERG, ULF HARRY
Applicants: BOC GROUP PLC, THE BOC GROUP PLC
Application year: 1996
Main classification: A61M25
IPC codes: A61M5, A61M25