WO2002076542A1

WO2002076542A1 - A disposable syringe

Info

Publication number: WO2002076542A1
Application number: PCT/DK2002/000131
Authority: WO
Inventors: Mikael Hetting
Original assignee: Mikael Hetting
Priority date: 2001-02-28
Filing date: 2002-02-27
Publication date: 2002-10-03

Abstract

A disposable syringe (1;25;35;42) serving for injecting a fluid (10), wherein the disposable syringe comprises a tubular cylinder (2) having an attachment opening (3) at the first end (16) for a needle (24,46) and a second opening (4) at the opposite second end (4), a plunger (5;29) displaceable between a first position and a second position and located in the cylinder (2), a link (14;26) connecting the plunger (5;29) and the finger handle (6) which is outside the second opening (4) of the cylinder (2) in the first position of the plunger (5;29) and inside the second opening (4) of the cylinder (2) in the second position of the plunger (5;29). The finger handle is completely received in the cylinder, as it can be displaced by means of e.g. the needle cap (9;47) covering the needle prior to use in direction towards the second position until it no longer is possible to grip the finger handle. The needle can subsequently be mounted again over the needle and the disposable syringe which has been prevented from being used again can be discarded

Description

A disposable syringe

The invention relates to a disposable syringe for injecting a fluid and comprising a tubular cylinder having an attachment opening for a needle at a first end and a second opening at the opposite end, a plunger displaceable between a first position and a second position and located in the cylinder, and a finger handle connected to the plunger.

Known disposable syringes are in many cases constructed so that they can be reused.

Due to lack of necessary medical equipment, it has become common in especially poor developing countries to reuse disposable syringes which only have been scanty cleaned and sterilised due to inadequately sanitary and hygienic conditions. Undesired reutilization is furthermore very widespread among drug abusers where one or more persons unhesitatingly utilise the same syringe and needle without prior sterilisation.

Such reused, badly sterilised syringes contribute to the spreading of bloodborne, infectious diseases such as HIV virus (AIDS) and hepatitis B.

Within the framework of U ICEF and WHO, a total number of vaccinations and injections of about 400,000 per day are done today, and reports from African health authorities indicate up to 200 reutilizations of syringes even at WHO approved vaccinations programs. UNICEF and WHO have estimated that only 50 to 70% of all vaccinations meet the safety requirements to avoid cross infection.

In recognition of these problems, WHO has utilised and urged utilisation of disposable syringes which have been made impossible to reuse for different structural reasons. Such disposable syringes are often expensive to manufacture and therefore expensive to use, and many nations therefore cannot afford to utilise these disposable syringes to a necessary extent .

From US Patent No. 4,013,073 is known a disposable syringe in which the collapsible walls of the syringe are locked together when the walls are pressed together to deliver the medicament whereby the syringe is impossible to reuse.

From US Patent No. 4,391,273 is known another disposable syringe having a plunger with a fixed pin that penetrates the cylinder base when injection has been accomplished. The cylinder walls are damaged during the displacement of the plunger into the cylinder by a knife so that reutilization is made impossible.

The disposable syringe according to Russian Patent Application SU 1816220 has a hollow plunger head and a detachable plunger rod which is receivable in the plunger head. The plunger rod is provided with barbs engaging and cooperating with a recess in the hollow plunger head to thereby allow initial filling of the syringe. When the syringe is emptied, the barbs are pushed out of the recess and folded so that refilling is not possible as the barbs are not able to engage the recess again.

Another known disposable syringe is described in the International Patent Application WO 94/12229. This known syringe acts a conventional syringe in use but is deactivated after use by drawing the plunger rod back and break it off in a weakened area arranged for this purpose.

US Patent No. 4,915,692 discloses a disposable hypodermic syringe having a cylinder and a reciprocating plunger consisting of two parts, and actuating rod and a connection link. The plunger and the plunger head can move a short distance independently of each other. The plunger rod has an edge portion for engaging with a recess in the interior wall of the syringe cylinder so that actuating rod and connection link are drawn away from each other if the syringe is attempted to be refilled.

One aspect of the present invention is to provide a disposable syringe of the kind mentioned in the opening paragraph, that has a simple structure, is easy to operate, is inexpensive to manufacture, and cannot be reused after use.

The novel and unique features whereby this is achieved are that the finger handle in the first position of the plunger is located outside the second opening of the cylinder and inside the second opening of the cylinder in the second position of the plunger .

When the plunger is thus completely received in the cylinder, a person cannot subsequently grip the finger handle to refill the disposable syringe whereby the disposable syringe according to the invention is ensured against reutilization in a simple and effective manner.

To ensure that the plunger is not drawn out of the cylinder during a complete or partial filling process, a stop can advantageously be designed in the cylinder for restricting the travel of the cylinder from the second to the first position. When the plunger as an example is displaced towards the first position until said end, facing in the opposite direction of the finger handle, of the link between the finger handle and the plunger is abutting the stop, the cylinder can be filled with a volume of injection fluid corresponding to a cylinder volume equivalent to a plunger travel .

By performing a number of reciprocating plunger travels between first and second position, the disposable syringe can quickly and easily be ventilated and filled with a preset volume of injection fluid. Ventilation can be done in a known manner by collecting an undesired, possible content of air in the cylinder at the first end of the disposable syringe and then push the plunger into the cylinder until the undesired air is displaced out of the cylinder through the attachment opening in this first end, the finger handle of the plunger constantly being kept in position outside the second opening of the cylinder.

In a first simple and inexpensive embodiment, the link between the finger handle and the plunger is a conventional plunger rod of e.g. a rigid plastic. As the plunger, finger handle and plunger rod in this embodiment together have an extent not exceeding the inner longitudinal extent of the cylinder and as the finger handle in the first position is located at least a distance outside the second opening of the cylinder to thereby allow the user with his fingers to grip the finger handle to manipulate the plunger, the plunger will in the first position be located in the cylinder at a distance from the first end of the cylinder to thereby leave a volume of residual air encapsulated in the cylinder between the plunger and the first end of the cylinder.

However, this residual air can easily be expelled in a known manner by, as mentioned above, ventilating the disposable syringe with a number of reciprocating plunger travels until the residual air has been substituted by the wanted volume of injection fluid which typically fills the volume between the plunger and the first end of the disposable syringe, the plunder abutting on or being located near the stop in the filled state of the disposable syringe.

In a second advantageous embodiment, the link between the finger handle and the plunger can be a plunger rod having a first section located nearest the finger handle and a second section located in tandem of the first section farther from the finger handle, the free end of this second section being designed with a collar which together with the second section of the plunger rod can extend into a chamber on the plunger.

This chamber can preferably be designed with a first base located nearest the first end of the cylinder and an opposite second base having an opening through which the second section of the plunger rod with the collar is extending.

If the longitudinal extent of the second section of the plunger rod and the collar together do not exceed the inner longitudinal extent of the plunger chamber, the plunger rod can at the transition between the first and second section of the plunger rod have a pressure face facing the plunger and hitting the second base of the chamber and serving for affecting the plunger with the necessary compressive force when the plunger is to be taken from the first position to the second position which e.g. is the case when the content of the disposable syringe is to be injected at a designated place of injection.

Alternatively, the second section of the plunger rod and the collar can together have an extent that substantially corresponds to or exceeds the longitudinal extent of the chamber. In this case, the collar on the second section of the plunger rod will abut on and hit the first base of the chamber in the second position of the plunger to thereby transmit the compressive force necessary for injection to the plunger.

The collar on the free end of the second section of the plunger rod can especially advantageously be designed as a pointed barb where the ratio between the collar diameter and the diameter of the opening in the second base of the plunger chamber is chosen so that the barb easily can be mounted in the plunger chamber through this opening when the syringe is prepared for use and cannot be forced out of the opening of the plunger chamber when the syringe is in use or has been used.

To obtain absolute certainty against the plunger not unintentionally being brought from the first position to the second position during storage or unwrapping of the syringe from an e.g. sterile packaging, the plunger rod and the cylinder can if required be supplied separately.

The chamber can expediently be designed as a hollow rubber plug lubricated with silicone along the outer periphery to allow the plunger to be displaced in the cylinder easily and unobstructedly.

To prevent the barb on the free end of the second section of the plunger rod from being able to freely return in full towards the second base of the plunger chamber after emptying of the syringe and thereby free the finger handle of the second end of the cylinder, the chamber can internally be provided with a constriction which advantageously can divide the chamber into a first sectional chamber facing the first base and a second sectional chamber facing the second base, the barb being located in the second sectional chamber when the disposable syringe is being filled while the plunger is' kept in its first position.

When the disposable syringe is to be emptied, the constriction will allow the pointed barb on the second section of the plunger rod to freely pass from the second sectional chamber into the first sectional chamber to possibly hit the first base of the chamber. The constriction will advantageously prevent the barb from freely returning to the first sectional chamber . Especially advantageously, the constriction in the plunger chamber can be located so that the entire longitudinal extent of the part of the second section of the plunger rod projecting from the chamber, after the barb during emptying of the disposable syringe being introduced into the first sectional chamber, and the first section of the plunger rod together are so much smaller than the distance between the stop of the cylinder and the second opening of the cylinder that the finger handle cannot project from the cylinder in the second position.

Alternatively, the side of the finger handle facing the second opening of the cylinder can be designed with locking means for locking the finger handle in cooperating locking means designed on the stop. Such locking means can e.g. be a circumferential barb designed on the finger handle and which can be hooked together with recess designed on the stop or vice versa.

In a third embodiment of the present invention, the link between the finger handle and the plunger can comprise a rigid first section located nearest the finger handle and a second section located in tandem of this first section, oppositely and farther from the finger handle, said second section having an extended state in which it can transmit drawing forces but not compressive forces, and a collapsed state in which it can transmit compressive forces but not drawing forces.

When the syringe is to be filled, the plunger is drawn out of the cylinder with a pull on the finger handle until the plunger is abutting on the stop. In this expedient third embodiment, the second section can be a strip or a wire of a flexible material, such as a flexible plastic as e.g. polyethylene or polypropylene, the material only being chosen so that it has a tensile strength sufficiently great to resist the drawing force required to be able to fill the disposable syringe. The size of the necessary drawing force will depend on the dimensions of the disposable syringe and the volume of injection fluid to be filled into the disposable syringe.

When the disposable syringe is to be emptied and the injection fluid e.g. injected into an individual, the plunger must be affected with a compressive force that will force the plunger from the first position to the second position. During this, the flexible material between the pressure face on the second section of the plunger rod and the plunger is folded and compressed. As the finger handle now will be completely received in the cylinder, the disposable syringe cannot be reused.

When the second section consists of a strip or a wire of a rigid material with a number of folding or rupture lines designed along the strip or wire, the strip and the wire will collapse at the weakened zones of the folding or rupture lines, and the strip or wire will be folded and compressed in a manner similar to the one described above for a strip or wire of a flexible material .

Especially expediently, the needle and the disposable syringe can be manufactured as an integrated unit. In this case, the needle will be premounted at the first end of the disposable syringe at the attachment opening for a needle.

Alternatively, a loose needle can be mounted on the nozzle of the disposable syringe in such a way that it subsequently cannot be demounted without thereby destroying either the needle and/or the disposable syringe. In this case, the nozzle and the needle can be provided with known locking means, the mutual engagement of which subsequently cannot be broken. Such locking means are known from e.g. a LUER-LOCK syringe nozzle. In both cases, the needle will preliminarily be capped by a detachable needle cap. Along at least a section of the cap, it can have a diameter equal to or smaller than the internal diameter of the cylinder, said section simultaneously having a length at least as great as the distance between the finger handle and the second opening of the cylinder in the second position of the plunger.

A needle cap designed in such a way can advantageously be utilised for assisting in the displacement of the plunger from the first position to the second position. This can especially advantageously be done when a recess or pin is designed in the free end face of the finger handle and when a complementary pin or recess is designed in the free end face on the needle cap at said section.

Recess or tap can advantageously engage with each other whereby the needle cap can be used in tandem of the plunger rod so that the finger handle can be pushed down in the cylinder in an especially easy manner. Alternatively, the hollowness of the needle cap can receive a pin designed on the finger handle or the plunger rod.

To ensure that the finger handle is not unintentionally displaced into the cylinder to the second position, the finger handle can advantageously have an extended area which is connected to the finger handle via a rupture line or weakened zone. Such an area can merely be one or more projecting flaps or tabs but can also be a circumferential collar on the finger handle.

When a finger handle designed in such a way hits the edge around the second opening of the cylinder, the rupture line will be affected to such an extent that the extended area will be completely or partly broken off or everted, this area being at least partly retained by the second opening or internal diameter of the cylinder and during this be everted in the direction opposite the travel of the plunger. In this way, the area will serve as sealing and/or barbs to counter the plunger from being drawn out of the cylinder after use.

Another way to prevent the finger handle from unintentionally being received in the cylinder consists in a finger handle cover being part of the finger handle, said cover preliminarily covering the finger handle in the first position of the disposable syringe and being removed and discarded when the content of the disposable syringe is to be injected into an individual .

In a second aspect of the present invention, a method for using the disposable syringe according to the invention is provided.

The method comprises that the disposable syringe is being filled by the needlepoint being placed in an injection fluid in a known manner, that the injection fluid is being drawn into the cylinder by means of at least one possibly reciprocating manipulation of the finger handle and thereby the plunger. When the injection fluid subsequently is to be injected into an individual, the finger handle is actuated in a simple way with a compressive force until the finger handle is under the second opening of the cylinder.

This operation can especially easily be done when a cover detachably mounted on the needle is fitted in tandem of the finger handle and used to press the finger handle into the cylinder until this handle is completely received in the cylinder.

After use, the used needle is sealed with the cap after which the now unusable disposable syringe can be discarded. The invention will be explained in greater detail below, giving further advantageous features and technical effects and describing only exemplary embodiments with reference to the drawing, in which

Fig. 1 is a longitudinal cross section through a first embodiment of a disposable syringe according to the invention and a vial shown in perspective,

Fig. 2 is the view in fig. 1 in a first filling step,

Fig. 3 is the view in fig. 1 in a first ventilation step,

Fig. 4 is the view in fig. 1 in a second filling step,

Fig. 5 is the view in fig. 1 in a second ventilation step,

Fig. 6 is the view in fig. 1 in a third filling step,

Fig. 7 is the view in fig. 1 during emptying,

Fig. 8 is the view in fig. 1 in completely empty state,

Fig. 9 is the view in fig. 1 in a second position in which the disposable syringe cannot be reused,

Fig. 10 is a longitudinal cross section through a second embodiment of a disposable syringe according to the invention and a vial shown in perspective,

Fig. 11 is the view in fig. 10 in filled state,

Fig. 12 is the view in fig. 10 in a first emptying step,

Fig. 13 is the view in fig. 10 in which the disposable syringe has been emptied, Fig. 14 is a view of the second position of the plunger in which the disposable syringe cannot be reused,

Fig. 15 is a longitudinal cross section through a third embodiment of a disposable syringe according to the invention and a vial shown in perspective,

Fig. 16 is the view in fig. 15 in filled state,

Fig. 17 is the view in fig. 15 in a first emptying step,

Fig. 18 is the view in fig. 15 in which the disposable syringe has been emptied,

Fig. 19 is a view of the disposable syringe with the plunger in its second position in which the disposable syringe cannot be reused,

Fig. 20 shows the second position of a modification of the second embodiment of the disposable syringe according to the present invention,

Fig. 21 is the view in fig. 20 but with the finger handle locked together with the stop,

Fig. 22 is a longitudinal cross section through a fourth embodiment of a disposable syringe according to the invention and a vial shown in perspective,

Fig. 23 is the view in fig. 22 in filled state,

Fig. 24 is the view in fig. 22 in a first emptying step,

Fig. 25 is the view in fig. 22 in a second emptying step, ly-uo- uuz

13

Fig. 26 is the view in fig. 22 in emptied state with the plunger in its second position in which the disposable syringe cannot be reused.

Fig. 27 shows a first emptying position of the second embodiment in which the finger handle has a pair of flaps designed with rupture zones for preventing the plunger from unintentionally being received in the cylinder,

Fig. 28 is the view in fig. 27 but in a second emptying position in which the flaps are abutting on the edge around the second opening of the cylinder,

Fig. 29 is the view in fig. 27 in which the flaps have been broken off and the plunger is in its first position,

Fig. 30 is a longitudinal cross section of an additional modification of the embodiment in figs. 1-9 in a first position in which the modification is arranged to be used with a conventional needle, and

Fig. 31 is the view in fig. 30 in the second position.

The different embodiments are modifications and variations of a disposable syringe and the same reference numerals have been used for like parts.

Figs. 1-9 show a first embodiment of a disposable syringe according to the invention in a number of different steps of a filling and an emptying of the disposable syringe.

The disposable syringe 1 for injecting a fluid into an individual has a tubular cylinder 2 having an attachment opening 3 for a needle 24 at the first end 16 and a second opening 4 at the opposite second end, a plunger 5 displaceable between a first position and a second position and located in the cylinder 2, a finger handle 6 which is connected to the plunger 5 and is outside the second opening 4 of the cylinder 2 in the first position of the plunger 5 and inside the second opening 4 of the cylinder 2 in the second position of the plunger 5.

The cylinder has an internal stop 7 restricting the travel of the plunger 5 from the second position to the first position, and a collar 8 designed externally at the second opening 8, said collar serving as abutment to fingers when the disposable syringe 1 is to be emptied. The stop 7 has a small clearance to the plunger rod 14 to allow air in the cavity 15 between the plunger 5 and the stop 7 to pass to the venting chamber in the direction of the arrows when the plunger 5 is drawn in direction out of the cylinder 2. The stop 7 also serves for preventing the plunger 5 from being drawn completely out of the cylinder 2.

The needle 24 is here shown premounted and covered by a needle cap 9 which is removed when the injection fluid 10 in the vial 11 is to be drawn into the disposable syringe 1.

In this case, the plunger 5 has two lips 12,13 between which an O-ring optionally can be fitted for ensuring that injection fluid 10 does not pass through from the fluid chamber 17 to the venting chamber 18.

In fig. 2, the needle cap 9 has been removed from the needle 24 which subsequently has been passed through the rubber plug 19 of the vial 11 down into the injection fluid 10. The plunger 5 is displaced towards the first position of the plunger 5 and is abutting on the stop 7, a volume of injection fluid 20 having been drawn into the fluid chamber 17 during this. The fluid chamber 17 is only partly filled and therefore contains a volume of residual air 21 which, as shown in fig. 3, is forced out as the disposable syringe being turned upside down and residual air 21 being displaced into the vial 11 by guiding the plunger 5 in the direction of the arrow whereby residual air 21 is transferred to the vial 11. During this, the cavities 15 is filled with air from the venting chamber 18 as shown with the arrows in the figure.

In fig. 4, the disposable syringe 1 has again been pointed in the position in fig. 2. As the plunger 5 is drawn in the direction of the arrow out of the cylinder 2 until the plunger is abutting on the stop 7, an additional volume of injection fluid 20 is transferred from the vial 11 to the fluid chamber 20. As shown in fig. 5, residual air 21 is yet again forced out in a way similar to the one described under fig. 3, and the cavities 15 are emptied as described above with reference to fig. 2.

The last residual air is removed as shown in fig. 5 in a way similar to the one shown and described with reference to fig. 3 after which the disposable syringe is returned to the position in fig. 2 and filled to a maximum in the same way as described with reference to fig. 2.

As shown in fig. 7, the needle 24 is drawn out of the vial 11 and the needle cap 9 is placed with its cap point 22 in a recess 23 designed on the finger handle 6.

The needle cap 9 is pressed in the direction shown with the arrow in figs . 7 and 8 with a compressive force towards the finger handle 6 whereby the injection fluid 20 is injected into an individual (not shown) or other receptacle (not shown), such as e.g. a drip tube (not shown) or another vial (not shown) . The plunger 5 is abutting on the first end 16 of the cylinder 2 in its final position in which the disposable syringe 1 has been emptied of injection fluid 20. The cap point 22 of the needle cap 9 is removed from the recess 23 and placed over the needle 24 again as shown in fig. 9. Fig. 10 shows a second embodiment 25 of a disposable syringe according to the invention. This embodiment corresponds to the first embodiment 1 described in figs. 1-9 but the plunger and the plunger rod have been modified.

In this second embodiment, the plunger rod 26 has a first section 27 located nearest the finger handle 6 and a second section 28 of a reduced cross section and located in tandem of the first section 27 farther from the finger handle 6. The first section 27 has a pressure face 30 facing the plunger 29, at the transition between the first section 27 and the second section 28, and the free end of the second section 28 has a pointed barb 31.

The plunger 29 is designed as a chamber 29 having a first base 32 located nearest the first end 16 of the cylinder 2 and an opposite second base 33 with an opening 34 through which the second section 27 of the plunger rod 26 is extending into the chamber 29. As shown in fig. 10, the barb 31 is abutting on the second base 33 of the chamber 29 in the first position of the plunger .

To fill the disposable syringe 25, the needle cap 9 is removed and the needle 24 guided into the injection fluid 10 via the rubber plug 19 of the vial 11.

As shown in fig. 11, the injection fluid 10 is transferred to the fluid chamber 17, as the plunger 29 is being drawn in the direction of the arrow out of the cylinder 2, as air present in the fluid chamber prior to filling of the disposable syringe 25 is passing out through the space between the stop 7 and the plunger rod 26. During filling, the barb 31 is gripping the second base 33 of the chamber 29 until the plunger 29 is abutting on the stop 7 and the fluid chamber 17 is full. To empty the syringe again, the cap point 22 of the needle cap 9 is mounted in a recess 23 in the finger handle 6 as shown in fig. 12. After filling, the plunger rod 26 is freely returned to a position in which the barb 31, as shown in fig. 12, is abutting on the first base 32 of the chamber 29. Alternatively, the plunger rod 26 is returned to a not shown position in which the pressure face 30 is abutting on the second base 33 of the chamber 29.

The chamber 29 is advantageously designed as a hollow rubber plug having a coefficient of friction in relation to the cylinder of a size that causes the plunger 29 not to be able to return by itself in a direction out of the cylinder 2. The opening 34 in the chamber is tight around the first section 28 of the plunger rod 26 so that the plunger 29 is secured against the finger handle 6 being caught through the second opening 16 of the cylinder 2.

As seen best in fig. 13, the injection fluid 20 is injected or forced out of the fluid chamber 17 through the needle 24, the needle cap 9 being pressed against the finger handle 6 with a compressive force in the direction indicated by the arrow in fig. 13 until the plunger 29 reaches its second position in which the finger handle 6 is fully received in the cylinder 2. Finally, the needle cap 9 is removed from, the recess 23 to again be fitted as protection cap 9 over the needle 24 so that the disposable syringe 25 can be discarded without risk of reutilization.

As in the first embodiment, the stop 7 is also serving to prevent the plunger 5 from being drawn completely out of the cylinder 2.

The third embodiment in figs. 15-19 of a disposable syringe according to the present invention is a modification of the second embodiment described in figs. 10-14. The chamber 29 has a constriction 36 at a distance from the first base 32 and the second base 33 respectively. The constriction 36 is dividing the chamber 29 into a first sectional chamber 37 and a second sectional chamber 38 in which the barb 31 is located prior to use.

The injection fluid 10 is transferred to the fluid chamber 17 as described with reference to fig. 11 and shown in fig. 16, the plunger 29 being drawn in the direction of the arrow out of the cylinder 2, and the barb 31 gripping the second base 33 of the chamber 29 during this until the plunger 29 is abutting on the stop 7.

The syringe is emptied as shown in fig. 17 by at first mounting the needle point 22 of the needle cap 9 in a recess 23 in the finger handle 6 and subsequently affecting the needle cap 9 with a compressive force in the direction indicated by the arrow in the figure, the barb 31 passing form the second sectional chamber 38 to the first sectional chamber 37 through the constriction 36 during this.

In fig. 17, the pressure face 30 is abutting on the second base 33 of the plunger 29 and the barb 29 on the first base 32 of the plunger 29 during the emptying process. To empty the disposable syringe 35 during e.g. an injection, it is however only necessary for the pressure face 30 to abut on the second base 33 of the plunger 29 or for the barb 29 to abut on the first base 32 of the plunger 29.

In fig. 18 is seen the emptied disposable syringe 35 with the needle cap 9 partly received in the cylinder 2 whereby the finger handle 6 and thereby the plunger 29 are in the second position in which the disposable syringe 35 has been prevented from being reused. In case of the opening 34 is not squeezing sufficiently around the first section 28 of the plunger rod 26, the barb 31 will, as shown in fig. 19, if required be able to be displaced between first base 32 of the chamber 29 and the constriction 36 but only so that the entire extent of part of the second section 28 of the plunger rod 26 located in the second sectional chamber 38 when the barb 31 is located in the first sectional chamber 37, and the first section 27 of the plunger rod 26 and the finger handle 6 is so small that the finger handle 6 cannot be brought to a freely manipulatable position outside the second opening 4 of the cylinder 2.

Figs. 20 and 21 shown a modification 39 of the second embodiment in figs. 10-14 of a disposable syringe according to the present invention.

The finger handle 6 has a circumferential barb 40 at the side of the finger handle 6 facing the second opening 4 of the cylinder 2, and the stop 7 has a cooperating barb 41. When the needle cap 9 on the finger handle 6 is displaced with a compressive force in the direction indicated by the arrow in fig. 20, the barbs 40 are made to engage the barbs 41 in a locking manner. The needle cap 9 is again mounted on the needle 4 and the disposable syringe 39 cannot be reused.

Figs. 22-26 show a fourth embodiment 42 of a disposable syringe according to the invention. This embodiment is a modification of the previously described embodiments and like parts are therefore similarly referenced.

The disposable syringe 42 has a cylinder 2 with a first opening 3, with an attachment opening 3 for a needle 24 which preliminarily is covered by a needle cap 9, and a second opening 4 for receiving a plunger 5, which via a plunger rod 26 having a first section 27 and a second section 28 is connected to a finger handle 6 in which a recess 23 is designed. The cylinder 2 has an internally designed stop 7 for restricting the travel of the plunger 5 between first and second position and an externally designed collar 8 for forming abutment to fingers during emptying of the disposable syringe. The second section 28 of the plunger rod 26 has a total number of six folding lines 43 in the example shown in figs. 22-26.

As seen best in fig. 23, the folding lines 43 in the first section 28 can withstand the drawing force necessary of the injection fluid 10 to be transferred to the fluid chamber 17 via the needle 24 placed in the vial 11 when the finger handle 6 is drawn in the direction indicated by the arrow in fig. 23 until the plunger 5 is abutting on the stop 7 and the fluid chamber 17 has been filled with a volume of injection fluid 20.

As shown in fig. 24, the cap point 22 of the needle cap 9 is fitted in the recess 23 on the finger handle 6 and by means of a compressive force on the needle cap 9 in the direction indicated by the arrow in fig. 24, the pressure face 30 of the plunger rod 26 is guided in direction towards the plunger 5, the folding lines 43 making the second section 28 of the plunger rod 26 collapse during this.

In fig. 25 is seen an initial emptying step in which the collapsed second section 28 is compressed against the plunger 5 and displaced past the stop 7 at the same time as the injection fluid 20 is displaced out of the disposable syringe 42 by means of the plunger 5 until the position in fig. 25 has been reached. As the second section of the plunger rod 26 has collapsed, the finger handle 6 cannot again be brought to a position in which it is outside the second opening 4 of the cylinder 2. As shown in fig. 26, the needle cap 9 is removed from the internal diameter of the cylinder 2 and placed over the needle 24 after which the disposable syringe 40 is discarded without possibility of being able to be reused.

Fig. 27 shows the second embodiment 25 in empty state with the cap point 22 of the needle cap 9 fitted in the recess 23 of the finger handle 6 where the finger handle 6 in addition has a pair of flaps 44 which is connected to the finger handle 6 via rupture zones 45. The flaps 44 ensure that the finger handle 6 not unintentionally can be received in the cylinder 2 when the disposable syringe e.g. is stored in its packaging.

By means of a compressive force in the direction indicated by the arrow in fig. 28, the finger handle 6 is displaced towards the second opening 4 of the cylinder 2 until the finger handle 6 is abutting on this second opening 4.

As seen in fig. 29, the flaps 44 are cut or broken off at the rupture zones 45 during the continued displacement of the plunger 5 towards its second position in direction towards the first end 3 of the cylinder 2 until the finger handle is completely received in the cylinder 2.

It is a joint and general concept of all the embodiments that the stop 7 is serving to prevent the plunger 5 from being drawn completely out of the cylinder 2.

Fig. 30 shows a modification of the embodiment in figs. 1-9 arranged to be able to be used with a conventional needle 46 which is covered by a conventional, mainly conic needle cap 47 having a diameter at least along a section that is equal to or smaller than the internal diameter of the cylinder 2. At the first end 16 of the cylinder, a LUER-LOCK 49 is designed and is arranged to be connected with the needle so that it subsequently cannot be demounted again.

In the finger handle 6, a depression 48 is designed that, as shown in fig. 31, is serving for receiving the needle cap 47 when the plunger 5 is displaced towards the second position incidentally in the same manner as described for the rest of the embodiments shown and described in figs. 1-29.

Within the scope of the invention, details of the different embodiments can be designed, combined and replace each other. The embodiments in figs. 1-29 can be designed at the first end 16 to be used with a loose needle and vice versa, the finger handle of the plunger in this case suitably being modified to cooperate with the associated needle cap.

It is also a general concept that the disposable syringe according to the present invention cannot be reused if it is merely half empty.

Claims

1. A disposable syringe (1; 25,-35,-42) for injecting a fluid (10) and comprising - a tubular cylinder (2) having an attachment opening

(3) for a needle (24;46) at the first end (16) and a second opening (4) at the opposite second end (4) , a plunger (5; 29) displaceable between a first position and a second position and located in the cylinder (2), a link (14; 26) connecting the plunger (5; 29) and the finger handle (6), characterised in that the finger handle (6) in the first position of the plunger (5;29) is outside the second opening (4) of the cylinder (2) and inside the second opening

(4) of the cylinder (2) in the second position of the plunger (5; 29) .

2. A disposable syringe (1; 25 ; 35 ; 42 ) according to claim 1, characterised in that a stop (7) is designed in the cylinder (2) that restricts the travel of the plunger (5; 29) in the direction from the second position to the first position, and that the end of the link (14; 26) , facing in the opposite direction of the finger handle (6) , between the finger handle (6) and the plunger (5; 29) is at or near this stop (7) in the first position of the plunger (5,-29) .

3. A disposable syringe (1; 25; 35; 42) according to claim 1 or 2, characterised in that the link (26) between the finger handle (6) and the plunger (5; 29) is a plunger rod (14) .

4. A disposable syringe (25; 35; 42) according to claim 1, 2 or 3 , characterised in that the link (26) between the finger handle (6) and the plunger (29) is a plunger rod (26) having a first section (27) located nearest the finger handle

(6) and a second section (28) located in tandem of this first section (27) , that at the transition between the first section

(27) and the second section (28) is located a pressure face (30) facing the plunger (29) , that the free end of the second section (28) is designed with a collar (31) , that the plunger (29) is designed with a chamber

(29) having a first base (32) located nearest the attachment opening (3) of the cylinder (2) and an opposite second base (33), that an opening (34) is designed in the second base

(33), that the second section (28) of the plunger rod (26) is extending into the chamber (29) via this opening

(34), that the collar (31) on the second section (28) of the plunger rod (26) is abutting on the second base

(33) of the chamber (29) in the first position of the plunger (29) , and that at least the pressure face (30) or the collar

(31) of the plunger rod (26) is hitting the second

(33) and first base (32) respectively of the chamber

(29) .

5. A disposable syringe (25; 35; 42) according to any of the claims 1-4, characterised in that the collar (31) on the free end of the second section (28) of the plunger rod (26) is designed as a barb (31) pointing its point towards the first opening (3) of the cylinder (2) .

6. A disposable syringe (42) according to any of the claims 1-5, characterised in that the link (26) between the finger handle (6) and the plunger (29) comprises a rigid first section (28) located nearest the finger handle (6), and a second section (27) located in tandem of this first section (28) oppositely and farther from the finger handle (6) and having an extended state in which it can transmit drawing forces but not compressive forces and a collapsed state in which it can transmit compressive forces but not drawing forces.

7. A disposable syringe (42) according to any of the claims 1-6, characterised in that the second section (27) is a strip or a wire of a flexible material, such as a flexible plastic.

8. A disposable syringe (42) according to any of the claims 1-7, characterised in that the second section (27) consists of a strip (28) or a wire of a rigid material having a number of folding or rupture lines (43) designed along the strip (28) or wire.

9. A disposable syringe (1; 25; 35; 42) according to any of the claims 1-8, characterised in that the needle (24,46) is premounted at the first opening (3) of the cylinder (2) .

10. A disposable syringe (1;25;35;42) according to any of the claims 1-8, where a needle (24; 46) is part of the disposable syringe (1; 25; 35, 42) and has a detachable needle cap (9) preliminarily covering the needle (24) , characterised in that the needle cap (9,47) along at least a section has a diameter equal to or smaller than the internal diameter of the cylinder (2) and that said section has a length at least as great as the space between the finger handle (6) and the second opening (4) of the cylinder (2) in the second position of the plunger (5;29) .

11. A disposable syringe (1; 25; 35; 42) according to claim 10, characterised in that a recess (23) or pin is designed in the free end face (6) of the finger handle (6) and that a complementarily shaped pin or recess is located in the free end face on the needle cap (9) at said section.

12. A disposable syringe (1; 25; 35; 42) according to any of the claims 1-11, characterised in that the finger handle (6) has an extended area (44) and that at least one rupture assignor (45) , located between this area and the rest of the finger handle, for assigning a break between said extended area (44) and the rest of the finger handle (6) when the finger handle is guided from its first position to its second position.

13. Method for using the disposable syringe (1; 25; 35; 42) according to claims 1-12, and comprising that the point of the needle (24; 46) is placed in the injection fluid (10) , that injection fluid (10) is drawn into the cylinder

(2) by means of at least one possibly reciprocating manipulation of the finger handle (6) and thereby the plunger (5; 29) characterised in that the injection fluid (10) is injected by affecting the finger handle (5; 29) with a compressive force until the finger handle in the cylinder is under the second opening (4) of the cylinder (2) .

14. A method according to claim 13, characterised in that a needle cap (9,47) detachably mounted on the needle (24,46) is fitted in tandem of the finger handle (6) , and that the needle cap (9,47) is used for pressing the finger handle (6) into the cylinder (2) during injection until it in the cylinder is under the second opening (4) of the cylinder (2) .

15. A method according to claim 13 or 14, characterised in that the used needle (24,46) is sealed with the needle cap (9) after injection and that the disposable syringe (1;25 ; 35 ;42) then is discarded.