GB2072017A - Medical syringe - Google Patents

Abstract

Apparatus for controlled slow administration of liquid to a patient, eg. by intravenous infusion comprises a frame 20 to receive a liquid containing cartridge 10 which is collapsed by a motor 21 which moves a mechanical coupling 26 which bears upon the cartridge. The cartridge has a collapsible bellows-type sidewall and is securely located to the frame at its front end by means 22. The nature of the cartridge 10 permits the apparatus to be made more compact and reduces the risk of contamination or air-ingress. <IMAGE>

Description

SPECIFICATION Medical apparatus The invention relates to medical apparatus.

The invention relates more particularly to medical apparatus for the automatic dispensing of a medicament from a syringe, usually at a very slow controlled rate, and to a novel syringe for use in the medical apparatus.

Pumps which are supported adjacent a patient or supported by the patient have already been proposed which are arranged to move a plunger of a conventional syringe so as to administer a drug to the patient in controlled manner either continuously or intermittently generally over long periods of time.

At present such arrangements tend to be relatively bulky.

According to one aspect of the present invention there is provided a medical apparatus for administering a drug from a bellows-type syringe comprising a frame, secured to the frame an electric motor arranged to be supplied from a power source, locating means on the frame for securely axially locating a forward end of the bellows-type syringe, and mechanical coupling means arranged to be driven by the motor to move the rear end of the bellows-type syringe towards said forward end.

According to another aspect of the invention, there is provided a bellows-type syringe for use with the above medical apparatus having a shoulder at its forward end for cooperation with locating means on said medical apparatus.

A medical apparatus and bellows-type syringe according to the invention will now be described, by way of example with reference to the accompanying diagrammatic drawing in which: Figure 1 shows the syringe; Figures 1A and B show different rear ends for the syringe; Figure 1C shows a view of a forward end of the syringe; and Figure 2 shows the apparatus and the syringe.

Referring to the drawings, in Figure 1 a bellowstype syringe 10 is provided at its forward end with a flange 11 adjacent an outlet 12. The flange 11 has a cut-away portion 13 (Figure 1 C) for use as described below. A second flange 14 is provided at the rear end of the syringe 10.

The syringe 10 is filled with medicament normally for use for injection intraveneously into a patient through a capillary catheter attached to the outlet 12.

It may be necessary or useful to provide additive or replacement medicament into the syringe 10 when placed in position on the frame 10 or beforehand. In Figure 1A a plastic injection port 14 is provided in the rearward facing surface of the bellows configuration of the syringe 10 through which an injection needle can be inserted. The port 14 is self-sealing as the needle is withdrawn. In alternative form Figure 1 B, an injection port 15 is provided and is provided with a removable plug 16. Normally, the plug 16 is removed for adding medicament but could be made of self-sealing material and remain in the port 15 during addition of medicament into the syringe.

In Figure 2, the medical apparatus comprises a frame 20 enclosing and supporting an electric motor 21. The motor may be supplied from a mains power supply or more conveniently be provided with a battery pack located within the frame 10. A locating bracket 22 is mounted on the frame 20 which engages behind the flange 11 of the syringe 10 and is provided with a forward projection 23 which fits into the cut-away portion 13 of the flange 11. The motor 21 is coupled through gear wheels to a threaded shaft 24 which extends through a threaded boss 25 secured to an arm 26. The arm 26 extends upwards to a fork (not shown) which engages between the body of the syringe 10 and the flange 14. The bracket 26 extends downwards to a key located to slide in a keyway 27.

In use, a full syringe 10 is placed on the frame 20 and the outlet 12 connected to a capillary catheter (not shown)for injection of medicament into a patient. The motor 21 is energised to rotate the shaft 24 and so urge the forked-end of the arm 26 towards the bracket 22 and axially compress the syringe 10.

Medicament is thus forced out of the syringe 10 and into the patient.

It will be noted that the bracket 22 prevents the outlet 12 moving in a direction towards the body of the syringe 10. Such movement could otherwise occur if the catheter is jostled by the patient in that direction. If the bracket 22 did not prevent such movement, it is quite possible consequent compression of the syringe however slight could force an unpredictable quantity of medicament into the catheter and hence into the patient. As the apparatus has particular application for controlled injection of strong drugs over a considerable time span intermittent and unexpected variations in the flow of the medicament may prove undesirable and even dangerous to the patient. For the same reason, it is desirable, at least, to prevent rotation of the syringe 10, as well as securing of the forward end of the syringe against axial movement.In the embodiment shown, rotation is prevented by engagement of the cut-away portion 13 of the syringe 10 with the projection 23.

It will be noted that axial and rotational movement of the forward end of the syringe 10 is prevented while still allowing easy insertion (and replacement) of the syringe for use onto the frame 20.

Other forms of fixing the forward end of the syringe to the frame to prevent axial and where necessary rotational movement of the syringe at its forward end can be used. For example, a clamp mounted on the frame 20 can be provided for gripping the forward end of the syringe (whether the flange 11 is provided or not). Also, a groove may be provided in the outer peripheries of some at least of the individual chambers of syringe and a lip provided on top of the frame 20 extending parallel to the axis of the syringe to cooperate with the groove or grooves thus preventing rotation of the syringe in use.

The flange 14 or similar is not always necessary but if the forked end of the bracket 26 is engaged between the flange 14 and the body of the syringe 10 as described, uncontrolled pressure exerted on the rear end of the syringe will not cause compression of the syringe, compression being controlled by the position of the bracket 26 relative to the frame 20.

Clearly, if the syringe is provided as may be normal in some applications with a cover supported by the frame 20 so that no untoward contact can be made with the syringe 10, the flange 14 or similar may not be required as such. Nevertheless the flange 14 or similar attaching means is useful for more securely locating and maintaining the end of the bracket 26 in contact with the syringe.

As is well known in comparable medical apparatus for pumping medicaments automatically into a patient, some such apparatus being attached to the body or limb of the patient, the electric motor and control thereof can be sophisticated. This enables the injection period to be extended over several hours or days and with the use of very little electrical energy. Such control systems may be arranged to provide continuous injection or timed and intermittent injection as required. In some cases the control of the motor may be arranged to monitor aspects of the patient's condition to vary rates of injection, or the quantity of medicament remaining to provide audible or visible alarms when desired.Whereas the simplest form of motor arrangement is herein described, it is within the scope of the invention to include such rate and conditions of medicamentflow control as may be required for different patients and different medicaments.

Further, the invention includes bellows-type syringes per se generally as described and provided with cooperating grippable means, say, a shoulder described in the form of a flange at or adjacent its forward end. The invention includes various forms of bellows-type syringe, for example, as generally described in U.K. Patent Specification No. 1477165.

There the perimeters of the outer edges of individual chambers forming the syringe increase from the forward end of the syringe so that, during compression, the individual chambers of the bellows tend to collapse inside one another to enable increased usage of the medicament supplied in the syringe.

The syringe may be also formed for the same purpose with the perimeters of the chambers decreasing from the forward end.

In all cases, the bellows-type syringe is much shorter overall especially in its full condition than an equivalent capacity conventional syringe having a body and movable plunger. This means that medical apparatus according to the present invention provided for use with a bellows-type syringe can be made with substantially smaller overall dimensions.

As a major application of medical apparatus for automatic injection is believed to be for use when strapped or otherwise attached to a patient, the successful reduction in overall dimensions of such apparatus provides a considerable advantage.

Further, the conventional syringe cannot normally be completely secure against egress of air and particles past the seal between the body and plunger so that storage of a full conventional syringe can sometimes be responsible for injection when used after storage. This disadvantage is also relevant during periods of automatic injection which can take place over periods of many hours during which time the medicament in the conventional syringe can become contaminated by egress into the body of the syringe. As the bellows-type syringe remains sealed during storage and throughout injection periods no such contamination can occur.

Claims (16)

1. Medical apparatus for administering a ~drug from a bellows-type syringe comprising a frame, securing to the frame an electric motor arranged to be supplied from a power source, locating means on the frame for securely axially locating a forward end - of the bellows-type syringe, and mechanical cou pling means arranged to be driven by the motor to move the rear end of the bellows-type towards said forward end.

2. Medical apparatus according to Claim 1, in which said locating means is arranged to prevent rotation of the bellows4ype syringe in use.

3. Medical apparatus according to Clam or 2, in which said locating means is arranged to allo X the bellows-type syringe to be readily remover n a direction at least substantially at right angles to the axis of the syringe.

4. A medical apparatus according to any of Claims 1 to 3, including engaging means ,ior provid ing secure axial engagement between said mechanical coupling means and said rear end.

5. A bellows-type syringe for medical apparatus according to any of Claims 1 to 4, having a shoulder at its forward end for cooperation with said locating means.

6. A bellows-type syringe according to Claim 5.

in which said shoulder is an annular flange.

7. A bellows-type syringe according to Claim 5 or 6, in which the shoulder has a cut-away section for cooperation with part of said locating means to prevent rotation of said syringe in use.

8. A bellows-type syringe according to Claim 5, in which said syringe has a longitudinal groove in some or all of the peripheries of individual chambers of the syringe for cooperating with a lip on said apparatus to prevent rotation of said syringe in use.

9. A bellows-type syringe according to any of Claims 5 to 8, in which said syringe is provided a shoulder at said rear end for cooperation with sated mechanical coupling means.

10. A bellows-type syringe according to Claim 9, in which said shoulder comprises an annular flange.

11. A bellows-type syringe according to any of Claims 5 to 10, in which said syringe is provided with a sealed or sealable injection port to enable insertion of replacement or supplemental medicament into the syringe.

12. A bellows-type syringe according to Claim 11, in which said injection port is at said rear end or the longitudinal axis of the syringe.

13. A bellows-type syringe according to Claim 12, in which said injection port is sealed with a removable plug.

14. A bellows-type syringe according to Claim 1 í; in which said injection port is positioned on a rear facing surface of one of said individual cham bers adjacent the periphery thereof.

15. A medical apparatus for a bellows-type syringe substantially as described herein with reference to the accompanying drawing.

16. A bellows-type syringe substantially as he rein described with reference to the accompanying drawing.