INFUSION DEVICEThe present invention relates to an infusion device which can be used to administer medicaments to patients over a prolonged period of time.
The invention is applicable particularly but not exclusively, to the administration of insulin to patients suffering from diabetes mellitus.
In the past patients have needed to inject long and short acting insulins to fulfil the daily need for insulin. It has been in the past only convenient for patients to inject early in the morning and to rely on the decaying characteristics of a long acting insulin to cope with the requirement for insulin throughout the day.
The present invention provides an infusion device which will allow patients to inject a natural insulin at any time, for example, prior to eating a main meal.
The device is worn by the patient either around the abdomen or on the arm, not unlike a wrist watch. To operate the device and infuse the drug a knurled thimble is rotated a given number of times according to the patient's requirements. An audible click indicates each time a dose is metered. The device is normally connected to the patient via a standard disposable cannula through which the drug is infused.
The device can be used for inter-muscular, intravenous or subcutaneous infusion although the cannula characteristics may have to change.
The invention will be illustrated by the following description of one embodiment of an infusion device according to the present invention.
Figure (1) is a diagrammatic view of the device in part section.
Figure (2) shows the "click" or clapper-hox mechanism.
Figure (3) shows the means of attaching the device to the patient.
The infusion device consists of a casing (1) to which is attached by screw thread a slotted cap (2). Behind the cap is located, complete with rubber plunger, a disposable drug reservoir (3).
The disposable drug reservoir is retained in place by a doubleended knurled hollow cap (4) which is screwed to the cam(5) of the clapper-box mechanism (see Figure (2)). The clapper-box mechanism consists of a pair of sliding pins (6) which are constrained from turning by a clapper-box body (7). The body itself is constrained in all axes by the pin (8) which is located in the knurled thimble body (9). the clapper-box pins are constrained from moving back by the circular collar (10), and are caused to rise over the cam by the action of the spring (11) which in turn is retained by the threaded ammulus (12). The plunger is caused to move down the drug reservoir by the action of the lead screw (13) on the lead screw nut (ill). The lead screw is connected to the knurled thimble by the knurled cap (15).
The device is illustrated on an abdominal belt (16). A butterfly type cannula (17) is shown for the purposes of illustration.
NOTES To PATENT APPLICATION (1) The device can be used as an injection device in place of aconventional syringe.
(2) The casing is slotted to allow cannula access.
The The base in the knurled cap is drilled off centre to preventthe lead screw unit (14) from turning.