Syringe for infusion

• US 6,123,685 A
• Filed: 08/25/1997
• Issued: 09/26/2000
• Est. Priority Date: 05/17/1993
• Status: Expired due to Fees

• Current Assignee: Duoject Medical Systems, Inc
• Original Assignee: David L. Reynolds
• Inventors: Reynolds, David L.
• Primary Examiner(s): Coggins, Wynn Wood
• Assistant Examiner(s): NGUYEN, ANH TUAN TUONG
• Application Number:
  US08/917,128
• Time in Patent Office: 1,128 Days
• Field of Search: 604/70, 604/86, 604/90, 604/132, 604/141, 604/142, 604/143, 604/150, 604/191, 604/200, 604/217, 604/221, 604/222, 604/228, 604/201, 604/205, 604/88
• US Class Current: 604/90
• CPC Class Codes: A61M 2005/14204 with gas-producing electrochemical cell
• CPC Class Codes: A61M 5/155 pressurised by gas introduced into the reservoir

Abstract

A syringe is modified to permit gradual administration of its contents with reduced problems due to seizing or stiction of its piston by dividing its piston axially into two parts, a front detached part and rear part which is the only part having provision for attachment to a syringe actuator. The rear part has a passage through which fluid can be gradually introduced from an actuator into a chamber between the parts so as to force the front part forward while the rear part is restrained against rearward movement. The passage may be initially closed by a septum which is penetrated by a cannula on the actuator. If the syringe actuator is a plunger, the syringe can be used conventionally.

Claims

1. A syringe comprising a syringe body, a piston (6) which is formed in two separate parts in longitudinal tandem within the syringe body (2), wherein the piston parts are a detached imperforate front part (6A) formed essentially of elastomeric material and nearer a forward end of the syringe body, and a normally abutting rear part (6B) defining a passageway for establishing communication between rear and front surfaces of that rear part, only the rear part having at its rear surface, surrounding the passageway, a connector (18) for connection of a syringe actuator when the syringe is used, wherein a retainer is engaged with a rear end of the syringe body to restrain the rear part (6B) against expulsion from the syringe body, said retainer defining an opening through which said connector is accessible to an actuator, and wherein the connector is configured to provide a fluid connection between said passage in said rear part and a pressurized fluid source in an actuator, and a mechanical coupling between said rear part and an actuator, whereby by selection of a suitable actuator, said connector provides one of means for mechanically actuating the syringe by application of mechanical pressure to the rear piston part, and means for fluid actuation of the syringe by allowing fluid to be introduced between said piston parts through said passageway.

2. A syringe according to claim 1, wherein the piston parts (6A, 6B) cooperate to form a chamber (28) between said parts with which said passageway (20) communicates.

3. A syringe according to claim 1, wherein the front part (6A) of the piston is of generally disc-shaped configurations, and thin enough to bow under the application of differential fluid pressures to front and rear surfaces thereof.

4. A syringe according to claim 1, wherein the front part (6A) of the piston is of lesser axial extent than the rear part (6B).

5. A syringe according to claim 1, wherein at least one of the piston parts is formed with protuberance (30) to limit contact with the other part.

6. A syringe according to claim 1, wherein the passageway is closed by a perforable septum (22).

7. A method of discharging contents of syringe, having a piston adapted for conventional actuation by a mechanical actuator, by use of a fluid pressure actuator, comprising forming a piston of the syringe in two separable but initially abutting parts, namely a detached imperforate front part formed essentially of elastomeric material, and a rear part formed with a passageway for establishing fluid communication between rear and front surfaces of said rear part, only the rear part having provision for mechanical connection to a syringe actuator, and actuating said piston by connecting said fluid pressure actuator to the rear part and introducing pressurized fluid through said passageway from said actuator while restraining said rear part against rearward motion.

8. A method according to claim 7, in which the front part of the piston is disk shaped and sufficiently flexible such that it will bow under pressure, and causing said front part to bow by the introduction of said pressurized fluid so as to overcome stiction effects.

9. A method according to claim 7, wherein the fluid pressure actuator is a gas generator.

10. A method according to claim 7, wherein the fluid pressure actuator is a coupling to a tube linked to a source of fluid pressure.

11. A method according to claim 7, wherein the step of coupling a fluid pressure actuator to the rear part includes penetration of a septum in the passageway by a cannula on the fluid pressure.