Syringe pumps

• US 20030205587A1
• Filed: 08/03/2001
• Published: 11/06/2003
• Est. Priority Date: 08/16/2000
• Status: Active Grant

• Current Assignee: Smiths Medical International Limited (ICU Medical Incorporated)
• Original Assignee: Smiths Group plc (Smiths Group International Holdings Ltd.)
• Inventors: Pickles, Chris, Tribe, Robert James
• Granted Patent: US 7,635,349 B2
• Time in Patent Office: Days
• US Class Current: 222/420
• CPC Class Codes: A61M 2005/16863 Occlusion detection
• CPC Class Codes: A61M 2205/18 with alarm
• CPC Class Codes: A61M 5/1456 with a replaceable reservoir comprising a piston rod to be moved into the reservoir, e.g. the piston rod is part of the removable reservoir
• CPC Class Codes: A61M 5/16854 by monitoring line pressure

Abstract

A syringe pump has a motor rotating a leadscrew, which drives a plunger head retainer to push a plunger along the barrel of a syringe so as to dispense medication to a patient. A force sensor in the head retainer measures the force on the plunger to detect when there is an occlusion restricting flow of medication. When an excess force is detected an alarm is generated and the motor is reversed to reduce the force to about 10% of that at which the occlusion is detected. The occlusion can be removed with a reduced risk of a bolus of medication being dispensed after which the user restarts the pump so that the plunger is driven normally.

Claims

1. A syringe pump adapted to receive a syringe having a plunger movable along a barrel, the pump comprising:

a drive mechanism for moving said plunger along said barrel; and

an occlusion detector responsive to occlusion to flow of medication from said syringe, wherein the pump is operable in response to a detected occlusion to reverse the drive applied to move said plunger along said barrel sufficiently to reduce excess force on the medication caused by said occlusion.

2. A pump according to claim 1, wherein said occlusion detector includes a force sensor.

3. A pump according to claim 2, wherein the pump is arranged to reverse the drive until force detected by said force sensor reaches a predetermined level.

4. A pump according to claim 3, wherein the pump is arranged to reverse the drive until force detected by said force sensor is substantially 10% of the force at which an occlusion is detected.

5. A syringe pump adapted to receive a syringe having a plunger movable along a barrel, the pump comprising:

a drive mechanism, said drive mechanism including a motor, a leadscrew driven by said motor and a plunger retainer movable along the leadscrew such as to move said plunger along said barrel; and

a force sensor mounted with said plunger retainer to detect excess force on said plunger, wherein the pump is operable in response to an output from said force sensor indicative of an excess force to reverse said motor sufficiently to reduce substantially said excess force.

6. A method of controlling a syringe pump comprising the steps of:

applying a force to drive a plunger along a barrel of a syringe to dispense medication;

detecting an occlusion to the flow of medication out of the syringe; and

responding to said detected occlusion by reversing the drive on said plunger sufficient to reduce excess pressure on the medication.

9. A method according to claim 6, wherein the pump generates an alarm when force on said plunger exceeds a predetermined value.

10. A method according to claim 6, wherein the pump only reapplies force to dispense medication when the pump is manually restarted after detection of an occlusion.

7. A method of controlling a syringe pump comprising the steps of:

applying a force to drive a plunger along a barrel of a syringe to dispense medication;

detecting force on said plunger, responding to a force on said plunger above a predetermined value by changing the force applied to drive said plunger such that said detected force reduces below said predetermined value.

8. A method according to claim 7, wherein force applied to drive said plunger is changed to reduce said detected force to substantially 10% of said predetermined value.