Syringe Infusion Pump

Abstract

One embodiment of the present patent application is a syringe infusion pump that includes a syringe, a syringe barrel holder, and a force sensor. The syringe includes a barrel and a plunger. The plunger has a plunger axis and the barrel has a barrel axis and a barrel diameter. The syringe is one of a plurality of syringes, each having a different barrel diameter. The force sensor is positioned for detecting a force along the barrel axis. The syringe holder provides the barrel axis automatically aligned with the force sensor for each syringe of the plurality of syringes.

What is claimed is: 
     
         1 . A syringe infusion pump for use with a plurality of different size syringes, each different size syringe having a different syringe barrel diameter, and each of said plurality of syringes including a plunger having a plunger axis received in the barrel along a barrel axis, said pump comprising:
 a drive head including a force sensor positioned to sense force applied to the plunger by the drive head, the force sensor having a center; and   a syringe barrel holder configured to hold each of said syringe barrels of different diameters in a fixed position with the barrel axis aligned with said force sensor center for each different diameter syringe barrel.   
     
     
         2 . A syringe infusion pump as recited in  claim 1 , further comprising a syringe plunger holder mounted on said drive head, wherein said syringe plunger holder engages the plunger with said plunger axis aligned with said force sensor center for each different diameter syringe barrel. 
     
     
         3 . A syringe infusion pump as recited in  claim 2 , wherein said syringe plunger holder comprises a first plunger holder element and a second plunger holder element, said first plunger holder element being constrained to move a distance equal to a distance moved by said second plunger holder element, but in an opposite direction. 
     
     
         4 . A syringe infusion pump as recited in  claim 2 , wherein:
 said drive head is configured and dimensioned to push the plunger into the barrel of each different size syringe; and   said force sensor is positioned to detect force exerted by said drive head on the plunger.   
     
     
         5 . A syringe infusion pump as recited in  claim 4 , wherein said force sensor is fixed in said drive head, and said syringe plunger holder engages the plunger with the plunger axis aligned with the barrel axis. 
     
     
         6 . A syringe infusion pump as recited in  claim 1 , wherein said syringe barrel holder is configured and dimensioned to provide a fixed position for the barrel axis with respect to said force sensor center and said fixed position is independent of size of the barrel for each different diameter syringe barrel. 
     
     
         7 . A syringe infusion pump as recited in  claim 1 , wherein said syringe barrel holder includes a barrel clamp comprising a first element and a second element, said first element and said second element being movable to engage and hold a syringe barrel in said fixed position independent of the diameter of said barrel. 
     
     
         8 . A syringe infusion pump as recited in  claim 7 , wherein said first element is constrained to move a distance equal to a distance moved by said second element, but in an opposite direction. 
     
     
         9 . A syringe infusion pump as recited in  claim 7 , wherein said barrel clamp further comprises:
 a first rack connected to the first element and a second rack connected to the second element, said racks having opposed toothed surfaces;   a gear disposed between said racks and meshing with each rack to control relative position of said first and second elements with respect to one another; and   a biasing element forcing the clamp elements together.   
     
     
         10 . A syringe infusion pump as recited in  claim 9 , wherein:
 said barrel clamp further comprises a guide shaft secured to the first clamp element and extending through said second clamp element; and   said pump further comprises a base, wherein the gear is disposed in said base and said guide shaft extends into said base.   
     
     
         11 . A syringe infusion pump as recited in  claim 7 , further comprising a barrel diameter sensor positioned and configured to detect a magnitude of separation between said first element and said second element. 
     
     
         12 . A syringe infusion pump as recited in  claim 11 , wherein said barrel diameter sensor includes an absolute encoder for detecting angular movement of said gear. 
     
     
         13 . A syringe infusion pump as recited in  claim 2 , wherein said syringe plunger holder comprises front and rear plunger clamps cooperating to position the plunger with the plunger axis aligned with the force sensor center independent of the diameter of the barrel of a syringe held in the syringe barrel holder. 
     
     
         14 . A syringe infusion pump as recited in  claim 2 , wherein said syringe barrel holder is configured to hold the barrel with the barrel axis aligned with the force sensor center in response to the syringe plunger holder positioning the plunger with the plunger axis aligned with the force sensor center. 
     
     
         15 . A syringe infusion pump as recited in  claim 1 , further comprising a processor and an alarm, wherein said force sensor is connected to provide force data to said processor, and said processor is programmed to activate said alarm if force applied exceeds a specified value. 
     
     
         16 . A syringe infusion pump as recited in  claim 1 , further comprising a drive head position sensing mechanism. 
     
     
         17 . A syringe infusion pump as recited in  claim 16 , wherein:
 said drive head position sensing mechanism includes a guide rod, a guide rod driver, and a guide rod sensor;   said guide rod has a helical groove and said guide rod driver includes a pin that fits in said helical groove; and   said guide rod sensor senses rotation of said guide rod.   
     
     
         18 . A syringe infusion pump as recited in  claim 17 , wherein said guide rod and lead screw are mounted on a base. 
     
     
         19 . A syringe infusion pump as recited in  claim 17 , wherein said helical groove extends once around said guide rod. 
     
     
         20 . A syringe infusion pump as recited in  claim 17 , wherein said guide rod sensor includes an absolute encoder for detecting angular movement of said guide rod. 
     
     
         21 . A syringe infusion pump for use with a plurality of different size syringes, each different size syringe having a different syringe barrel diameter, and each of said plurality of syringes including a plunger having a plunger axis received in the syringe barrel along a barrel axis, said pump comprising:
 a drive head configured to apply force to the plunger to operate the syringe, said drive head including a force sensor positioned to sense force applied to the plunger by the drive head, the force sensor having a center;   a syringe barrel holder comprising a barrel clamp including a first clamp element and a second clamp element, said first and second clamp elements being movable to engage and hold syringe barrels of different diameters in a fixed position with the barrel axis automatically aligned with said force sensor center independent of the diameter of the barrel for each different diameter syringe barrel; and   a syringe plunger holder mounted on said drive head comprising front and rear plunger clamps cooperating to automatically position the plunger with the plunger axis in alignment with the force sensor center, and with the plunger axis in alignment with the barrel axis independent of the diameter of the barrel of a syringe held in the barrel holder for each different diameter syringe barrel.   
     
     
         22 . A syringe infusion pump as recited in  claim 21 , wherein said syringe barrel holder is configured to hold the barrel with the barrel axis aligned with the force sensor center in response to the syringe plunger holder positioning the plunger with the plunger axis aligned with the force sensor center. 
     
     
         23 . A syringe infusion pump for use with a plurality of different size syringes, each different size syringe having a different syringe barrel diameter, and each of said plurality of syringes including a plunger with a plunger flange having a plunger axis received in the barrel along a barrel axis, said pump comprising:
 a drive head positioned and configured to push the plunger into the syringe barrel for each different size syringe, said drive head including a force sensor configured to sense force applied to the plunger by the drive head, said force sensor having a center;   a syringe plunger holder configured and dimensioned to engage the plunger of each different size syringe with the plunger axis aligned with said force sensor center for each said different size syringe; and   a syringe barrel holder configured to hold each of the syringe barrels of different diameters in a fixed position when the drive head pushes the plunger into the syringe barrel.   
     
     
         24 . A syringe infusion pump as recited in  claim 23 , wherein:
 said syringe plunger holder is mounted on said drive head; and   said syringe plunger holder comprises a first plunger holder element and a second plunger holder element, said first plunger holder element being constrained to move a distance equal to a distance moved by said second plunger holder element, but in an opposite direction.   
     
     
         25 . A syringe infusion pump as recited in  claim 24 , wherein said first and second plunger holder elements engage the plunger with the plunger flange positioned between said elements and the force sensor, and with the plunger axis automatically centered on said force sensor. 
     
     
         26 . A syringe infusion pump as recited in  claim 25 , wherein said syringe plunger holder comprises:
 a first plunger holder drive member connected to said first plunger holder element; and   a second plunger holder drive member connected to said second plunger holder element, said drive members providing said movement of said first element and said second element.   
     
     
         27 . A syringe infusion pump as recited in  claim 26 , wherein said first and second plunger holder drive members comprise opposite facing, spaced apart gear racks and said plunger holder further comprises a plunger holder gear disposed therebetween and mating therewith. 
     
     
         28 . A syringe infusion pump as recited in  claim 23 , wherein:
 said syringe barrel holder is configured and dimensioned to provide a fixed position for the barrel axis with respect to said force sensor center, said fixed position being independent of size of said barrel for each different diameter syringe barrel; and   said syringe plunger holder engages each said plunger of each different size syringe with said plunger automatically axis aligned with the barrel axis of the syringe that said syringe barrel holder is holding.