Pumping devices, systems and methods for use with medical fluids including compensation for variations in pressure or flow rate

Abstract

A system for delivery of a medical fluid to a patient includes a pump system including a pressurizing unit to pressurize the medical fluid and a drive system in operative connection with the pressurizing unit. The pump system exhibits variation in pressure during operation. The system further includes a compensating system in fluid connection with the medical fluid pressurized by the pressurizing unit. The compensating system defines a displacement volume in fluid connection with the pressurized medical fluid that is altered in a predetermined manner to alter the variation in pressure. The compensating system can, for example, reduce pulsatility of pressure during flow.

What is claimed is: 
     
         1 . A compensating system for reducing variations in pressure of a fluid, comprising:
 a rigid conduit defining a lumen;   a flexible conduit disposed within the lumen of the rigid conduit and defining an inlet adapted to place the flexible conduit in fluid connection with the fluid; and   a compressible fluid entrapped in a volume between the rigid conduit and the flexible conduit.   
     
     
         2 . The compensating system of  claim 1 , wherein the flexible conduit further comprises an outlet, and wherein the flexible conduit is adapted to be placed in line with a flow of the fluid. 
     
     
         3 . The compensating system of  claim 1 , further comprising:
 a first connector configured for connection with an outlet port of a pump system; and   a second connector configured for connection to a fluid delivery set.   
     
     
         4 . The compensating system of  claim 3 , wherein the first connector and the second connector are Luer-type connectors. 
     
     
         5 . The compensating system of  claim 1 , wherein the compressible fluid is a gas. 
     
     
         6 . The compensating system of  claim 1 , wherein the gas is at ambient pressure. 
     
     
         7 . The compensating system of  claim 1 , wherein the compressible fluid is air. 
     
     
         8 . The compensating system of  claim 1 , wherein the compensating system provides a restorative force or biasing force against the variations in pressure of the fluid. 
     
     
         9 . The compensating system of  claim 8 , wherein the restorative force or biasing force causes compression of the flexible conduit in response to a decreased pressure of the fluid in the flexible conduit. 
     
     
         10 . The compensating system of  claim 9 , wherein the restorative force or biasing force increases a flow rate of fluid in the flexible conduit in response to the decreased pressure of the fluid in the flexible conduit. 
     
     
         11 . The compensating system of  claim 8 , wherein the restorative force or biasing force is provided by at least one of a strength or modulus of a material of the flexible conduit, a thickness of a wall of the flexible conduit, a bore of the flexible conduit, and a pressure increase of the compressible fluid entrapped in the volume between the rigid conduit and the flexible conduit. 
     
     
         12 . The compensating system of  claim 1 , wherein an increased fluid pressure in the system expands the flexible conduit and reduces flow rate of the fluid through the flexible conduit. 
     
     
         13 . The compensating system of  claim 12 , wherein a drop in the fluid pressure from the increased fluid pressure causes the restorative force or biasing force to compress the flexible conduit and thereby increase the flow rate of the fluid through the flexible conduit. 
     
     
         14 . A fluid path set for an injector comprising:
 a compensating system for reducing variations in pressure of a fluid, comprising:
 a rigid conduit defining a lumen; 
 a flexible conduit disposed within the lumen of the rigid conduit and defining an inlet adapted to place the flexible conduit in fluid connection with the fluid and an outlet; and 
 a compressible fluid entrapped in a volume between the rigid conduit and the flexible conduit; and 
   a fluid delivery set attached to the outlet of the compensating system to deliver the fluid to a patient.   
     
     
         15 . The fluid path set of  claim 14 , wherein the compressible fluid is a gas. 
     
     
         16 . The fluid path set of  claim 15 , wherein the gas is at ambient pressure. 
     
     
         17 . The fluid path set of  claim 14 , wherein the compensating system provides a restorative force or biasing force against the variations in pressure of the fluid. 
     
     
         18 . The fluid path set of  claim 17 , wherein the restorative force or biasing force is provided by at least one of a strength or modulus of a material of the flexible conduit, a thickness of a wall of the flexible conduit, a bore of the flexible conduit, and a pressure increase of the compressible fluid entrapped in the volume between the rigid conduit and the flexible conduit.