Multi-stage fluid delivery device and method

Abstract

A fluid delivery device for delivering a substance to a patient by way of infusion delivers the preparation at a rate of flow which varies in steps from a substantially constant higher rate, to a stepped-down substantially constant lower rate or rates. The delivery device includes one or more reservoirs, and one or more Belleville springs for applying generally constant pressures to the substance contained in the reservoirs. Each reservoir will have a different constant pressure applied in a mid-range of operation. The reservoirs can be interconnected to each other and to an infusion device in a number of arrangements, including various manifolds and flow restrictors, such that the rate of flow is controlled in steps in accordance with the pressures applied by the springs of the plurality of reservoirs.

1 . A fluid delivery device to deliver a substance to a patient at a stepped decreasing delivery rate comprising: 
 a reservoir system having at least first and second reservoirs, adapted to apply at least one substantially constant first pressure to a fluid contained in said reservoir system throughout at least one first mid-range of operation to provide a fluid flow;    said reservoir system further adapted to apply at least one substantially constant second pressure to a fluid contained in said reservoir system throughout at least one second mid-range of operation to provide a fluid flow, wherein said second pressure is less than or equal to said first pressure wherein at least a first spring positioned adjacent to said first reservoir to apply pressure to said first reservoir and in response, said first reservoir applying said first pressure to said fluid;    at least a second spring positioned adjacent to said second reservoir to apply pressure to said second reservoir and in response, said second reservoir applying said second pressure to said fluid;    said reservoir system further adapted to apply said first pressure and thereafter said second pressure as fluid flows from said reservoir system, said second pressure applied as a stepped decrease in applied pressure from said first pressure;    an infusion device; and    a fluid connection for communicating said fluid flow from said reservoir system to said infusion device.    
   
   
       2 . A fluid delivery device as recited in  claim 1  wherein: 
 said first spring applies a decreasing pressure as said first spring contracts below said first mid-range of operation; and    said second spring applies a decreasing pressure as said second spring contracts below said second mid-range of operation.    
   
   
       3 . A fluid delivery device as recited in  claim 1  wherein: 
 said first spring provides said first mid-range of operation while maintaining said first substantially constant pressure on said first reservoir, and provides said fluid flow from said reservoir system at said first substantially constant rate; and    said first substantially constant pressure prevents said second spring from contracting into said second mid-range of operation.    
   
   
       4 . A fluid delivery device as recited in  claim 1  wherein: 
 said first spring applies said decreasing pressure as said first spring contracts below said first mid-range of operation and allows said second spring to contract into said second mid-range of operation; and    said second spring provides said second mid-range of operation while maintaining said second substantially constant pressure on said second reservoir, and provides said fluid flow from said reservoir system at said second substantially constant rate, wherein said second substantially constant rate is lower than or equal to said first substantially constant rate.    
   
   
       5 . A fluid delivery device as recited in  claim 1  wherein: 
 said fluid connection comprises at least one series connection between an outlet of said first reservoir and an inlet of said second reservoir; and    said fluid connection further comprises a series connection between an outlet of said second reservoir and said infusion device, said outlet of said second reservoir being separate from said inlet of said second reservoir.    
   
   
       6 . A fluid delivery device to deliver a substance to a patient at a stepped decreasing delivery rate comprising: 
 at least first and second reservoirs;    at least first and second springs having at least a mid-range of operation and being positioned adjacent to said first and second reservoirs respectively;    at least one infusion device;    a fluid communication path including said first and second reservoirs, and said at least one infusion device; and    at least one flow restrictor in said fluid communication path.    
   
   
       7 . A fluid delivery device as claimed in  claim 6  wherein said first and second reservoirs are in parallel in said fluid communication path.  
   
   
       8 . A fluid delivery device as claimed in  claim 6  wherein said first and second reservoirs are in series in said fluid communication path.  
   
   
       9 . A fluid delivery device as claimed in  claim 6  wherein at least one reservoir and at least one flow restrictor are in series in said fluid communication path, and at least two reservoirs are in parallel in said fluid communication path.  
   
   
       10 . A fluid delivery device as claimed in  claim 6  wherein: 
 a fluid flow is provided by said first and second reservoirs at a first substantially constant flow rate when said first spring is in said first mid-range of operation; and    a fluid flow is provided by said first and second reservoirs at a second substantially constant flow rate when said second spring is in said second mid-range of operation, wherein said second flow rate is less than or equal to said first flow rate.    
   
   
       11 . A fluid delivery device to deliver a substance to a patient at a stepped decreasing delivery rate comprising: 
 first and second reservoirs having at least one common reservoir wall, wherein said first reservoir is disposed on a first surface of said common reservoir wall and said second reservoir disposed on a second surface of said common reservoir wall;    at least first and second springs having at least a mid-range of operation and being positioned adjacent to said first and second reservoirs respectively;    a fluid communication path including said reservoirs and at least one infusion device; and    a flow restrictor in said fluid communication path.    
   
   
       12 . A fluid delivery device as claimed in  claim 11  further comprising a fill port within said common reservoir wall and accessing said first and second reservoirs.  
   
   
       13 . A fluid delivery device as claimed in  claim 11  further comprising an outlet port within said common reservoir wall and accessing at least one of said first and second reservoirs.  
   
   
       14 . A fluid delivery device as claimed in  claim 11  wherein: 
 a fluid flow is provided by said first and second reservoirs at a first substantially constant flow rate when said first spring is in said first mid-range of operation; and    a fluid flow is provided by said first and second reservoirs at a second substantially constant flow rate when said second spring is in said second mid-range of operation, wherein said second flow rate is less than or equal to said first flow rate.    
   
   
       15 . A method for infusing a fluid at a stepped decreasing delivery rate comprising: 
 applying at least one substantially constant first pressure to a fluid contained in a reservoir system having first and second reservoirs to provide a fluid flow;    applying at least one substantially constant second pressure to a fluid contained in said reservoir system to continue said fluid flow at a reduced rate, wherein said second pressure is less than or equal to said first pressure and is applied as a stepped decrease in applied pressure from said first pressure; and    directing said fluid flow to an infusion device.    
   
   
       16 . A method for infusing a fluid as claimed in claim  32  wherein said first and second reservoirs are connected in parallel.  
   
   
       17 . A method for infusing a fluid as claimed in claim  32  wherein said first and second reservoirs are connected in series.