Double fiber bundle dialyzer

Abstract

A dialyzer composed of: first and second dialyzation chambers, and an intermediate chamber interposed between the first and second dialyzation chambers. Each dialyzation chamber has opposed first and second ends and contains a filter member that separates the chamber into a blood compartment and a dialysate compartment. Each of the compartments extends between first and second ends. Each of the chambers has a respective one of a blood inlet or outlet and a dialysate inlet or outlet arranged so that blood and dialysate flow in counter-current to one another in both chambers. The intermediate chamber is connected to form a dialysate-free blood flow passage between the blood compartments.

What is claimed is: 
     
         1 . A dialyzer comprising:
 first and second dialyzation chambers, and an intermediate chamber interposed between said first and second dialyzation chambers, wherein, each of said dialyzation chambers has opposed first and second ends;   each of said dialyzation chambers contains a filter member that separates said dialyzation chamber into a blood compartment and a dialysate compartment, each of said compartments extending between said first and second ends;   said filter member in said first dialyzation chamber is made of a filter material for filtering out plasma water from blood;   said filter member in said second dialyzation chamber is made of a filter material for passing dialysate from said dialysate compartment to said blood compartment;   said first dialyzation chamber has, at said first end thereof, a blood inlet communicating with said blood compartment and a dialysate outlet communicating with said dialysate compartment;   said second dialyzation chamber has, at said first end thereof, a blood outlet communicating with said blood compartment and a dialysate inlet communicating with said dialysate compartment;
 said intermediate chamber extends between said second end of said first dialyzation chamber and said second end of said second dialyzation chamber and communicates only with said blood compartments during operation of said dialyzer to perform blood dialysis; 
 said blood and dialysate inlets and outlets are located to produce dialysate flows in counter-current to blood flows in both of said dialyzation chambers; and 
 said first and second dialyzation chambers are constructed to provide a dialysate flow path between said dialysate compartments at said second ends of said chambers, said dialysate flow path forming a constricted passage for dialysate that produces a dialysate pressure drop between said second dialyzation chamber and said first dialyzation chamber, wherein said constricted passage is dimensioned such that, during operation of said dialyzer, the dialysate pressure drop between said second dialyzation chamber and said first dialyzation chamber causes plasma water to be removed from blood in said blood compartment of said first dialyzation chamber and causes dialysate to be filtered from said dialysate compartment into said blood compartment of said second dialyzation chamber. 
   
     
     
         2 . The dialyzer of  claim 1 , wherein each said filter member is composed of a fiber membrane bundle having a fiber membrane surface area, and the fiber membrane surface area of said filter in said first dialyzation chamber is different from the fiber membrane surface area of said filter in said second dialyzation chamber. 
     
     
         3 . The dialyzer of  claim 2 , wherein each said filter member has a fiber membrane surface area of 0.9 m 2  to 1.8 m 2 . 
     
     
         4 . The dialyzer of  claim 1 , wherein each said filter member is composed of a fiber bundle having a coefficient of ultrafiltration (Kuf) of 20-26 ml/h/(mmHg transmembrane pressure).