Multi-lumen catheter system used in a blood treatment process

Abstract

A catheter system facilitates blood treatments such as apheresis that require simultaneous withdrawal and return of blood to a patient at high flow rates. A multi-lumen catheter has an external coupling device connected to a pump and blood treatment device. All of the lumens are designed to be used in the blood treatment process. The catheter includes two or more lumens for withdrawing blood and a return lumen for returning treated blood. The combined flow resistance of the withdrawal lumens is less than or equal to the flow resistance of the return lumen so that the flow rate of blood through the withdrawal lumens does not require a pressure differential sufficient to collapse the lumens. High flow rates are achievable through the catheter by using a pair of withdrawal lumens instead of a single, large withdrawal lumen. The lumens may be used for general medical use when the catheter system is not being used for exchange treatments. To help reduce mixing of blood between the withdrawal lumens and the return lumens, the catheter has a beveled distal end for angling the distal ends of the withdrawal lumens away from the distal end of the return lumen. A catheter cutting tool is provided for cutting the catheter to a selected length and for providing a precise beveled distal end.

1 . A multi-lumen catheter comprising: 
 a) an elongated cylindrical tube having a distal and a proximal end and a lumen therethrough, said distal end of the tube having a first beveled surface and a second beveled surface angled away from the first beveled surface; and    b) a transverse septum extending from the distal end to the proximal end of the tube within the lumen of the tube and dividing the tube into a withdrawal passageway and a return passageway, the withdrawal passageway open at the first beveled surface at the distal end of the tube, and the return passageway open at the second beveled surface at the distal end of the tube.    
   
   
       2 . A multi-lumen catheter according to  claim 1  comprising a supporting septum extending from the distal end to the proximal end of the tube and dividing the withdrawal passageway into first and second withdrawal lumens.  
   
   
       3 . A multi-lumen catheter according to  claim 2  wherein the supporting septum resists vertical displacement.  
   
   
       4 . A multi-lumen catheter according to  claim 1  wherein the transverse septum includes a non-diametral septum.  
   
   
       5 . A multi-lumen catheter according to  claim 1  wherein the catheter is an indwelling catheter.  
   
   
       6 . A multi-lumen catheter according to  claim 1  comprising a return septum extending from the distal end to the proximal end of the tube and dividing the return passageway into first and second return lumens.  
   
   
       7 . A multi-lumen catheter according to  claim 6  wherein the return septum resists vertical displacement.  
   
   
       8 . A multi-lumen catheter according to  claim 6  wherein the withdrawal lumens have a total cross-sectional area greater than or equal to that of the total cross-sectional area of the return lumens.  
   
   
       9 . A multi-lumen catheter according to  claim 6  wherein the withdrawal lumens have a combined flow resistance less than or equal to the combined flow resistance of the return lumens so that the total flow rate for blood flowing through the withdrawal lumens does not create a pressure differential sufficient to cause the withdrawal lumens to collapse.  
   
   
       10 . A multi-lumen catheter according to  claim 6  wherein the withdrawal lumens have distal ends disposed at the first beveled surface and the return lumens have distal ends disposed at the second beveled surface to reduce the mixing of blood between the return lumens and the withdrawal lumens.  
   
   
       11 . A multi-lumen catheter according to  claim 6  wherein the withdrawal lumens and the return lumens have cross-sectional shapes that are substantially devoid of sharp angles that are less than 90 degrees.  
   
   
       12 . A multi-lumen catheter according to  claim 6  comprising an external flow coupler connecting the withdrawal lumens of the catheter to an external withdrawal tube and connecting the return lumens of the catheter to an external return tube.  
   
   
       13 . A multi-lumen catheter according to  claim 1  wherein the return passageway comprises a single return lumen.  
   
   
       14 . A multi-lumen catheter according to  claim 13  wherein the withdrawal lumens have a total cross-sectional area greater than or equal to that of the return lumen.  
   
   
       15 . A multi-lumen catheter according to  claim 13  wherein the withdrawal lumens have a combined flow resistance less than or equal to the flow resistance of the return lumen so that the total flow rate for blood flowing through the withdrawal lumens does not create a pressure differential sufficient to cause the withdrawal lumens to collapse.