Apparatus and method for in-vivo plasmapheresis using periodic backflush

Abstract

Apparatus and method for in-vivo plasmapheresis utilizing a plurality of elongated hollow microporous filter fibers periodically interrupt diffusion of blood plasma from a patient, and, for a selected time, backflush fluid into the fibers at a pressure and interval sufficient to cleanse the fiber pores, after which plasma diffusion is resumed. The backflush fluid, preferably a normal saline solution, may contain an anticoagulant such as heparin in suitable concentration for systemic anti-coagulation or for treating the fiber for thromboresistance.

What is claimed is:  
     
         1 . A method of carrying out human in-vivo plasmapheresis comprising: 
 implanting a filter device within a blood vessel of a patient, said filter device comprising a plurality of elongated hollow microporous fibers;    providing a multiple lumen catheter in fluid communication with the hollow interior of said fibers, and diffusing plasma and toxins from the patient's blood through the wall of said fibers into the hollow interior thereof; and    periodically interrupting said diffusion of plasma and toxins and backflushing said fibers by directing a backflush fluid containing an amount of anticoagulant at least sufficient to provide fiber thromboresistance through a lumen of said catheter into said fibers at a pressure and for an interval sufficient to substantially cleanse the pores of said filter, and after said interval, resuming said diffusion of plasma.    
     
     
         2 . A method of  claim 1  using a backflush fluid comprising a saline solution containing at least 1 IU heparin per kilogram of human patient body weight.  
     
     
         3 . A method of  claim 1  using a backflush fluid comprising saline solution containing about 2 or more IU per kilogram of human patient body weight.  
     
     
         4 . A method of  claim 1  using a backflush fluid comprising saline solution having a heparin concentration of between about 25 IU per ml and about 300 IU per ml.  
     
     
         5 . A method of  claim 1  using a backflush fluid comprising saline solution having a heparin concentration of between about 75 IU per ml and about 150 IU per ml.  
     
     
         6 . A method of  claim 1 ,  2 ,  3 ,  4  or  5  wherein the fluid is backflushed at a pressure of between about 15 and about 100 mg Hg for an interval of between about 5 and about 50 seconds.  
     
     
         7 . A method of  claim 4  wherein heparin concentration is sufficient to provide systemic anti-coagulation in a human patient.  
     
     
         8 . A method of  claim 1  for inducing systemic anti-coagulation comprising using a single bolus of backflush fluid containing between about 50 IU and about 150 IU heparin per kilogram of patient body weight.  
     
     
         9 . A method of  claim 1  for maintaining systemic anti-coagulation comprising using a backflush fluid containing more than about 150 IU heparin per ml and less than about 50 IU per kilogram of patient body weight.  
     
     
         10 . A method of  claim 1  wherein toxin-containing plasma from said fibers is directed to plasma treatment apparatus through a second lumen of said catheter.  
     
     
         11 . A method of  claim 1  wherein plasma from plasma treatment apparatus is directed to a third lumen of said catheter and returned to said patient.  
     
     
         12 . A method of  claim 6  wherein plasma from plasma treatment apparatus is directed to a third lumen of said catheter and returned to said patient.  
     
     
         13 . A method of  claim 6  wherein plasma from plasma treatment apparatus is directed to a third lumen of said catheter and returned to said patient.