Many factors make hemodialysis inefficient, difficult, and expensive. These factors include the complexity of hemodialysis, the safety concerns related to hemodialysis, and the very large amount of dialysate needed for hemodialysis. Moreover, hemodialysis is typically performed in a dialysis center requiring skilled technicians. Therefore any increase in the ease and efficiency of the dialysis process could have an impact on treatment cost or patient outcome.
FIG. 1 is a schematic representation of a hemodialysis system. The system 5 includes two flow paths, a blood flow path 10 and a dialysate flow path 20. Blood is drawn from a patient. A blood flow pump 13 causes the blood to flow around blood flow path 10, drawing the blood from the patient, causing the blood to pass through the dialyzer 14, and returning the blood to the patient. Optionally, the blood may pass through other components, such as a filter and/or an air trap 19, before returning to the patient. In addition, in some cases, anticoagulant may be supplied from an anticoagulant supply 11 via an anticoagulant valve 12.
A dialysate pump 15 draws dialysate from a dialysate supply 16 and causes the dialysate to pass through the dialyzer 14, after which the dialysate can pass through a waste valve 18 and/or return to the dialysate feed via dialysate pump 15. A dialysate valve 17 controls the flow of dialysate from the dialysate supply 16. The dialyzer is constructed such that the blood from the blood flow circuit flows through tiny tubes and the dialysate solution circulates around the outside of the tubes. Therapy is achieved by the passing of waste molecules (e.g., urea, creatinine, etc.) and water from the blood through the walls of the tubes and into the dialysate solution. At the end of treatment, the dialysate solution is discarded.