Method and device for measuring access flow

摘要

An arterial needle removes blood from the access to an extracorporeal circuit comprising a dialyzer and a venous needle returns the blood to the access site. Blood passes along one side of the membrane of the dialyzer and dialysis fluid along the other side. The concentration (Cd norm and Cd rev) of urea in the dialysate emitted from the dialyzer is measured with the needles in the normal position and in a reversed position. The access flow rate before the arterial needle is calculated according to the formula:in which Keff is the effective clearance of the dialyzer and Qa is the access flow rate.