Importance

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Abstract

Access recirculation in a shunt is determined quantitatively by a method in which a standard solution, such as a saline, is injected into a patient's bloodstream upstream of the shunt. At a point in the access line, a photometric measurement is conducted of the change in hematocrit (.DELTA.H) with respect to time. Electronic circuitry receives signals from the detector and compares the integrated area of .DELTA.H with respect to time of the standard solution initially flowing through the access and of the recirculated solution and provides display of access recirculation. In another aspect, access recirculation and access blood flow are quantitatively determined without injecting a solution into the bloodstream. In this aspect the extent of access recirculation and/or access blood flow is determined quantitatively by a method in which the dialyzer blood flow rate or the ultrafiltration rate (UFR) is changed and the corresponding change in concentration of a blood constituent is measured. In this technique, the concentration of a blood constituent is measured as a function of dialyzer blood flow rate or UFR and electronic circuitry converts these measurements into quantitative determinations of access recirculation and/or access blood flow that can be displayed.

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First Claim