In vivo measurement of blood recirculation during "Y" type single needle dialysis

A method has been described and validated for obtaining a sample of blood, without separate venapuncture, which has the same urea and creatinine composition as systemic venous blood during hemodialysis. Using this technique, recirculation in vivo during "Y" type single needle dialysis, measured in 20 bovine fistulas, ranged from 6.9% to 56.5% and averaged 19.4% of blood flow rate as calculated from blood urea nitrogen; and averaged 22.0% with a range of 3.3% to 62.1% of blood flow rate as calculated from serum creatinine concentration. These results suggest that fistula puncture methods and devices that eliminate recirculation in the ex vivo blood circuit should be used to maximize dialysis efficiency.