An in vitro comparison of recirculation in "Y" flow and coaxial flow single needle dialysis systems

A conventional "Y" type and a new coaxial dual-flow single needle dialysis blood access device have been compared with regard to blood recirculation in an in vitro model. The new coaxial flow design eliminates all sources of within needle recirculation, and effectively minimizes within fistula recirculation except at very low fistular flow rates. The striking recirculation resulting from countercurrent, placement of either needle in the fistula documents the critical importance of needle insertion concurrent with fistula flow. This in vitro study indicates significant advantage of the coaxial dual-flow single needle over the conventional "Y" type needle with respect to blood recirculation.