Influence of utilizing hemodialysis membranes outside-in on solute clearance and filtration efficiency – One step towards a novel combined lung and kidney support device
Ana Martins Costa, Frank R. Halfwerk, Jan‐Niklas Thiel, Bettina Wiegmann, Michael Neidlin, Jutta Arens
Abstract
Many membrane oxygenator patients suffer from renal disfunction. For these patients, a novel device integrating artificial lung and kidney support is being developed. Although outside-in blood flow is standard for membrane oxygenators, this is not typical for hemodialysis systems. The effect of outside-in blood flow on the efficiency of hemodialysis fibers for continuous hemodialysis and hemofiltration is yet unclear. This study evaluates the efficiency of commercial hemodialyzer membranes utilized outside-in compared to traditional inside-out mode regarding clearance of urea and creatinine, and ultrafiltration coefficient during in-vitro tests with porcine blood. Our results showed that dialyzers (1.2 m2, asymmetric hollow fibers) utilized outside-in had similar clearances of urea and creatinine compared to dialyzers used in the traditional mode (p > 0.7). However, outside-in dialyzers had an ultrafiltration coefficient four times lower than dialyzers applied in a conventional way, but adequate fluid removal could be achieved by controlling pressures in the system. This in-vitro study indicates that outside-in fibers could be sufficiently effective to maintain typical continuous renal replacement therapy doses. We regard this as one step towards a novel device with a mixed membrane fiber bundle utilizing blood flow outside both hemodialysis fibers and gas exchange fibers to provide simultaneous lung and kidney support.