Development of a novel lung and kidney support device – influence of utilizing hemodialysis membranes outside-in on solute clearance and filtration efficiency in full blood
Ana Martins Costa (ET-BE, Engineering Organ Support Technologies Group (EOST), UT), Frank Halfwerk (ET-BE, EOST, UT; Medisch Spectrum Twente, Netherlands), Jan-Niklas Thiel (Department of Cardiovascular Engineering RTWH Aachen University, Germany), Bettina Wiegmann (Hannover Medical School; Implant Research and Development (NIFE); German Center for Lung Research, Germany), Michael Neidlin (Department of Cardiovascular Engineering RTWH Aachen University, Germany), Jutta Arens (ET-BE, EOST, UT) *All authors are part of SPP 2014 project Towards an Implantable Lung, German Research Foundation.
Abstract
Introduction & Objective
A novel artificial lung and kidney assist device (RenOx) that combines gas exchange and hemodialysis fibers is being developed. In a previous study, we evaluated how gas exchange and dialysis fibers could be combined to maintain sufficient lung support. However, this device also needs to provide sufficient kidney support by utilizing dialysis fibers in a new approach with blood flowing outside the fibers (outside-in). Thus, this study evaluated the efficiency of commercial dialyzer fibers utilized outside-in compared to traditional inside-out mode regarding toxins clearance and fluid removal during continuous renal replacement therapy.
Methods
The performance of commercial dialyzers utilized outside-in and inside-out was compared during in-vitro blood tests adapting the ISO8637:2016. Clearance of urea and creatinine was measured during continuous hemodialysis (blood flow = 150 mL/min and dialysate flows = 30 mL/min, 50 mL/min), and continuous hemofiltration (filtration-rate = 20 mL/min). In addition, filtration efficiency was evaluated in terms of ultrafiltration coefficient.
Results
Clearance of urea and creatinine during continuous hemodialysis and hemofiltration was equal between dialyzers utilized outside-in and inside-out, except for tests with higher dialysate flow, where outside-in fibers achieved higher urea clearance. Ultrafiltration coefficient of dialyzers utilized outside-in was 4 times smaller than the one obtained for inside-out dialyzers. However, required fluid removal rates could be achieved by managing system pressures and using dedicated modified fibers.
Conclusions
Our study shows that hemodialyzers utilized outside-in could deliver sufficient clearance during continuous hemodialysis and hemofiltration. We consider this a step towards the development of a new artificial lung and kidney device.