Original article submission: Platelet stress accumulation analysis to predict thrombogenicity of an artificial kidney

Abstract

An implantable artificial kidney using a hemofilter constructed from an array of silicon membranes to provide ultrafiltration requires a suitable blood flow path to ensure stable operation in vivo. Two types of flow paths distributing blood to the array of membranes were evaluated: parallel and serpentine. Computational fluid dynamics (CFD) simulations were used to guide the development of the blood flow paths. Pressure data from animal tests were used to obtain pulsatile flow conditions imposed in the transient simulations. A key consideration for stable operation in vivo is limiting platelet stress accumulation to avoid platelet activation and thrombus formation. Platelet stress exposure was evaluated by CFD particle tracking methods through the devices to provide distributions of platelet stress accumulation. The distributions of stress accumulation over the duration of a platelet lifetime for each device revealed that stress accumulation for the serpentine flow path exceeded levels expected to cause platelet activation while the accumulated stress for the parallel flow path was below expected activation levels.

A Rigid Parallel-Plate Artificial Placenta Oxygenator with a Hemocompatible Blood Flow Path

“…The peak shear stress was 6.3 Pa, well below the number needed to induce red blood cell hemolysis (100 Pa) 13 . Previous literature has demonstrated the role of cumulative shear stress in causing platelet activation and subsequent thrombosis [14][15][16] . A linear stress accumulation model was created to simulate an average platelet undergoing 3000 passes through the device.…”

Advances in extracorporeal membrane oxygenator design for artificial placenta technology

“…The composite membranes offer the advantage of providing a rigid, yet, thin structure that can be readily stacked into a parallel plate configuration. Importantly, the parallel plate design allows optimization of the blood flow path to minimize shear stresses and stagnancy 140 . In addition, these composite membranes feature an ultrathin gas‐permeable PDMS membrane, only 5 µm thick, an order of magnitude thinner than the steel mesh composite membranes described above.…”

“…Importantly, the parallel plate design allows optimization of the blood flow path to minimize shear stresses and stagnancy. 140 In addition, these composite membranes feature an ultrathin gas-permeable PDMS membrane, only 5 µm thick, an order of magnitude thinner than the steel mesh composite membranes described above. When tested in water, individual membranes with a gas exchange surface area of 0.89 cm 2 exhibit a high gas permeability, demonstrating 0.03 mL/min of oxygen flux.…”

Ambulatory Hemodialysis-Technology Landscape and Potential for Patient-Centered Treatment

“…The hemofiltration unit is constructed from biocompatible silicon nanopore membranes, which exhibit high flux and high selectivity such that cardiac perfusion pressure is sufficient enough to drive blood flow without need for battery or electrical power. Various components of the implantable artificial kidney are being evaluated via a series of preclinical studies (18,(49)(50)(51)(52)(53). Membranes configured in a parallel-plate hemofilter format were implanted in six dogs that received only antithrombotic therapy (acetylsalicylic acid) (18).…”