Validation and Testing of Sorbents for Renal Replacement Therapy (RRT) following Combat Injuries

Renal failure is significant adverse event of combat injury that increases mortality rate present in over 50% of wound related deaths. Renal replacement therapy (RRT) greatly reduces the mortality rate (> 90%). The current hemodialysis systems provide reasonable control over serum potassium levels but also require the use of large volumes of dialysate solution in a membrane contactor to replicate the function of the kidney. Hence, these devices are poorly suited for prolonged field care as they require specially trained personnel, bulky equipment that weighs ~70 lbs, and use large volumes of sterile dialysate solution. TDA research developed a compact, single-person portable, ruggedized, battery-operated, advanced filtration system for serum potassium (a bridge dialysis system) that can be used in the post traumatic care of combat casualties suffering from hyperkalemia; providing prolonged care before a patient arrives at a facility where appropriate RRT can be provided. TDA‘s bridge dialysis system uses an advanced sorbent that will remove only potassium (K + ) ions from blood via highly adsorption process. This allows minimization (regeneration and re-use) or even elimination of the use of dialysate solution. UAB in collaboration with TDA has been actively involved with testing the efficiency, efficacy, and potential biotoxicity of TDA sorbents. In this paper, we detail extensive characterization of the various formulations of the TDA sorbent to estimate, potassium removal rate, selectivity for potassium over other metabolites and ions and preliminary biotoxicity evaluation of the sorbent using cell culture models. Our results demonstrate that the sorbent is indeed capable of efficient removal of potassium, is highly selective for potassium and is non-toxic to microvascular endothelial cells as evaluated using both direct contact and with medium conditioned with the sorbent. While more rigorous characterization and evaluation needs to be performed, preliminary studies confirm that Z-4 formulation TDA sorbent has great potential for RRT following combat injuries.