P13: Hemodynamic Study of an Implantable Artificial Kidney Device Using a Computational Model

Study: Gradual loss of kidney function is experienced by patients diagnosed with chronic kidney disease (CKD) and may escalate to a severe condition of end-stage kidney disease. A treatment approach alternative to hemodialysis could be the implantation of an artificial kidney that filters blood using the natural pressure drop in the systemic circulation. This study aims to investigate the hemodynamic performance of several variations of two previously reported implantable artificial kidney device (IAKD) designs using a computational hemodynamic model. Methods: An in-house custom hemodynamic lumped parameter model was developed to analyze the implantation of an IAKD on the combined patient-device hemodynamics. The time-varying hemodynamic model (HM) consisted of all four cardiac chambers, systemic and venous circulations and included the implantation of an IAKD in parallel with the systemic circulation (Figure 1a). Two major IAKD configurations were analyzed: (i) a serpentine configuration (series flow path through the device) and (ii) a parallel configuration (parallel flow path through the device). For each configuration, several variations of the internal device resistance were analyzed to investigate the resulting pressure drop across and flow through the device, in order to investigate the customization of IAKD designs depending on a perceived patient-specific need. Results: We tested 8 variations of the serpentine IAKD and 6 variations of the parallel IAKD. For each case, the virtual patient characteristics were maintained constant (i.e. all cardiac, systemic and pulmonary circulatory parameters) and only the device resistance was varied. Preliminary data indicated that for the serpentine configuration, the flow through the IAKD reduced by over 50% as the resistance was increased, also causing an increase in the pressure drop across the IAKD for each variation (Figure 1b). This behavior was similar for the variations in the parallel configuration (Figure 1c), with an increase in flow up to 35% through the IAKD due to the overall reduced flow resistance of the parallel design in comparison to the serpentine design. Interestingly, as the device resistance was decreased, the patient MAP was reduced by more than 11% due to the shunting of more flow through the IAKD, and thereby less flow available to pass through the systemic circulation – this behavior was seen for both configurations. Conclusions: The HM developed in this study is capable of investigating several clinically-relevant scenarios to tailor an IAKD for patients with renal failure. Our analysis suggests that there is a complex interplay between the patient’s systemic circulatory network and the IAKD, necessitating detailed hemodynamic analysis such as that performed in this study. Depending on the patient’s needs, it is possible to tailor an IAKD, potentially with variable resistance configurations, that can best serve to maintain hemodynamic stability and hemodialysis efficiency.