Mock Circulatory Loop With Autoregulated Renal Circulation Based on Perfusion Pressure for Circulatory Support...

Renal hypoperfusion, driven by reduced mean arterial pressure or increased venous congestion, contributes to acute kidney injury in cardiogenic shock. Assessing cardiovascular support strategies for patients with cardiogenic shock requires controlled platforms such as mock circulatory loops (MCLs). However, most MCLs lack renal autoregulation or do not account for venous pressure, risking inaccurate renal flow estimation. Here, we describe how to implement a perfusion pressure-based autoregulated renal circulation within an MCL.

A renal circulation was integrated into an existing biventricular MCL. Renal vascular resistance was dynamically adjusted according to a perfusion pressure-renal flow relationship. Autoregulation performance was quantified by mean square error between measured and theoretical renal flow. Left, right, and biventricular cardiogenic shock were simulated. Extracorporeal Membrane Oxygenation (ECMO) support and fluid doses were used as clinically relevant interventions to modify the arterial and venous determinants of perfusion pressure.

Renal autoregulation closely reproduced the target relationship, with mean square error 0.001 (L/min)². Increasing ECMO flow increased perfusion pressure through higher mean arterial pressure (MAP) and lower mean right atrial pressure (MRAP) across all ventricular failure phenotypes. Conversely, fluid doses increased both MAP and MRAP, with the magnitude of MRAP elevation varying by ventricular failure phenotype and partially offsetting the increase in MAP, resulting in smaller increases in perfusion pressure. Renal flow responses reflected perfusion pressure rather than arterial pressure alone.

Renal flow-perfusion pressure autoregulation can be accurately implemented in an MCL. Incorporating such renal autoregulation improves physiological fidelity of MCLs and evaluation of cardiovascular devices.