Low-flow assessment of current ECMO/ECCO2R rotary blood pumps and the potential effect on hemocompatibility

Sascha Gross-Hardt,Leen Vercaemst,Daniel Brodie,Christian Karagiannidis,Wolfram Windisch,Jutta Arens,Felix Hesselmann,Ulrich Steinseifer

doi:10.1186/s13054-019-2622-3

Abstract

BackgroundExtracorporeal carbon dioxide removal (ECCO2R) uses an extracorporeal circuit to directly remove carbon dioxide from the blood either in lieu of mechanical ventilation or in combination with it. While the potential benefits of the technology are leading to increasing use, there are very real risks associated with it. Several studies demonstrated major bleeding and clotting complications, often associated with hemolysis and poorer outcomes in patients receiving ECCO2R. A better understanding of the risks originating specifically from the rotary blood pump component of the circuit is urgently needed.MethodsHigh-resolution computational fluid dynamics was used to calculate the hemodynamics and hemocompatibility of three current rotary blood pumps for various pump flow rates.ResultsThe hydraulic efficiency dramatically decreases to 5–10% if operating at blood flow rates below 1 L/min, the pump internal flow recirculation rate increases 6–12-fold in these flow ranges, and adverse effects are increased due to multiple exposures to high shear stress. The deleterious consequences include a steep increase in hemolysis and destruction of platelets.ConclusionsThe role of blood pumps in contributing to adverse effects at the lower blood flow rates used during ECCO2R is shown here to be significant. Current rotary blood pumps should be used with caution if operated at blood flow rates below 2 L/min, because of significant and high recirculation, shear stress, and hemolysis. There is a clear and urgent need to design dedicated blood pumps which are optimized for blood flow rates in the range of 0.5–1.5 L/min.

Highlights

Extracorporeal carbon dioxide removal (ECCO2R) uses an extracorporeal circuit to directly remove carbon dioxide from the blood either in lieu of mechanical ventilation or in combination with it
Extracorporeal life support (ECLS), which is comprised of extracorporeal membrane oxygenation (ECMO) and extracorporeal carbon dioxide removal (ECCO2R) [1], is an emerging technology in the field of respiratory medicine used for various indications, including the acute respiratory distress syndrome (ARDS) and acute exacerbations of chronic obstructive pulmonary disease (COPD), or as a bridge to lung transplantation [2,3,4,5,6,7,8]
Additional file 1B demonstrates the typical appearance of clotting within the pump, inducing severe hemolysis as a side effect of the treatment

Summary

Introduction

Extracorporeal carbon dioxide removal (ECCO2R) uses an extracorporeal circuit to directly remove carbon dioxide from the blood either in lieu of mechanical ventilation or in combination with it. While the potential benefits of the technology are leading to increasing use, there are very real risks associated with it. Several studies demonstrated major bleeding and clotting complications, often associated with hemolysis and poorer outcomes in patients receiving ECCO2R. The EOLIA trial demonstrated a survival benefit for patients treated with ECMO compared to standard of care in severe ARDS [9, 10]. Extracorporeal systems have substantial side effects, in particular, bleeding or clotting may occur in many patients. Greater safety has not been established, and recent studies demonstrate increased bleeding complications in patients treated with ECCO2R [5, 11]. ECCO2R systems were developed from renal replacement therapy (RRT) and driven by roller pumps [12,13,14] or from high-flow extracorporeal

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