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. 2019 Nov 6;23(1):348.
doi: 10.1186/s13054-019-2622-3.

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

Sascha Gross-Hardt  1 , Felix Hesselmann  1 , Jutta Arens  1 , Ulrich Steinseifer  1 , Leen Vercaemst  2 , Wolfram Windisch  3 , Daniel Brodie  4 , Christian Karagiannidis  5
Affiliations

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

Sascha Gross-Hardt et al. Crit Care. .

Abstract

Background: 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. A better understanding of the risks originating specifically from the rotary blood pump component of the circuit is urgently needed.

Methods: High-resolution computational fluid dynamics was used to calculate the hemodynamics and hemocompatibility of three current rotary blood pumps for various pump flow rates.

Results: The 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.

Conclusions: The 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.

Keywords: ARDS; Centrifugal blood pumps; ECCO2R; ECLS; ECMO.

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Conflict of interest statement

CK received travel grants and lecture fees from Maquet, Rastatt, Germany. WW received fees for advisory board meetings and lectures from Maquet Cardiopulmonary, Rastatt, Germany. CK and WW received an open research grant for the hospital from Maquet Cardiopulmonary, Rastatt, Germany. DB reports serving as the co-chair of the trial steering committee for the VENT-AVOID trial sponsored by ALung Technologies; serving on the medical advisory boards for Baxter, BREETHE, and Hemovent (unpaid); and previously serving on the medical advisory board of ALung Technologies. SGH is half-time employed at enmodes GmbH Aachen. FH, JA, LV, and US declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
a Main (pump flow) and secondary flows and flow paths (top and bottom gap flows) that add up to the impeller flow exemplified using the geometry details of the DP3. b Hydraulic efficiency curves of the three blood pumps under study for two constant impeller speeds to realize the pressure head target of 150 mmHg (lower speed in each case) and 250 mmHg
Fig. 2
Fig. 2
a Device-specific secondary gap flows for the high pressure (250 mmHg) and low flow (0.5 L/min) case. The negative sign indicates flow recirculation. b Recirculation ratio of the three pump systems for a pressure head of 150 and 250 mmHg
Fig. 3
Fig. 3
a Shear stress histograms for the three pump systems for 0.5 L/min, low- and high-pressure head (150 and 250 mmHg). The blood volume of impeller and secondary gaps associated with a certain shear stress interval (x-axis) is plotted (DP3, 9.5 mL; Rotaflow, 18.2 mL; Revolution, 48 mL). The shear stress interval between 0 and 5 Pa contains most of the associated volume and was not shown for an improved view. Figure 4b details the associated volume above 100 Pa. c Volume rendering of shear stresses above 50 Pa illustrating potential hotspots within the pumps
Fig. 4
Fig. 4
a Examples of shear stress profiles along blood streamlines are shown which result from pump flows of 0.5 and 4 L/min. b Three representative streamlines and their exposure to shear stress are shown
Fig. 5
Fig. 5
The numerically derived hemolysis index for pump speeds according to the low- and high-pressure head targets (150 and 250 mmHg) and various pump flows
See this image and copyright information in PMC

References

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