R27 - Smart Blood Pump Console Design for Extracorporeal Membrane Oxygenation Technology Development

Introduction: : Extracorporeal membrane oxygenation (ECMO) is a mechanical circulatory support treatment for lung or heart failure. ECMO is rapidly growing as a life support therapy: the last five years make up nearly half of all ECMO-runs reported since 1989. Given the exponential increase in ECMO cases, there is a dire need to innovate ECMO technology. ECMO provides support by pumping venous blood through a membrane oxygenator and returning oxygen-rich blood back to the patient. Clinical ECMO blood pump consoles are well-established, but difficult for researchers to use due to high cost and level of security. Clinical systems use centrifugal pumps coupled to magnetic discs, completely enclosed within bio-consoles. This inhibits cross-compatibility between consoles and multiple pump heads, and the ability to control pump performance flexibly. These barriers hinder researchers from customizing blood pump consoles for their investigational needs, preventing advancements in ECMO technology.
Previously, our group presented a low-cost, open-access ECMO pump console. Despite favorable performance, the fit was only adequate with one clinical pump head and required laser-cut parts for assembly. Here we present the second version to universalize and increase ease of manufacturability of the console. The new version is customizable to accommodate different pump heads –Rotaflow, Quantum, and Affinity. This console can be assembled using off-the-shelf parts and doesn’t require advanced equipment to assemble. The pump console can be Arduino-programmed to customize circuit waveform. Here, a pulsatile flow and pressure profile are demonstrated to better resemble physiological arterial waveforms.

Materials and

Methods: : Our design uses aluminum T-slot framing rails (McMaster-Carr), a DC motor (XD-3420, Amazon), and a magnetic coupling disc (9199T, McMaster-Carr) for versatility and easy accessibility (Fig. 1). The motor is directly programmable with an Arduino and motor driver. Three types of centrifugal blood pumps were evaluated: Rotaflow Centrifugal Pump (Getinge), Quantum Centrifugal Pump (Spectrum), and Affinity Centrifugal pump (Medtronic). The magnet and the pump head were optimized for maximal magnetic coupling by adjusting the distance between the two. Our pump console allows for three-dimensional adjustment of this configuration (Fig. 1). Ideal magnetic coupling was attained when the highest circuit pressures and flows are achieved.
To assess hydraulic performance, a 40% glycerol solution designed to mimic blood viscosity was pumped through a benchtop circuit. The closed-loop circuit consisted of 3/8” medical tubing, the custom pump console, and a Hoffman clamp to modulate circuit resistance. The pump motor input voltage was set from 6-16 V, and circuit flow was then decreased in increments of 0.5 L/min using the Hoffman clamp until zero flow was reached. Pressure-flow (HQ) curves were computed, aiming to meet clinical ECMO operating conditions of > 4 L/min circuit flow and > 250 mmHg pressure head. A pulsatile wave profile to mimic arterial blood waveform was achieved by providing summation of two sinusoidal voltage signals to the motor through pulse width modulation (frequencies of 1 and 2 Hz) with the Rotaflow pump head.

Results, Conclusions, and Discussions:: Pressure-Flow Curves (Fig. 2). The Affinity pump was able to achieve pressures between 48-386 mmHg and circuit flow up to 6.6 L/min when tested at a range of input motor voltage 6-13 V (N=2). The Quantum pump was able to achieve pressures between 22-429 mmHg and circuit flow up to 7.1 L/min when tested at a range of input motor voltages 6-16 V (N=2). The Rotaflow pump was able to achieve pressures between 36-420 mmHg and circuit flows up to 7.2 L/min at a range of input motor voltages 6-15V (N=1). All 3 tested pump heads met the clinically relevant levels of flow and pressure for veno-arterial ECMO applications at >250 mmHg and >4 L/min. This range was acquired at a motor input voltage of 12V, 14V, and 14V for the Affinity, Quantum, and Rotaflow pumps respectively. Pulsatility (Fig. 3). Representative waveforms demonstrate 3000-3500 RPM, 170 and 230 mmHg, and 3.5 and 4 L/min (Figure 3). The dicrotic notch, characteristic of an arterial waveform, is identifiable in motor RPM, pressure head generated, and circuit flow. Conclusions. We demonstrate the robustness and versatility of our custom pump console’s functionality for 3 clinically relevant pump heads at ECMO operating conditions. We also illustrate the customizability of the pressure and flow waveforms to mimic an arterial profile. This demonstrates how our pump console allows for research investigation into improving ECMO technology. Future work in further development of this console includes making the design and hardware more portable to promote ambulation during treatment, and using the platform to test and develop a closed-loop blood pump controller.

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