Development of a Miniaturized Heart-Lung Machine for Neonates With Congenital Heart Defect

Abstract

Predominantly, standard adult heart lung machines are used for pediatric cardiac surgery, only with individually downsized components. Downsizing is limited, e.g., by the required gas exchange surface. To diminish complications, we developed a new miniaturized heart lung machine (MiniHLM) for neonates, with significantly reduced priming volume and blood contact surface by integration of all major system components in one single device. In particular, a rotary blood pump is centrically integrated into the oxygenator and the cardiotomy reservoir with integrated heat exchanger is directly connected. Thus, tubing is only necessary between patient and MiniHLM. A total priming volume of 102 ml could be achieved for the entire extracorporeal circuit (including arterial/venous line), in contrast to the currently smallest device on the market with 213 ml. In first animal experiments with female New Zealand rabbits, the MiniHLM guaranteed both a sufficient gas exchange and an adequate blood flow; 12 rabbits could successfully be weaned off after 1 hour of aortic clamp time. The first in vitro and in vivo tests confirm the concept of the MiniHLM. Its low priming volume and blood contact surface may significantly reduce complications during heart surgery in neonates.

Fast-tracking in pediatric cardiac surgery - The current standing

“…Efforts should be made to reduce the inflammatory response typically seen with long CPB times and circulatory arrest. Various ultrafiltration techniques are already being used frequently, [34][35][36] and newer developments such as low priming volume CPB circuits for infants and small children, [37,38] and the use of hypertonic solutions, [39,40] are promising strategies to decrease blood transfusion requirements, extravascular lung water, and positive fluid balance, all of which can influence the fasttracking. A detailed discussion about the pros and cons of these techniques is beyond the scope of this review.…”

Darcy Permeability of Hollow Fiber Membrane Bundles Made from Membrana Polymethylpentene Fibers Used in Respiratory Assist Devices

“…1–5 Computational fluid dynamics (CFD) is often used as a tool to design these devices. 6–11 Modeling the flow at the fiber level of the bundle can be computationally difficult as the bundles are composed of thousands of individual fibers. Instead modeling approaches typically treat the fiber bundle as a packed bed or porous medium in which the effect of local fluid drag from the individual fibers is incorporated using a Darcy permeability coefficient for the fiber bundle.…”

“…Instead modeling approaches typically treat the fiber bundle as a packed bed or porous medium in which the effect of local fluid drag from the individual fibers is incorporated using a Darcy permeability coefficient for the fiber bundle. 11–14 The Darcy permeability, k , is estimated using the empirical Blake – Kozeny equation: $$k=\frac{1}{150}\frac{{\epsilon }^3{D}_p^2}{{(1-\epsilon )}^2}$$ in which ε is the bundle porosity and $D_p^2$ is the effective fiber diameter. 15 …”

In Vitro Performance Testing of a Pediatric Oxygenator With an Integrated Pulsatile Pump

“…6 Up to July 2008, 35,050 recorded ECMO cases were associated with patients under the age of 18 years. 9,11,[14][15][16][17][18] This research group investigates a novel approach to pump integration by using collapsing and expanding silicone tubes placed in a fiber bundle in combination with active valves. 2 Currently, different approaches are followed to improve the devices of extracorporeal circuits.…”