Preliminary Implementation of the Next Generation Cannulation Simulator

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Extracorporeal Membrane Oxygenation (ECMO) is a highly complex/critical lifesaving procedure known to support patients with cardiac and respiratory issues. Patients on ECMO are monitored 24/7 by a team of highly trained ECMO team comprising nurses, physicians, respiratory therapists, and perfusionists promptly intervening to any potential emergency situation. Simulation-Based Training (SBT) allows clinicians to experience and practice realistic hands-on procedures and scenarios without any risk. In ECMO, cannulation is a critical procedure performed to externally reroute the blood flow so it can be re-oxygenated by the ECMO machine before being recirculated through the patient's body. In a close collaboration with Hamad Medical Corporation (HMC), this project aims to develop a cost effective, realistic, and user-friendly ECMO simulator focusing on the venous and arterial cannulation procedure, The main features of this simulator include cannulation emergencies caused by low pressure flow, excessive force, recirculation, or mispositioned wire/cannula. Therefore, the ECMO cannulation simulator will not only greatly contribute to the initial and ongoing local training of HMC ECMO clinicians but also contribute to improving patient care by lowering the risks associated with the cannulation process

Silicon Membranes for Extracorporeal Membrane Oxygenation (ECMO)

In cases of severe lung or heart failure, extracorporeal membrane oxygenation (ECMO) is a life-saving therapy in which a patient’s blood is passed into a circuit outside of their body to provide respiratory support. The circuit’s main component is the membrane oxygenator that drives oxygen into the blood from a sweep gas source and removes excess carbon dioxide from the blood. At present, clinical use of ECMO is limited by its high risk profile, owing to two intertwined risks: thrombosis from the large circuit, and bleeding from the anticoagulation needed to prevent thrombosis. Improvements to the gas exchange efficiency and hemocompatibility of the oxygenator could enable the development of a longer-term supportive ECMO therapy, intended as a bridge-to-transplant or destination therapy for chronic lung failure. Here we describe a novel blood oxygenator concept based on parallel plate silicon membranes developed for high precision geometry, mechanical rigidity, and high efficiency membrane transport. Using these membranes, we create blood oxygenator prototypes consisting of arrays of silicon membranes, and endeavor to improve the efficiency and hemocompatibility of this concept.First, multiple types of silicon membranes were evaluated systematically for mechanical rigidity and oxygen exchange efficiency, indicators of suitability for a future oxygenator. The combination of a silicon micropore membrane (SµM) and a 5 µm-thick polydimethylsiloxane (PDMS) layer maximized both qualities, withstanding over 260 cmHg of applied pressure and producing 0.03 mL/min of O2 flux. These membranes were then assembled into prototype flow cells, and tested for in vitro and in vivo oxygenation, successfully yielding an oxygen permeability of 1.92 ± 1.04 ml O2 STP/min/m2/cmHg. From this benchmark, we then attempted to optimize the surface hemocompatibility of the Si-PDMS composite through application of multiple polyethylene glycol (PEG)-based coatings. Although successful application of PEG to the surfaces was demonstrated, none of the coatings appeared to reduce protein adhesion to the SµM -PDMS membranes. Finally, we inserted turbulence-inducing spacer meshes into the channels of the SµM-PDMS prototypes to disrupt the transport boundary layer adjacent to the membranes, with the goal of substantially improving oxygenation. Though a threefold increase in oxygen flux was observed in vitro with the spacer meshes, the disruptive turbulence resulted in thrombosis and channel occlusion within the channels despite heavy anticoagulation of the blood. In summary, the work in this dissertation demonstrates the successful construction and testing of SµM-PDMS oxygenator prototypes, laying the foundation for future work to optimize this concept and create a large-scale blood oxygenator that can expand the clinical use of this life-saving therapy

On the improvement of alveolar-like microfluidic devices for efficient blood oxygenation

In this work, we study alveolar-like microfluidic devices with a horizontal membrane arrangement that demonstrate a great potential as small-scale blood oxygenator. The design criteria for the fabricated devices were to maximize the oxygen saturation level and minimize liquid chamber volume while ensuring the physiological blood flow in order to avoid thrombus formation and channel blockage during operation. The liquid chamber architecture was iteratively modified upon analysis of the fluid dynamics by computer modelling. Accordingly, two alveolar type architectures were fabricated, Alveolar Design 1 (AD1) and Alveolar Design 2 (AD2), and evaluated for oxygenation of sheep blood. The attained O2 transfer rate at 1 mL/min of blood flow rate for both devices was rather similar: 123 mL·min-1 ·m-2 and 127 mL·min-1 ·m-2 for AD1 and AD2 microfluidic devices, respectively. Among the studied, AD2 type geometry would lead to the lowest pressure drop and shear stress value upon implementation in a scaled microfluidic artificial lung (µAL) to satisfy oxygenation requirements of a 2.0 kg neonate.Government of Aragon and the Education, Audiovisual and Culture Executive Agency (EU-EACEA) within the EUDIME – ‘Erasmus Mundus Doctorate in Membrane Engineering’ program (FPA 2011-0014, SGA 2012-1719, http://eudime.unical.it). CIBER-BBN is an initiative funded by the VI National R&D&i Plan 2008–2011 financed by the Instituto de Salud Carlos III with the assistance of the European Regional Development Fund

Evaluation of Peritoneal Microbubble Oxygenation Therapy in a Rabbit Model of Hypoxemia

Alternative extrapulmonary oxygenation technologies are needed to treat patients suffering from severe hypoxemia refractory to mechanical ventilation. We previously demonstrated that peritoneal microbubble oxygenation (PMO), in which phospholipid-coated oxygen microbubbles (OMBs) are delivered into the peritoneal cavity, can successfully oxygenate rats suffering from a right pneumothorax. This study addressed the need to scale up the procedure to a larger animal with a splanchnic cardiac output similar to humans. Our results show that PMO therapy can double the survival time of rabbits experiencing complete tracheal occlusion from6.6 ± 0.6 min for the saline controls to 12.2 ± 3.0 min for the bolus PMO-treated cohort. Additionally, we designed and tested a new peritoneal delivery system to circulate OMBs through the peritoneal cavity. Circulation achieved a similar survival benefit to bolus delivery under these conditions. Overall, these results support the feasibility of the PMO technology to provide extrapulmonary ventilation for rescue of severely hypoxic patients

Platelets in the Newborn

Platelets were first described in the mid-nineteenth century. Since then, their roles were identified in hemostasis and thrombosis, inflammation, leukocyte interactions, angiogenesis, and cancer growth. But there is little information about such platelet functions in the newborn. Several studies highlighted some platelet differences between newborns and adults. Yet, in spite of these differences, healthy newborns appear to be adequately protected. A number of factors, however, were reported to negatively affect neonatal platelets. These include maternal hypertensive disorders or infections, neonatal asphyxia or respiratory distress, therapies such as ampicillin or indomethacin, and treatment modalities such as ventilators, nitric oxide, or extracorporeal membrane oxygenation (ECMO). Their effects on newborn platelets are usually transitory, lasting from several hours to a few days or weeks. If these effects are well characterized, they could serve as reporters for diagnosis and monitoring during therapy. Careful studies of neonatal platelets are needed to improve the understanding of basic physiology and pathophysiology in this cohort and to identify possible targets for intervention and therapy