NeonatOx: A Pumpless Extracorporeal Lung Support for Premature Neonates

Scaled-up Microfluidic Lung Assist Device for Artificial Placenta Application with High Gas Exchange Capacity

Premature neonates with underdeveloped lungs experience respiratory issues and need respiratory support, such as mechanical ventilation or extracorporeal membrane oxygenation (ECMO). The "artificial placenta" (AP) is a noninvasive approach that supports their lungs and reduces respiratory distress, using a pumpless oxygenator connected to the systemic circulation, and can address some of the morbidity issues associated with ECMO. Over the past decade, microfluidic blood oxygenators have garnered significant interest for their ability to mimic physiological conditions and incorporate innovative biomimetic designs. Achieving sufficient gas transfer at a low enough pressure drop for a pumpless operation without requiring a large volume of blood to prime such an oxygenator has been the main challenge with microfluidic lung assist devices (LAD). In this study, we improved the gas exchange capacity of our microfluidic-based artificial placenta-type LAD while reducing its priming volume by using a modified fabrication process that can accommodate large-area thin film microfluidic blood oxygenator (MBO) fabrication with a very high gas exchange surface. Additionally, we demonstrate the effectiveness of a LAD assembled by using these scaled-up MBOs. The LAD based on our artificial placenta concept effectively increases oxygen saturation levels by 30% at a flow rate of 40 mL/min and a pressure drop of 23 mmHg in room air, which is sufficient to support partial oxygenation for 1 kg preterm neonates in respiratory distress. When the gas ambient environment was changed to pure oxygen at atmospheric pressure, the LAD would be able to support premature neonates weighing up to 2 kg. Furthermore, our experiments reveal that the LAD can handle high blood flow rates of up to 150 mL/min and increase oxygen saturation levels by ∼20%, which is equal to an oxygen transfer of 7.48 mL/min in an enriched oxygen environment and among the highest for microfluidic AP type devices. Such performance makes this LAD suitable for providing essential support to 1-2 kg neonates in respiratory distress.

Impact of the Addition of a Centrifugal Pump in a Preterm Miniature Pig Model of the Artificial Placenta

The recent demonstration of normal development of preterm sheep in an artificial extrauterine environment has renewed interest in artificial placenta (AP) systems as a potential treatment strategy for extremely preterm human infants. However, the feasibility of translating this technology to the human preterm infant remains unknown. Here we report the support of 13 preterm fetal pigs delivered at 102 ± 4 days (d) gestation, weighing 616 ± 139 g with a circuit consisting of an oxygenator and a centrifugal pump, comparing these results with our previously reported pumpless circuit (n = 12; 98 ± 4 days; 743 ± 350 g). The umbilical vessels were cannulated, and fetuses were supported for 46.4 ± 46.8 h using the pumped AP versus 11 ± 13 h on the pumpless AP circuit. Upon initiation of AP support on the pumped system, we observed supraphysiologic circuit flows, tachycardia, and hypertension, while animals maintained on a pumpless AP circuit exhibited subphysiologic flows. On the pumped AP circuit, there was a progressive decline in umbilical vein (UV) flow and oxygen delivery. We conclude that the addition of a centrifugal pump to the AP circuit improves survival of preterm pigs by augmenting UV flow through the reduction of right ventricular afterload. However, we continued to observe the development of heart failure within a matter of days.

Interprofessional Consensus Regarding Design Requirements for Liquid-Based Perinatal Life Support (PLS) Technology

Liquid-based perinatal life support (PLS) technology will probably be applied in a first-in-human study within the next decade. Research and development of PLS technology should not only address technical issues, but also consider socio-ethical and legal aspects, its application area, and the corresponding design implications. This paper represents the consensus opinion of a group of healthcare professionals, designers, ethicists, researchers and patient representatives, who have expertise in tertiary obstetric and neonatal care, bio-ethics, experimental perinatal animal models for physiologic research, biomedical modeling, monitoring, and design. The aim of this paper is to provide a framework for research and development of PLS technology. These requirements are considering the possible respective user perspectives, with the aim to co-create a PLS system that facilitates physiological growth and development for extremely preterm born infants.

In-Vitro Visualization of Thrombus Growth in Artificial Lungs Using Real-Time X-Ray Imaging: A Feasibility Study

PURPOSE

Extracorporeal membrane oxygenation has gained increasing attention in the treatment of patients with acute and chronic cardiopulmonary and respiratory failure. However, clotting within the oxygenators or other components of the extracorporeal circuit remains a major complication that necessitates at least a device exchange and bears risks of adverse events for the patients. In order to better predict thrombus growth within oxygenators, we present an approach for in-vitro visualization of thrombus growth using real-time X-ray imaging.

METHODS

An in-vitro test setup was developed using low-dose anticoagulated ovine blood and allowing for thrombus growth within 4 h. The setup was installed in a custom-made X-ray setup that uses phase-contrast for imaging, thus providing enhanced soft-tissue contrast, which improves the differentiation between blood and potential thrombus growth. During experimentation, blood samples were drawn for the analysis of blood count, activated partial thromboplastin time and activated clotting time. Additionally, pressure and flow data was monitored and a full 360° X-ray scan was performed every 15 min.

RESULTS

Thrombus formation indicated by a pressure drop and changing blood parameters was monitored in all three test devices. Red and white thrombi (higher/lower attenuation, respectively) were successfully segmented in one set of X-ray images.

CONCLUSION

We showed the feasibility of a new in-vitro method for real-time thrombus growth visualization by means of phase contrast X-ray imaging. In addition, with more blood parameters that are clinically relevant, this approach might contribute to improved oxygenator exchange protocols in the clinical routine.

Achieving sustained extrauterine life: Challenges of an artificial placenta in fetal pigs as a model of the preterm human fetus

Artificial placenta (AP) technology aims to maintain fetal circulation, while promoting the physiologic development of organs. Recent reports of experiments performed in sheep indicate the intrauterine environment can be recreated through the cannulation of umbilical vessels, replacement of the placenta with a low-resistance membrane oxygenator, and incubation of the fetus in fluid. However, it remains to be seen whether animal fetuses similar in size to the extremely preterm human infant that have been proposed as a potential target for this technology can be supported in this way. Preterm Yucatan miniature piglets are similar in size to extremely preterm human infants and share similar umbilical cord anatomy, raising the possibility to serve as a good model to investigate the AP. To characterize fetal cardiovascular physiology, the carotid artery (n = 24) was cannulated in utero and umbilical vein (UV) and umbilical artery were sampled. Fetal UV flow was measured by MRI (n = 16). Piglets were delivered at 98 ± 4 days gestation (term = 115 days), cannulated, and supported on the AP (n = 12) for 684 ± 228 min (range 195-3077 min). UV flow was subphysiologic (p = .002), while heart rate was elevated on the AP compared with in utero controls (p = .0007). We observed an inverse relationship between heart rate and UV flow (r2  = .4527; p < .001) with progressive right ventricular enlargement that was associated with reduced contractility and ultimately hydrops and circulatory collapse. We attribute this to excessive afterload imposed by supraphysiologic circuit resistance and augmented sympathetic activity. We conclude that short-term support of the preterm piglet on the AP is feasible, although we have not been able to attain normal fetal physiology. In the future, we propose to investigate the feasibility of an AP circuit that incorporates a centrifugal pump in our miniature pig model.

Advances in extracorporeal membrane oxygenator design for artificial placenta technology

Extreme prematurity, defined as a gestational age of fewer than 28 weeks, is a significant health problem worldwide. It carries a high burden of mortality and morbidity, in large part due to the immaturity of the lungs at this stage of development. The standard of care for these patients includes support with mechanical ventilation, which exacerbates lung pathology. Extracorporeal life support (ECLS), also called artificial placenta technology when applied to extremely preterm (EPT) infants, offers an intriguing solution. ECLS involves providing gas exchange via an extracorporeal device, thereby doing the work of the lungs and allowing them to develop without being subjected to injurious mechanical ventilation. While ECLS has been successfully used in respiratory failure in full-term neonates, children, and adults, it has not been applied effectively to the EPT patient population. In this review, we discuss the unique aspects of EPT infants and the challenges of applying ECLS to these patients. In addition, we review recent progress in artificial placenta technology development. We then offer analysis on design considerations for successful engineering of a membrane oxygenator for an artificial placenta circuit. Finally, we examine next-generation oxygenators that might advance the development of artificial placenta devices.

Artificial lungs--Where are we going with the lung replacement therapy?

Lung transplantation may be a final destination therapy in lung failure, but limited donor organ availability creates a need for alternative management, including artificial lung technology. This invited review discusses ongoing developments and future research pathways for respiratory assist devices and tissue engineering to treat advanced and refractory lung disease. An overview is also given on the aftermath of the coronavirus disease 2019 pandemic and lessons learned as the world comes out of this situation. The first order of business in the future of lung support is solving the problems with existing mechanical devices. Interestingly, challenges identified during the early days of development persist today. These challenges include device-related infection, bleeding, thrombosis, cost, and patient quality of life. The main approaches of the future directions are to repair, restore, replace, or regenerate the lungs. Engineering improvements to hollow fiber membrane gas exchangers are enabling longer term wearable systems and can be used to bridge lung failure patients to transplantation. Progress in the development of microchannel-based devices has provided the concept of biomimetic devices that may even enable intracorporeal implantation. Tissue engineering and cell-based technologies have provided the concept of bioartificial lungs with properties similar to the native organ. Recent progress in artificial lung technologies includes continued advances in both engineering and biology. The final goal is to achieve a truly implantable and durable artificial lung that is applicable to destination therapy.

Toward a Long-Term Artificial Lung

Only a very small portion of end-stage organ failures can be treated by transplantation because of the shortage of donor organs. Although artificial long-term organ support such as ventricular assist devices provide therapeutic options serving as a bridge-to-transplantation or destination therapy for end-stage heart failure, suitable long-term artificial lung systems are still at an early stage of development. Although a short-term use of an extracorporeal lung support is feasible today, the currently available technical solutions do not permit the long-term use of lung replacement systems in terms of an implantable artificial lung. This is currently limited by a variety of factors: biocompatibility problems lead to clot formation within the system, especially in areas with unphysiological flow conditions. In addition, proteins, cells, and fibrin are deposited on the membranes, decreasing gas exchange performance and thus, limiting long-term use. Coordinated basic and translational scientific research to solve these problems is therefore necessary to enable the long-term use and implantation of an artificial lung. Strategies for improving the biocompatibility of foreign surfaces, for new anticoagulation regimes, for optimization of gas and blood flow, and for miniaturization of these systems must be found. These strategies must be validated by in vitro and in vivo tests, which remain to be developed. In addition, the influence of long-term support on the pathophysiology must be considered. These challenges require well-connected interdisciplinary teams from the natural and material sciences, engineering, and medicine, which take the necessary steps toward the development of an artificial implantable lung.

Extracorporeal Circulation Membrane Oxygenation Therapy for Acute Respiratory Diseases

Extracorporeal circulation membrane oxygenation provides pulmonary and/or cardiac support over a limited period of time for severe reversible cardio pulmonary diseases. It is an invasive technique with large risks associated but an improved survival rate of around 80%. It has strict selection criteria for neonatal and pediatric patients. The main complications are hemorrhage, stroke, convulsions, cardiac failure, kidney failure, arterial hypertension, and hemolysis. Extracorporeal circulation membrane oxygenation must be implemented only in high-complexity neonatal and pediatric centers with trained personnel.

The Perfect Womb: Promoting Equality of (Fetal) Opportunity

This paper aims to address how artificial gestation might affect equality of opportunity for the unborn and any resultant generation of "ectogenetic" babies. It will first explore the current legal obstacles preventing the development of ectogenesis, before looking at the benefits of allowing this technology to control fetal growth and development. This will open up a discussion of the treatment/enhancement divide regarding the use of reproductive technologies, a topic featured in various bioethical debates on the subject. Using current maternity practices in Western society as a comparator, this paper will conclude that neither naturally nor artificially gestated fetuses have interests that can conflict with those of potential parents who might want to use this technology to control fetal development. Such control may include selective implantation of embryos of a desired gender, deliberate choice of genetic traits, or maintenance of an ideal incubation environment to avoid fetal damage. Objections on the basis of disability as well as concerns regarding eugenics will be addressed. The paper will conclude that none of these objections are compelling grounds to prevent the development and use of ectogenesis technologies for the purpose of achieving specific reproductive goals, particularly when compared to current practices in pre-implantation genetic diagnosis and selective abortion on the grounds of undesired traits. As such, when deciding whether to support ectogenesis research, the enduring interests of parents must be the primary consideration, with societal concerns regarding potential misuse the only valid secondary consideration.

Neonatal and pediatric extracorporeal membrane oxygenation in developing Latin American countries

OBJECTIVE

To review the principles of neonatal-pediatric extracorporeal membrane oxygenation therapy, prognosis, and its establishment in limited resource-limited countries in Latino America.

SOURCES

The PubMed database was explored from 1985 up to the present, selecting from highly-indexed and leading Latin American journals, and Extracorporeal Life Support Organization reports.

SUMMARY OF THE FINDINGS

Extracorporeal membrane oxygenation provides "time" for pulmonary and cardiac rest and for recovery. It is used in the neonatal-pediatric field as a rescue therapy for more than 1300 patients with respiratory failure and around 1000 patients with cardiac diseases per year. The best results in short- and long-term survival are among patients with isolated respiratory diseases, currently established as a standard therapy in referral centers for high-risk patients. The first neonatal/pediatric extracorporeal membrane oxygenation Program in Latin America was established in Chile in 2003, which was also the first program in Latin America to affiliate with the Extracorporeal Life Support Organization. New extracorporeal membrane oxygenation programs have been developed in recent years in referral centers in Argentina, Colombia, Brazil, Mexico, Perú, Costa Rica, and Chile, which are currently funding the Latin American Extracorporeal Life Support Organization chapter.

CONCLUSIONS

The best results in short- and long-term survival are in patients with isolated respiratory diseases. Today extracorporeal membrane oxygenation therapy is a standard therapy in some Latin American referral centers. It is hoped that these new extracorporeal membrane oxygenation centers will have a positive impact on the survival of newborns and children with respiratory or cardiac failure, and that they will be available for an increasing number of patients from this region in the near future.

Artificial placenta: Analysis of recent progress

The artificial placenta (AP) has for many decades captured the imagination of scientists and authors with popular fiction including The Matrix and Aldous Huxley's "Brave New World", depicting a human surviving ex-utero in an artificial uterine environment (AUE). For scientists this has fascinated as a way forward for extremely preterm infants (EPIs) born less than 28 weeks of gestation. Early successes with mechanical ventilation (MV) for infants born above 28 weeks of gestation meant that AP research lost momentum. More recently, the gestational age limit for survival now borders on 23 weeks and corresponds to the biological milestone of lung development marked by the early canalicular stage of lung morphogenesis. The so called greyzone of 23-25 weeks represents a steep increase in mortality with decreasing gestational age and current options in neonatal care are on the fringes of efficacy for this population. A shift in thinking recognizes the vitality of EPIs as a fetus rather than a 37-40 week neonate and this has reinvigorated the concept of the AP. This review will discuss the scale of extreme preterm birth with special reference to previable infants born in the greyzone. Recent AP studies using sheep models are compared, technical obstacles discussed and future research themes identified.

Artificial placenta: Recent advances and potential clinical applications

Lung immaturity remains a major cause of morbidity and mortality in extremely premature infants. Positive-pressure mechanical ventilation, the method of choice for respiratory support in premature infants, frequently promotes by itself lung injury and a negative impact in the circulatory function. Extracorporeal lung support has been proposed for more than 50 years as a potential alternative to mechanical ventilation in the treatment of severe respiratory failure of extremely premature infants. Recent advances in this field included the development of miniaturized centrifugal pumps and polymethylpentene oxygenators, as well as the successful use of pump-assisted veno-venous extracorporeal gas exchange systems in experimental artificial placenta models. This review, which includes studies published from 1958 to 2015, presents an update on the artificial placenta concept and its potential clinical applications. Special focus will be devoted to the milestones achieved so far and to the limitations that must be overcome before its clinical application. Notwithstanding, the artificial placenta stands as a promising alternative to mechanical ventilation in extremely premature infants. Pediatr Pulmonol. 2016;51:643-649. © 2016 Wiley Periodicals, Inc.

Pre-clinical evaluation of an adult extracorporeal carbon dioxide removal system with active mixing for pediatric respiratory support

The objective of this work was to conduct pre-clinical feasibility studies to determine if a highly efficient, active-mixing, adult extracorporeal carbon dioxide removal (ECCO2R) system can safely be translated to the pediatric population. The Hemolung Respiratory Assist System (RAS) was tested in vitro and in vivo to evaluate its performance for pediatric veno-venous applications. The Hemolung RAS operates at blood flows of 350-550 ml/min and utilizes an integrated pump-gas exchange cartridge with a membrane surface area of 0.59 m² as the only component of the extracorporeal circuit. Both acute and seven-day chronic in vivo tests were conducted in healthy juvenile sheep using a veno-venous cannulation strategy adapted to the in vivo model. The Hemolung RAS was found to have gas exchange and pumping capabilities relevant to patients weighing 3-25 kg. Seven-day animal studies in juvenile sheep demonstrated that veno-venous extracorporeal support could be used safely and effectively with no significant adverse reactions related to device operation.

Simulation of blood oxygenation in capillary membrane oxygenators using modified sulfite solution

Blood oxygenation is the main performance characteristic of capillary membrane oxygenators (CMOs). Handling of natural blood in in vitro investigations of CMOs is quite complex and time-consuming. Since the conventional blood analog fluids (e.g. water/glycerol) lack a substance with an affinity to capture oxygen comparable to hemoglobin's affinity, in this study a novel approach using modified sulfite solution is proposed to address this challenge. The solution comprises sodium sulfite as a component, simulating the role of hemoglobin in blood oxygenation. This approach is validated by OTR (oxygen transfer rate) measured using native porcine blood, in two types of commercially available CMOs. Consequently, the number of complicated natural blood investigations in the evolution procedure of newly developed oxygenators would considerably decrease. Moreover, the reassessing of failed devices, in clinics, would be performed more precisely using a modified sulfite solution than simple water/glycerol testing.

A paradigm shift in the treatment of extreme prematurity: the artificial placenta

PURPOSE OF REVIEW

Extremely low gestational age newborns (ELGANs), born at less than 28 weeks' estimated gestational age, suffer the greatest consequences of prematurity. There have been significant advances in their care over the last several decades, but the prospects for major advances within traditional treatment modalities appear limited. An artificial placenta using extracorporeal life support (ECLS) has been investigated in the laboratory as a new advance in the treatment of ELGANs. We review the concept of an artificial placenta, the purported benefits, and the most recent research efforts in this area.

RECENT FINDINGS

For 50 years, researchers have attempted to develop an artificial placenta based on ECLS. Traditional artificial placenta strategies have been based on arteriovenous ECLS using the umbilical vessels with moderate success. Recently, the use of venovenous ECLS and miniaturization of ECLS components have shown potential for creating a next-generation artificial placenta.

SUMMARY

ELGANs suffer the greatest morbidity and mortality of prematurity, and are poised to benefit from a paradigm shift in the treatment. Although challenges remain, the artificial placenta is feasible. An artificial placenta would not only protect ELGANs from the complications of mechanical ventilation, but also support their development until a stage of greater maturity, preparing them for a life free of the sequelae of prematurity.

Artificial Placenta - Lung Assist Devices for Term and Preterm Newborns with Respiratory Failure

Respiratory insufficiency is a major cause of neonatal mortality and long-term morbidity, especially in very low birth weight infants. Today, non-invasive and mechanical ventilation are commonly accepted procedures to provide respiratory support to newborns, but they can reach their limit of efficacy. To overcome this technological plateau and further reduce mortality rates, the technology of an “artificial placenta”, which is a pumpless lung assist device connected to the umbilical vessels, would serve to expand the therapeutic spectrum when mechanical ventilation becomes inadequate to treat neonates with severe respiratory insufficiency.

The first attempts to create such an artificial placenta took place more than 60 years ago. However, there has been a recent renaissance of this concept, including developments of its major components like the oxygenator, vascular access via umbilical vessels, flow control, as well as methods to achieve hemocompatibility in extracorporeal circuits. This paper gives a review of past and current development, animal experiments and human case studies of artificial placenta technology.

Impact of a unique international conference on pediatric mechanical circulatory support and pediatric cardiopulmonary perfusion research

There is no question that the International Conference on Pediatric Mechanical Circulatory Support Systems and Pediatric Cardiopulmonary Perfusion is a unique event that has had a significant impact on the treatment of neonatal, infantile, and pediatric cardiopulmonary patients around the globe since 2005. This annual event will continue as long as there is a need to fill the gap for underserved patient population. It will also continue to recognize promising young investigators based on their full manuscripts for young investigator awards.

[Reproduction without a uterus? State of the art of ectogenesis]

The concept of reproduction without uterus, or ectogenesis, has long been considered a myth. Nowadays, however, the in vitro conception (IVF) and embryo culture before implantation are largely used in humans with more than 50,000 IVF and ICSI procedures yearly in France, but also in ruminants where about 400,000 bovine embryos are produced in vitro worldwide each year. In order to proceed with gestation, a 3D structure enabling implantation is needed. Ex-vivo implantation of human embryos was obtained both in a perfused ex-vivo uterus and in a 3 dimensional culture of endometrial cells, but these experiments were stopped because of ethical concerns. The implantation of a mouse embryo in a similar 3D structure has been reported but did not lead to the production of a live pup. Another interest for an artificial uterus or placenta would be to use it for ex-vivo maturation of very premature fetuses. Extra-corporal membrane oxygenation (ECMO) was developed for many years but its use remains disappointing in preterm infants when compared to the important progress made with more classical clinical care. In any case, goat fetuses have been maintained alive up to 9 days in an artificial amniotic pouch, being oxygenated via ECMO.

Advances in neonatal extracorporeal support: the role of extracorporeal membrane oxygenation and the artificial placenta

This review addresses the history and evolution of neonatal extracorporeal membrane oxygenation (ECMO), with a discussion of the indications, contraindications, modalities, outcomes, and impact of ECMO. Controversies surrounding novel uses of ECMO in neonates, namely ECMO for premature infants and ex utero intrapartum therapy with transition to ECMO, are discussed. The development of an extracorporeal artificial placenta for support of premature infants is presented, including the rationale, research, and challenges. ECMO has had a dramatic effect on the care of critically ill neonates over the past 4 decades, and there is great potential to expand these benefits in the future.

Artificial organs 2011: a year in review

In this Editor's Review, articles published in 2011 are organized by category and briefly summarized. As the official journal of The International Federation for Artificial Organs, The International Faculty for Artificial Organs, and the International Society for Rotary Blood Pumps, Artificial Organs continues in the original mission of its founders "to foster communications in the field of artificial organs on an international level."Artificial Organs continues to publish developments and clinical applications of artificial organ technologies in this broad and expanding field of organ replacement, recovery, and regeneration from all over the world. We take this time also to express our gratitude to our authors for offering their work to this journal. We offer our very special thanks to our reviewers who give so generously of time and expertise to review, critique, and especially provide meaningful suggestions to the author's work whether eventually accepted or rejected. Without these excellent and dedicated reviewers, the quality expected from such a journal would not be possible. We also express our special thanks to our Publisher, Wiley-Blackwell, for their expert attention and support in the production and marketing of Artificial Organs. In this Editor's Review, that historically has been widely well-received by our readership, we aim to provide a brief reflection of the currently available worldwide knowledge that is intended to advance and better human life while providing insight for continued application of technologies and methods of organ replacement, recovery, and regeneration. We look forward to recording further advances in the coming years.