Impact of tubing length on hemodynamics in a simulated neonatal extracorporeal life support circuit

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.

Special equipment considerations for neonatal ECMO

Extracorporeal membrane oxygenation (ECMO) for neonates is applied routinely at major children's hospitals around the world. While the practice seems routine, the peculiar physiology of the small human imposes particular constraints on selection of equipment, performance of the circuit, and risks to the child. The physiology of small patients and physics of circuit elements leave many areas opaque and far from optimal, but still allow assembly of a set of useful heuristics for good practice. Here, we examine individual mechanical components of the ECMO circuit with attention to selection, pitfalls, and peculiarities of each when applied to the neonate.

Mechanical circulatory support for end-stage heart failure in repaired and palliated congenital heart disease

Approximately one in one hundred children is born with congenital heart disease. Most can be managed with corrective or palliative surgery but a small group will develop severe heart failure, leaving cardiac transplantation as the ultimate treatment option. Unfortunately, due to the inadequate number of available donor organs, only a small number of patients can benefit from this therapy, and mortality remains high for pediatric patients awaiting heart transplantation, especially compared to adults. The purpose of this review is to describe the potential role of mechanical circulatory support in this context and to review current experience. For patients with congenital heart disease, ventricular assist devices are most commonly used as a bridge to cardiac transplantation, an application which has been shown to have several important advantages over medical therapy alone or support with extracorporeal membrane oxygenation, including improved survival to transplant, less exposure to blood products with less immune sensitization, and improved organ function. While these devices may improve wait list mortality, the chronic shortage of donor organs for children is likely to remain a problem into the foreseeable future. Therefore, there is great interest in the development of mechanical ventricular assist devices as potential destination therapy for congenital heart disease patients with end-stage heart failure. This review first discusses the experience with the currently available ventricular assist devices in children with congenital heart disease, and then follows to discuss what devices are under development and may reach the bedside soon.

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.

Challenges at the Bedside With ECMO and VAD

Patients on circulatory support can be the source of multiple challenges including optimizing the circuit for specific congenital heart lesions, troubleshooting circuit failures, transporting patients on the circuit, anticoagulation and bleeding, transitioning to more mobile ventricular assist device, listing for thoracic organ transplantation, weaning from the circuit, and educating the patient and family about mechanical support. These challenges ideally require a specialized multidisciplinary team, which includes anesthesiologists, child life specialists, extracorporeal membrane oxygenation (ECMO) specialists, intensivists, nurses, nutritionists, perfusionists, pharmacists, respiratory therapists, social workers, and surgeons.

Artificial organs 2010: a year in review

In this Editor's Review, articles published in 2010 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 such meaningful suggestions to the author's work whether eventually accepted or rejected and especially to those whose native tongue is not English. Without these excellent and dedicated reviewers the quality expected from such a journal could 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 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.

Translational Research in Pediatric Extracorporeal Life Support Systems and Cardiopulmonary Bypass Procedures: 2011 Update

Over the past 6 years at Penn State Hershey, we have established the pediatric cardiovascular research center with a multidisciplinary research team with the goal to improve the outcomes for children undergoing cardiac surgery with cardiopulmonary bypass (CPB) and extracorporeal life support (ECLS). Due to the variety of commercially available pediatric CPB and ECLS devices, both in vitro and in vivo translational research have been conducted to achieve the optimal choice for our patients. By now, every component being used in our clinical settings in Penn State Hershey has been selected based on the results of our translational research. The objective of this review is to summarize our translational research in Penn State Hershey Pediatric Cardiovascular Research Center and to share the latest results with all the interested centers.

Hemodynamic evaluation of arterial and venous cannulae performance in a simulated neonatal extracorporeal life support circuit

Objective: To construct an ideal extracorporeal life support (ECLS) circuit in terms of hemodynamic performance, each component of the circuit should be evaluated. Most cannulae manufacturers evaluate their products using water as the priming solution. We conducted this study to evaluate the different sizes of arterial and venous cannulae in a simulated neonatal ECLS circuit primed with human blood.

Methods: The simulated neonatal ECLS circuit was composed of a Capiox Baby RX05 oxygenator, a Rotaflow centrifugal pump and a heater & cooler unit. Three Medtronic Bio-Medicus arterial cannulae (8Fr, 10Fr, 12Fr) and three venous cannulae (10Fr, 12Fr, 14Fr) were tested in seven combinations (8A-10V, 8A-12V, 10A-10V, 10A-12V, 10A-14V, 12A-12V, 12A-14V). All the experiments were conducted using human blood at a hematocrit of 40% and at a constant temperature of 37°C. The “tip to tip” priming volume of the entire circuit was 135ml. The blood volume of the pseudo patient was 500ml.

Results: Flow rates increased linearly with increasing size in both venous and arterial cannulae at the same pump speeds. The increase in flow rate was greater when changing the arterial cannulae (next size larger) compared to changing the venous cannulae (next size larger). The pressure drops of the arterial cannula were correlated with the flow rates, regardless of the pseudo patient pressure and the venous cannula used simultaneously.

Conclusions: The results show the difference in flow ranges and pressure drops of seven combinations of arterial and venous cannulae. It also suggests that the arterial cannula, not the venous cannula, has greater impact on the flow rate when a centrifugal pump is used in a neonatal ECLS circuit. The results of this study have been translated to further advancing the clinical practice in our institution.

Current status of pediatric/neonatal extracorporeal life support: clinical outcomes, circuit evolution, and translational research

Extracorporeal life support (ECLS) offers lifesaving mechanical circulatory support for patients afflicted with respiratory and/or cardiac failure. Neonatal respiratory patients have higher survival rates compared to pediatric patients, while, for cardiac cases, pediatric patients are more likely to survive. The indications for ECLS have been expanded due to the improved technology and favorable outcomes. However, the rate of mortality and morbidity for ECLS patients remains significant. Mechanical complications still comprise a large percentage of ECLS complications, leaving definite room for improvement in ECLS circuit technology in the future. As a pre-clinical evaluating tool, translational research will provide more useful information for the selection of ECLS devices, encourage further development of ECLS technology, and, ultimately, benefit the patients.

Evaluation of two pediatric polymethyl pentene membrane oxygenators with pulsatile and non-pulsatile perfusion

Objectives: This experiment sought to compare two polymethyl pentene (PMP) hollow-fiber membrane oxygenators: the Medos HILITE 2400 LT and the Maquet Quadrox-iD Pediatric in terms of transmembrane pressure gradients and hemodynamic energy preservation under both pulsatile and non-pulsatile conditions.

Methods: A simulated pediatric extracorporeal life support (ECLS) circuit was used to test these two oxygenators. The circuit consisted of a roller pump, ¼ inch tubing for both arterial and venous lines, an oxygenator, and a venous reservoir served as a pseudo-patient. Three pressure transducers were placed upstream and downstream of the oxygenator and the distal arterial line. The experimental system was primed with lactated Ringer’s solution and packed human red blood cells to maintain a hematocrit of 40%.The total volume was 600 ml, including the 350 ml volume of the pseudo-patient.The tests were performed at six flow rates (250, 500, 750, 1000, 1250, 1500 ml/min) and three distal arterial line pressures (MAP) (60, 80, 100 mmHg), under both pulsatile and non-pulsatile perfusion modes.The temperature was kept constant at 37°C for all tests.

Results: Both oxygenators had adequate performances in pressure drop and hemodynamic energy preservation. There were no significant differences between pre- and post-oxygenators for mean pressure (MP), energy equivalent pressure (EEP) and total hemodynamic energy (THE). During the pulsatile perfusion mode, the HILITE 2400 LT retained a greater percentage of surplus hemodynamic energy (SHE) across the oxygenator.

Conclusions: Both the Quadrox-iD Pediatric and HILITE 2400LT PMP membrane oxygenators are suitable for pediatric ECLS therapy under both non-pulsatile and pulsatile perfusion. An optimized combination of flow rate and MAP should be achieved in order to deliver the maximal pulsatile energy in the extracorporeal circuit.