A Computational Model of Heat Loss and Water Condensation on the Gas-Side of Blood Oxygenators

Quantitative Gas Exchange in Extracorporeal Membrane Oxygenation-A New Device: Accuracy, Approach-based Difficulties, and Caloric Targeting

Measurement of oxygen uptake (VO 2 ) and carbon dioxide removal (VCO 2 ) on membrane lungs (MLs) during extracorporeal membrane oxygenation (ECMO) provides potential for improved and safer therapy. Real-time monitoring of ML function and degradation, calculating caloric needs as well as cardiac output, and weaning algorithms are among the future possibilities. Our study compared the continuous measurement of the standalone Quantum Diagnostics System (QDS) with the published Measuring Energy Expenditure in ECMO patients (MEEP) approach, which calculates sequential VO 2 and VCO 2 values via blood gas analysis and a physiologic gas content model. Thirty-nine datasets were acquired during routine venovenous ECMO intensive care treatment and analyzed. VO 2 was clinically relevant underestimated via the blood-sided measurement of the QDS compared to the MEEP approach (mean difference -42.61 ml/min, limits of agreement [LoA] -2.49/-87.74 ml), which could be explained by the missing dissolved oxygen fraction of the QDS equation. Analysis of VCO 2 showed scattered values with wide limits of agreement (mean difference 54.95 ml/min, LoA 231.26/-121.40 ml/min) partly explainable by a calculation error of the QDS. We described potential confounders of gas-sided measurements in general which need further investigation and recommendations for enhanced devices.

SARS-CoV-2 Leakage From the Gas Outlet Port During Extracorporeal Membrane Oxygenation for COVID-19

Patients with the coronavirus disease 2019 (COVID-19) sometimes develop refractory respiratory failure and may require venovenous extracorporeal membrane oxygenation (VV-ECMO). It is known that the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is sometimes present in the blood of COVID-19 patients. VV-ECMO is often used for several weeks, and plasma leaks can occur, albeit rarely. Hence, in terms of infection control, a concern is that SARS-CoV-2 may leak from the gas outlet port of the oxygenator during ECMO support of critically ill COVID-19 patients. The aim of this study was to clarify whether SARS-CoV-2 leaks from the oxygenator during ECMO support. Five patients with critical COVID-19 pneumonia were placed on VV-ECMO. Silicone-coated polypropylene membrane oxygenators were used in the ECMO circuits for these patients. SARS-CoV-2 ribonucleic acid (RNA) was measured by quantitative reverse transcription polymerase chain reaction in serum and at the gas outlet port of the ECMO circuit at the time of circuit replacement or liberation from ECMO. SARS-CoV-2 RNA was detected in the gas outlet port of the ECMO circuit for three of the five patients. None of the medical staff involved in the care of these five patients has been infected with COVID-19. In conclusion, SARS-CoV-2 could leak to the gas outlet port of the ECMO circuit through silicone-coated polypropylene membranes during ECMO support of critically ill COVID-19 patients.

Water Condensation and Gas Exchange Correlation in Different Models and Fibers of Blood Oxygenators: "How Can We Improve Performance?"

Creation of water condensation in blood oxygenators is a phenomenon that is constantly present during cardiopulmonary bypass and in medium- to long-term extracorporeal life support. Clinical observation of condensation at the oxygenator exit is still a common event normally associated with sudden cooling of the gas flow proximal to the outlet cover (after exiting the fiber bundle), where the warming effect of blood is no longer present. Condensation could progressively obstruct a certain number of fibers, reducing the efficiency of gaseous exchange in the membrane of the oxygenator surface. The study included 48 patients divided into four oxygenator groups of 12 each: group 1 used an Inspire 6 F oxygenator from Livanova; group 2, an Affinity Fusion from Medtronic; group 3, an Alone from Eurosets, and group 4, an ECMO Alone from Eurosets; while the last group used an ECMO Alone oxygenator from Eurosets with polymethylpentene fiber. Each group of oxygenators comprising 12 patients were divided into two groups, namely, A and B, with six patients in each group. Group A used mild hypothermia during the procedure, and group B of six patients used normothermia; Groups A and B were further subdivided into four subgroups: A1, A2, B1, and B2, each consists of three patients; subgroups A1 and B1 used negative aspiration (-8 mmHg) measuring humidity (%) and temperature (°C) in the gas oxygenator output; consequently, a measurement system was necessary to be created; Subgroups A2 and B2 did not use negative aspiration in the oxygenator outlet. No statistically significant difference for PaO₂ and humidity values was found in polypropylene and polymethylpentene oxygenators with mild hypothermia management with vacuum and without vacuum in the gas outlet in the first 60 minutes and 60 minutes later during cardiopulmonary bypass. In normothermia, a statistically significant difference in the PaO₂-humidity relationship was observed with polypropylene and polymethylpentene fiber models. Results of this study show an inversely proportional correlation between gas exchange and condensation in statistically significant values during the use of normothermia and a reduction in oxygenation performance, in polypropylene and polymethylpentene fiber oxygenators.

Artificial Organs 2018: A Year in Review

In this Editor's Review, articles published in 2018 are organized by category and summarized. We provide a brief reflection of the research and progress in artificial organs intended to advance and better human life while providing insight for continued application of these technologies and methods. 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. Peer-reviewed special issues this year included contributions from the 13th International Conference on Pediatric Mechanical Circulatory Support Systems and Pediatric Cardiopulmonary Perfusion edited by Dr. Akif Undar, and the 25th Congress of the International Society for Mechanical Circulatory Support edited by Dr. Marvin Slepian. Additionally, many editorials highlighted the worldwide survival differences in hemodialysis and perspectives on mechanical circulatory support and stem cell therapies for cardiac support. 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 could not be possible. We also express our special thanks to our Publisher, John Wiley & Sons for their expert attention and support in the production and marketing of Artificial Organs. We look forward to reporting further advances in the coming years.