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Limb ischaemia is a clinically relevant complication of venoarterial extracorporeal membrane oxygenation (VA ECMO) with femoral artery cannulation. No selective distal perfusion or other advanced techniques were used in the past to maintain adequate distal limb perfusion. A more recent trend is the shift from the reactive or emergency management to the pro-active or prophylactic placement of a distal perfusion cannula to avoid or reduce limb ischaemia-related complications. Multiple alternative cannulation techniques to the distal perfusion cannula have been developed to maintain distal limb perfusion, including end-to-side grafting, external or endovascular femoro-femoral bypass, retrograde limb perfusion (e.g., via the posterior tibial, dorsalis pedis or anterior tibial artery), and, more recently, use of a bidirectional cannula. Venous congestion has also been recognized as a potential contributing factor to limb ischaemia development and specific techniques have been described with facilitated venous drainage or bilateral cannulation being the most recent, to reduce or avoid venous stasis as a contributor to impaired limb perfusion. Advances in monitoring techniques, such as nearinfrared spectroscopy and duplex ultrasound analysis, have been applied to improve decision-making regarding both the monitoring and management of limb ischaemia. This narrative review describes the evolution of techniques used for distal limb perfusion during peripheral VA ECMO. [ABSTRACT FROM AUTHOR]

Introduction: An analysis on the ECLS use for patients with respiratory or cardiac support in COVID-19 based on an international response to EuroELSO survey, aims to generate a more comprehensive understanding of ECLS role during the recent viral pandemic. Methods: EuroELSO announced the survey at the 10th annual congress in London, May 2022. The survey covered 26 multiple-choice questions. Results: The survey returned 69 questionnaires from 62 centers across 22 European countries and seven centers across five non-European countries. Most of the centers providing ECLS for COVID-19 patients had more than 30 runs for respiratory support since December 2019. In the same period, at least 31 runs in adult COVID-19 patients have been performed in 48 of 69 centers (69.6%). The reported pediatric data from 18 centers is limited to less than the patients per center. Conclusion: Majority of the COVID-19 patients received respiratory ECLS support and adult patients dominated. The indications and contraindications are broadly aligned with available guidelines. Most of the centers considered age >65 or biological age as a relative or absolute contraindication for ECLS in COVID-19. ECLS withdrawal criteria in COVID-19 are controversial because the long-term outcomes after ECLS in COVID-19 and the impact of critical illness and the impact of long-COVID are still not known. [ABSTRACT FROM AUTHOR]

Background: Adverse neurological events during extracorporeal membrane oxygenation (ECMO) are common and may be associated with devastating consequences. Close monitoring, early identification and prompt intervention can mitigate early and late neurological morbidity. Neuromonitoring and neurocognitive/neurodevelopmental follow-up are critically important to optimize outcomes in both adults and children. Objective: To assess current practice of neuromonitoring during ECMO and neurocognitive/neurodevelopmental follow-up after ECMO across Europe and to inform the development of neuromonitoring and follow-up guidelines. Methods: The EuroELSO Neurological Monitoring and Outcome Working Group conducted an electronic, web-based, multi-institutional, multinational survey in Europe. Results: Of the 211 European ECMO centres (including non-ELSO centres) identified and approached in 23 countries, 133 (63%) responded. Of these, 43% reported routine neuromonitoring during ECMO for all patients, 35% indicated selective use, and 22% practiced bedside clinical examination alone. The reported neuromonitoring modalities were NIRS (n = 88, 66.2%), electroencephalography (n = 52, 39.1%), transcranial Doppler (n = 38, 28.5%) and brain injury biomarkers (n = 33, 24.8%). Paediatric centres (67%) reported using cranial ultrasound, though the frequency of monitoring varied widely. Before hospital discharge following ECMO, 50 (37.6%) reported routine neurological assessment and 22 (16.5%) routinely performed neuroimaging with more paediatric centres offering neurological assessment (65%) as compared to adult centres (20%). Only 15 (11.2%) had a structured longitudinal follow-up pathway (defined followup at regular intervals), while 99 (74.4%) had no follow-up programme. The majority (n = 96, 72.2%) agreed that there should be a longitudinal structured follow-up for ECMO survivors. Conclusions: This survey demonstrated significant variability in the use of different neuromonitoring modalities during and after ECMO. The perceived importance of neuromonitoring and follow-up was noted to be very high with agreement for a longitudinal structured follow-up programme, particularly in paediatric patients. Scientific society endorsed guidelines and minimum standards should be developed to inform local protocols. [ABSTRACT FROM AUTHOR]

Introduction: In the last decade, dual-lumen cannulae have been increasingly applied in patients undergoing extracorporeal life support. Well-performing vascular access is crucial for efficient extracorporeal membrane oxygenation support; thus, guidance for proper cannulae size is required. Pressure–flow charts provided by manufacturers are often based on tests performed using water, rarely blood. However, blood is a shear-thinning and viscoelastic fluid characterized by different flow properties than water. Methods: We performed a study evaluating pressure–flow curves during standardized conditions using human whole blood in two commonly available dual-lumen cannulae used in neonates, pediatric, and adult patients. Results were merged and compared with the manufacturer's corresponding curves obtained from the public domain. Results: The results showed that using blood as compared with water predominantly influenced drainage flow. A 10-80% higher pressure-drop was needed to obtain same drainage flow (hematocrit of 26%) compared with manufacturer's water charts in 13-31 Fr bi-caval dual-lumen cannulae. The same net difference was found in cavo-atrial cannulae (16-32 Fr), where a lower drainage pressure was required (Hct of 26%) compared with the manufacturer's test using blood with an Hct of 33%. Return pressure–flow data were similar, independent whether pumping blood or water, to the data reported by manufacturers. Conclusion: Non-standardized testing of pressure–flow properties of extracorporeal membrane oxygenation dual-lumen cannulae prevents an adequate prediction of pressure–flow results when these cannulae are used in patients. Properties of dual-lumen cannulae may vary between sizes within same cannula family, in particular concerning the drainage flow. [ABSTRACT FROM AUTHOR]

Commercially available products used for antithrombin supplementation, for example, in extracorporeal life support, may contain latent antithrombin, a hyper-stable strongly procoagulative and anti-angiogenic residue. Latent antithrombin is associated with severe thrombosis in the critically ill. In the manufacturing process of fractionated antithrombin from plasma, heat treatment, citrate, and freeze drying speed up the transformation of native antithrombin to latent antithrombin. Manufacturers are not required to assess and report the latent antithrombin content of their products. When reported, the latent antithrombin fractions in their product range from <1% to 40% of total antithrombin compared with <3% in the healthy adult and less in children. The aims of this work were (1) to convey increased awareness to clinicians who may experience defaulted, expected effect after antithrombin supplementation in, for example, heparin anticoagulation during extracorporeal life support and (2) to urge manufacturers to assess and disclose latent antithrombin content in their products. [ABSTRACT FROM AUTHOR]

With ongoing progress of components of extracorporeal membrane oxygenation including improvements of oxygenators, pumps, and coating materials, extracorporeal membrane oxygenation became increasingly accepted in the clinical practice. A suitable testing in an adequate setup is essential for the development of new technical aspects. Relevant tests can be conducted in ex vivo models specifically designed to test certain aspects. Different setups have been used in the past for specific research questions. We conducted a systematic literature review of ex vivo models of extracorporeal membrane oxygenation components. MEDLINE and Embase were searched between January 1996 and October 2017. The inclusion criteria were ex vivo models including features of extracorporeal membrane oxygenation technology. The exclusion criteria were clinical studies, abstracts, studies in which the model of extracorporeal membrane oxygenation has been reported previously, and studies not reporting on extracorporeal membrane oxygenation components. A total of 50 studies reporting on different ex vivo extracorporeal membrane oxygenation models have been identified from the literature search. Models have been grouped according to the specific research question they were designed to test for. The groups are focused on oxygenator performance, pump performance, hemostasis, and pharmacokinetics. Pre-clinical testing including use of ex vivo models is an important step in the development and improvement of extracorporeal membrane oxygenation components and materials. Furthermore, ex vivo models offer valuable insights for clinicians to better understand the consequences of choice of components, setup, and management of an extracorporeal membrane oxygenation circuit in any given condition. There is a need to standardize the reporting of pre-clinical studies in this area and to develop best practice in their design. [ABSTRACT FROM AUTHOR]

The substantial increase in the number of patients receiving extracorporeal membrane oxygenation over the last decade has led to an evolution of indications and an expansion into wider patient groups. One of the unanticipated benefits of the increase in extracorporeal membrane oxygenation has been a change in the understanding of the natural history of many respiratory diseases. Development in technology and materials, reduced extracorporeal membrane oxygenation–specific complications, and improvement of critical care, in general, have facilitated longer extracorporeal membrane oxygenation runs, and the definition of prolonged extracorporeal membrane oxygenation was recently expanded to continuous support for more than 28 days. This survey aimed to describe European ECMO centers' perception and arbitrary definition of prolonged extracorporeal membrane oxygenation, patient management, and futility. Of 94 center responses, 37% regarded 14-21 days, 30% 21-28 days, and 28% >28 days as prolonged treatment. Bridge to recovery (64%) or to transplantation (20%) was the most common causes. Awake, and ambulation while on extracorporeal membrane oxygenation was reported from 34% of the centers. In case of perceived futility, decision to withdraw was taken in 65% of the centers in agreement between profession and family and in 30% by profession only. One-fourth of the centers did not discontinue support. Large differences prevail among European ECMO centers concerning local perception and patient management in prolonged extracorporeal membrane oxygenation. [ABSTRACT FROM AUTHOR]

Adequate extracorporeal membrane oxygenation support in the adult requires cannulae permitting blood flows up to 6-8 L/minute. In accordance with Poiseuille's law, flow is proportional to the fourth power of cannula inner diameter and inversely proportional to its length. Poiseuille's law can be applied to obtain the pressure drop of an incompressible, Newtonian fluid (such as water) flowing in a cylindrical tube. However, as blood is a pseudoplastic non-Newtonian fluid, the validity of Poiseuille's law is questionable for prediction of cannula properties in clinical practice. Pressure–flow charts with non-Newtonian fluids, such as blood, are typically not provided by the manufacturers. A standardized laboratory test of return (arterial) cannulae for extracorporeal membrane oxygenation was performed. The aim was to determine pressure–flow data with human whole blood in addition to manufacturers' water tests to facilitate an appropriate choice of cannula for the desired flow range. In total, 14 cannulae from three manufacturers were tested. Data concerning design, characteristics, and performance were graphically presented for each tested cannula. Measured blood flows were in most cases 3-21% lower than those provided by manufacturers. This was most pronounced in the narrow cannulae (15-17 Fr) where the reduction ranged from 27% to 40% at low flows and 5-15% in the upper flow range. These differences were less apparent with increasing cannula diameter. There was a marked disparity between manufacturers. Based on the measured results, testing of cannulae including whole blood flows in a standardized bench test would be recommended. [ABSTRACT FROM AUTHOR]

The use of extracorporeal life support devices such as extracorporeal membrane oxygenation in adults requires cannulation of the patient's vessels with comparatively large diameter cannulae to allow circulation of large volumes of blood (>5 L/min). The cannula diameter and length are the major determinants for extracorporeal membrane oxygenation flow. Manufacturing companies present pressure-flow charts for the cannulae; however, these tests are performed with water. Aims of this study were 1. to investigate the specified pressure-flow charts obtained when using human blood as the circulating medium and 2. to support extracorporeal membrane oxygenation providers with pressure-flow data for correct choice of the cannula to reach an optimal flow with optimal hydrodynamic performance. Eighteen extracorporeal membrane oxygenation drainage cannulae, donated by the manufacturers (n = 6), were studied in a centrifugal pump driven mock loop. Pressure-flow properties and cannula features were described. The results showed that when blood with a hematocrit of 27% was used, the drainage pressure was consistently higher for a given flow (range 10%-350%) than when water was used (data from each respective manufacturer's product information). It is concluded that the information provided by manufacturers in line with regulatory guidelines does not correspond to clinical performance and therefore may not provide the best guidance for clinicians. [ABSTRACT FROM AUTHOR]

Venoarterial extracorporeal membrane oxygenation, indicated for severe cardio-respiratory failure, may result in anatomic regional differences in oxygen saturation. This depends on cannulation, hemodynamic state, and severity of respiratory failure. Differential hypoxemia, often discrete, may cause clinical problems in peripheral femoro-femoral venoarterial extracorporeal membrane oxygenation, when the upper body is perfused with low saturated blood from the heart and the lower body with well-oxygenated extracorporeal membrane oxygenation blood. The key is to diagnose and manage fulminant differential hypoxemia, that is, a state that may develop where the upper body is deprived of oxygen. We summarize physiology, assessment of diagnosis, and management of fulminant differential hypoxemia during venoarterial extracorporeal membrane oxygenation. A possible solution is implantation of an additional jugular venous return cannula. In this article, we propose an even better solution, to drain the venous blood from the superior vena cava. Drainage from the superior vena cava provides superiority to venovenoarterial configuration in terms of physiological rationale, efficiency, safety, and simplicity in clinical circuit design. [ABSTRACT FROM AUTHOR]

The objective of this animal study was to evaluate the hemodynamic performance of a new centrifugal pump for extra-corporeal membrane oxygenation (ECMO) support in neonates.Six healthy swines were supported with veno-venous ECMO with the New Born ECMOLife centrifugal pump (Eurosets, Medolla, Italy) at different flow rates: 0.25, 0.5, 0.6, and 0.8 L/min; three animals were evaluated at low-flows (0.25 and 0.5 L/min) and three at high-flows (0.6 and 0.8 L/min). Each flow was maintained for 4 hours. Blood samples were collected at different time-points. Hematological and biochemical parameters and ECMO parameters [flow, revolutions per minute (RPM), drainage pressure, and the oxygenator pressure drop] were evaluated.The increase of the pump flow from 0.25 to 0.5 L/min or from 0.6 to 0.8 L/min required significantly higher RPM and produced significantly higher pump pressures [from 0.25 to 0.5 L/min: 1470 (1253–1569) versus 2652 (2589–2750) RPM and 40 (26–57) versus 125 (113–139) mmHg, respectively; p < .0001 for both - from 0.60 to 0.8 L/min: 1950 (1901–2271) versus 2428 (2400–2518) RPM and 66 (62–86) versus 106 (101–113) mmHg, respectively; p < .0001 for both]. Median drainage pressure significantly decreased from −18 (−22; −16) mmHg to −55 (−63; −48) mmHg when the pump flow was increased from 0.25 to 0.5 L/min (p < .0001). When pump flow increased from 0.6 to 0.8 L/min, drainage pressure decreased from −32 (−39; −24) mmHg to −50 (−52; −43) mmHg, (p < .0001). Compared to pre-ECMO values, the median levels of lactate dehydrogenase, d-dimer, hematocrit, and platelet count decreased after ECMO start at all flow rates, probably due to hemodilution. Plasma-free hemoglobin, instead, showed a modest increase compared to pre-ECMO values during all experiments at different pump flow rates. However, these changes were not clinically relevant.In this animal study, the “New Born ECMOLife” centrifugal pump showed good hemodynamic performance. Long-term studies are needed to evaluate biocompatibility of this new ECMO pump. [ABSTRACT FROM AUTHOR]