Extracorporeal Membrane Oxygenation Then and Now; Broadening Indications and Availability

ECPR-the evolving role in cardiac arrest

Extracorporeal cardiopulmonary resuscitation (ECPR) describes the use of venoarterial extracorporeal membrane oxygenation (VA-ECMO) to restore blood circulation in patients during refractory cardiac arrest. So far, ECPR is not the standard of care but has become part of clinical routine for select patients in many places. As ECPR is a highly invasive support option associated with considerable risks for fatal complications, premature use in patients who may have return of spontaneous circulation should be avoided. However, the selection criteria for ECPR are still evolving, as the search for evidence is ongoing. Recent randomized controlled trials of different ECPR strategies support its use within integrated systems built around highly specialized ECPR centers. The ECPR caseload is an important predictor of patient survival, and continuous training is key for evidence-based quality of care. Typical complications after ECPR include vascular injury or malposition of cannulas, thrombotic complications, hemolysis, and bleeding events that require early detection and interdisciplinary management. When provided by highly specialized and well-trained expert teams in dedicated ECPR centers within integrated pre-hospital and intra-hospital emergency care systems, ECPR may improve survival in select patients with refractory cardiac arrest. This article is freely available.

Definitions of adverse events associated with extracorporeal membrane oxygenation in children: results of an international Delphi process from the ECMO-CENTRAL ARC

Extracorporeal membrane oxygenation (ECMO) is a high-risk and low-volume life support with increasing clinical study. However, heterogenous outcome definitions impede data assimilation into evidence to guide practice. The Academic Research Consortium (ARC), an international collaborative forum committed to facilitating the creation of stakeholder-driven consensus nomenclature and outcomes for clinical trials of medical devices, supported the ECMO Core Elements Needed for Trials Regulation And quality of Life (ECMO-CENTRAL) ARC. The ECMO-CENTRAL ARC was assembled to develop definitions of paediatric ECMO adverse events for use in clinical trials and regulatory device evaluation. An initial candidate list of ECMO adverse events derived from the mechanical circulatory support ARC was supplemented with a review of ECMO-relevant adverse event definitions collated from literature published between Jan 1, 1988, and Feb 20, 2023. Distinct teams of international topic experts drafted separate adverse event definitions that were harmonised to existing literature when appropriate. Draft definitions were revised for paediatric ECMO relevance with input from patients, families, and an international expert panel of trialists, clinicians, statisticians, biomedical engineers, device developers, and regulatory agencies. ECMO-CENTRAL ARC was revised and disseminated across research societies and professional organisations. Up to three rounds of internet-based anonymous surveys were planned as a modified Delphi process. The expert panel defined 13 adverse event definitions: neurological, bleeding, device malfunction, acute kidney injury, haemolysis, infection, vascular access-associated injury, non-CNS thrombosis, hepatic dysfunction, right heart failure, left ventricular overload, lactic acidaemia, and hypoxaemia. Definitional structure varied. Among 165 expert panel members, 114 were eligible to vote and 111 voted. Consensus was achieved for all proposed definitions. Agreement ranged from 82% to 95%. ECMO-CENTRAL ARC paired rigorous development with methodical stakeholder involvement and dissemination to define paediatric ECMO adverse events. These definitions will facilitate new research and the assimilation of data across clinical trials and ECMO device evaluation in children.

Best Practices for Vessel Management in Pediatric Extracorporeal Membrane Oxygenation Cannulation, Decannulation, and Follow-up: A Narrative Review

Extracorporeal membrane oxygenation (ECMO) to support neonates and children with cardiopulmonary failure was first described in the 1970s, since which time its use has expanded to an increasingly complex and heterogenous pediatric population. Despite preserved survival outcomes, complications of ECMO use, including iatrogenic vascular injury, are common. Here, we provide a brief overview of the epidemiology of pediatric ECMO and associated vascular complications; describe common peripheral cannulation equipment and techniques, trends in cannulation and decannulation strategies, and respective incidence of vascular complications; and review existing evidence for best practices in cannula site selection, cannulation technique, decannulation strategies, and management of vascular complications, with the goal of providing a comprehensive review for interventionalists involved in the care of pediatric ECMO patients. Areas of wide practice variation in vessel management-application of vessel-sparing cervical venoarterial cannulation, the use of distal perfusion catheters in femoral arterial cannulation, and best practices for percutaneous single-lumen venovenous cannulation, as examples-areas of focus for future research, and the potential role of vascular surgeons and other subspecialty proceduralists in the care of pediatric ECMO patients are highlighted. LEVEL OF EVIDENCE: V.

Brain death determination in patients with veno-arterial extracorporeal membrane oxygenation: A systematic study to address the Harlequin syndrome

PURPOSE

The Harlequin syndrome may occur in patients treated with venoarterial extracorporal membrane oxygenation (VA-ECMO), in whom blood from the left ventricle and the ECMO system supply different parts of the body with different paCO2-levels. The purpose of this study was to compare two variants of paCO2-analysis to account for the Harlequin syndrome during apnea testing (AT) in brain death (BD) determination.

MATERIALS AND METHODS

Twenty-seven patients (median age 48 years, 26-76 years; male n = 19) with VA-ECMO treatment were included who underwent BD determination. In variant 1, simultaneous arterial blood gas (ABG) samples were drawn from the right and the left radial artery. In variant 2, simultaneous ABG samples were drawn from the right radial artery and the postoxygenator ECMO circuit. Differences in paCO2-levels were analysed for both variants.

RESULTS

At the start of AT, median paCO2-difference between right and left radial artery (variant 1) was 0.90 mmHg (95%-confidence intervall [CI]: 0.7-1.3 mmHg). Median paCO2-difference between right radial artery and postoxygenator ECMO circuit (variant 2) was 3.3 mmHg (95%-CI: 1.5-6.0 mmHg) and thereby significantly higher compared to variant 1 (p = 0.001). At the end of AT, paCO2-difference according to variant 1 remained unchanged with 1.1 mmHg (95%-CI: 0.9-1.8 mmHg). In contrast, paCO2-difference according to variant 2 increased to 9.9 mmHg (95%-CI: 3.5-19.2 mmHg; p = 0.002).

CONCLUSIONS

Simultaneous paCO2-analysis from right and left distal arterial lines is the method of choice to reduce the risk of adverse effects (e.g. severe respiratory acidosis) while performing AT in VA-ECMO patients during BD determination.

Use of point-of-care ultrasound (POCUS) to monitor neonatal and pediatric extracorporeal life support

Extracorporeal membrane oxygenation (ECMO) is an invasive life support technique that requires a blood pump, an artificial membrane lung, and vascular cannulae to drain de-oxygenated blood, remove carbon dioxide, oxygenate, and return it to the patient. ECMO is generally used to provide advanced and prolonged cardiopulmonary support in patients with refractory acute cardiac and/or respiratory failure. After its first use in 1975 to manage a severe form of meconium aspiration syndrome with resultant pulmonary hypertension, the following years were dominated by the use of ECMO to manage neonatal respiratory failure and limited to a few centers across the world. In the 1990s, evidence for neonatal respiratory ECMO support increased; however, the number of cases began to decline with the use of newer pharmacologic therapies (e.g., inhaled nitric oxide, exogenous surfactant, and high-frequency oscillatory ventilation). On the contrary, pediatric ECMO sustained steady growth. Combined advances in ECMO technology and bedside medical management have improved general outcomes, although ECMO-related complications remain challenging. Point-of-care ultrasound (POCUS) is an essential tool to monitor all phases of neonatal and pediatric ECMO: evaluation of ECMO candidacy, ultrasound-guided ECMO cannulation, daily evaluation of heart and lung function and brain perfusion, detection and management of major complications, and weaning from ECMO support.  Conclusion: Based on these considerations and on the lack of specific guidelines for the use of POCUS in the neonatal and pediatric ECMO setting, the aim of this paper is to provide a systematic overview for the application of POCUS during ECMO support in these populations. What is Known: • Extracorporeal membrane oxygenation (ECMO) provides advanced cardiopulmonary support for patients with refractory acute cardiac and/or respiratory failure and requires appropriate monitoring. • Point-of-care ultrasound (POCUS) is an accessible and adaptable tool to assess neonatal and pediatric cardiac and/or respiratory failure at bedside. What is New: • In this review, we discussed the use of POCUS to monitor and manage at bedside neonatal and pediatric patients supported with ECMO. • We explored the potential use of POCUS during all phases of ECMO support: pre-ECMO assessment, ECMO candidacy evaluation, daily evaluation of heart, lung and brain function, detection and troubleshooting of major complications, and weaning from ECMO support.

In vivo measurement of pediatric extracorporeal oxygenator insensible losses; a single center pilot study

Introduction

Fluid overload on Extracorporeal Membrane Oxygenation (ECMO) is associated with worse outcomes. Previous in vitro studies have attempted to quantify oxygenator-related insensible losses, as failure to account for this fluid loss may lead to inaccurate fluid balance assessment and potentially harmful clinical management, such as unnecessary exposure to diuretics, slow continuous ultrafiltration (SCUF), or continuous kidney replacement therapy (CKRT). We performed a novel in vivo study to measure insensible fluid losses in pediatric ECMO patients.

Methods

Pediatric ECMO patients were approached over eleven months in the pediatric and cardiac intensive care units. The water content of the oxygenator inflow sweep gas and exhaust gas were calculated by measuring the ambient temperature and relative humidity at frequent intervals and various sweep flow.

Results and discussion

Nine subjects were enrolled, generating 431 data points. The cohort had a median age of 11 years IQR [0.83, 13], weight of 23.2 kg IQR [6.48, 44.28], and body surface area of 0.815 m2 IQR [0.315, 1.3725]. Overall, the cohort had a median sweep of 2.5 L/min [0.9, 4], ECMO flow of 3.975 L/m2/min [0.75, 4.51], and a set ECMO temperature of 37 degrees Celsius [36.6, 37.2]. The calculated net water loss per L/min of sweep was 75.93 ml/day, regardless of oxygenator size or patient weight. There was a significant difference in median documented vs. calculated fluid balance incorporating the insensible fluid loss, irrespective of oxygenator size (pediatric oxygenator: 7.001 ml/kg/day [-12.37, 28.59] vs. -6.11 ml/kg/day [-17.44, 13.01], respectively, p = 0.005 and adult oxygenator: 14.36 ml/kg/day [1.54, 25.77] and 9.204 ml/kg/day [-1.28, 22.05], respectively, p = <0.001). We present this pilot study of measured oxygenator-associated insensible fluid losses on ECMO. Our results are consistent with prior in vitro methods and provide the basis for future studies evaluating the impact of incorporating these fluid losses into patients' daily fluid balance on patient management and outcomes.

Prevalence of delirium among critically ill patients who received extracorporeal membrane oxygenation therapy: A systematic review and proportional meta-analysis

OBJECTIVES

To pool the overall prevalence of delirium among critically ill patients who received extracorporeal membrane oxygenation (ECMO) support.

METHODOLOGY

This systematic review and proportional meta-analysis was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Meta-analysis of Observational Studies in Epidemiology (MOOSE) reporting guidelines. Six electronic databases including PubMed, Cochrane Library, Web of Science, EMBASE, CINAHL, and PsycINFO were searched from inception to March 2023. The Newcastle-Ottawa Scale was used to assess the methodological quality of the included studies. A random effects model was used to pool the summary prevalence estimates and 95% CIs using the score statistic and the exact binomial method and incorporates the Freeman-Tukey double arcsine transformation of proportions. Sensitivity analyses including subgroup analysis, meta-regression, and outlier detection were carried out.

SETTING

Intensive care units.

MAIN OUTCOME MEASURES

Prevalence of delirium.

RESULTS

A total of 10 studies involving 8,580 patients were included for meta-analysis. All studies had a low risk of bias in methodological quality. The pooled prevalence rate of 40.79% [95% CI, 17.58%-66.25%] was observed. The between-study heterogeneity (I2) was 98.28%. The subgroup analysis reveals the pooled prevalence of delirium for veno-arterial (V-A) ECMO, veno-venous (V-V) ECMO, and mixed sample of V-A and V-V ECMO were 63.57% [95% CI, 55.77%-71.04%], 51.84% [95% CI, 37.43%-66.12%] and 35.23% [95% CI, 11.84%-62.95%], respectively. Sample size (p = 0.024) was a significant factor associated with the heterogeneity. No evidence for small-study effects was observed (Egger's test: p = 0.5664).

CONCLUSION

This systematic review and proportional meta-analysis reveals a high prevalence of delirium among critically ill patients who received ECMO support.

IMPLICATIONS FOR CLINICAL PRACTICE

The results of this meta-analysis can be epidemiological evidence to inform the awareness of clinicians and researchers in critical care clinical practice and research.