Extra-corporeal membrane oxygenation in paediatric acute respiratory distress syndrome: overrated or underutilized?

Ventilatory management of critically ill children in the emergency setting, during transport and retrieval

Critical illness in children is uncommon. The acute stabilization and resuscitation of critically ill children remains challenging to even the most experienced operator. Cardiorespiratory illness represents the largest subgroup of diseases causing critical illness and, thus adds a layer of complexity and additional challenge to the safe intubation and establishment of effective ventilation of this group of children. Children have unique physiological and anatomical differences to adults, and present the team involved in their resuscitation and stabilization with challenges exaggerated by critical illness. The consideration of pathophysiological implications of disease and the equipment available during transport and retrieval from the roadside or nonspecialist setting to pediatric intensive care allows the clinician involved in resuscitation, stabilization, and establishment of ventilation to employ targeted strategies to optimize ventilatory success. This review focuses on the types of ventilatory challenges that must be addressed when managing critically ill children in the local settings in which they present, and the resources available to optimize the outcome prior to and during transfer to a higher level of care.

Venovenous vs. Venoarterial Extracorporeal Membrane Oxygenation in Infection-Associated Severe Pediatric Acute Respiratory Distress Syndrome: A Prospective Multicenter Cohort Study

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) has been increasingly used as rescue therapy for severe pediatric acute respiratory distress syndrome (PARDS) over the past decade. However, a contemporary comparison of venovenous (VV) and venoarterial (VA) ECMO in PARDS has yet to be well described. Therefore, the objective of our study was to assess the difference between VV and VA ECMO in efficacy and safety for infection-associated severe PARDS patients.

METHODS

This prospective multicenter cohort study included patients with infection-associated severe PARDS who received VV or VA ECMO in pediatric intensive care units (PICUs) of eight university hospitals in China between December 2018 to June 2021. The primary outcome was in-hospital mortality. Secondary outcomes included ECMO weaning rate, duration of ECMO and mechanical ventilation (MV), ECMO-related complications, and hospitalization costs.

RESULTS

A total of 94 patients with 26 (27.66%) VV ECMO and 68 (72.34%) VA ECMO were enrolled. Compared to the VA ECMO patients, VV ECMO patients displayed a significantly lower in-hospital mortality (50 vs. 26.92%, p = 0.044) and proportion of neurologic complications, shorter duration of ECMO and MV, but the rate of successfully weaned from ECMO, bleeding, bloodstream infection complications and pump failure were similar. By contrast, oxygenator failure was more frequent in patients receiving VV ECMO. No significant intergroup difference was observed for the hospitalization costs.

CONCLUSION

These positive findings showed the conferred survival advantage and safety of VV ECMO compared with VA ECMO, suggesting that VV ECMO may be an effective initial treatment for patients with infection-associated severe PARDS.

Ethical Considerations in Ever-Expanding Utilization of ECLS: A Research Agenda

Technological advancements and rapid expansion in the clinical use of extracorporeal life support (ECLS) across all age ranges in the last decade, including during the COVID-19 pandemic, has led to important ethical considerations. As a costly and resource intensive therapy, ECLS is used emergently under high stakes circumstances where there is often prognostic uncertainty and risk for serious complications. To develop a research agenda to further characterize and address these ethical dilemmas, a working group of specialists in ECLS, critical care, cardiothoracic surgery, palliative care, and bioethics convened at a single pediatric academic institution over the course of 18 months. Using an iterative consensus process, research questions were selected based on: (1) frequency, (2) uniqueness to ECLS, (3) urgency, (4) feasibility to study, and (5) potential to improve patient care. Questions were categorized into broad domains of societal decision-making, bedside decision-making, patient and family communication, medical team dynamics, and research design and implementation. A deeper exploration of these ethical dilemmas through formalized research and deliberation may improve equitable access and quality of ECLS-related medical care.

Pediatric ECMO Candidates at Non-ECMO Centers: Transfer, Cannulate, or Treat Locally?

Pediatric inpatient and intensive care specialists working outside of tertiary medical centers confront difficult clinical scenarios related to how best to care for extremely ill children who may or may not benefit from advanced medical technology, and these clinicians are often faced with limited local availability. Extracorporeal membrane oxygenation (ECMO) is a technology that is only available at a subset of tertiary care centers, and the decision to risk the transfer of a child for the potential benefit of ECMO is challenging. This article is aimed at addressing the main factors and ethical principles related to this decision-making: (1) whether ECMO is the standard of care, (2) clinical decision analysis of the risks and benefits, (3) informed consent and education of the parents and/or guardians, and (4) institutional leadership decision-making. A decisional framework is proposed that incorporates a thoughtful shared decision-making algorithm.

Paediatrics: how to manage acute respiratory distress syndrome

Background

Acute respiratory distress syndrome (ARDS) is a significant cause of mortality and morbidity amongst critically ill children. The purpose of this narrative review is to provide an up-to-date review on the evaluation and management of paediatric ARDS (PARDS).

Methods

A PubMed search was performed with Clinical Queries using the key term "acute respiratory distress syndrome". The search strategy included clinical trials, meta-analyses, randomized controlled trials, observational studies and reviews. Google, Wikipedia and UpToDate were also searched to enrich the review. The search was restricted to the English literature and children.

Discussion

Non-invasive positive pressure ventilation, lung-protective ventilation strategies, conservative fluid management and adequate nutritional support all have proven efficacy in the management of PARDS. The Pediatric Acute Lung Injury Consensus Conference recommends the use of corticosteroids, high-frequency oscillation ventilation and inhaled nitric oxide in selected scenarios. Partial liquid ventilation and surfactant are not considered efficacious based on evidence from clinical trials.

Conclusion

PARDS is a serious but relatively rare cause of admission into the paediatric intensive care unit and is associated with high mortality. Non-invasive positive pressure ventilation, lung-protective ventilation strategies, conservative fluid management and adequate nutrition are advocated. As there has been a lack of progress in the management of PARDS in recent years, further well-designed, large-scale, randomized controlled trials in this field are urgently needed.

Bridging the Gap Between Intensivists and Primary Care Clinicians in Extracorporeal Membrane Oxygenation for Respiratory Failure in Children: A Review

IMPORTANCE

Extracorporeal membrane oxygenation (ECMO) is a form of advanced life support that may be used in children with refractory respiratory or cardiac failure. While it is required infrequently, in the US, ECMO is used to support childhood respiratory failure as often as children receive kidney or heart transplants. ECMO is complex, resource intensive, and potentially lifesaving, but it is also associated with risks of short-term complications and long-term adverse effects, most importantly with neurodevelopmental outcomes that are relevant to all pediatric clinicians, even those remote from the child's critical illness.

OBSERVATIONS

The 2009 influenza A(H1N1) pandemic, along with randomized clinical trials of adult respiratory ECMO support and conventional management, have catalyzed sustained growth in the use of ECMO. The adult trials built on earlier neonatal ECMO randomized clinical trials that demonstrated improved survival in severe perinatal lung disease. For children outside of the neonatal period, there appear to have been no respiratory ECMO clinical trials. Applying evidence from adult respiratory failure or perinatal lung disease to children outside the neonatal period has important potential pitfalls. For these children, the underlying diseases and risks of ECMO are different. Despite these differences, both neonates and older children are at risk of neurologic complications, such as intracranial hemorrhage, ischemic stroke, and seizures, and those complications may contribute to adverse neurodevelopmental outcomes. Without specific screening, subtle neurodevelopmental impairments may be missed, but when they are identified, children have the opportunity to receive therapy to optimize long-term development.

CONCLUSIONS AND RELEVANCE

All pediatric clinicians should be aware not only of the potential benefits and complications of ECMO but also that survivors need effective screening, support, and follow-up.

Hemolysis at low blood flow rates: in-vitro and in-silico evaluation of a centrifugal blood pump

Background

Treating severe forms of the acute respiratory distress syndrome and cardiac failure, extracorporeal membrane oxygenation (ECMO) has become an established therapeutic option. Neonatal or pediatric patients receiving ECMO, and patients undergoing extracorporeal CO₂ removal (ECCO₂R) represent low-flow applications of the technology, requiring lower blood flow than conventional ECMO. Centrifugal blood pumps as a core element of modern ECMO therapy present favorable operating characteristics in the high blood flow range (4 L/min–8 L/min). However, during low-flow applications in the range of 0.5 L/min–2 L/min, adverse events such as increased hemolysis, platelet activation and bleeding complications are reported frequently.

Methods

In this study, the hemolysis of the centrifugal pump DP3 is evaluated both in vitro and in silico, comparing the low-flow operation at 1 L/min to the high-flow operation at 4 L/min.

Results

Increased hemolysis occurs at low-flow, both in vitro and in silico. The in-vitro experiments present a sixfold higher relative increased hemolysis at low-flow. Compared to high-flow operation, a more than 3.5-fold increase in blood recirculation within the pump head can be observed in the low-flow range in silico.

Conclusions

This study highlights the underappreciated hemolysis in centrifugal pumps within the low-flow range, i.e. during pediatric ECMO or ECCO₂R treatment. The in-vitro results of hemolysis and the in-silico computational fluid dynamic simulations of flow paths within the pumps raise awareness about blood damage that occurs when using centrifugal pumps at low-flow operating points. These findings underline the urgent need for a specific pump optimized for low-flow treatment. Due to the inherent problems of available centrifugal pumps in the low-flow range, clinicians should use the current centrifugal pumps with caution, alternatively other pumping principles such as positive displacement pumps may be discussed in the future.