Association of Cerebral Oximetry with Outcomes after Extracorporeal Membrane Oxygenation

Update in Pediatric Neurocritical Care: What a Neurologist Caring for Critically Ill Children Needs to Know

Currently nearly one-quarter of admissions to pediatric intensive care units (PICUs) worldwide are for neurocritical care diagnoses that are associated with significant morbidity and mortality. Pediatric neurocritical care is a rapidly evolving field with unique challenges due to not only age-related responses to primary neurologic insults and their treatments but also the rarity of pediatric neurocritical care conditions at any given institution. The structure of pediatric neurocritical care services therefore is most commonly a collaborative model where critical care medicine physicians coordinate care and are supported by a multidisciplinary team of pediatric subspecialists, including neurologists. While pediatric neurocritical care lies at the intersection between critical care and the neurosciences, this narrative review focuses on the most common clinical scenarios encountered by pediatric neurologists as consultants in the PICU and synthesizes the recent evidence, best practices, and ongoing research in these cases. We provide an in-depth review of (1) the evaluation and management of abnormal movements (seizures/status epilepticus and status dystonicus); (2) acute weakness and paralysis (focusing on pediatric stroke and select pediatric neuroimmune conditions); (3) neuromonitoring modalities using a pathophysiology-driven approach; (4) neuroprotective strategies for which there is evidence (e.g., pediatric severe traumatic brain injury, post-cardiac arrest care, and ischemic stroke and hemorrhagic stroke); and (5) best practices for neuroprognostication in pediatric traumatic brain injury, cardiac arrest, and disorders of consciousness, with highlights of the 2023 updates on Brain Death/Death by Neurological Criteria. Our review of the current state of pediatric neurocritical care from the viewpoint of what a pediatric neurologist in the PICU needs to know is intended to improve knowledge for providers at the bedside with the goal of better patient care and outcomes.

The State of the Field of Pediatric Multimodality Neuromonitoring

BACKGROUND

The use of multimodal neuromonitoring in pediatrics is in its infancy relative to adult neurocritical care. Multimodal neuromonitoring encompasses the amalgamation of information from multiple individual neuromonitoring devices to gain a more comprehensive understanding of the condition of the brain. It allows for adaptation to the changing state of the brain throughout various stages of injury with potential to individualize and optimize therapies.

METHODS

Here we provide an overview of multimodal neuromonitoring in pediatric neurocritical care and its potential application in the future.

RESULTS

Multimodal neuromonitoring devices are key to the process of multimodal neuromonitoring, allowing for visualization of data trends over time and ideally improving the ability of clinicians to identify patterns and find meaning in the immense volume of data now encountered in the care of critically ill patients at the bedside. Clinical use in pediatrics requires more study to determine best practices and impact on patient outcomes. Potential uses include guidance for targets of physiological parameters in the setting of acute brain injury, neuroprotection for patients at high risk for brain injury, and neuroprognostication. Implementing multimodal neuromonitoring in pediatric patients involves interprofessional collaboration with the development of a simultaneous comprehensive program to support the use of multimodal neuromonitoring while maintaining the fundamental principles of the delivery of neurocritical care at the bedside.

CONCLUSIONS

The possible benefits of multimodal neuromonitoring are immense and have great potential to advance the field of pediatric neurocritical care and the health of critically ill children.

First Characterization of Tissue Oxygen Saturation Recovery Patterns in Pediatric Cardiac Surgery Patients Undergoing Remote Ischemic Preconditioning and the Association With Clinical Outcomes

OBJECTIVE

This study aimed to delineate the recovery patterns of regional oxygen saturation (SrO2) in pediatric cardiac surgery patients subjected to remote ischemic preconditioning (RIPC), utilizing near-infrared spectroscopy (NIRS) for quantification. It also sought to establish the correlation between these perfusion patterns and postoperative clinical outcomes.

DESIGN

A prospective longitudinal observational study.

SETTING

The study was conducted at Fundación Valle Del Lili, a high-complexity service provider institution in Fundación Valle Del Lili.

PARTICIPANTS

Pediatric patients (younger than 18 years of age) scheduled for elective cardiac surgery requiring cardiopulmonary bypass between August 2022 and July 2023.

INTERVENTIONS

RIPC was performed after anesthetic induction, involving cycles of ischemia and reperfusion on a lower limb. Monitoring included SrO2 using NIRS.

MEASUREMENTS AND MAIN RESULTS

The study identified 4 distinct patterns of SrO2 during RIPC. Findings demonstrated a significant association between the negative SrO2 pattern and increased postoperative adverse events, including extended hospital stays and higher mortality, while a positive pattern was associated with better outcomes.

CONCLUSIONS

Specific patterns of SrO2 response to RIPC may serve as important indicators for risk stratification in congenital heart surgery. This study illustrated the potential of NIRS in detecting hypoxic states and predicting postoperative outcomes, emphasizing the need for standardized clinical interpretation of RIPC patterns.

Cerebral Autoregulation: A Target for Improving Neurological Outcomes in Extracorporeal Life Support

Despite improvements in survival after illnesses requiring extracorporeal life support, cerebral injury continues to hinder successful outcomes. Cerebral autoregulation (CA) is an innate protective mechanism that maintains constant cerebral blood flow in the face of varying systemic blood pressure. However, it is impaired in certain disease states and, potentially, following initiation of extracorporeal circulatory support. In this review, we first discuss patient-related factors pertaining to venovenous and venoarterial extracorporeal membrane oxygenation (ECMO) and their potential role in CA impairment. Next, we examine factors intrinsic to ECMO that may affect CA, such as cannulation, changes in pulsatility, the inflammatory and adaptive immune response, intracranial hemorrhage, and ischemic stroke, in addition to ECMO management factors, such as oxygenation, ventilation, flow rates, and blood pressure management. We highlight potential mechanisms that lead to disruption of CA in both pediatric and adult populations, the challenges of measuring CA in these patients, and potential associations with neurological outcome. Altogether, we discuss individualized CA monitoring as a potential target for improving neurological outcomes in extracorporeal life support.

Cerebral Tissue Oxygen Saturation Measurements in Perinatal Asphyxia Cases Treated with Therapeutic Hypothermia

Cerebral tissue oxygen saturation (CrSO2) measured with near-infrared spectroscopy (NIRS) technology has recently become the subject of several research studies. The aim of this study was to investigate the diagnostic value of CrSO2 measurements in perinatal asphyxia (PA) cases. The study included a patient group of 42 PA cases, who were to be applied with therapeutic hypothermia (TH), and a control group of 42 healthy term newborns. PA cases were determined as moderate or severe encephalopathy (Sarnat score stage II or III) in clinical evaluation. In both groups, left (CrSO2L) and right (CrSO2R) NIRS measurements were taken for 10 minutes on the scalp. The arithmetic mean value of measurements was calculated and compared. The mean measurements were CrSO2R 67.38 ± 9.39 and CrSO2L 66.73 ± 7.76 in the patient group, and CrSO2R 80.28 ± 8.04 and CrSO2L 79.14 ± 8.49 in the control group. The mean CrSO2R and CrSO2L measurements of the patient group were statistically significantly lower than those of the control group (p < 0.001). In the Pearson correlation analysis, a significant correlation was determined in the patient group between cord blood gas pH and CrSO2R (r: 0.539, p < 0.001) and CrSO2L (r: 0.54, p < 0.001). For a cutoff value of CrSO2L ≤ 72%, the positive predictive value was 80 and the negative predictive value was 84.6. For a cutoff value of CrSO2R ≤ 74%, the positive predictive value was 79.5 and the negative predictive value was 82.5. Low CrSO2 measurements obtained with the NIRS method in PA cases to be applied with TH together with cord blood gas parameters can be considered a helpful parameter in diagnosis.

Neuromonitoring During ECMO Support in Children

Extracorporeal membrane oxygenation is a potentially lifesaving intervention for children with severe cardiac or respiratory failure. It is used with increasing frequency and in increasingly more complex and severe diseases. Neurological injuries are important causes of morbidity and mortality in children treated with extracorporeal membrane oxygenation and include ischemic stroke, intracranial hemorrhage, hypoxic-ischemic injury, and seizures. In this review, we discuss the epidemiology and pathophysiology of neurological injury in patients supported with extracorporeal membrane oxygenation, and we review the current state of knowledge for available modalities of monitoring neurological function in these children. These include structural imaging with computed tomography and ultrasound, cerebral blood flow monitoring with near-infrared spectroscopy and transcranial Doppler ultrasound, and physiological monitoring with electroencephalography and plasma biomarkers. We highlight areas of need and emerging advances that will improve our understanding of neurological injury related to extracorporeal membrane oxygenation and help to reduce the burden of neurological sequelae in these children.

Clinical Guidelines for Routine Neuromonitoring in Neonatal and Pediatric Patients Supported on Extracorporeal Membrane Oxygenation

DISCLAIMER

These guidelines for routine neuromonitoring in neonatal and pediatric patients supported on extracorporeal membrane oxygenation (ECMO) are intended for educational use to build the knowledge of physicians and other health professionals in assessing the conditions and managing the treatment of patients undergoing extracorporeal life support (ECLS)/ECMO and describe what are believed to be useful and safe practice for ECLS and ECMO but these are not necessarily consensus recommendations. The aim of clinical guidelines was to help clinicians to make informed decisions about their patients. However, adherence to a guideline does not guarantee a successful outcome. Healthcare professionals must make their own treatment decisions about care on a case-by-case basis, after consultation with their patients, using their clinical judgment, knowledge, and expertise. These guidelines do not take the place of physicians' and other health professionals' judgment in diagnosing and treatment of patients. These guidelines are not intended to and should not be interpreted as setting a standard of care or being deemed inclusive of all proper methods of care nor exclusive of other methods of care directed at obtaining the same results. The ultimate judgment must be made by the physician and other health professionals and the patient considering all the circumstances presented by the individual patient, and the known variability and biologic behavior of the clinical condition. These guidelines reflect the data at the time the guidelines were prepared; the results of subsequent studies or other information may cause revisions to the recommendations in these guidelines to be prudent to reflect new data, but ELSO is under no obligation to provide updates. In no event will ELSO be liable for any decision made or action taken in reliance upon the information provided through these guidelines.

Pediatric ECLS Neurologic Management and Outcomes

Neurologic complications associated with extracorporeal life support (ECLS), including seizures, ischemia/infarction, and intracranial hemorrhage significantly increase morbidity and mortality in pediatric and neonatal patients. Prompt recognition of adverse neurologic events may provide a window to intervene with neuroprotective measures. Many neuromonitoring modalities are available with varying benefits and limitations. Several pre-ECLS and ECLS-related factors have been associated with an increased risk for neurologic complications. These may be patient- or circuit-related and include modifiable and non-modifiable factors. ECLS survivors are at risk for long-term neurological sequelae affecting neurodevelopmental outcomes. Possible long-term outcomes range from normal development to severe impairment. Patients should undergo a neurological evaluation prior to discharge, and neurodevelopmental assessments should be included in each patient's structured, multidisciplinary follow-up. Safe pediatric and neonatal ECLS management requires a thorough understanding of neurological complications, neuromonitoring techniques and limitations, considerations to minimize risk, and an awareness of possible long-term ramifications. With a focus on ECLS for respiratory failure, this manuscript provides a review of these topics and summarizes best practice guidelines from international organizations and expert consensus.

Association Between Disrupted Cerebral Autoregulation and Radiographic Neurologic Injury for Children on Extracorporeal Membrane Oxygenation: A Prospective Pilot Study

Validation of a real-time monitoring device to evaluate the risk or occurrence of neurologic injury while on extracorporeal membrane oxygenation (ECMO) may aid clinicians in prevention and treatment. Therefore, we performed a pilot prospective cohort study of children under 18 years old on ECMO to analyze the association between cerebral blood pressure autoregulation as measured by diffuse correlation spectroscopy (DCS) and radiographic neurologic injury. DCS measurements of regional cerebral blood flow were collected on enrolled patients and correlated with mean arterial blood pressure to determine the cerebral autoregulation metric termed DCSx. The primary outcome of interest was radiographic neurologic injury on eligible computed tomography (CT) or magnetic resonance imaging (MRI) scored by a blinded pediatric neuroradiologist utilizing a previously validated scale. Higher DCSx scores, which indicate disruption of cerebral autoregulation, were associated with higher radiographic neurologic injury score (slope, 11.0; 95% confidence interval [CI], 0.29-22). Patients with clinically significant neurologic injury scores of 10 or more had higher median DCSx measures than patients with lower neurologic injury scores (0.48 vs . 0.13; p = 0.01). Our study indicates that obtaining noninvasive DCS measures for children on ECMO is feasible and disruption of cerebral autoregulation determined from DCS is associated with higher radiographic neurologic injury score.

International survey of neuromonitoring and neurodevelopmental outcome in children and adults supported on extracorporeal membrane oxygenation in Europe

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.

ECMO in neonates: The association between cerebral hemodynamics with neurological function

Extracorporeal membrane oxygenation (ECMO) is a superior life support technology, commonly employed in critical patients with severe respiratory or hemodynamic failure to provide effective respiratory and circulatory support, which is especially recommended for the treatment of critical neonates. However, the vascular management of neonates with veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is still under controversy. Reconstruction or ligation for the right common carotid artery (RCCA) after ECMO is inconclusive. This review summarized the existed studies on hemodynamics and neurological function after vascular ligation or reconstruction hoping to provide better strategies for vessel management in newborns after ECMO. After reconstruction, the right cerebral blood flow can increase immediately, and the normal blood supply can be restored rapidly. But the reconstructed vessel may be occluded and stenotic in long-term follow-ups. Ligation may cause lateralization damage, but there could be no significant effect owing to the establishment of collateral circulation. The completion of the circle of Willis, the congenital anomalies of cerebral or cervical vasculature, the duration of ECMO, and the vascular condition at the site of arterial catheterization should be assessed carefully before making the decision. It is also necessary to follow up on the reconstructed vessel sustainability, and the association between cerebral hemodynamics and neurological function requires further large-scale multi-center studies.

Application of Near-Infrared Spectroscopy to Monitor Perfusion During Extracorporeal Membrane Oxygenation After Pediatric Heart Surgery

Objective: Venoarterial extracorporeal membrane oxygenation is an effective mechanical circulatory support that is used to rescue critically ill patients after congenital heart surgery. As there was still no recommended guideline for monitoring parameters during extracorporeal membrane oxygenation (ECMO), this study aimed to investigate the role of near-infrared spectroscopy (NIRS) in the early period of venoarterial (VA)-ECMO. Method: This study enrolled patients with NIRS monitoring during ECMO after pediatric cardiac surgery at Shanghai Children's Medical Center (2018-2020). The information obtained from the retrospective, the observational dataset included the demographic information, diagnoses, baseline characteristics, procedural details, ECMO data, monitoring data, in-hospital mortality, and complications of the patients. Results: The overall mortality rate was 43.6%. Lactate was significantly higher in non-survivors compared to survivors at 12 h (11.25 ± 7.26 vs. 6.96 ± 5.95 mmol/l, p = 0.022) and 48 h [2.2 (0.7, 20) vs. 1.4 (0.7, 5.8) mmol/l, p = 0.008] after initiation of ECMO. The cranial regional oxygen saturation (CrSO₂) was significantly higher in survivors compared to non-survivors at 24 h (62.5 ± 14.61 vs. 52.05 ± 13.98%, p = 0.028), 36 h (64.04 ± 14.12 vs. 51.27 ± 15.65%, p = 0.005), and 48 h (65.32 ± 11.51 vs. 55.00 ± 14.18%, p = 0.008). Multivariate logistics regression analysis of the hemodynamic and laboratory parameters revealed that the CrSO₂ at 36 h (OR = 0.945, p = 0.049) and 48 h (OR = 0.919, p = 0.032) was related to mortality. The use of continuous renal replacement therapy (OR = 14.940, p = 0.039) was also related to mortality. The optimal cutoff values for CrSO₂ for predicting mortality after weaning off ECMO at 36 and 48 h were 57% (sensitivity: 61.5%, specificity: 80%) and 56% (sensitivity: 76.9%, specificity: 70%), respectively. The risk of mortality was higher among patients with a CrSO₂(36h) < 57% (p = 0.028) by Kaplan-Meier analysis. Conclusion: Near-infrared spectroscopy may be a useful tool for monitoring the hemodynamic stability during the early period of ECMO, while CrSO₂ can predict the in-hospital mortality after ECMO.

Near-infrared spectroscopy for perioperative assessment and neonatal interventions

Perioperative applications of near-infrared spectroscopy (NIRS) to monitor regional tissue oxygenation and perfusion in cardiac and noncardiac surgery are of increasing interest in neonatal care. Complex neonatal surgery can impair adequate oxygen delivery and tissue oxygen consumption and increase the risk of neurodevelopmental delay. Coupled with conventional techniques, NIRS monitoring may enable targeted hemodynamic management of the circulation in both cardiac and noncardiac surgical procedures. In this narrative review, we discuss the application of perioperative NIRS in specific neonatal interventions, including surgical intervention for congenital heart defects, definitive closure of the patent ductus arteriosus, neurological and gastrointestinal disorders, and use of extracorporeal membrane oxygenation. We identified areas for future research within disease-specific indications and offer a roadmap to aid in developing evidence-based targeted diagnostic and management strategies in neonates. IMPACT: There is growing recognition that perioperative NIRS monitoring, used in conjunction with conventional monitoring, may provide critical hemodynamic information that either complements clinical impressions or delivers novel physiologic insight into the neonatal circulatory and perfusion pathways.

Noninvasive neurocritical care monitoring for neonates on extracorporeal membrane oxygenation: where do we stand?

OBJECTIVE

To determine practice variation in the utilization of neuromonitoring modalities in neonatal extracorporeal membrane oxygenation (ECMO) patients across Level IV neonatal intensive care units (NICUs).

STUDY DESIGN

Cross-sectional survey design using electronic surveys sent to site sponsors of a multicenter collaborative of 34 Level IV NICUs of the Children's Hospitals Neonatal Consortium (CHNC) from June to August 2018.

RESULTS

We had 22 survey respondents from CHNC ECMO centers. Twenty-seven percent of respondents routinely monitored for seizures using electroencephalogram. Cerebral near infrared spectroscopy was used by 50%. Head ultrasound was performed by 95% but the frequency, duration, and type of views varied. Post ECMO screening brain MRI prior to hospital discharge was routinely performed by 77% of respondents. A majority of centers (95%) performed neurodevelopmental follow-up after hospital discharge.

CONCLUSIONS

There is variation in neuromonitoring practices in Level IV NICUs performing ECMO. Lack of evidence and clear outcome benefits has contributed to practice variation across institutions.

Association of Cerebral Oxymetry with Short-Term Outcome in Critically ill Children Undergoing Extracorporeal Membrane Oxygenation

BACKGROUND

Acute brain injury (ABI) is a frequent complication of pediatric extracorporeal membrane oxygenation (ECMO) that could be detected by continuous neuromonitoring. Cerebral near-infrared spectroscopy (NIRS) allows monitoring of cerebral oxygenation.

OBJECTIVE

To assess whether an impaired cerebral oxygenation was associated with short-term outcome during pediatric ECMO.

METHODS

We conducted a single-center retrospective study in a pediatric intensive care unit. Children under 18 years old were included if receiving veno-venous or veno-arterial ECMO with concurrent NIRS monitoring. Cerebral saturation impairment was defined as rScO2 under 50% or 20% from the baseline for desaturation, and above 80%. Cerebral imaging (magnetic resonance imaging or CT scan) was performed in case of neurological concern. A radiologist blinded for patient history identified ABI as any hemorragic or ischemic lesion, then classified as major or minor. Primary endpoint was the outcome at hospital discharge. Poor outcome was defined as death or survival with a pediatric cerebral performance category scale (PCPC) score ≥ 3 and/or a major ABI. Good outcome was defined as survival with a PCPC score ≤ 2 and/or a minor or no ABI. Secondary endpoint was mortality before PICU discharge.

RESULTS

Sixty-three patients met inclusion criteria; 48 (76%) had veno-arterial ECMO. Mortality rate was 51%. Forty-eight of sixty-three patients (76%) evolved with a poor outcome, including 20 major ABI. Mean rScO2 in the right/left hemisphere was 73 ± 9%/75 ± 9%. Cerebral desaturation and decline of rScO₂ below 20% from the baseline, regardless of side, were each associated with poor outcome (multivariable-adjusted odds ratio (OR), 4 [95%CI 1.2; 15.1], p = 0.03, and 3.9 [95%CI 1.1; 14.9], p = 0.04, respectively), as well as a mean right rScO₂ < 70% during the ECMO course (adjusted OR, 5.6 [95%CI 1.3; 34], p = 0.04). Left rSCO₂ ≥ 80% was inversely correlated with hospital mortality (adjusted OR of 0.14 [95%CI 0.02; 0.8], p = 0.04).

CONCLUSIONS

Cerebral desaturation attested by NIRS was associated with a poor short-term outcome in children of all ages undergoing ECMO, and rScO2 > 80% seemed to be protective. NIRS monitoring might be included within multimodal neuromonitoring to assess the risk of the brain injury related to pediatric ECMO.

Cerebral Tissue Regional Oxygen Saturation as a Valuable Monitoring Parameter in Pediatric Patients Undergoing Extracorporeal Membrane Oxygenation

Objective: Brain function monitoring technology for extracorporeal membrane oxygenation (ECMO) support has been developing quite slowly. Our objective was to explore the data distribution, variation trend, and variability of cerebral tissue regional oxygen saturation (CrSO₂) in pediatric patients undergoing ECMO. Methods: Eight patients who received venoarterial ECMO (V-A ECMO) were included in our study. All of them accepted continuous CrSO₂ monitoring by near-infrared spectroscopy (NIRS) within 12 h of ECMO initiation until ECMO wean. Differences in the CrSO₂ distribution characteristic, the variation trend of daily CrSO₂, and the variability of CrSO₂ for the first 5 days following ECMO initiation were compared between survivors and non-survivors according to pediatric intensive care unit (PICU) mortality. Results: The percentage of time of CrSO₂ <60% against the whole monitoring time was significantly lower in survivors in both hemispheres {right: 4.34% [interquartile range (IQR) = 0.39-8.55%] vs. 47.45% [IQR = 36.03-64.52%], p = 0.036; left: 0.40% [IQR = 0.01-1.15%] vs. 30.9% [IQR = 26.92-49.62%], p = 0.036}. Survivors had significantly higher CrSO₂ on the first 4 days. Root mean of successive squared differences (RMSSD), the variability variable of CrSO₂, was significantly lower in survivors (right: 3.29 ± 0.79 vs. 6.16 ± 0.67, p = 0.002; left: 3.56 ± 1.20 vs. 6.04 ± 1.44, p = 0.039). Conclusion: Lower CrSO₂, CrSO₂ <60% over a longer period of time, and higher fluctuation of CrSO₂ are likely associated with PICU mortality in pediatric patients undergoing V-A ECMO. Clinical Trial Registry: URL: http://www.chictr.org.cn/showproj.aspx?proj=46639, trial registry number: ChiCTR1900028021.