Early Fluid Accumulation and Intensive Care Unit Mortality in Children Receiving Extracorporeal Membrane Oxygenation

An update on the role of fluid overload in the prediction of outcome in acute kidney injury

Over the past two decades, our understanding of the impact of acute kidney injury, disorders of fluid balance, and their interplay have increased significantly. In recent years, the epidemiology and impact of fluid balance, including the pathologic state of fluid overload on outcomes has been studied extensively across multiple pediatric and neonatal populations. A detailed understating of fluid balance has become increasingly important as it is recognized as a target for intervention to continue to work to improve outcomes in these populations. In this review, we provide an update on the epidemiology and outcomes associated with fluid balance disorders and the development of fluid overload in children with acute kidney injury (AKI). This will include a detailed review of consensus definitions of fluid balance, fluid overload, and the methodologies to define them, impact of fluid balance on the diagnosis of AKI and the concept of fluid corrected serum creatinine. This review will also provide detailed descriptions of future directions and the changing paradigms around fluid balance and AKI in critical care nephrology, including the incorporation of the sequential utilization of risk stratification, novel biomarkers, and functional kidney tests (furosemide stress test) into research and ultimately clinical care. Finally, the review will conclude with novel methods currently under study to assess fluid balance and distribution (point of care ultrasound and bioimpedance).

Quantifying potential fluid transfused through pressure monitoring and circuit flushes in pediatric ECMO patients

Pressure monitoring on pediatric Extracorporeal Membrane Oxygenation (ECMO) circuits is used to aid in the evaluation of patient hemodynamics and circuit health. Extracorporeal Life Support Organization (ELSO) recommends monitoring pressures on the venous line, pre-, and post-oxygenator. In order to keep pressure ports patent, crystalloid can be used as a flush. The fluid transfused to the patient through these lines can be challenging to quantify accurately due to variance in clinician practice. Currently, there is no published data or practice suggestions on this topic. In Vitro experiments using Edwards True Wave transducers and pressure bags were constructed, allowing for common negative and positive pressures to be simulated. Passive volume infused through the transducer as well as intermittent active flushing by pulling the snap tab were measured and the volumes were recorded. When the pressure transducer and associated tubing are kept patent by using a pressurized IV bag, per the instructions for use, the daily volume transfused was found to be 319.6 mL or close to a typical neonate's total blood volume. Rather than using passive or active flushing, the use of automated syringe pumps can reduce the transfused volume to 24 mL per day. Further study is recommended to develop and publish best practices.

Neonatal Extracorporeal Membrane Oxygenation: Associations between Continuous Renal Replacement Therapy, Thrombocytopenia, and Outcomes

INTRODUCTION

The incidence of thrombocytopenia in neonates receiving extracorporeal membrane oxygenation (ECMO) with and without concurrent continuous renal replacement therapy (CRRT) and associated complications have not been well described. The primary aims of the current study were to (1) characterize thrombocytopenia in neonates receiving ECMO (including those treated concurrently with CRRT) and (2) evaluate risk factors (including CRRT utilization) associated with severe thrombocytopenia. In a planned exploratory secondary aim, we explored the association of severe thrombocytopenia with outcomes in neonates receiving ECMO.

METHODS

We conducted a retrospective single-center chart review of neonates who received ECMO 07/01/14-03/01/20 and evaluated associations between CRRT, severe thrombocytopenia (platelet count <50,000/mm3), and outcomes (ECMO duration, length of stay, and survival).

RESULTS

Fifty-two neonates received ECMO; 35 (67%) received concurrent CRRT. Severe thrombocytopenia occurred in 27 (52%) neonates overall and in 21 (60%) neonates who received concurrent CRRT. Underlying diagnosis, ECMO mode, care unit, and moderate/severe hemolysis differed between those who did and did not receive CRRT. CRRT receivers experienced shorter hospital stays than CRRT non-receivers, but ECMO duration, length of intensive care unit (ICU) stay, and survival did not differ between groups. CRRT receipt was associated with severe thrombocytopenia. Exploratory classification and regression tree (CART) analysis suggests CRRT use, birthweight, and ICU location are all predictors of interest for severe thrombocytopenia.

CONCLUSIONS

In our cohort, CRRT use during ECMO was associated with severe thrombocytopenia, and patients who received ECMO with CRRT experienced shorter hospital stays than those who did not receive CRRT. Exploratory CART analysis suggests CRRT use, birthweight, and ICU location are all predictors for severe thrombocytopenia and warrant further investigations in larger studies.

Fluid Management in Veno-Arterial Extracorporeal Membrane Oxygenation Therapy-Analysis of an Experimental Pig Model

(1) Background: Fluid resuscitation is a necessary part of therapeutic measures to maintain sufficient hemodynamics in extracorporeal membrane oxygenation (ECMO) circulation. In a post-hoc analysis, we aimed to investigate the impact of increased volume therapy in veno-arterial ECMO circulation on renal function and organ edema in a large animal model. (2) Methods: ECMO therapy was performed in 12 female pigs (Deutsche Landrasse × Pietrain) for 10 h with subsequent euthanasia. Applicable volume, in regard to the necessary maintenance of hemodynamics, was divided into moderate and extensive volume therapy (MVT/EVT) due to the double quantity of calculated physiologic urine output for the planned study period. Respiratory and hemodynamic data were measured continuously. Additionally, renal function and organ edema were assessed by blood and tissue samples. (3) Results: Four pigs received MVT, and eight pigs received EVT. After 10 h of ECMO circulation, no major differences were seen between the groups in regard to hemodynamic and respiratory data. The relative change in creatinine after 10 h of ECMO support was significantly higher in EVT (1.3 ± 0.3 MVT vs. 1.8 ± 0.5 EVT; p = 0.033). No major differences were evident for lung, heart, liver, and kidney samples in regard to organ edema in comparison of EVT and MVT. Bowel tissue showed a higher percentage of edema in EVT compared to MVT (77 ± 2% MVT vs. 80 ± 3% EVT; p = 0.049). (4) Conclusions: The presented data suggest potential deterioration of renal function and intestinal mucosa function by an increase in tissue edema due to volume overload in ECMO therapy.

Factors affecting in-hospital mortality among pediatric patients with myocarditis treated with mechanical circulatory support

BACKGROUND

Mechanical circulatory support (MCS) is a common treatment modality for circulatory failure caused by pediatric myocarditis. Despite improvements in treatment strategy, the mortality rate of pediatric patients with myocarditis treated with MCS is still high. Identifying the factors associated with mortality among pediatric patients with myocarditis treated with MCS may help reduce the mortality rate.

METHODS

This retrospective cohort study examined the data of patients aged <16 years who were admitted to a hospital between July 2010 and March 2018 for myocarditis; the data were collected from the Diagnosis Procedure Combination database, which is a national inpatient database in Japan.

RESULTS

During the study period, 105 of the 598 patients with myocarditis were treated with MCS. We excluded seven patients who died within 24 h of admission, resulting in 98 eligible patients. The overall in-hospital mortality was 22 %. In-hospital mortality was higher among patients aged <2 years and those who received cardiopulmonary resuscitation (CPR). Multivariable logistic regression analysis showed significantly higher in-hospital mortality among patients aged <2 years old [odds ratio (OR), 6.57; 95 % confidence interval (CI), 1.89-22.87] and those who received CPR (OR, 4.70; 95 % CI, 1.51-14.63; p < 0.01).

CONCLUSION

The in-hospital mortality of pediatric patients with myocarditis treated with MCS was high, particularly of children younger than 2 years and those who received CPR.

Impact of the Magnitude and Timing of Fluid Overload on Outcomes in Critically Ill Children: A Report From the Multicenter International Assessment of Worldwide Acute Kidney Injury, Renal Angina, and Epidemiology (AWARE) Study

OBJECTIVES

With the recognition that fluid overload (FO) has a detrimental impact on critically ill children, the critical care nephrology community has focused on identifying clinically meaningful targets for intervention. The current study aims to evaluate the epidemiology and outcomes associated with FO in an international multicenter cohort of critically ill children. The current study also aims to evaluate the association of FO at predetermined clinically relevant thresholds and time points (FO ≥ 5% and FO ≥ 10% at the end of ICU days 1 and 2) with outcomes.

DESIGN

Prospective cohort study.

SETTING

Multicenter, international collaborative of 32 pediatric ICUs.

PATIENTS

A total of 5,079 children and young adults admitted consecutively to pediatric ICUs as part of the Assessment of the Worldwide Acute Kidney Injury, Renal Angina and Epidemiology Study.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The FO thresholds at the time points of interest occurred commonly in the cohort (FO ≥ 5%Day1 in 38.1% [ n = 1753], FO ≥ 10%Day1 in 11.7% [ n = 537], FO ≥ 5%Day2 in 53.3% [ n = 1,539], FO ≥ 10%Day2 in 25.1% [ n = 724]). On Day1, multivariable modeling demonstrated that FO ≥ 5% was associated with fewer ICU-free days, and FO ≥ 10% was associated with higher mortality and fewer ICU and ventilator-free days. On multivariable modeling, FO-peak, Day2 FO ≥ 5%, and Day2 FO ≥ 10% were associated with higher mortality and fewer ICU and ventilator-free days.

CONCLUSIONS

This study found that mild-to-moderate FO as early as at the end of ICU Day1 is associated with adverse outcomes. The current study fills an important void in the literature by identifying critical combinations of FO timing and quantity associated with adverse outcomes (FO ≥ 5%Day1, FO ≥10%Day1, FO ≥ 5%Day2, and FO ≥ 10%Day2). Those novel findings will help guide the development of interventional strategies and trials targeting the treatment and prevention of clinically relevant FO.

Mortality prediction in pediatric postcardiotomy veno-arterial extracorporeal membrane oxygenation: A comparison of scoring systems

Background

Pediatric postcardiotomy veno-arterial extracorporeal membrane oxygenation (VA-ECMO) patients have high mortality and morbidity. There are currently three scoring systems available to predict mortality: the Pediatric Extracorporeal Membrane Oxygenation Prediction (PEP) model, Precannulation Pediatric Survival After VA-ECMO (Pedi-SAVE) score, and Postcannulation Pedi-SAVE score. These methods provide risk stratification scores for pediatric patients requiring ECMO for cardiac support. However, comparative validation of these scoring systems remains scarce. We aim to assess the ability of these models to predict outcomes in a cohort of pediatric patients undergoing VA-ECMO after cardiac surgery, and identify predictors of in-hospital mortality.

Methods

A retrospective analysis of 101 children admitted to Fuwai Hospital who received VA-ECMO from January 1, 2010 to December 31, 2020 was performed. Patients were divided into two groups, survivors (n = 49) and non-survivors (n = 52) according to in-hospital mortality. PEP model and Pedi-SAVE scores were calculated. The primary outcomes were the risk factors of in-hospital mortality, and the ability of the PEP model, Precannulation Pedi-SAVE and Postcannulation Pedi-SAVE scores to predict in-hospital mortality.

Results

Postcannulation Pedi-SAVE score accessing the entire ECMO process had the greatest area under receiver operator curve (AUROC), 0.816 [95% confidence interval (CI): 0.733–0.899]. Pre-ECMO PEP model could predict in-hospital mortality [AUROC = 0.691 (95% CI: 0.565–0.817)], and Precannulation Pedi-SAVE score had the poorest prediction [AUROC = 0.582(95% CI: 0.471–0.694)]. Lactate value at ECMO implantation [OR = 1.199 (1.064–1.351), P = 0.003] and infectious complications [OR = 5.169 (1.652–16.172), P = 0.005] were independent risk factors for in-hospital mortality.

Conclusion

Pediatric cardiac ECMO scoring systems, including multiple risk factors before and during ECMO, were found to be useful in this cohort. Both the pre-ECMO PEP model and the Postcannulation Pedi-SAVE score were found to have high predictive value for in-hospital mortality in pediatric postcardiotomy VA-ECMO.

An Ovine Model of Awake Veno-Arterial Extracorporeal Membrane Oxygenation

Background: Large animal models are developed to help understand physiology and explore clinical translational significance in the continuous development of veno-arterial extracorporeal membrane oxygenation (VA-ECMO) technology. The purpose of this study was to investigate the establishment methods and management strategies in an ovine model of VA-ECMO. Methods: Seven sheep underwent VA-ECMO support for 7 days by cannulation via the right jugular vein and artery. The animals were transferred into the monitoring cages after surgery and were kept awake after anesthesia recovery. The hydraulic parameters of ECMO, basic hemodynamics, mental state, and fed state of sheep were observed in real time. Blood gas analysis and activated clotting time (ACT) were tested every 6 h, while the complete blood count, blood chemistry, and coagulation tests were monitored every day. Sheep were euthanized after 7 days. Necropsy was performed and the main organs were removed for histopathological evaluation. Results: Five sheep survived and successfully weaned from ECMO. Two sheep died within 24-48 h of ECMO support. One animal died of fungal pneumonia caused by reflux aspiration, and the other died of hemorrhagic shock caused by bleeding at the left jugular artery cannulation site used for hemodynamic monitoring. During the experiment, the hemodynamics of the five sheep were stable. The animals stayed awake and freely ate hay and feed pellets and drank water. With no need for additional nutrition support or transfusion, the hemoglobin concentration and platelet count were in the normal reference range. The ECMO flow remained stable and the oxygenation performance of the oxygenator was satisfactory. No major adverse pathological injury occurred. Conclusions: The perioperative management strategies and animal care are the key points of the VA-ECMO model in conscious sheep. This model could be a platform for further research of disease animal models, pathophysiology exploration, and new equipment verification.

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.

Continuous renal replacement therapy in patients treated with extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation (ECMO) is a life‐saving therapy utilized for patients with severe life‐threatening cardiorespiratory failure. Patients treated with ECMO are among the most severely ill encountered in critical care and are at high‐risk of developing multiple organ dysfunction, including acute kidney injury (AKI) and fluid overload. Continuous renal replacement therapy (CRRT) is increasingly utilized inpatients on ECMO to manage AKI and treat fluid overload. The indications for renal replacement therapy for patients on ECMO are similar to those of other critically ill populations; however, there is wide practice variation in how renal supportive therapies are utilized during ECMO. For patients requiring both CRRT and ECMO, CRRT may be connected directly to the ECMO circuit, or CRRT and ECMO may be performed independently. This review will summarize current knowledge of the epidemiology of AKI, indications and timing of CRRT, delivery of CRRT, and the outcomes of patients requiring CRRT with ECMO.