Early postoperative fluid overload precedes acute kidney injury and is associated with higher morbidity in pediatric cardiac surgery patients

Syndecan-1 as a Biomarker for Fluid Overload After High-Risk Pediatric Cardiac Surgery: A Pilot Study

OBJECTIVE

Fluid overload (FO) after pediatric cardiac surgery with cardiopulmonary bypass (CPB) is common and has been associated with poor outcomes. We aimed to describe the relationship between plasma concentrations of syndecan-1 (SD1), a biomarker of endothelial glycocalyx injury, and FO in a cohort of children undergoing cardiac surgery.

DESIGN

Single-center prospective observational pilot study, 2022-2023.

SETTING

Twenty-six-bed pediatric cardiac ICU (CICU) at a quaternary pediatric referral center.

PATIENTS

Children younger than 18 years old undergoing Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery congenital heart surgery mortality category 3, 4, and 5 cardiac surgeries with CPB.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We enrolled 15 patients. Blood samples were collected preoperatively and 4 hours postoperatively, then processed for plasma. SD1 concentrations were measured using enzyme-linked immunosorbent assays and compared with fluid balance on postoperative days (PODs) 1, 2, 3, and peak. SD1 discriminated fluid balance of greater than or equal to 10% on POD-1, POD-2, and POD-3 with an area under the receiver operating characteristic curve (AUROC) of 0.74, 0.84, and 0.88, respectively. SD1 also discriminated peak fluid balance of greater than or equal to 10% occurring on any day over the first seven PODs with an AUROC of 0.94. Patients with greater than or equal to 10% fluid balance on POD-2 ( p = 0.037), POD-3 ( p = 0.020), or peak ( p = 0.021) had significantly elevated delta SD1 when compared with those reaching less than 10%. Fluid balance of greater than or equal to 10% on POD-2 was associated with adverse events including longer duration of mechanical ventilation and CICU stay.

CONCLUSIONS

Plasma SD1 was associated with FO in pediatric patients undergoing high-risk cardiac surgery with CPB. Further studies exploring the clinical utility of SD1 as a biomarker for FO in the postoperative management of children who undergo cardiac surgery with CPB should be pursued.

Relationship between fluid overload and mortality and morbidity in pediatric intensive care unit

OBJECTIVE

The relationship between fluid overload and clinical outcomes was investigated.

DESIGN

This study is an observational and analytic study of a retrospective cohort.

SETTINGS

Pediatric intensive care units.

PATIENTS OR PARTICIPANTS

Between 2019 and 2021 children who needed intensive care were included in the study.

INTERVENTIONS

No intervention.

MAIN VARIABLE OF INTEREST

Early, peak and cumulative fluid overload were evaluated.

RESULTS

The mortality rate was 11.7% (68/513). When fluid overloads were examined in terms of mortality, the percentage of early fluid overload was 1.86 and 3.35, the percent of peak fluid overload was 2.87 and 5.54, and the percent of cumulative fluid overload was 3.40 and 8.16, respectively, in the survivor and the non-survivor groups. After adjustment for age, severity of illness, and other potential confounders, peak (aOR = 1.15; 95%CI 1.05-1.26; p: 0.002) and cumulative (aOR = 1.10; 95%CI 1.04-1.16; p < 0.001) fluid overloads were determined as independent risk factors associated with mortality. When the cumulative fluid overload is 10% or more, a 3.9-fold increase mortality rate was calculated. It is found that the peak and cumulative fluid overload, had significant negative correlation with intensive care unit free days and ventilator free days.

CONCLUSIONS

It is found that peak and cumulative fluid overload in critically ill children were independently associated with intensive care unit mortality and morbidity.

Acute Effects of Aminophylline Effects on Hemodynamic Parameters and Fluid Balance in Pediatric Cardiac Intensive Care Patients: Machine Learning Insights Using High Fidelity Data

Fluid overload is associated with increased morbidity and mortality after pediatric cardiac surgery. Management of fluid overload can be difficult and conventional tools may increase the risk of acute kidney injury. This study aimed to study the effects of aminophylline on fluid balance, urine output, blood urea nitrogen, and serum creatinine. Pediatric cardiac surgical patients who received aminophylline between September 2022 and December 2023 were identified. Data for various clinical parameters before and after an aminophylline dose were collected. Paired univariable analyses and a random forest classifier were conducted to help characterize the effects of aminophylline. A total of 169 aminophylline administrations in 72 unique patients were included in the final analyses. Fluid balance decreased by 115% in the 24 h after aminophylline administration compared to the 24 h preceding. Urine output peaked at 2 h after administration and increased 100% from baseline. Heart rate increased by 5% after administration and peaked between 2 and 4 h after. In pediatric patients after cardiac surgery, a 5 mg/kg dose of aminophylline is safe and is associated with a reduction in fluid balance and increase in urine output without significantly changing blood urea nitrogen or serum creatinine levels.

Fluid deresuscitation in critically ill children: comparing perspectives of intensivists and nephrologists

Introduction

Fluid accumulation, presently defined as a pathologic state of overhydration/volume overload associated with clinical impact, is common and associated with worse outcomes. At times, deresuscitation, the active removal of fluid via diuretics or ultrafiltration, is necessary. There is no consensus regarding deresuscitation in children admitted to the pediatric intensive care unit. Little is known regarding perceptions and practices among pediatric intensivists and nephrologists regarding fluid provision and deresuscitation.

Methods

Cross-sectional electronic survey of pediatric nephrologists and intensivists from academic societies in the United States designed to better understand fluid management between disciplines. A clinical vignette was used to characterize the perceptions of optimal timing and method of deresuscitation initiation at four timepoints that correspond to different stages of shock.

Results

In total, 179 respondents (140 intensivists, 39 nephrologists) completed the survey. Most 75.4% (135/179) providers believe discussing fluid balance and initiating fluid deresuscitation in pediatric intensive care unit (PICU) patients is "very important". The first clinical vignette time point (corresponding to resuscitation phase of early shock) had the most dissimilarity between intensivists and nephrologists (p = 0.01) with regards to initiation of deresuscitation. However, providers demonstrated increasing agreement in their responses to initiate deresuscitation as the clinical vignette progressed. Compared to intensivists, nephrologists were more likely to choose "dialysis or ultrafiltration" as a deresuscitation method during the optimization [10.3 vs. 2.9% (p = 0.07)], stabilization [18.0% vs. 3.6% (p < 0.01)], and evacuation [48.7% vs. 23.6% (p < 0.01)] phases of shock. Conversely, intensivists were more likely to utilize scheduled diuretics than nephrologists [47.1% vs. 28.2% (p = 0.04)] later on in the patient course.

Discussion

Most physicians believe that discussing fluid balance and deresuscitation is important. Nevertheless, when to initiate deresuscitation and how to accomplish it differed between nephrologist and intensivists. Widely understood and operationalizable definitions, further research, and eventually evidence-based guidelines are needed to help guide care.

Fluid Overload and AKI After the Norwood Operation: The Correlation and Characterization of Routine Clinical Markers

The purpose of this study was to determine the correlation of different methods of assessing fluid overload and determine which metrics are associated with development of acute kidney injury (AKI) in the period immediately following Norwood palliation. This was a retrospective single-center study of Norwood patients from January 2011 through January 2021. AKI was defined using the Kidney Disease Improving Global Outcomes (KDIGO). Patients were separated into two groups: those with AKI and those without. A logistic regression analysis was conducted with AKI at any point in the study period as the dependent variable and clinical and laboratory data as independent variables. Analysis was conducted as a stepwise regression. The coefficients from the logistic regression were then used to develop a cumulative AKI risk score. Spearman correlations were conducted to analyze the correlation of fluid markers. 116 patients were included, and 49 (42.4%) developed AKI. The duration of open chest, duration of mechanical ventilation, need for dialysis, need for extracorporeal membrane oxygenation, and inpatient mortality were associated with AKI (p ≤ 0.05). Stepwise logistic regression demonstrated the following significant independent associations AKI: age at Norwood in days (p < 0.01), blood urea nitrogen (p < 0.01), central venous pressure (p = 0.04), and renal oxygen extraction ratio (p < 0.01). The area under the receiver operating characteristic curve for the logistic regression was 0.74. The fluid markers had weak R-value. Urea, central venous pressure, and renal oxygen extraction ratio are associated with AKI after the Norwood operation. Common clinical metrics used to assess fluid overload are poorly correlated with each other for postoperative Norwood patients.

The effect of high-volume intraoperative fluid administration on outcomes among pediatric patients undergoing living donor liver transplantation

BACKGROUND

Pediatric patients undergoing liver transplantation are particularly susceptible to complications arising from intraoperative fluid management strategies. Conventional liberal fluid administration has been challenged due to its association with increased perioperative morbidity. This study aimed to assess the impact of intraoperative high-volume fluid therapy on pediatric patients who are undergoing living donor liver transplantation (LDLT).

METHODS

Conducted at the Children's Hospital of Chongqing Medical University from March 2018 to April 2021, this retrospective study involved 90 pediatric patients divided into high-volume and non-high-volume fluid administration groups based on the 80th percentile of fluid administered. We collected the perioperative parameters and postoperative information of two groups. Multivariable logistic regression was utilized to assess the association between estimated blood loss (EBL) and high-volume FA. Kaplan-Meier survival analysis was used to compare patient survival after pediatric LDLT.

RESULTS

Patients in the high-volume FA group received a higher EBL and longer length of stay than that in the non-high-volume FA group. Multivariate logistic regression analysis indicated that hours of maintenance fluids and fresh frozen plasma were significantly associated risk factors for the occurrence of EBL during pediatric LDLT. In addition, survival analysis showed no significant differences in one-year mortality between the groups.

CONCLUSIONS

High-volume fluid administration during LDLT is linked with poorer intraoperative and postoperative outcomes among pediatric patients. These findings underscore the need for more conservative fluid management strategies in pediatric liver transplantations to enhance recovery and reduce complications.

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).

An evaluation of the outcomes associated with peritoneal catheter use in neonates undergoing cardiac surgery: A multicenter study

Objective

The study objective was to determine if intraoperative peritoneal catheter placement is associated with improved outcomes in neonates undergoing high-risk cardiac surgery with cardiopulmonary bypass.

Methods

This propensity score-matched retrospective study used data from 22 academic pediatric cardiac intensive care units. Consecutive neonates undergoing Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery category 3 to 5 cardiac surgery with cardiopulmonary bypass at centers participating in the NEonatal and Pediatric Heart Renal Outcomes Network collaborative were studied to determine the association of the use of an intraoperative placed peritoneal catheter for dialysis or passive drainage with clinical outcomes, including the duration of mechanical ventilation.

Results

Among 1490 eligible neonates in the NEonatal and Pediatric Heart Renal Outcomes Network dataset, a propensity-matched analysis was used to compare 395 patients with peritoneal catheter placement with 628 patients without peritoneal catheter placement. Time to extubation and most clinical outcomes were similar. Postoperative length of stay was 5 days longer in the peritoneal catheter placement cohort (17 vs 22 days, P = .001). There was a 50% higher incidence of moderate to severe acute kidney injury in the no-peritoneal catheter cohort (12% vs 18%, P = .02). Subgroup analyses between specific treatments and in highest risk patients yielded similar associations.

Conclusions

This study does not demonstrate improved outcomes among neonates with placement of a peritoneal catheter during cardiac surgery. Outcomes were similar apart from longer hospital stay in the peritoneal catheter cohort. The no-peritoneal catheter cohort had a 50% higher incidence of moderate to severe acute kidney injury (12% vs 18%). This analysis does not support indiscriminate peritoneal catheter use, although it may support the utility for postoperative fluid removal among neonates at risk for acute kidney injury. A multicenter controlled trial may better elucidate peritoneal catheter effects.

Cardiac Surgery-Associated Acute Kidney Injury

AKI is a common and serious complication of cardiac surgery that has a significant impact on patient morbidity and mortality. The Kidney Disease Improving Global Outcomes definition of AKI is widely used to classify and identify AKI associated with cardiac surgery (cardiac surgery-associated AKI [CSA-AKI]) on the basis of changes in serum creatinine and/or urine output. There are various preoperative, intraoperative, and postoperative risk factors for the development of CSA-AKI which should be recognized and addressed as early as possible to expedite its diagnosis, reduce its occurrence, and prevent or ameliorate its devastating complications. Crucial issues are the inaccuracy of serum creatinine as a surrogate parameter of kidney function in the perioperative setting of cardiothoracic surgery and the necessity to discover more representative markers of the pathophysiology of AKI. However, except for the tissue inhibitor of metalloproteinase-2 and insulin-like growth factor binding protein 7 ratio, other diagnostic biomarkers with an acceptable sensitivity and specificity are still lacking. This article provides a comprehensive review of various aspects of CSA-AKI, including pathogenesis, risk factors, diagnosis, biomarkers, classification, prevention, and treatment management.

Fluid assessment, fluid balance, and fluid overload in sick children: a report from the Pediatric Acute Disease Quality Initiative (ADQI) conference

BACKGROUND

The impact of disorders of fluid balance, including the pathologic state of fluid overload in sick children has become increasingly apparent. With this understanding, there has been a shift from application of absolute thresholds of fluid accumulation to an appreciation of the intricacies of fluid balance, including the impact of timing, trajectory, and disease pathophysiology.

METHODS

The 26th Acute Disease Quality Initiative was the first to be exclusively dedicated to pediatric and neonatal acute kidney injury (pADQI). As part of the consensus panel, a multidisciplinary working group dedicated to fluid balance, fluid accumulation, and fluid overload was created. Through a search, review, and appraisal of the literature, summative consensus statements, along with identification of knowledge gaps and recommendations for clinical practice and research were developed.

CONCLUSIONS

The 26th pADQI conference proposed harmonized terminology for fluid balance and for describing a pathologic state of fluid overload for clinical practice and research. Recommendations include that the terms daily fluid balance, cumulative fluid balance, and percent cumulative fluid balance be utilized to describe the fluid status of sick children. The term fluid overload is to be preserved for describing a pathologic state of positive fluid balance associated with adverse events. Several recommendations for research were proposed including focused validation of the definition of fluid balance, fluid overload, and proposed methodologic approaches and endpoints for clinical trials.

Activation of renal epithelial Na+ channels (ENaC) in infants with congenital heart disease

Introduction

This study was designed to measure the concentration and activity of urinary proteases that activate renal epithelial sodium channel (ENaC) mediated Na+ transport in infants with congenital heart disease, a potential mechanism for fluid retention.

Methods

Urine samples from infants undergoing cardiac surgery were collected at three time points: T1) pre-operatively, T2) 6-8 h after surgery, and T3) 24 h after diuretics. Urine was collected from five heathy infant controls. The urine was tested for four proteases and whole-cell patch-clamp testing was conducted in renal collecting duct M-1 cells to test whether patient urine increased Na+ currents consistent with ENaC activation.

Results

Heavy chain of plasminogen, furin, and prostasin were significantly higher in cardiac patients prior to surgery compared to controls. There was no difference in most proteases before and after surgery. Urine from cardiac patients produced a significantly greater increase in Na+ inward currents compared to healthy controls.

Conclusion

Urine from infants with congenital heart disease is richer in proteases and has the potential to increase activation of ENaC in the nephron to enhance Na+ reabsorption, which may lead to fluid retention in this population.

Promising results of a clinical feasibility study: CIRBP as a potential biomarker in pediatric cardiac surgery

Objective

Cold-inducible RNA binding Protein (CIRBP) has been shown to be a potent inflammatory mediator and could serve as a novel biomarker for inflammation. Systemic inflammatory response syndrome (SIRS) and capillary leak syndrome (CLS) are frequent complications after pediatric cardiac surgery increasing morbidity, therefore early diagnosis and therapy is crucial. As CIRBP serum levels have not been analyzed in a pediatric population, we conducted a clinical feasibility establishing a customized magnetic bead panel analyzing CIRBP in pediatric patients undergoing cardiac surgery.

Methods

A prospective hypothesis generating observational clinical study was conducted at the German Heart Center Berlin during a period of 9 months starting in May 2020 (DRKS00020885, https://drks.de/search/de/trial/DRKS00020885). Serum samples were obtained before the cardiac operation, upon arrival at the pediatric intensive care unit, 6 and 24 h after the operation in patients up to 18 years of age with congenital heart disease (CHD). Customized multiplex magnetic bead-based immunoassay panels were developed to analyze CIRBP, Interleukin-1β (IL-1β), Interleukin-6 (IL-6), Interleukin-8 (IL-8), Interleukin-10 (IL-10), Monocyte chemotactic protein 1 (MCP-1), Syndecan-1 (SDC-1), Thrombomodulin (TM), Vascular endothelial growth factor (VEGF-A), Angiopoietin-2 (Ang-2), and Fibroblast growth factor 23 (FGF-23) in 25 µl serum using the Luminex MagPix® system.

Results

19 patients representing a broad range of CHD (10 male patients, median age 2 years, 9 female patients, median age 3 years) were included in the feasibility study. CIRBP was detectable in the whole patient cohort. Relative to individual baseline values, CIRBP concentrations increased 6 h after operation and returned to baseline levels over time. IL-6, IL-8, IL-10, and MCP-1 concentrations were significantly increased after operation and except for MCP-1 concentrations stayed upregulated over time. SDC-1, TM, Ang-2, as well as FGF-23 concentrations were also significantly increased, whereas VEGF-A concentration was significantly decreased after surgery.

Discussion

Using customized magnetic bead panels, we were able to detect CIRBP in a minimal serum volume (25 µl) in all enrolled patients. To our knowledge this is the first clinical study to assess CIRBP serum concentrations in a pediatric population.

Fluid overload in newborns undergoing abdominal surgery: a retrospective study

BACKGROUND

Fluid management in newborns undergoing surgery can be challenging due to difficulties in accurately assessing volume status in context of high fluid needs perioperatively and postoperative third-space fluid loss. Fluid overload can be associated with an increase in neonatal morbidity and mortality.

OBJECTIVE

Our objective was to determine the burden of fluid overload and to evaluate their associations with adverse effects among infants undergoing abdominal surgery at a tertiary perinatal center.

METHODS

Patients from our Neonatal Intensive Care Unit who underwent abdominal surgery from January 2017 to June 2019 were included in this retrospective cohort study. Fluid balance was assessed based on the maximum percentage change in body weight at 3- and 7-postoperative days.

RESULTS

Sixty infants were included, with a median [interquartile range] gestational age (GA) of 29 [25-36] weeks and birth weight of 1240 [721-2871] grams. The median daily actual fluid intake was significantly higher than the prescribed fluid intake in the first 7 postoperative days (163 vs. 145 mL/kg, p < .01). The median maximum change of body weight by postoperative days 3 and 7 were 6% [3-13] and 11% [5-17], respectively. A 1% increase in weight within the first 3 postoperative days was associated with a 0.6-day increase for invasive ventilatory support (p = .012). The correlation was still significant after adjusting for GA (p = .033).

CONCLUSION

Fluid overload within the first 3 postoperative days was associated with an increase in ventilator support among infants. Careful attention to fluid management may affect the optimization of outcomes for newborns undergoing abdominal surgery.

Nutritional and clinical factors associated with acute kidney injury development in critically ill children

BACKGROUND

Acute kidney injury (AKI) is common in the pediatric intensive care unit (ICU) and is associated with poorer clinical outcomes. There is scarce data to support an association between nutritional status and nutrient delivery in critically ill pediatric patients. Therefore, the present study aimed to identify the nutritional and clinical factors associated with the development of AKI during pediatric ICU stay.

METHODS

This prospective study included critically ill pediatric patients aged < 15 years who were admitted to the medical and surgical pediatric ICU. Clinical, laboratory, nutritional status, nutritional therapy parameters, and AKI data were recorded. Adjusted logistic regression was applied and expressed as odds ratio (OR) and 95% confidence interval (95%CI). P-value < 0.05 was considered significant.

RESULTS

We enrolled 108 patients with a median age of 9 months (interquartile range/IQR 2.4-62.5), and 43.5% developed AKI. Sepsis/septic shock (OR 8.00; 95% CI 2.06-32.51, p = 0.003), higher severity of illness (OR 1.89; 95% CI 1.24-2.90, p = 0.003), hypoalbuminemia (OR 4.11; 95% CI 1.61-10.46, p = 0.006), edema (OR 3.42, 95% CI 1.10-10.67, p = 0.034), fluid overload (OR 3.52, 95% CI 1.56-7.96, p = 0.003), need for mechanical ventilation (OR 3.62, 95% CI 1.45-9.04, p = 0.006) and adequate protein intake (OR 0.79, 95% CI 0.63-1.00, p = 0.048) were associated with development of AKI.

CONCLUSIONS

Hypoalbuminemia, need for mechanical ventilation, fluid overload, severity of illness, sepsis/septic shock, and edema were risk factors for AKI in pediatric ICU. Furthermore, adequate protein intake is associated with AKI during pediatric ICU stay, making it important to implement nutritional assessment and nutritional therapy protocols for critically ill pediatric patients.

Nonresuscitation Fluid Accumulation and Outcomes After Pediatric Cardiac Surgery: Single-Center Retrospective Cohort Study

OBJECTIVES

Postoperative patients after congenital cardiac surgery are at high risk of fluid overload (FO), which is known to be associated with poor outcomes. "Fluid creep," or nonresuscitation IV fluid in excess of maintenance requirement, is recognized as a modifiable factor associated with FO in the general PICU population, but has not been studied in congenital cardiac surgery patients. Our objective was to characterize fluid administration after congenital cardiac surgery, quantify fluid creep, and the association between fluid creep, FO, and outcome.

DESIGN

Retrospective, observational cohort study.

SETTING

Single-center urban mixed-medical and cardiac PICU.

PATIENTS

Patients admitted to the PICU after cardiac surgery between January 2010 and December 2020.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

There were 1,459 postoperative encounters with 1,224 unique patients. Total fluid intake was greater than maintenance requirements on 3,103 of 4,661 patient days (67%), with fluid creep present on 2,624 patient days (56%). Total nonresuscitation intake was higher in patients with FO (defined as cumulative fluid balance 10% above body weight) versus those without. Fluid creep was higher among patients with FO than those without for each of the first 5 days postoperatively. Each 10 mL/kg of fluid creep in the first 24 hours postoperatively was associated with 26% greater odds of developing FO (odds ratio [OR] 1.26; 95% CI, 1.17-1.35) and 17% greater odds of mortality (OR 1.17; 95% CI, 1.05-1.30) after adjusting for risk of mortality based on surgical procedure, age, and day 1 resuscitation volume. Increasing fluid creep in the first 24 hours postoperatively was associated with increased postoperative duration of mechanical ventilation and PICU length of stay.

CONCLUSIONS

Fluid creep is present on most postoperative days for pediatric congenital cardiac surgery patients, and fluid creep is associated with higher-risk procedures. Fluid creep early in the postoperative PICU stay is associated with greater odds of FO, mortality, length of mechanical ventilation, and PICU length of stay. Fluid creep may be under-recognized in this population and thus present a modifiable target for intervention.

Early postoperative weight-based fluid overload is associated with worse outcomes after neonatal cardiac surgery

OBJECTIVES

Evaluate the association of postoperative day (POD) 2 weight-based fluid balance (FB-W) > 10% with outcomes after neonatal cardiac surgery.

METHODS

Retrospective cohort study of 22 hospitals in the NEonatal and Pediatric Heart and Renal Outcomes Network (NEPHRON) registry from September 2015 to January 2018. Of 2240 eligible patients, 997 neonates (cardiopulmonary bypass (CPB) n = 658, non-CPB n = 339) were weighed on POD2 and included.

RESULTS

Forty-five percent (n = 444) of patients had FB-W > 10%. Patients with POD2 FB-W > 10% had higher acuity of illness and worse outcomes. Hospital mortality was 2.8% (n = 28) and not independently associated with POD2 FB-W > 10% (OR 1.04; 95% CI 0.29-3.68). POD2 FB-W > 10% was associated with all utilization outcomes, including duration of mechanical ventilation (multiplicative rate of 1.19; 95% CI 1.04-1.36), respiratory support (1.28; 95% CI 1.07-1.54), inotropic support (1.38; 95% CI 1.10-1.73), and postoperative hospital length of stay (LOS 1.15; 95% CI 1.03-1.27). In secondary analyses, POD2 FB-W as a continuous variable demonstrated association with prolonged durations of mechanical ventilation (OR 1.04; 95% CI 1.02-1.06], respiratory support (1.03; 95% CI 1.01-1.05), inotropic support (1.03; 95% CI 1.00-1.05), and postoperative hospital LOS (1.02; 95% CI 1.00-1.04). POD2 intake-output based fluid balance (FB-IO) was not associated with any outcome.

CONCLUSIONS

POD2 weight-based fluid balance > 10% occurs frequently after neonatal cardiac surgery and is associated with longer cardiorespiratory support and postoperative hospital LOS. However, POD2 FB-IO was not associated with clinical outcomes. Mitigating early postoperative fluid accumulation may improve outcomes but requires safely weighing neonates in the early postoperative period. A higher resolution version of the Graphical abstract is available as Supplementary information.

Association of Urine Biomarkers With Acute Kidney Injury and Fluid Overload in Infants After Cardiac Surgery: A Single Center Ancillary Cohort of the Steroids to Reduce Systemic Inflammation After Infant Heart Surgery Trial

To examine the association between three perioperative urine biomarker concentrations (urine cystatin C [uCysC], urine neutrophil gelatinase-associated lipocalin [uNGAL], and urine kidney injury molecule 1 [uKIM-1]), and cardiac surgery-associated acute kidney injury (CS-AKI) and fluid overload (FO) in infants with congenital heart disease undergoing surgery on cardiopulmonary bypass. To explore how urine biomarkers are associated with distinct CS-AKI phenotypes based on FO status.

DESIGN

Ancillary prospective cohort study.

SETTING

Single U.S. pediatric cardiac ICU.

PATIENTS

Infants less than 1 year old enrolled in the Steroids to Reduce Systemic Inflammation after Infant Heart Surgery trial (NCT03229538) who underwent heart surgery from June 2019 to May 2020 and opted into biomarker collection at a single center. Infants with preoperative CS-AKI were excluded.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Forty infants met inclusion criteria. Median (interquartile) age at surgery was 103 days (5.5-161 d). Modified Kidney Disease Improving Global Outcomes-defined CS-AKI was diagnosed in 22 (55%) infants and 21 (53%) developed FO. UCysC and uNGAL peaked in the early postoperative period and uKIM-1 peaked later. In unadjusted analysis, bypass time was longer, and Vasoactive-Inotropic Score at 24 hours was higher in infants with CS-AKI. On multivariable analysis, higher uCysC (odds ratio [OR], 1.023; 95% CI, 1.004-1.042) and uNGAL (OR, 1.019; 95% CI, 1.004-1.035) at 0-8 hours post-bypass were associated with FO. UCysC, uNGAL, and uKIM-1 did not significantly correlate with CS-AKI. In exploratory analyses of CS-AKI phenotypes, uCysC and uNGAL were highest in CS-AKI+/FO+ infants.

CONCLUSIONS

In this study, uCysC and uNGAL in the early postoperative period were associated with FO at 48 hours. UCysC, uNGAL, and uKIM-1 were not associated with CS-AKI. Further studies should focus on defining expected concentrations of these biomarkers, exploring CS-AKI phenotypes and outcomes, and establishing clinically meaningful endpoints for infants post-cardiac surgery.

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.

Fluid Overload in Pediatric Univentricular Patients Undergoing Fontan Completion

BACKGROUND

Fluid overload (FO) is known to occur frequently after pediatric cardiac surgery and is associated with morbidity and mortality. Fontan patients are at risk to develop FO due to their critical fluid balance. Furthermore, they need an adequate preload in order to maintain adequate cardiac output. This study aimed to identify FO in patients undergoing Fontan completion and the impact of FO on pediatric intensive care unit (PICU) length of stay (LOS) and cardiac events, defined as death, cardiac re-surgery or PICU re-hospitalization during follow-up.

METHODS

In this retrospective single center study, the presence of FO was assessed in 43 consecutive children undergoing Fontan completion.

RESULTS

Patients with more than 5% maximum FO had an extended PICU LOS (3.9 [2.9-6.9] vs. 1.9 [1.0-2.6] days; p < 0.001) and an increased length of mechanical ventilation (21 [9-121] vs. 6 [5-10] h; p = 0.001). Regression analysis demonstrated that an increase of 1% maximum FO was associated with a prolonged PICU LOS of 13% (95% CI 1.042-1.227; p = 0.004). Furthermore, patients with FO were at higher risk to develop cardiac events.

CONCLUSIONS

FO is associated with short-term and long-term complications. Further studies are needed to determine the impact of FO on the outcome in this specific population.

Assessment of fluid balance after neonatal cardiac surgery: a description of intake/output vs. weight-based methods

BACKGROUND

Fluid overload associates with poor outcomes after neonatal cardiac surgery, but consensus does not exist for the most clinically relevant method of measuring fluid balance (FB). While weight change-based FB (FB-W) is standard in neonatal intensive care units, weighing infants after cardiac surgery may be challenging. We aimed to identify characteristics associated with obtaining weights and to understand how intake/output-based FB (FB-IO) and FB-W compare in the early postoperative period in this population.

METHODS

Observational retrospective study of 2235 neonates undergoing cardiac surgery from 22 hospitals comprising the NEonatal and Pediatric Heart and Renal Outcomes Network (NEPHRON) database.

RESULTS

Forty-five percent (n = 998) of patients were weighed on postoperative day (POD) 2, varying from 2 to 98% among centers. Odds of being weighed were lower for STAT categories 4 and 5 (OR 0.72; 95% CI 0.53-0.98), cardiopulmonary bypass (0.59; 0.42-0.83), delayed sternal closure (0.27; 0.19-0.38), prophylactic peritoneal dialysis use (0.58; 0.34-0.99), and mechanical ventilation on POD 2 (0.23; 0.16-0.33). Correlation between FB-IO and FB-W was weak for every POD 1-6 and within the entire cohort (correlation coefficient 0.15; 95% CI 0.12-0.17). FB-W measured higher than paired FB-IO (mean bias 12.5%; 95% CI 11.6-13.4%) with wide 95% limits of agreement (- 15.4-40.4%).

CONCLUSIONS

Weighing neonates early after cardiac surgery is uncommon, with significant practice variation among centers. Patients with increased severity of illness are less likely to be weighed. FB-W and FB-IO have weak correlation, and further study is needed to determine which cumulative FB metric most associates with adverse outcomes. A higher resolution version of the Graphical abstract is available as Supplementary information.

Fluid Accumulation in Mechanically Ventilated, Critically Ill Children: Retrospective Cohort Study of Prevalence and Outcome

OBJECTIVES

To describe the prevalence, patterns, explanatory variables, and outcomes associated with fluid accumulation (FA) in mechanically ventilated children.

DESIGN

Retrospective cohort study.

SETTING

Tertiary PICU.

PATIENTS

Children mechanically ventilated for greater than or equal to 24 hours.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Between July 2016 and July 2021, 1,636 children met eligibility criteria. Median age was 5.5 months (interquartile range [IQR], 0.7-46.5 mo), and congenital heart disease was the most common diagnosis. Overall, by day 7 of admission, the median maximum cumulative FA, as a percentage of estimated admission weight, was 7.5% (IQR, 3.3-15.1) occurring at a median of 4 days after admission. Overall, higher FA was associated with greater duration of mechanical ventilation (MV) (mean difference, 1.17 [95% CI, 1.13-1.22]; p < 0.001]), longer intensive care length of stay (LOS) (mean difference, 1.16 [95% CI, 1.12-1.21]; p < 0.001]), longer hospital LOS (mean difference, 1.19 [95% CI, 1.13-1.26]; p < 0.001]), and increased mortality (odds ratio, 1.31 [95% CI, 1.08-1.59]; p = 0.005). However, these associations depended on the effects of children with extreme values, and there was no increase in risk up to 20% FA, overall, in children following cardiopulmonary bypass and in children in the general ICU. When excluding children with maximum FA of >10%, there was no association with duration of MV (mean difference, 0.99 [95% CI, 0.94-1.04]; p = 0.64) and intensive care or hospital LOS (mean difference, 1.01 [95% CI, 0.96-1.06]; p = 0.70 and 1.01 [95% CI, 0.95-1.08]; 0.79, respectively) but an association with reduced mortality 0.71 (95% CI, 0.53-0.97; p = 0.03).

CONCLUSIONS

In mechanically ventilated critically ill children, greater maximum FA was associated with longer duration of MV, intensive care LOS, hospital LOS, and mortality. However, these findings were driven by extreme values of FA of greater than 20%, and up to 10%, there was reduced mortality and no signal of harm.

Update on Pediatric Acute Kidney Injury

Acute kidney injury (AKI) is common in children and is associated with significant morbidity and mortality. In the last decade our understanding of AKI has improved significantly, and it is now considered a systemic disorder that affects other organs including heart, lung, and brain. In spite of its limitations, serum creatinine remains the mainstay in the diagnosis of AKI. However, newer approaches such as urinary biomarkers, furosemide stress test, and clinical decision support are being increasingly used and have the potential to improve the accuracy and timeliness of AKI diagnosis.

Intraoperative fluid balance and cardiac surgery-associated acute kidney injury: a multicenter prospective study

BACKGROUND

Recent data suggest the regime of fluid therapy intraoperatively in patients undergoing major surgeries may interfere in patient outcomes. The development of postoperative Acute Kidney Injury (AKI) has been associated with both Restrictive Fluid Balance (RFB) and Liberal Fluid Balance (LFB) during non-cardiac surgery. In patients undergoing cardiac surgery, this influence remains unclear. The study objective was to evaluate the relationship between intraoperative RFB vs. LFB and the incidence of Cardiac-Surgery-Associated AKI (CSA-AKI) and major postoperative outcomes in patients undergoing on-pump Coronary Artery Bypass Grafting (CABG).

METHODS

This prospective, multicenter, observational cohort study was set at two high-complexity university hospitals in Brazil. Adult patients who required postoperative intensive care after undergoing elective on-pump CABG were allocated to two groups according to their intraoperative fluid strategy (RFB or LFB) with no intervention.

RESULTS

The primary endpoint was CSA-AKI. The secondary outcomes were in-hospital mortality, cardiovascular complications, ICU Length of Stay (ICU-LOS), and Hospital LOS (H-LOS). After propensity score matching, 180 patients remained in each group. There was no difference in risk of CSA-AKI between the two groups (RR = 1.15; 95% CI, 0.85-1.56, p = 0.36). The in-hospital mortality, H-LOS and cardiovascular complications were higher in the LFB group. ICU-LOS was not significantly different between the two groups. ROCcurve analysis determined a fluid balance above 2500 mL to accurately predict in-hospital mortality.

CONCLUSION

Patients undergoing on-pump CABG with LFB when compared with patients with RFB present similar CSA-AKI rates and ICU-LOS, but higher in-hospital mortality, cardiovascular complications, and H-LOS.

The Effect of Aminophylline on Urine Output and Fluid Balance after a Single Dose in Children Admitted to the Pediatric Cardiac Intensive Care Unit

The purpose of this retrospective study was to investigate the effects of a single dose of aminophylline on urine output and fluid balance in children admitted to the cardiac intensive care unit. A retrospective study was performed to compare variables of interest before and 24 hours after aminophylline administration in children under the age of 18 years who were admitted to the cardiac intensive care unit at our institution from January 2011 onwards. Variables of interest included age, weight, aminophylline dose, concurrently administered diuretics, specific hemodynamic parameters, and blood urea nitrogen and creatinine levels. Variables such as urine output and fluid balance were measured through a binary endpoint. Data were compared in a paired fashion and continuous variables were compared through paired t-tests. Analyses were conducted using SPSS Version 23.0. A total of 14 patients were included in the study. There was no significant change in hemodynamic parameters or creatinine levels before and after intravenous aminophylline administration of 5 mg/kg. There was a significant difference in urine output, fluid balance, and blood urea nitrogen levels from the baseline value. Concurrent usage of diuretics did not show significant association with a difference in urine output or fluid balance from baseline. No significant adverse reactions were noted 24 hours after administration of aminophylline. Use of aminophylline dosed at 5 mg/kg is safe and leads to improvement in urine output and fluid balance without negatively impacting systemic oxygen delivery or renal filtration function.

Risk factors for the in-hospital mortality of CRRT-therapy patients with cardiac surgery-associated AKI: a single-center clinical study in China

OBJECTIVE

We retrospectively analyzed risk factors on in-hospital mortality in CRRT-therapy patients with open cardiac surgery (CS)-induced acute kidney injury (AKI), to provide the clinical basis for predicting and lowering the in-hospital mortality after CS.

METHODS

84 CS-AKI patients with CRRT were divided into survival and death groups according to discharge status, and the perioperative data were analyzed with R version 4.0.2.

RESULTS

There were significant differences between the two groups, including: urea nitrogen, Sequential Organ Failure Assessment (SOFA) score and vasoactive-inotropic score (VIS) on the first day after operation; VIS just before CRRT; SOFA score and negative balance of blood volume 24 h after CRRT; the incidence rate of bleeding, severe infection and MODS after operation; and the interval between AKI and CRRT. Univariate logistic regression analysis showed that SOFA score and VIS on the first day after operation; VIS just before CRRT; VIS and negative balance of blood volume 24 h after CRRT; the incidence rate of bleeding, infection and multiple organ dysfunction syndrome (MODS) after operation; bootstrap resampling analysis showed that SOFA score and VIS 24 h after CRRT, as well as the incidence of bleeding after operation were the independent risk factors.

CONCLUSION

Maintaining stable hemodynamics and active prevention of bleeding are expected to decrease the in-hospital mortality.

Lung Ultrasound versus Chest X-Ray for the Detection of Fluid Overload in Critically Ill Children: A Systematic Review

Fluid overload is a common complication of critical illness, associated with increased morbidity and mortality. Pulmonary fluid status is difficult to evaluate clinically and many clinicians utilize chest X-ray (CXR) to identify fluid overload. Adult data have shown lung ultrasound (LUS) to be a more sensitive modality. Our objective was to determine the performance of LUS for detecting fluid overload, with comparison to CXR, in critically ill children. We conducted a systematic review using multiple electronic databases and included studies from inception to November 15, 2020. The sensitivity and specificity of each test were evaluated. Out of 1,209 studies screened, 4 met eligibility criteria. Overall, CXR is reported to have low sensitivity (44–58%) and moderate specificity (52–94%) to detect fluid overload, while LUS is reported to have high sensitivity (90–100%) and specificity (94–100%). Overall, the quality of evidence was moderate, and the gold standard was different in each study. Our systematic review suggests LUS is more sensitive and specific than CXR to identify pulmonary fluid overload in critically ill children. Considering the clinical burden of fluid overload and the relative ease of obtaining LUS, further evaluation of LUS to diagnose volume overload is warranted.

Consensus-Based Recommendations on Priority Activities to Address Acute Kidney Injury in Children: A Modified Delphi Consensus Statement

IMPORTANCE

Increasing evidence indicates that acute kidney injury (AKI) occurs frequently in children and young adults and is associated with poor short-term and long-term outcomes. Guidance is required to focus efforts related to expansion of pediatric AKI knowledge.

OBJECTIVE

To develop expert-driven pediatric specific recommendations on needed AKI research, education, practice, and advocacy.

EVIDENCE REVIEW

At the 26th Acute Disease Quality Initiative meeting conducted in November 2021 by 47 multiprofessional international experts in general pediatrics, nephrology, and critical care, the panel focused on 6 areas: (1) epidemiology; (2) diagnostics; (3) fluid overload; (4) kidney support therapies; (5) biology, pharmacology, and nutrition; and (6) education and advocacy. An objective scientific review and distillation of literature through September 2021 was performed of (1) epidemiology, (2) risk assessment and diagnosis, (3) fluid assessment, (4) kidney support and extracorporeal therapies, (5) pathobiology, nutrition, and pharmacology, and (6) education and advocacy. Using an established modified Delphi process based on existing data, workgroups derived consensus statements with recommendations.

FINDINGS

The meeting developed 12 consensus statements and 29 research recommendations. Principal suggestions were to address gaps of knowledge by including data from varying socioeconomic groups, broadening definition of AKI phenotypes, adjudicating fluid balance by disease severity, integrating biopathology of child growth and development, and partnering with families and communities in AKI advocacy.

CONCLUSIONS AND RELEVANCE

Existing evidence across observational study supports further efforts to increase knowledge related to AKI in childhood. Significant gaps of knowledge may be addressed by focused efforts.

Diagnostic Utility of Point-of-Care Ultrasound in the Pediatric Cardiac Intensive Care Unit

Purpose of Review

Recent Findings

Summary

Supplementary Information

Risk Factors for Sepsis-Associated Acute Kidney Injury in the PICU: A Retrospective Cohort Study

OBJECTIVES

Acute kidney injury (AKI), particularly of greater severity and longer duration, is associated with increased morbidity and mortality in the pediatric population. AKI frequently occurs during sepsis, yet the knowledge of risk factors for sepsis-associated AKI in the PICU is limited. We aimed to identify risk factors for AKI that develops or persists after 72 hours from sepsis recognition in pediatric patients with severe sepsis.

DESIGN

Retrospective cohort study.

SETTING

PICU at an academic, tertiary-care center.

PATIENTS

Children greater than 1 month and less than or equal to 18 years with severe sepsis in the combined cardiac and medical/surgical PICU between December 1, 2013, and December 31, 2020, at the University of Virginia Children's Hospital.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The cohort included 124 patients with severe sepsis with 33 patients (27%) who were postcardiac surgery with cardiopulmonary bypass. AKI was defined by the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. The primary outcome was severe AKI, defined as KDIGO stage 2 or 3 AKI present at any point between days 3 and 7 after sepsis recognition. Severe AKI was present in 25 patients (20%). Factors independently associated with severe AKI were maximum vasoactive-inotropic score (VIS) within 48 hours after sepsis recognition and fluid overload. The presence of severe AKI was associated with increased inhospital mortality.

CONCLUSIONS

In children with severe sepsis, the degree of hemodynamic support as measured by the VIS and the presence of fluid overload may identify patients at increased risk of developing severe AKI.

Evaluation of acute kidney injury after surgery for congenital heart disease in neonates: a tertiary hospital experience

PURPOSE OF THE ARTICLE

Acute kidney injury (AKI) after cardiac surgery in children with congenital heart disease (CHD) is a serious complication closely associated with high morbidity and mortality. Despite numerous studies on AKI in children, most studies have excluded neonates. We sought to characterize AKI associated with cardiac surgery in neonates, determine its incidence, perioperative and postoperative risk factors, and short-term results.

MATERIALS AND METHODS

This retrospective study included 177 neonates who were operated on for CHD in our hospital between January 2015 and December 2019. Data of the patients were analyzed according to nKDIGO (neonatal Kidney Disease Improving Global Outcomes) and nRIFLE (neonatal Risk, Injury, Failure, Loss of function, End-stage kidney disease) criteria for evaluating AKI retrospectively. Data of groups with and without AKI were analyzed.

RESULTS

The average age of 177 neonates were 8.2 ± 6.1 (1-28) days. Twenty-two (12.4%) neonates had CS-AKI defined according to nKDIGO criteria. Four (2.3%) neonates reached nKDIGO stage I, 1 (0.6%) reached stage II, 17 (9.6%) reached stage III. Thirty-eight (21.5%) neonates had CS-AKI defined according to nRIFLE criteria. Twenty-four (13.6%) neonates reached nRIFLE stage risk(R), 6 (3.4%) reached stage injury(I), 8 (4.5%) reached stage failure (F). The incidence of cardiac surgery-associated acute kidney injury (CS-AKI) in neonates was 12.5% and 21.5% for nKDIGO and nRIFLE, respectively. The percentage difference between nKDIGO and nRIFLE for AKI assessment was due to the criteria for nRIFLE stage risk(R) urine output < 1.5 mL/kg/h for 24 h. In both classifications, the duration of cardiopulmonary bypass, operation, inotropic treatment, and mechanical ventilation, length of intensive care unit (ICU), and hospital stay were significantly higher in the AKI group than those without AKI group (p˂.05). The mortality rate in the groups with AKI was found to be significantly higher (p˂.05) than in the groups without AKI. In Kappa analysis, when two classifications were compared according to AKI stages, a significant agreement was found between nKDIGO and nRIFLE classifications (p˂.05) (Kappa: 0.299).

CONCLUSION

AKI and mortality rates were similar between groups according to the nKDIGO and nRIFLE criteria. For early prediction of AKI and adverse outcomes, diagnostic reference intervals might be specified in more detail in neonates undergoing cardiac surgery for CHD.

Renal Dysfunction Criteria in Critically Ill Children: The PODIUM Consensus Conference

CONTEXT

Renal dysfunction is associated with poor outcomes in critically ill children.

OBJECTIVE

To evaluate the current evidence for criteria defining renal dysfunction in critically ill children and association with adverse outcomes. To develop contemporary consensus criteria for renal dysfunction in critically ill children.

DATA SOURCES

PubMed and Embase were searched from January 1992 to January 2020.

STUDY SELECTION

Included studies evaluated critically ill children with renal dysfunction, performance characteristics of assessment tools for renal dysfunction, and outcomes related to mortality, functional status, or organ-specific or other patient-centered outcomes. Studies with adults or premature infants (≤36 weeks' gestational age), animal studies, reviews, case series, and studies not published in English with inability to determine eligibility criteria were excluded.

DATA EXTRACTION

Data were extracted from included studies into a standard data extraction form by task force members.

RESULTS

The systematic review supported the following criteria for renal dysfunction: (1) urine output <0.5 mL/kg per hour for ≥6 hours and serum creatinine increase of 1.5 to 1.9 times baseline or ≥0.3 mg/dL, or (2) urine output <0.5 mL/kg per hour for ≥12 hours, or (3) serum creatinine increase ≥2 times baseline, or (4) estimated glomerular filtration rate <35 mL/minute/1.73 m2, or (5) initiation of renal replacement therapy, or (6) fluid overload ≥20%. Data also support criteria for persistent renal dysfunction and for high risk of renal dysfunction.

LIMITATIONS

All included studies were observational and many were retrospective.

CONCLUSIONS

We present consensus criteria for renal dysfunction in critically ill children.

Advances in Neonatal Acute Kidney Injury

In this state-of-the-art review, we highlight the major advances over the last 5 years in neonatal acute kidney injury (AKI). Large multicenter studies reveal that neonatal AKI is common and independently associated with increased morbidity and mortality. The natural course of neonatal AKI, along with the risk factors, mitigation strategies, and the role of AKI on short- and long-term outcomes, is becoming clearer. Specific progress has been made in identifying potential preventive strategies for AKI, such as the use of caffeine in premature neonates, theophylline in neonates with hypoxic-ischemic encephalopathy, and nephrotoxic medication monitoring programs. New evidence highlights the importance of the kidney in "crosstalk" between other organs and how AKI likely plays a critical role in other organ development and injury, such as intraventricular hemorrhage and lung disease. New technology has resulted in advancement in prevention and improvements in the current management in neonates with severe AKI. With specific continuous renal replacement therapy machines designed for neonates, this therapy is now available and is being used with increasing frequency in NICUs. Moving forward, biomarkers, such as urinary neutrophil gelatinase-associated lipocalin, and other new technologies, such as monitoring of renal tissue oxygenation and nephron counting, will likely play an increased role in identification of AKI and those most vulnerable for chronic kidney disease. Future research needs to be focused on determining the optimal follow-up strategy for neonates with a history of AKI to detect chronic kidney disease.

Should we use diastolic function parameters to determine preload responsiveness in cardiac surgery? A pilot study

BACKGROUND

Left ventricular (LV) diastolic function (DF) may play an important role in predicting fluid responsiveness. However, few studies assessed the role of diastolic function in predicting fluid responsiveness. The aim of this pilot study was to assess whether parameters of right and left diastolic function assessed with transesophageal echocardiography, including the mitral E/e' ratio, is associated with fluid responsiveness among patients undergoing elective bypass graft surgery. We also sought to compare other methods of fluid responsiveness assessment, including echocardiographic and hemodynamic parameters, pulse pressure variation, and stroke volume variation (SVV) (arterial pulse contour analysis, Flotrac/Vigileo system).

RESULTS

We prospectively studied seventy patients undergoing coronary artery bypass grafting (CABG) monitored with a radial arterial catheter, transesophageal echocardiography (TEE), and a pulmonary artery catheter (for cardiac output measurements), before and after the administration of 500 mL of crystalloid over 10 min after the anesthetic induction. Thirteen patients were excluded (total of 57 patients). Fluid responsiveness was defined as an increase in cardiac index of ≥ 15%. There were 21 responders (36.8%) and 36 non-responders (63.2%). No difference in baseline pulsed wave Doppler echocardiographic measurements of any components of the mitral, tricuspid, and pulmonary and hepatic venous flows were found between responders and non-responders. There was no difference in MV tissue Doppler measurements between responders and non-responders, including E/e' ratio (8.7 ± 4.1 vs. 8.5 ± 2.8 in responders vs. non-responders, P = 0.85). SVV was the only independent variable to predict an increase in cardiac index by multivariate analysis (P = 0.0208, OR = 1.196, 95% CI (1.028-1.393)).

CONCLUSIONS

In this pilot study, we found that no parameters of right and left ventricular diastolic function were associated with fluid responsiveness in patients undergoing CABG. SVV was the most useful parameter to predict fluid responsiveness.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT02714244 . Registered 21 March 2016-retrospectively registered.

Fluid Balance Management Informs Renal Replacement Therapy Use During Pediatric Extracorporeal Membrane Oxygenation: A Survey Report From the Kidney Intervention During Extracorporeal Membrane Oxygenation Group

Fluid overload (FO) and acute kidney injury (AKI) occur commonly in children supported with extracorporeal membrane oxygenation (ECMO). Continuous renal replacement therapy (CRRT) may be used to manage AKI and FO in children on ECMO. In 2012, our group surveyed ECMO centers to begin to understand the practice patterns around CRRT and ECMO. Since then, more centers are initiating ECMO for increasingly diverse indications and an increased volume of research quantifies the detrimental impacts of AKI and FO. We, therefore, investigated practice patterns of CRRT utilization during ECMO in children. A multi-point survey instrument was distributed to 116 international neonatal and pediatric ECMO centers. Sixty of 116 (51.7%) international neonatal and pediatric ECMO centers responded. All reports using CRRT on ECMO, compared with 75% from the 2012 survey. Eighty-five percent use CRRT to treat or prevent FO, an increased from 59%. The modality of CRRT therapy differed between in-line (slow continuous ultrafiltration, 84.4%) and machine-based (continuous venovenous hemodiafiltration, 87.3%) methods. Most (65%) do not have protocols for fluid management, AKI, or CRRT on ECMO. Trialing off CRRT is dictated by physician preference in 90% (54/60), with varying definitions of success. In this survey study, we found that CRRT use during pediatric ECMO has increased since 2012 with fluid management representing the predominant indication for initiation. Despite the expanded utilization of CRRT with ECMO, there remains significant practice variation in terms of method, modality, indication, the timing of initiation, fluid management, and discontinuation.

Post-operative fluid overload as a predictor of hospital and long-term outcomes in a pediatric heart transplant population

BACKGROUND

Pediatric patients undergoing heart transplant have a number of factors predisposing them to become fluid-overloaded, including capillary leak syndrome. Capillary leak and FO are associated with organ injury and may influence both short- and long-term outcomes. This study aimed to 1) determine the extent, timing, and predictors of post-operative FO and 2) investigate the association of FO with clinically important outcomes.

METHODS

Between 2000 and 2012, 70 children less than 6 years old had a heart transplant at our institution. This was a secondary analysis of data from an ongoing prospective cohort study.

RESULTS

FO, defined as cumulative fluid balance greater than 10% of body weight in the first 5 post-operative days, occurred in 16/70 patients (23%); 7 of these had more than 20% FO. Shorter donor ischemic time and longer cardiopulmonary bypass time were independently associated with increased risk of FO. FO >20% was a statistically significant independent predictor of mortality (P = .005), ventilation time, and PICU length of stay. There was no statistically significant association between identified neurodevelopment domains and FO.

CONCLUSIONS

Our single-center experience demonstrates that FO was common after pediatric heart transplant and was associated with worse clinical outcomes. FO is a potentially modifiable factor, and research is needed to better determine risk factors and whether intervention to reduce FO can improve outcomes in pediatric heart transplant patients.

A systematic review of the evidence supporting post-operative diuretic use following cardiopulmonary bypass in children with Congenital Heart Disease

BACKGROUND

Paediatric cardiac surgery on cardiopulmonary bypass induces substantial physiologic changes that contribute to post-operative morbidity and mortality. Fluid overload and oedema are prevalent complications, routinely treated with diuretics. The optimal diuretic choice, timing of initiation, dose, and interval remain largely unknown.

METHODS

To guide clinical practice and future studies, we used PubMed and EMBASE to systematically review the existing literature of clinical trials involving diuretics following cardiac surgery from 2000 to 2020 in children aged 0-18 years. Studies were assessed by two reviewers to ensure that they met eligibility criteria.

RESULTS

We identified nine studies of 430 children across four medication classes. Five studies were retrospective, and four were prospective, two of which included randomisation. All were single centre. There were five primary endpoints - urine output, acute kidney injury, fluid balance, change in serum bicarbonate level, and required dose of diuretic. Included studies showed early post-operative diuretic resistance, suggesting higher initial doses. Two studies of ethacrynic acid showed increased urine output and lower diuretic requirement compared to furosemide. Children receiving peritoneal dialysis were less likely to develop fluid overload than those receiving furosemide. Chlorothiazide, acetazolamide, and tolvaptan demonstrated potential benefit as adjuncts to traditional diuretic regimens.

CONCLUSIONS

Early diuretic resistance is seen in children following cardiopulmonary bypass. Ethacrynic acid appears superior to furosemide. Adjunct diuretic therapies may provide additional benefit. Study populations were heterogeneous and endpoints varied. Standardised, validated endpoints and pragmatic trial designs may allow investigators to determine the optimal diuretic, timing of initiation, dose, and interval to improve post-operative outcomes.

Cardiac critical care of the post-operative congenital heart disease patient

Cardiac critical care has become an increasingly complex subspecialty, involving multiple subspecialists to support patients with congenital heart disease. This requires understanding of their physiology and the impact of medical interventions. The purpose of this article is to provide a concise review of the current strategies utilized by cardiac intensivists to optimize outcomes for this vulnerable patient population, with the goal of broadening the knowledge of other members of the multi-disciplinary team.

Cardiorenal Syndrome

Cardiorenal syndrome (CRS) describes a specific acute and chronic clinical picture in which the heart or the kidney are primarily dysfunctioning and secondarily affect each other. CRS is divided into five classes: acute and chronic CRS, acute and chronic renocardiac syndromes, and secondary dysfunction of heart and kidneys. This article specifically details the classification and the epidemiology, some risk factors, and the pathophysiology of CRS. Some emerging aspects of CRS are also discussed, such as CRS in patients with end-stage heart failure, with mechanical ventricular assistance, and after heart transplantation. Finally, some aspects of pediatric CRS are detailed.

Are there any further modalities for prediction of subclinical volume overload in advanced stages of chronic kidney disease?

BACKGROUND

Subclinical volume overload in chronic kidney disease (CKD) patient represents a debatable issue. Although many tools were used to detect volume overload in such patients, many non-specific results were due to presence of comorbidities. Bioimpedance spectroscopy is an objective fluid status assessment method, which is shown superior to classical methods in many studies. Combining some of these tools may improve their accuracy and specificity. Inferior vena cava collapsibility index (IVCCI) with brain natriuretic peptide (BNP) can be combined for more specific volume assessment. This study was performed to assess the usage of combined IVCCI and BNP levels in CKD patients to predict subclinical volume overload.

METHODS

One hundred and ten patients with CKD (stages 4 and 5) not on dialysis and having normal left ventricular systolic function were included in this study. Exclusion criteria were: (1) patients with other causes of raised BNP than volume overload and (2) patients on diuretics. A complete medical history was obtained, and thorough examination and laboratory tests were performed for all included patients. IVCCI and BNP serum levels were evaluated. The patients who exhibited an overhydration (OH)/extracellular water (ECW) ratio of >15% were considered to have volume overload.

RESULTS

Twenty-six patients (23.6%) had subclinical hypervolemia as diagnosed by OH/ECW ratio of >15%. IVCCI ≤ 38% had higher diagnostic performance than BNP ≥ 24 pg/mL. Combining both IVCCI ≤ 38% and BNP ≥ 24 pg/mL increased the specificity and positive predictive value for detection of subclinical hypervolemia.

CONCLUSION

Combined elevated BNP level and decreased IVCCI are more precise tools for subclinical volume overload detection in CKD patients.

Association Between Furosemide Exposure and Clinical Outcomes in a Retrospective Cohort of Critically Ill Children

Furosemide is commonly prescribed in critically ill patients to increase the urine output and prevent fluid overload (FO) and acute kidney injury (AKI), but not supported by conclusive evidence. There remain conflicting findings on whether furosemide associates with AKI and adverse outcomes. Information on the impact of furosemide on adverse outcomes in a general population of pediatric intensive care unit (PICU) is limited. The aim of the cohort study was to investigate the associations of furosemide with AKI and clinical outcomes in critically ill children. Study Design: We retrospectively reviewed a cohort of 456 critically ill children consecutively admitted to PICU from January to December 2016. The exposure of interest was the use of furosemide in the first week after admission. FO was defined as ≥5% of daily fluid accumulation, and mean FO was considered significant when mean daily fluid accumulation during the first week was ≥5%. The primary outcomes were AKI in the first week after admission and mortality during PICU stay. AKI diagnosis was based on Kidney Disease: Improving Global Outcomes criteria with both serum creatinine and urine output. Results: Furosemide exposure occurred in 43.4% of all patients (n = 456) and 49.3% of those who developed FO (n = 150) in the first week after admission. Patients who were exposed to furosemide had significantly less degree of mean daily fluid accumulation than those who were not (1.10 [-0.33 to 2.61%] vs. 2.00 [0.54-3.70%], P < 0.001). There was no difference in the occurrence of AKI between patients who did and did not receive furosemide (22 of 198 [11.1%] vs. 36 of 258 [14.0%], P = 0.397). The mortality rate was 15.4% (70 of 456), and death occurred more frequently among patients who received furosemide than among those who did not (21.7 vs. 10.5%, P = 0.002). Furosemide exposure was associated with increased odds for mortality in a multivariate logistic regression model adjusted for body weight, gender, illness severity assessed by PRISM III score, the presence of mean FO, and AKI stage [adjusted odds ratio (AOR) 1.95; 95%CI, 1.08-3.52; P = 0.026]. Conclusion: Exposure to furosemide might be associated with increased risk for mortality, but not AKI, in critically ill children.

Efficacy and safety of tolvaptan after pediatric congenital heart disease surgery

It is not clear whether tolvaptan is safe and effective irrespective of various underlying clinical conditions including the functional ventricle morphology, chromosomal abnormalities, and renal function after complex pediatric congenital heart disease surgery. Also, the appropriate dose of tolvaptan in these patients has not been previously identified. We retrospectively assessed the urine volume, body weight, patient clinical characteristics, laboratory data, and vital signs before and on days 1 and 7 of the tolvaptan administration after congenital heart disease surgery. Also, we assessed the relationship between the tolvaptan dose and its effects. A total of 86 patients were included the study. The mean time from the surgery to the tolvaptan administration was 23.5 ± 3.7 days. After administering tolvaptan, the urine volume significantly increased and body weight significantly decreased from baseline by days 1 and 7 (p < 0.0001). The urine volume significantly increased more in the survivors than the deceased. Of the 22 patients who had low serum sodium concentrations at baseline, 20 had an increased serum sodium concentration on day 7. The clinical effect of tolvaptan was not affected by the functional ventricle morphology, chromosomal abnormalities, or renal function. There was a positive correlation between the tolvaptan dose and change in the urine volume until a tolvaptan dose of up to 0.3 mg/kg/day but not at more than 0.3 mg/kg/day. Tolvaptan administration is safe and effective after congenital heart disease surgery irrespective of various underlying clinical conditions. Though the urine volume tends to increase until a tolvaptan dose of up to 0.3 mg/kg/day in pediatric congenital heart disease patients, there was no further benefit with more than 0.3 mg/kg/day.

Positive fluid balance as an early biomarker for acute kidney injury: a prospective study in critically ill adult patients

OBJECTIVES

Positive fluid balance is frequent in critically ill patients and has been considered a potential biomarker for acute kidney injury (AKI). This study aimed to evaluate positive fluid balance as a biomarker for the early detection of AKI in critically ill patients.

METHODS

This was a prospective cohort study. The sample was composed of patients ≥18 years old who stayed ≥3 days in an intensive care unit. Fluid balance, urinary output and serum creatinine were assessed daily. AKI was diagnosed by the Kidney Disease Improving Global Outcome criteria.

RESULTS

The final cohort was composed of 233 patients. AKI occurred in 92 patients (40%) after a median of 3 (2-6) days following ICU admission. When fluid balance was assessed as a continuous variable, a 100-ml increase in fluid balance was independently associated with a 4% increase in the odds of AKI (OR 1.04; 95% CI 1.01-1.08). Positive fluid balance categorized using different thresholds was always significantly associated with subsequent detection of AKI. The mixed effects model showed that increased fluid balance preceded AKI by 4 to 6 days.

CONCLUSION

These results suggest that a positive fluid balance might be an early biomarker for AKI development in critically ill patients.

Timing of Fluid Overload and Association With Patient Outcome

OBJECTIVES

To determine if the timing of excess fluid accumulation (fluid overload) is associated with adverse patient outcomes.

DESIGN

Secondary analysis of a prospectively collected dataset.

SETTING

PICU of a tertiary care hospital.

PATIENTS

Children 3 months to 25 years old admitted to the PICU with expected length of stay greater than or equal to 48 hours.

INTERVENTIONS

Patients were dichotomized by time of peak overload: peak fluid overload from ICU admission (Day0) to 48 hours (Day3-7) and peak fluid overload value after 48 hours of ICU admission, as well as time of first-time negative daily fluid balance: net fluid out greater than net fluid in for that 24-hour period.

MEASUREMENTS AND MAIN RESULTS

There were 177 patients who met inclusion criteria, 92 (52%) male, with an overall mortality rate of 7% (n = 12). There were no differences in severity of illness scores or fluid overload on Day0 between peak fluid overload from ICU admission (Day0) to 48 hours (Day3-7) (n = 97; 55%) and peak fluid overload value after 48 hours of ICU admission (n = 80; 45%) groups. Peak fluid overload value after 48 hours of ICU admission was associated with a longer median ICU course (8 [4-15] vs 4 d [3-8 d]; p ≤ 0.001], hospital length of stay (18 [10-38) vs 12 [8-24]; p = 0.01], and increased risk of mortality (n = 10 [13%] vs 2 [2%]; χ2 = 7.6; p = 0.006]. ICU length of stay was also longer in the peak fluid overload value after 48 hours of ICU admission group when only patients with at least 7 days of ICU stay were analyzed (p = 0.02). Timing of negative fluid balance was also correlated with outcome. Compared with Day0-2, a negative daily fluid balance on Day3-7 was associated with increased length of mechanical ventilation (3 [1-7] vs 1 d [2-10 d]; p ≤ 0.001) and increased hospital (17 [10-35] vs 11 d [7-26 d]; p = 0.006) and ICU (7 [4-13] vs 4 d [3-7 d]; p ≤ 0.001) length of stay compared with a negative fluid balance between Day0-2.

CONCLUSIONS

Our results show timing of fluid accumulation not just peak percentage accumulated is associated with patient outcome. Further exploration of the association between time and fluid accumulation is warranted.

Validation of Point-of-Care Ultrasound to Measure Perioperative Edema in Infants With Congenital Heart Disease

Purpose: Fluid overload is a common post-operative issue in children following cardiac surgery and is associated with increased morbidity and mortality. There is currently no gold standard for evaluating fluid status. We sought to validate the use of point-of-care ultrasound to measure skin edema in infants and assess the intra- and inter-user variability. Methods: Prospective cohort study of neonates (≤30 d/o) and infants (31 d/o to 12 m/o) undergoing cardiac surgery and neonatal controls. Skin ultrasound was performed on four body sites at baseline and daily post-operatively through post-operative day (POD) 3. Subcutaneous tissue depth was manually measured. Intra- and inter-user variability was assessed using intraclass correlation coefficient (ICC). Results: Fifty control and 22 surgical subjects underwent skin ultrasound. There was no difference between baseline surgical and control neonates. Subcutaneous tissue increased in neonates starting POD 1 with minimal improvement by POD 3. In infants, this pattern was less pronounced with near resolution by POD 3. Intra-user variability was excellent (ICC 0.95). Inter-user variability was very good (ICC 0.82). Conclusion: Point-of-care skin ultrasound is a reproducible and reliable method to measure subcutaneous tissue in infants with and without congenital heart disease. Acute increases in subcutaneous tissue suggests development of skin edema, consistent with extravascular fluid overload. There is evidence of skin edema starting POD 1 in all subjects with no substantial improvement by POD 3 in neonates. Point-of-care ultrasound could be an objective way to measure extravascular fluid overload in infants. Further research is needed to determine how extravascular fluid overload correlates to clinical outcomes.

The Effect of Postoperative Fluid Balance on the Occurrence and Progression of Acute Kidney Injury After Cardiac Surgery

OBJECTIVES

In addition to the association between positive fluid balance (FB) and acute kidney injury (AKI) after cardiac surgery reported by former studies, this study examined the relationship between FB and progressive AKI.

DESIGN

A retrospective, observational study.

SETTING

University teaching, grade A tertiary hospital in Shanghai, China.

PARTICIPANTS

Adult patients after cardiac surgery from July-December 2016.

INTERVENTIONS

Perioperative data relating to postoperative fluid intake and output were collected. AKI progression was defined as a worsening of AKI stage. FB was calculated as (fluid intake [L] - fluid output [L]/body weight [kg] × 100%).

MEASUREMENTS AND MAIN RESULTS

The study comprised 1,522 patients. The incidences of AKI and progressive AKI were 33.1% (n = 504) and 18.1% (n = 91), respectively. There was an exponential increase between 24-hour FB and AKI occurrence, and an approximate "U"-shape association between 48-hour FB and AKI progression. Multivariate logistic regression showed that 24-hour FB ≥5% was an independent risk factor for AKI incidence (odds ratio [OR] 3.976; p < 0.001) and 48-hour FB <-5% or ≥3% was associated with an increase of AKI progression (FB <-5%, OR 7.078 [p = 0.031]; FB 3%-5%, OR 6.598 [p = 0.020]; FB ≥5%, OR 16.453 [p < 0.001]).

CONCLUSIONS

An exponential increase was found between 24-hour FB and AKI occurrence and a "U"-shape association between 48-hour FB and AKI progression. Both excessively negative and positive accumulative 48-hour FB increased the risk of AKI progression, suggesting cautious monitoring and application of fluid load in clinical practice.