Assessment of the Independent and Synergistic Effects of Fluid Overload and Acute Kidney Injury on Outcomes of Critically Ill Children

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.

Fluid Management Bundle in Critically Ill Children With Respiratory Failure Is Associated With a Reduced Prevalence of Excess Fluid Accumulation

OBJECTIVES

To report the feasibility of a fluid management practice bundle and describe the pre- vs. post-implementation prevalence and odds of cumulative fluid balance greater than 10% in critically ill pediatric patients with respiratory failure.

DESIGN

Retrospective cohort from May 2022 to December 2022.

SETTING

Quaternary care PICU in Pittsburgh, PA.

PATIENTS

Children older than 28 days receiving invasive mechanical ventilation for greater than 48 hours.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We reviewed data from 205 patients; 104 before bundle implementation and 101 after bundle implementation. At the time of implementation in 2022, our PICU clinicians were educated on the use of the fluid management practice bundle, which included the following during daily rounds: goal-setting for daily fluid balance; assessing transition to enteral nutrition; and fluid conservation measures such as concentrating infusions or using enteral formulations of medications. A cumulative fluid balance greater than 10% occurred in 46 of 104 patients (44%) pre-implementation and 26 of 101 patients (26%) post-implementation. We failed to identify an association between implementation epoch grouping (pre- and post-) and adverse outcomes, including mortality, duration of mechanical ventilation, acute kidney injury, and ICU length of stay. In a multivariable logistic regression model, management during the fluid management bundle was associated with lower odds of a cumulative fluid balance greater than 10% (adjusted odds ratio, 0.35 [95% CI, 0.18-0.68]).

CONCLUSIONS

In our PICUs 2022 peri-implementation testing of a fluid management bundle in critically ill children with respiratory failure, we have first found that such a practice change is feasible. Second, we identified an associated decrease in the prevalence and lower odds of fluid accumulation. We continue to use this fluid management bundle in our center but more widespread prospective studies are needed to test the benefit in clinical practice.

Fluid management in adult patients undergoing venoarterial extracorporeal membrane oxygenation: A scoping review

BACKGROUND

The use of venoarterial extracorporeal membrane oxygenation (VA-ECMO) as a cardiocirculatory support has tremendously increased in critically ill patients. Although fluid therapy is an essential component of the hemodynamic management of VA-ECMO patients, the optimal fluid resuscitation strategy remains controversial. We performed a scoping review to map out the existing knowledge on fluid management in terms of fluid type, dosing and the impact of fluid balance on VA-ECMO patient outcomes.

METHODS

A literature search within PubMed and EMBASE was conducted from database inception to April 2024. We included all studies involving critically ill adult patients, supported by VA-ECMO regardless of clinical indication (cardiogenic shock or extracorporeal cardiopulmonary resuscitation) with or without Renal Replacement Therapy and describing fluid resuscitation strategies or focusing on fluid type or reporting the impact of fluid balance on clinical outcomes and mortality. Details of study population, ECMO indications, fluid types, resuscitation strategies, fluid balance and outcome measures were extracted.

RESULTS

Sixteen studies met inclusion criteria, including 14 clinical studies and two experimental animal studies. We found a lack of studies comparing restrictive and liberal approaches. No study has compared the efficacy and safety of balanced and saline solutions. The place of albumin, as an alternative fluid, should be investigated. Despite their heterogeneity, studies found a negative impact of both early and cumulative fluid overload on survival and renal outcomes.

CONCLUSIONS

The available literature on the fluid management in VA-ECMO setting is scarce. More high-quality evidence is needed regarding optimal fluid dosing, type and resuscitation endpoints in order to standardize practice and improve outcomes.

Urine biomarkers, acute kidney injury, and fluid overload in neonatal cardiac surgery

BACKGROUND

Cardiac surgery-associated acute kidney injury (CS-AKI) and fluid overload (FO) are common among neonates who undergo cardiopulmonary bypass, and increase mortality risk. Current diagnostic criteria may delay diagnosis. Thus, there is a need to identify urine biomarkers that permit earlier and more accurate diagnosis.

METHODS

This single-centre ancillary prospective cohort study describes age- and disease-specific ranges of 14 urine biomarkers at perioperative time points and explores associations with CS-AKI and FO. Neonates (≤28 days) undergoing cardiac surgery were included. Preterm neonates or those who had pre-operative acute kidney injury were excluded. Urine biomarkers were measured pre-operatively, at 0 to < 8 hours after surgery, and at 8 to 24 hours after surgery. Exploratory outcomes included CS-AKI, defined by the modified Kidney Disease Improving Global Outcomes criteria, and>10% FO, both measured at 48 hours after surgery.

RESULTS

Overall, α-glutathione S-transferase, β-2 microglobulin, albumin, cystatin C, neutrophil gelatinase-associated lipocalin, osteopontin, uromodulin, clusterin, and vascular endothelial growth factor concentrations peaked in the early post-operative period; over the sampling period, kidney injury molecule-1 increased and trefoil factor-3 decreased. In the early post-operative period, β-2 microglobulin and α-glutathione S-transferase were higher in neonates who developed CS-AKI; and clusterin, cystatin C, neutrophil gelatinase-associated lipocalin, osteopontin, and α-glutathione S-transferase were higher in neonates who developed FO.

CONCLUSION

In a small, single-centre cohort, age- and disease-specific urine biomarker concentrations are described. These data identify typical trends and will inform future studies.

Continuous frusemide infusion versus intermittent bolus therapy in paediatric intensive care: A single centre retrospective study

Objective

Frusemide is a common diuretic administered to critically ill children intravenously, by either continuous infusion (CI) or intermittent bolus (IB). We aim to describe the characteristics of children who receive intravenous frusemide, patterns of use, and incidence of acute kidney injury (AKI), and to investigate factors associated with commencing CI.

Design

Retrospective observational study.

Setting

Paediatric intensive care unit (PICU), the Royal Children's Hospital Melbourne.

Participants

Children who received intravenous frusemide during PICU admission lasting ≥24 h between 2017 and 2022.

Main outcome measures

The primary outcome was the daily dose of frusemide. Secondary outcomes included timing of therapy from PICU admission, fluid balance at frusemide initiation, additional diuretic therapy, and the incidence of AKI at admission and frusemide initiation. Children who received CI were compared with those who received IB only using multivariable logistic regression analyses.

Results

Nine thousand three ninety-four children were admitted during the study period. A total of 1387 children (15 %) received intravenous frusemide, including 220 children (16 %) by CI. The CI group were younger (132 vs 202 days, p = 0.01), had higher PIM-3 scores (2.2 vs 1.5, p-value <0.001), more congenital heart disease (CHD) (72.3 % vs 60.6 %, p <0.01), and higher incidence and severity of AKI at frusemide initiation than the IB group (65.7 % vs 40.1 %, p-value <0.001). CI were commenced later than IB (46 vs 19 h into admission, p <0.001) and at higher doses (4.3 vs 1.5 mg/kg/day, p-value <0.001). In multivariable analyses, CHD (aOR 1.67, 95 % CI 1.16-2.40, p <0.01) was associated with CI.

Conclusion

Frusemide infusions are administered more commonly to children with CHD, later in PICU admission, and at higher daily doses compared to IB. Children who receive CI have a higher incidence and severity of AKI at initiation.

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).

Persistent acute kidney injury and fluid accumulation with outcomes after the Norwood procedure: report from NEPHRON

BACKGROUND

Cardiac surgery-associated acute kidney injury (CS-AKI) is common, but its impact on clinical outcomes is variable. Parsing AKI into sub-phenotype(s) and integrating pathologic positive cumulative fluid balance (CFB) may better inform prognosis. We sought to determine whether durational sub-phenotyping of CS-AKI with CFB strengthens association with outcomes among neonates undergoing the Norwood procedure.

METHODS

Multicenter, retrospective cohort study from the Neonatal and Pediatric Heart and Renal Outcomes Network. Transient CS-AKI: present only on post-operative day (POD) 1 and/or 2; persistent CS-AKI: continued after POD 2. CFB was evaluated per day and peak CFB during the first 7 postoperative days. Primary and secondary outcomes were mortality, respiratory support-free and hospital-free days (at 28, 60 days, respectively). The primary predictor was persistent CS-AKI, defined by modified neonatal Kidney Disease: Improving Global Outcomes criteria.

RESULTS

CS-AKI occurred in 59% (205/347) neonates: 36.6% (127/347) transient and 22.5% (78/347) persistent; CFB > 10% occurred in 18.7% (65/347). Patients with either persistent CS-AKI or peak CFB > 10% had higher mortality. Combined persistent CS-AKI with peak CFB > 10% (n = 21) associated with increased mortality (aOR: 7.8, 95% CI: 1.4, 45.5; p = 0.02), decreased respiratory support-free (predicted mean 12 vs. 19; p < 0.001) and hospital-free days (17 vs. 29; p = 0.048) compared to those with neither.

CONCLUSIONS

The combination of persistent CS-AKI and peak CFB > 10% after the Norwood procedure is associated with mortality and hospital resource utilization. Prospective studies targeting intra- and postoperative CS-AKI risk factors and reducing CFB have the potential to improve outcomes.

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.

Advances in pediatric acute kidney injury pharmacology and nutrition: a report from the 26th Acute Disease Quality Initiative (ADQI) consensus conference

BACKGROUND

In the past decade, there have been substantial advances in our understanding of pediatric AKI. Despite this progress, large gaps remain in our understanding of pharmacology and nutritional therapy in pediatric AKI.

METHODS

During the 26th Acute Disease Quality Initiative (ADQI) Consensus Conference, a multidisciplinary group of experts reviewed the evidence and used a modified Delphi process to achieve consensus on recommendations for gaps and advances in care for pharmacologic and nutritional management of pediatric AKI. The current evidence as well as gaps and opportunities were discussed, and recommendations were summarized.

RESULTS

Two consensus statements were developed. (1) High-value, kidney-eliminated medications should be selected for a detailed characterization of their pharmacokinetics, pharmacodynamics, and pharmaco-"omics" in sick children across the developmental continuum. This will allow for the optimization of real-time modeling with the goal of improving patient care. Nephrotoxin stewardship will be identified as an organizational priority and supported with necessary resources and infrastructure. (2) Patient-centered outcomes (functional status, quality of life, and optimal growth and development) must drive targeted nutritional interventions to optimize short- and long-term nutrition. Measures of acute and chronic changes of anthropometrics, body composition, physical function, and metabolic control should be incorporated into nutritional assessments.

CONCLUSIONS

Neonates and children have unique metabolic and growth parameters compared to adult patients. Strategic investments in multidisciplinary translational research efforts are required to fill the knowledge gaps in nutritional requirements and pharmacological best practices for children with or at risk for AKI.

A proposed framework for advancing acute kidney injury risk stratification and diagnosis in children: a report from the 26th Acute Disease Quality Initiative (ADQI) conference

Acute kidney injury (AKI) in children is associated with increased morbidity, reduced health-related quality of life, greater resource utilization, and higher mortality. Improvements in the timeliness and precision of AKI diagnosis in children are needed. In this report, we highlight existing, novel, and on-the-horizon diagnostic and risk-stratification tools for pediatric AKI, and outline opportunities for integration into clinical practice. We also summarize pediatric-specific high-risk diagnoses and exposures for AKI, as well as the potential role of real-time risk stratification and clinical decision support to improve outcomes. Lastly, the key characteristics of important pediatric AKI phenotypes will be outlined. Throughout, we identify key knowledge gaps, which represent prioritized areas of focus for future research that will facilitate a comprehensive, timely and personalized approach to pediatric AKI diagnosis and management.

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

Introduction

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

Methods

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

Results and discussion

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

Fluid Balance and Its Association With Mortality and Health-Related Quality of Life: A Nonprespecified Secondary Analysis of the Life After Pediatric Sepsis Evaluation

OBJECTIVES

To evaluate the association between fluid balance (FB) and health-related quality of life (HRQL) among children at 1 month following community-acquired septic shock.

DESIGN

Nonprespecified secondary analysis of the Life After Pediatric Sepsis Evaluation. FB was defined as 100 × [(cumulative PICU fluid input - cumulative PICU fluid output)/PICU admission weight]. Three subgroups were identified: low FB (< 5%), medium FB (5%-15%), and high FB (> 15%) based on cumulative FB on days 0-3 of ICU stay. HRQL was measured at ICU admission and 1 month after using Pediatric Quality of Life Inventory 4.0 Generic Core or Infant Scales or the Stein-Jessop Functional Status Scale. The primary outcome was a composite of mortality or greater than 25% decline in HRQL 1 month after admission compared with baseline.

SETTING

Twelve academic PICUs in the United States.

PATIENTS

Critically ill children between 1 month and 18 years, with community-acquired septic shock who survived to at least day 4.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Two hundred ninety-three patients were included of whom 66 (23%) had low FB, 127 (43%) had medium FB, and 100 (34%) had high FB. There was no difference in Pediatric Risk of Mortality Score 3 (median 11 [6, 17]), age (median 5 [1, 12]), or gender (47% female) between FB groups. After adjusting for potential confounders and comparing with medium FB, higher odds of mortality or greater than 25% HRQL decline were seen in both the low FB (odds ratio [OR] 2.79 [1.20, 6.57]) and the high FB (OR 2.16 [1.06, 4.47]), p = 0.027. Compared with medium FB, low FB (OR 4.3 [1.62, 11.84]) and high FB (OR 3.29 [1.42, 8.00]) had higher odds of greater than 25% HRQL decline.

CONCLUSIONS

Over half of the children who survived septic shock had low or high FB, which was associated with a significant decline in HRQL scores. Prospective studies are needed to determine if optimization of FB can improve HRQL outcomes.

Agreement Between Measured Weight and Fluid Balance in Mechanically Ventilated Children in Intensive Care

OBJECTIVES

To investigate the agreement between change in body weight (BW) and fluid balance (FB), and the precision and safety of BW measurement in mechanically ventilated infants in intensive care.

DESIGN

Prospective observational study.

SETTING

Tertiary PICU.

PATIENTS

Infants following cardiac surgery, at baseline, 24 hours, and 48 hours.

INTERVENTIONS

BW and FB measurement at three time points.

MEASUREMENTS AND MAIN RESULTS

Between May 2021 and September 2022, we studied 61 children. The median age was 8 days (interquartile range [IQR], 1.0-14.0 d). The median BW at baseline was 3,518 g (IQR, 3,134-3,928 g). Change in BW was -36 g (IQR, -145 to 105 g) and -97 g (IQR, -240 to -28 g) between baseline and 24 hours, and between 24 and 48 hours, respectively. Change in FB was -82 mL (IQR, -173 to 12 mL) and -107 mL (IQR, -226 to 103) between baseline and 24 hours, and between 24 and 48 hours, respectively. In Bland-Altman analyses, the mean bias between BW and FB at 24 and 48 hours was 54 g (95% CI, 12-97) and -43 g (95% CI, -108 to 23), respectively. This exceeded 1% of the median BW, and limits of agreement ranged from 7.6% to 15% of baseline BW. The precision of paired weight measurements, performed sequentially at each time interval, was high (median difference of ≤1% of BW at each time point). The median weight of connected devices ranged from 2.7% to 3% of BW. There were no episodes of tube or device dislodgments and no change in vasoactive therapies during weight measurements.

CONCLUSIONS

There is moderate agreement between the changes in FB and BW, albeit greater than 1% of baseline BW, and the limits of this agreement are wide. Weighing mechanically ventilated infants in intensive care is a relatively safe and precise method for estimating change in fluid status. Device weight represents a relatively large proportion of BW.

Premature infants born <28 weeks with acute kidney injury have increased bronchopulmonary dysplasia rates

BACKGROUND

Despite a growing understanding of bronchopulmonary dysplasia (BPD) and advances in management, BPD rates remain stable. There is mounting evidence that BPD may be due to a systemic insult, such as acute kidney injury (AKI). Our hypothesis was that severe AKI would be associated with BPD.

METHODS

We conducted a secondary analysis of premature infants [24-27 weeks gestation] in the Recombinant Erythropoietin for Protection of Infant Renal Disease cohort (N = 885). We evaluated the composite outcome of Grade 2/3 BPD or death using generalized estimating equations. In an exploratory analysis, urinary biomarkers of angiogenesis (ANG1, ANG2, EPO, PIGF, TIE2, FGF, and VEGFA/D) were analyzed.

RESULTS

594 (67.1%) of infants had the primary composite outcome of Grade 2/3 BPD or death. Infants with AKI (aOR: 1.69, 95% CI: 1.16-2.46) and severe AKI (aOR: 2.05, 95% CI: 1.19-3.54). had increased risk of the composite outcome after multivariable adjustment Among 106 infants with urinary biomarkers assessed, three biomarkers (VEGFA, VEGFD, and TIE2) had AUC > 0.60 to predict BPD.

CONCLUSIONS

Infants with AKI had a higher likelihood of developing BPD/death, with the strongest relationship seen in those with more severe AKI. Three urinary biomarkers of angiogenesis may have potential to predict BPD development.

IMPACT

AKI is associated with lung disease in extremely premature infants, and urinary biomarkers may predict this relationship. Infants with AKI and severe AKI have higher odds of BPD or death. Three urinary angiogenesis biomarkers are altered in infants that develop BPD. These findings have the potential to drive future work to better understand the mechanistic pathways of BPD, setting the framework for future interventions to decrease BPD rates. A better understanding of the mechanisms of BPD development and the role of AKI would have clinical care, cost, and quality of life implications given the long-term effects of BPD.

Acute Kidney Injury Defined by Fluid-Corrected Creatinine in Premature Neonates: A Secondary Analysis of the PENUT Randomized Clinical Trial

Importance

Acute kidney injury (AKI) and disordered fluid balance are common in premature neonates; a positive fluid balance dilutes serum creatinine, and a negative fluid balance concentrates serum creatinine, both of which complicate AKI diagnosis. Correcting serum creatinine for fluid balance may improve diagnosis and increase diagnostic accuracy for AKI.

Objective

To determine whether correcting serum creatinine for fluid balance would identify additional neonates with AKI and alter the association of AKI with short-term and long-term outcomes.

Design, Setting, and Participants

This study was a post hoc cohort analysis of the Preterm Erythropoietin Neuroprotection Trial (PENUT), a phase 3, randomized clinical trial of erythropoietin, conducted at 19 academic centers and 30 neonatal intensive care units in the US from December 2013 to September 2016. Participants included extremely premature neonates born at less than 28 weeks of gestation. Data analysis was conducted in December 2022.

Exposure

Diagnosis of fluid-corrected AKI during the first 14 postnatal days, calculated using fluid-corrected serum creatinine (defined as serum creatinine multiplied by fluid balance [calculated as percentage change from birth weight] divided by total body water [estimated 80% of birth weight]).

Main Outcomes and Measures

The primary outcome was invasive mechanical ventilation on postnatal day 14. Secondary outcomes included death, hospital length of stay, and severe bronchopulmonary dysplasia (BPD). Categorical variables were analyzed by proportional differences with the χ2 test or Fisher exact test. The t test and Wilcoxon rank sums test were used to compare continuous and ordinal variables, respectively. Odds ratios (ORs) and 95% CIs for the association of exposure with outcomes of interest were estimated using unconditional logistic regression models.

Results

A total of 923 premature neonates (479 boys [51.9%]; median [IQR] birth weight, 801 [668-940] g) were included, of whom 215 (23.3%) received a diagnosis of AKI using uncorrected serum creatinine. After fluid balance correction, 13 neonates with AKI were reclassified as not having fluid-corrected AKI, and 111 neonates previously without AKI were reclassified as having fluid-corrected AKI (ie, unveiled AKI). Therefore, fluid-corrected AKI was diagnosed in 313 neonates (33.9%). Neonates with unveiled AKI were similar in clinical characteristics to those with AKI whose diagnoses were made with uncorrected serum creatinine. Compared with those without AKI, neonates with unveiled AKI were more likely to require ventilation (81 neonates [75.0%] vs 254 neonates [44.3%] and have longer hospital stays (median [IQR], 102 [84-124] days vs 90 [71-110] days). In multivariable analysis, a diagnosis of fluid-corrected AKI was associated with increased odds of adverse clinical outcomes, including ventilation (adjusted OR, 2.23; 95% CI, 1.56-3.18) and severe BPD (adjusted OR, 2.05; 95% CI, 1.15-3.64).

Conclusions and Relevance

In this post hoc cohort study of premature neonates, fluid correction increased the number of premature neonates with a diagnosis of AKI and was associated with increased odds of adverse clinical outcomes, including ventilation and BPD. Failing to correct serum creatinine for fluid balance underestimates the prevalence and impact of AKI in premature neonates. Future studies should consider correcting AKI for fluid balance.

Trial Registration

ClinicalTrials.gov Identifier: NCT01378273.

A Clinical Score for Quantifying Edema in Mechanically Ventilated Children With Congenital Heart Disease in Intensive Care

Standardized clinical measurements of edema do not exist.

OBJECTIVES

To describe a 19-point clinical edema score (CES), investigate its interobserver agreement, and compare changes between such CES and body weight.

DESIGN SETTING AND PARTICIPANTS

Prospective observational study in a tertiary PICU of mechanically ventilated children with congenital heart disease.

MAIN OUTCOMES AND MEASURES

Differences in the median CES between observer groups.

RESULTS

We studied 61 children, with a median age of 8.0 days (interquartile range, 1.0-14.0 d). A total of 539 CES were performed by three observer groups (medical 1 [reference], medical 2, and bedside nurse) at 0, 24, and 48 hours from enrollment. Overall, there was close agreement between observer groups in mean, median, and upper quartile of CES scores, with least agreement observed in the lower quartile of scores. Across all quartiles of CES, after adjusting for baseline weight, cardiac surgical risk, duration of cardiopulmonary bypass, or peritoneal dialysis during the study, observer groups returned similar mean scores (medical 2: 25th centile +0.1 [95% CI, -0.2 to 0.5], median +0.6 [95% CI, -0.4 to 1.5], 75th centile +0.1 [95% CI, -1.1 to 1.4] and nurse: 25th centile +0.5 [95% CI, 0.0-0.9], median +0.7 [95% CI, 0.0-1.5], 75th centile -0.2 [95% CI, -1.3 to 1.0]) Within a multivariable mixed-effects linear regression model, including adjustment for baseline CES, each 1 point increase in CES was associated with a 12.1 grams (95% CI, 3.2-21 grams) increase in body weight.

CONCLUSIONS AND RELEVANCE

In mechanically ventilated children with congenital heart disease, three groups of observers tended to agree when assessing overall edema using an ordinal clinical score assessed in six body regions, with agreement least at low edema scores. An increase in CES was associated with an increase in body weight, suggesting some validity for quantifying edema. Further exploration of the CES as a rapid clinical tool is indicated.

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.

Fluid balance in critically ill children with lower respiratory tract viral infection: a cohort study

BACKGROUND

Increasing evidence has associated positive fluid balance of critically ill patients with poor outcomes. The aim of this study was to explore the pattern of daily fluid balances and their association with outcomes in critically ill children with lower respiratory tract viral infection.

METHODS

A retrospective single-center study was conducted, in children supported with high-flow nasal cannula, non-invasive ventilation, or invasive ventilation. Median (interquartile range) daily fluid balances, cumulative fluid overload (FO) and peak FO variation, indexed as the % of admission body weight, over the first week of Pediatric Intensive Care Unit admission, and their association with the duration of respiratory support were assessed.

RESULTS

Overall, 94 patients with a median age of 6.9 (1.9-18) months, and a respiratory support duration of 4 (2-7) days, showed a median (interquartile range) daily fluid balance of 18 (4.5-19.5) ml/kg at day 1, which decreased up to day 3 to 5.9 (- 14 to 24.9) ml/kg and increased to 13 (- 11 to 29.9) ml/kg at day 7 (p = 0.001). Median cumulative FO% was 4.6 (- 0.8 to 11) and peak FO% was 5.7 (1.9-12.4). Daily fluid balances, once patients were stratified according to the respiratory support, were significantly lower in those requiring mechanical ventilation (p = 0.003). No correlation was found between all examined fluid balances and respiratory support duration or oxygen saturation, even after subgroup analysis of patients with invasive mechanical ventilation, or respiratory comorbidities, or bacterial coinfection, or of patients under 1 year old.

CONCLUSIONS

In a cohort of children with bronchiolitis, fluid balance was not associated with duration of respiratory support or other parameters of pulmonary function.

Synergistic association of fluid overload and acute kidney injury on outcomes in pediatric cardiac ECMO: a retrospective analysis of the KIDMO database

BACKGROUND

Acute kidney injury (AKI) and fluid overload (FO) are associated with poor outcomes in children receiving extracorporeal membrane oxygenation (ECMO). Our objective is to evaluate the impact of AKI and FO on pediatric patients receiving ECMO for cardiac pathology.

METHODS

We performed a secondary analysis of the six-center Kidney Interventions During Extracorporeal Membrane Oxygenation (KIDMO) database, including only children who underwent ECMO for cardiac pathology. AKI was defined using Kidney Disease: Improving Global Outcomes (KDIGO) creatinine criteria. FO was defined as < 10% (FO-) vs. ≥ 10% (FO +) and was evaluated at ECMO initiation, peak during ECMO, and ECMO discontinuation. Primary outcomes were mortality and length of stay (LOS).

RESULTS

Data from 191 patients were included. Non-survivors (56%) were more likely to be FO + than survivors at peak ECMO fluid status and ECMO discontinuation. There was a significant interaction between AKI and FO. In the presence of AKI, the adjusted odds of mortality for FO + was 4.79 times greater than FO- (95% CI: 1.52-15.12, p = 0.01). In the presence of FO + , the adjusted odds of mortality for AKI + was 2.7 times higher than AKI- [95%CI: 1.10-6.60; p = 0.03]. Peak FO + was associated with a 55% adjusted relative increase in LOS [95%CI: 1.07-2.26, p = 0.02].

CONCLUSIONS

The association of peak FO + with mortality is present only in the presence of AKI + . Similarly, AKI + is associated with mortality only in the presence of peak FO + . FO + was associated with LOS. Studies targeting fluid management have the potential to improve LOS and mortality outcomes. A higher resolution version of the Graphical abstract is available as Supplementary information.

Fluid management of the critically Ill child

PURPOSE OF REVIEW

This review summarizes current literature pertaining to fluid management for critically ill children. It includes an overview on crystalloid fluid used throughout the critical illness course, management of fluid output and complications with fluid overload.

RECENT FINDINGS

Observational paediatric studies and adult randomized trials show mixed results regarding risk of mortality and kidney injury with 0.9% saline and crystalloid fluid. A recent adult randomized trial suggests that a fluid restrictive strategy may be well tolerated in critically ill adults with septic shock, but further randomized trials are needed in paediatrics. Fluid overload has been associated with increased morbidity and mortality. Trials exploring ways to decrease fluid accumulation must be done in paediatrics.

SUMMARY

Additional high-quality studies are needed to precisely define the type, timing and rate of intravenous fluid critically ill children should receive throughout their clinical illness course.

Fluid Removal in Children on Continuous Renal Replacement Therapy Improves Organ Dysfunction Score

The objective is to assess impact of fluid removal on improvement in organ function in children who received continuous renal replacement therapy (CRRT) for management of acute kidney injury and/or fluid overload (FO). A retrospective review of eligible patients admitted to a tertiary level intensive care unit over a 3-year period was performed. Improvement in nonrenal organ function, the primary outcome, was defined as decrease in nonrenal component of Pediatric Logistic Organ Dysfunction (PELOD) score on day 3 of CRRT. The cohort was categorized into Group 1 (improvement) and Group 2 (no improvement or worsening) in nonrenal PELOD score. Multivariable logistic regression analysis was performed to identify independent predictors. A higher PELOD score at CRRT initiation (odds ratio [OR]: 1.11, 95% confidence interval [CI]: 1.05, 1.18, p < 0.001), belonging to infant-age group (OR: 4.53, 95% CI: 4.40, 5.13, p = 0.02) and greater fluid removal during initial 3 days of CRRT (OR: 1.05, 95% CI: 1.01, 1.10, p = 0.01) were associated with an improvement in nonrenal PELOD score at day 3 of CRRT. FO at CRRT initiation (OR: 0.66, 95% CI: 0.46, 0.93, p = 0.02) and having an underlying oncologic diagnosis (OR: 0.28, 95% CI: 0.09, 0.85, p = 0.03) were associated with worsening of nonrenal PELOD score at day 3 of CRRT. Careful consideration of certain modifiable patient and/or fluid removal kinetic factors may have an impact on outcomes.

Effect of a standardized fluid management algorithm on acute kidney injury and mortality in pediatric patients on extracorporeal support

Acute kidney injury (AKI), fluid overload (FO), and mortality are common in pediatric patients supported by extracorporeal membrane oxygenation (ECMO). The aim of this study is to evaluate if using a fluid management algorithm reduced AKI and mortality in children supported by ECMO. We performed a retrospective study of pediatric patients aged birth to 25 years requiring ECMO at a quaternary level children's hospital from 2007 to 2019 In October 2017, a fluid management algorithm was implemented for protocolized fluid removal after deriving a daily fluid goal using a combination of diuretics and ultrafiltration. Daily algorithm compliance was defined as ≥ 12 h on the algorithm each day. The primary and secondary outcomes were AKI and mortality, respectively, and were assessed in the entire cohort and the sub-analysis of children from the era in which the algorithm was implemented. Two hundred and ninety-nine (median age 5.3 months; IQR: 0.2, 62.3; 45% male) children required ECMO (venoarterial in 85%). The fluid algorithm was applied in 74 patients. The overall AKI rate during ECMO was 38% (26% severe-stage 2/3). Both AKI incidence and mortality were significantly lower in patients managed on the algorithm (p = 0.02 and p = 0.05). After adjusting for confounders, utilization of the algorithm was associated with lower odds of AKI (aOR: 0.40, 95%CI: 0.21, 0.76; p = 0.005) but was not associated with a reduction in mortality. In the sub-analysis, algorithm compliance of 80-100% was associated with a 54% reduction in mortality (ref: < 60% compliant; aOR:0.46, 95%CI:0.22-1.00; p = 0.05).  Conclusion: Among the entire cohort, the use of a fluid management algorithm reduced the odds of AKI. Better compliance on the algorithm was associated with lower mortality. Multicenter studies that implement systematic fluid removal may represent an opportunity for improving ECMO-related outcomes. What is Known: • Acute kidney injury and fluid overload are associated with morbidity and mortality in children supported by extracorporeal membrane oxygenation. What is New: • A systematic and protocolized approach to fluid removal in children supported by extracorporeal membrane oxygenation reduces acute kidney injury incidence. • Greater adherence to a protocolized fluid removal algorithm is associated with a reduction in mortality.

Acute Kidney Injury in Very Low Birth Weight Infants: A Major Morbidity and Mortality Risk Factor

BACKGROUND AND OBJECTIVES

Very low birth weight (VLBW) infants are at high risk of developing acute kidney injury (AKI), presumably secondary to low kidney reserves, stressful postnatal events, and drug exposures. Our study aimed to identify the prevalence, risk factors, and outcomes associated with AKI in VLBW infants.

STUDY DESIGN

Records of all VLBW infants admitted to two medical campuses between January 2019 and June 2020 were retrospectively reviewed. AKI was classified using the modified KDIGO definition to include only serum creatinine. Risk factors and composite outcomes were compared between infants with and without AKI. We evaluated the main predictors of AKI and death with forward stepwise regression analysis.

RESULTS

152 VLBW infants were enrolled. 21% of them developed AKI. Based on the multivariable analysis, the most significant predictors of AKI were the use of vasopressors, patent ductus arteriosus, and bloodstream infection. AKI had a strong and independent association with neonatal mortality.

CONCLUSIONS

AKI is common in VLBW infants and is a significant risk factor for mortality. Efforts to prevent AKI are necessary to prevent its harmful effects.

Association of hyperchloremia and acute kidney injury in pediatric patients with moderate and severe traumatic brain injury

PURPOSE

Acute kidney injury (AKI) is an established complication of adult traumatic brain injury (TBI) and known risk factor for mortality. Evidence demonstrates an association between hyperchloremia and AKI in critically ill adults but studies in children are scarce. Given frequent use of hypertonic saline in the management of pediatric TBI, we believe the incidence of hyperchloremia will be high and hypothesize that it will be associated with development of AKI.

METHODS

Single-center retrospective cohort study was completed at an urban, level 1 pediatric trauma center. Children > 40 weeks corrected gestational age and < 21 years of age with moderate or severe TBI (presenting GCS < 13) admitted between January 2016 and December 2021 were included. Primary study outcome was presence of AKI (defined by pediatric Kidney Disease: Improving Global Outcomes criteria) within 7 days of hospitalization and compared between patients with and without hyperchloremia (serum chloride ≥ 110 mEq/L).

RESULTS

Fifty-two children were included. Mean age was 5.75 (S.D. 5.4) years; 60% were male (31/52); and mean presenting GCS was 6 (S.D. 2.9). Thirty-seven patients (71%) developed hyperchloremia with a mean peak chloride of 125 (S.D. 12.0) mEq/L and mean difference between peak and presenting chloride of 16 (S.D. 12.7) mEq/L. Twenty-three patients (44%) developed AKI; of those with hyperchloremia, 62% (23/37) developed AKI, while among those without hyperchloremia, 0% (0/15) developed AKI (difference 62%, 95% CI 42-82%, p < 0.001). Attributable risk of hyperchloremia leading to AKI was 62.2 (95% CI 46.5-77.8, p = 0.0015).

CONCLUSION

Hyperchloremia is common in the management of pediatric TBI and is associated with development of AKI. Risk appears to be associated with both the height of serum chloride and duration of hyperchloremia.

Neonatal fluid overload-ignorance is no longer bliss

Excessive accumulation of fluid may result in interstitial edema and multiorgan dysfunction. Over the past few decades, the detrimental impact of fluid overload has been further defined in adult and pediatric populations. Growing evidence highlights the importance of monitoring, preventing, managing, and treating fluid overload appropriately. Translating this knowledge to neonates is difficult as they have different disease pathophysiologies, and because neonatal physiology changes rapidly postnatally in many of the organ systems (i.e., skin, kidneys, and cardiovascular, pulmonary, and gastrointestinal). Thus, evaluations of the optimal targets for fluid balance need to consider the disease state as well as the gestational and postmenstrual age of the infant. Integration of what is known about neonatal fluid overload with individual alterations in physiology is imperative in clinical management. This comprehensive review will address what is known about the epidemiology and pathophysiology of neonatal fluid overload and highlight the known knowledge gaps. Finally, we provide clinical recommendations for monitoring, prevention, and treatment of fluid overload.

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.

Fluid balance in pediatric critically ill patients (with and without kidney dysfunction)

PURPOSE OF REVIEW

The issues of fluid balance and fluid overload are currently considered crucial aspects of pediatric critically ill patients' care.

RECENT FINDINGS

This review describes current understanding of fluid management in critically ill children in terms of fluid balance and fluid overload and its effects on patients' outcomes. The review describes current evidence surrounding definitions, monitoring, and treatment of positive fluid balance. In particular, the review focuses on specific patient conditions, including perioperative cardiac surgery, severe acute respiratory failure, and extracorporeal membrane oxygenation therapy, as the ones at highest risk of developing fluid overload and poor clinical outcomes. Gaps in understanding include specific thresholds at which fluid overload occurs in all critically ill children or specific populations and optimal timing of decongestion of positive fluid balance.

SUMMARY

Current evidence on fluid balance in critically ill children is mainly based on retrospective and observational studies, and intense research should be recommended in this important field. In theory, active decongestion of patients with fluid overload could improve mortality and other clinical outcomes, but randomized trials or advanced pragmatic studies are needed to better understand the optimal timing, patient characteristics, and tools to achieve this.

The complement system in pediatric acute kidney injury

The complement cascade is an important part of the innate immune system. In addition to helping the body to eliminate pathogens, however, complement activation also contributes to the pathogenesis of a wide range of kidney diseases. Recent work has revealed that uncontrolled complement activation is the key driver of several rare kidney diseases in children, including atypical hemolytic uremic syndrome and C3 glomerulopathy. In addition, a growing body of literature has implicated complement in the pathogenesis of more common kidney diseases, including acute kidney injury (AKI). Complement-targeted therapeutics are in use for a variety of diseases, and an increasing number of therapeutic agents are under development. With the implication of complement in the pathogenesis of AKI, complement-targeted therapeutics could be trialed to prevent or treat this condition. In this review, we discuss the evidence that the complement system is activated in pediatric patients with AKI, and we review the role of complement proteins as biomarkers and therapeutic targets in patients with AKI.

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.

Acute Kidney Injury and Fluid Overload in Pediatric Extracorporeal Cardio-Pulmonary Resuscitation: A Multicenter Retrospective Cohort Study

Acute kidney injury (AKI) and fluid overload (FO) are common complications of extracorporeal membrane oxygenation (ECMO). The purpose of this study was to characterize AKI and FO in children receiving extracorporeal cardiopulmonary resuscitation (eCPR). We performed a multicenter retrospective study of children who received eCPR. AKI was assessed during ECMO and FO defined as <10% [FO-] vs. ≥10% [FO+] evaluated at ECMO initiation and discontinuation. A composite exposure, defined by a four-group discrete phenotypic classification [FO-/AKI-, FO-/AKI+, FO+/AKI-, FO+/AKI+] was also evaluated. Primary outcome was mortality and hospital length of stay (LOS) among survivors. 131 patients (median age 29 days (IQR:9, 242 days); 51% men and 82% with underlying cardiac disease) were included. 45.8% survived hospital discharge. FO+ at ECMO discontinuation, but not AKI was associated with mortality [aOR=2.3; 95% CI: 1.07-4.91]. LOS for FO+ patients was twice as long as FO- patients, irrespective of AKI status [(FO+/AKI+ (60 days; IQR: 49-83) vs. FO-/AKI+ (30 days, IQR: 19-48 days); P = 0.01]. FO+ at ECMO initiation and discontinuation was associated with an adjusted 66% and 50% longer length of stay respectively. Prospective studies that target timing and strategy of fluid management, including its removal in children receiving ECPR are greatly needed.

Acute kidney injury in pediatric hematopoietic cell transplantation: critical appraisal and consensus

Hematopoietic cell transplantation (HCT) is a common therapy for the treatment of neoplastic and metabolic disorders, hematological diseases, and fatal immunological deficiencies. HCT can be subcategorized as autologous or allogeneic, with each modality being associated with their own benefits, risks, and post-transplant complications. One of the most common complications includes acute kidney injury (AKI). However, diagnosing HCT patients with AKI early on remains quite difficult. Therefore, this evidence-based guideline, compiled by the Pediatric Continuous Renal Replacement Therapy (PCRRT) working group, presents the various factors that contribute to AKI and recommendations regarding optimization of therapy with minimal complications in HCT patients.

Effect of Early Nutritional Assessment and Nutritional Support on Immune Function and Clinical Prognosis of Critically Ill Children

The aim of this study was to study the effect of early nutritional assessment and nutritional support on immune function and clinical prognosis of critically ill children. 90 critically ill children at the same level of severity admitted to the pediatric intensive care unit (PICU) of our hospital (June 2019-June 2020) were chosen as the research objects and were equally separated into the experimental group and the control group by the random number table method. The children in the control group were admitted to the PICU according to the routine process, and the nutritional support was provided to the malnourished ones. After admission to the PICU, the children in the experimental group were given nutritional assessment, nutritional risk screening, and nutritional support according to the screening results. The PICU stay time and total hospitalization time of the experimental group were obviously shorter than those of the control group (P < 0.05), the hospitalization expenses of the experimental group were obviously lower than those of the control group (P < 0.05), the clinical outcomes and immune function of the experimental group were obviously better than those of the control group (P < 0.05), and the nutrition indicators of the experimental group were obviously higher than those of the control group (P < 0.05). Early nutritional assessment and nutritional support can effectively improve the immune function and reduce the incidence of adverse clinical outcomes of critically ill children, which are worthy of clinical application and promotion.

Creatinine correction to account for fluid overload in children with acute respiratory distress syndrome treated with extracorporeal membrane oxygenation: an initial exploratory report

BACKGROUND

Creatinine is distributed between the intracellular and extracellular compartments, and as a result, the measurement of its concentration is strongly related to the fluid status of the patient. An interest has been shown in correcting measured serum creatinine levels according to the fluid balance in order to better specify the degree of acute kidney injury (AKI).

METHODS

We conducted a retrospective observational study of 33 children, aged 0 to 5 years, admitted to the pediatric intensive care unit for acute respiratory distress syndrome treated by extracorporeal membrane oxygenation. We compared measured and corrected creatinine and assessed the degree of agreement between these values using both Cohen's kappa and Krippendorff's alpha coefficient.

RESULTS

In our cohort, 37% of the classifications made according to measured creatinine levels were erroneous and, in the majority of cases, the degree of AKI was underestimated.

CONCLUSION

Correction of the measured creatinine value according to the degree of fluid overload may result in more accurate diagnosis of AKI. Graphical abstract A higher resolution version of the Graphical abstract is available as Supplementary information.

Prospective Cohort Study on Cumulative Fluid Balance and Outcome in Critically Ill Children Using a Restrictive Fluid Protocol

OBJECTIVE

To study the association of cumulative fluid balance and clinical outcomes in a pediatric intensive care unit (PICU) practicing restrictive fluid protocol.

METHODS

In this prospective cohort study, children aged less than 13 y admitted for more than 48 h were screened. Children with unstable hemodynamics throughout the stay were excluded. Fluid balance was calculated by percentage fluid overload (%FO) for the first 7 d. Patients were divided into positive fluid and negative fluid balance groups. The primary outcome was all-cause 28-d mortality.

RESULTS

A total of 888 patients (positive fluid balance group = 531, negative fluid balance group = 357) were analyzed. Mean (SD) cumulative %FO was 1.52 (0.67) vs. -1.18 (0.71), p = < 0.001, and minimum and maximum cumulative %FO were -3.0% and 3.1%, respectively. There was no significant difference in all-cause 28-d mortality between the two groups (n = 104/531, 19.6% vs. n = 60/357, 16.8%, RR = 1.17, 95% CI 0.87 to 1.55; p = 0.29). There was no difference in organ dysfunction [mean (SD) sequential organ failure assessment (SOFA) score 3.3 (0.7) vs. 3.3 (0.6)], acute kidney injury (65% vs. 63.6%), need for renal replacement therapy (14% vs. 13%), and duration of ventilation (median, IQR 4, 2-6 vs. 4, 2-6 d). Longer stay in PICU (5, 3-9 vs. 4, 3-7 d; p = 0.014) and in hospital (8, 5-11 vs. 7, 4-10 d; p = 0.007) were noted in the positive fluid balance group.

CONCLUSION

Cumulative fluid balance within 3% using restrictive fluid protocol was not associated with a significant difference in PICU mortality and morbidity.

Fluid Homeostasis and Diuretic Therapy in the Neonate

Understanding physiologic water balance and homeostasis mechanisms in the neonate is critical for clinicians in the NICU as pathologic fluid accumulation increases the risk for morbidity and mortality. In addition, once this process occurs, treatment is limited. In this review, we will cover fluid homeostasis in the neonate, explain the implications of prematurity on this process, discuss the complexity of fluid accumulation and the development of fluid overload, identify mitigation strategies, and review treatment options.

Early and late acute kidney injury: temporal profile in the critically ill pediatric patient

Background

Increasing AKI diagnosis precision to refine the understanding of associated epidemiology and outcomes is a focus of recent critical care nephrology research. Timing of onset of acute kidney injury (AKI) during pediatric critical illness and impact on outcomes has not been fully explored.

Methods

This was a secondary analysis of the Assessment of Worldwide Acute Kidney Injury, Renal Angina and Epidemiology (AWARE) database. AKI was defined as per Kidney Disease: Improving Global Outcomes criteria. Early AKI was defined as diagnosed at ≤48 h after intensive care unit (ICU) admission, with any diagnosis >48 h denoted as late AKI. Transient AKI was defined as return to baseline serum creatinine ≤48 h of onset, and those without recovery fell into the persistent category. A second incidence of AKI ≥48 h after recovery was denoted as recurrent. Patients were subsequently sorted into distinct phenotypes as early-transient, late-transient, early-persistent, late-persistent and recurrent. Primary outcome was major adverse kidney events (MAKE) at 28 days (MAKE28) or at study exit, with secondary outcomes including AKI-free days, ICU length of stay and inpatient renal replacement therapy.

Results

A total of 1262 patients had AKI and were included. Overall mortality rate was 6.4% (n = 81), with 34.2% (n = 432) fulfilling at least one MAKE28 criteria. The majority of patients fell in the early-transient cohort (n = 704, 55.8%). The early-persistent phenotype had the highest odds of MAKE28 (odds ratio 7.84, 95% confidence interval 5.45–11.3), and the highest mortality rate (18.8%). Oncologic and nephrologic/urologic comorbidities at AKI diagnosis were associated with MAKE28.

Conclusion

Temporal nature and trajectory of AKI during a critical care course are significantly associated with patient outcomes, with several subtypes at higher risk for poorer outcomes. Stratification of pediatric critical care-associated AKI into distinct phenotypes is possible and may become an important prognostic tool.

Precision of weight measurement in critically ill infants: a technical report

Objectives: To investigate the precision of weight measurements in critically ill infants in a paediatric intensive care unit (PICU). Design: Prospective cohort study. Setting: Royal Children's Hospital PICU. Participants: Mechanically ventilated infants admitted to the Royal Children's Hospital PICU between September 2020 and February 2021. Main outcome measures: Mean percentage difference and agreement of consecutive weight measurements. Results: Thirty infants were enrolled, of which 17 were receiving post-surgical care for congenital heart disease and four were receiving extracorporeal membrane oxygenation (ECMO). The median age was 13 days (interquartile range [IQR], 3.1-52.4 days). The mean difference in weight was 1.3% (standard deviation [SD], 1.0%), and the test-retest agreement intraclass correlation was 0.99 (95% CI, 0.99-0.99; P < 0.01). The percentage difference between measurements was ≤ 2.5% in 26/30 (87%) children, and the range was < 0.1% to 3.6%. In 26 children not receiving ECMO, the mean difference in weight was 1.1% (SD, 1.0%). There were no complications. Conclusions: Weighing mechanically ventilated, critically ill infants in intensive care can be performed safely, with a mean difference between consecutive weights of 1.3%, making it a potentially useful additional measure of fluid accumulation.

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.

Renal angina index predicts fluid overload in critically ill children: an observational cohort study

Background

Fluid overload and acute kidney injury are common and associated with poor outcomes among critically ill children. The prodrome of renal angina stratifies patients by risk for severe acute kidney injury, but the predictive discrimination for fluid overload is unknown.

Methods

Post-hoc analysis of patients admitted to a tertiary care pediatric intensive care unit (PICU). The primary outcome was the performance of renal angina fulfillment on day of ICU admission to predict fluid overload ≥15% on Day 3.

Results

77/139 children (55%) fulfilled renal angina (RA+). After adjusting for covariates, RA+ was associated with increased odds of fluid overload on Day 3 (adjusted odds ratio (aOR) 5.1, 95% CI 1.23–21.2, p = 0.025, versus RA-). RA- resulted in a 90% negative predictive value for fluid overload on Day 3. Median fluid overload was significantly higher in RA+ patients with severe acute kidney injury compared to RA+ patients without severe acute kidney injury (% fluid overload on Day 3: 8.8% vs. 0.73%, p = 0.002).

Conclusion

Among critically ill children, fulfillment of renal angina was associated with increased odds of fluid overload versus the absence of renal angina and a higher fluid overload among patients who developed acute kidney injury. Renal angina directed risk classification may identify patients at highest risk for fluid accumulation. Expanded study in larger populations is warranted.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02540-6.

Utility of Kinetic GFR for Predicting Severe Persistent AKI in Critically Ill Children and Young Adults

Kinetic eGFR can be part of a multidimensional approach for AKI prediction combined with biomarkers, fluid corrected creatinine, and renal angina.Kinetic eGFR on day 1 is not independently associated with severe day-3 AKI in children and young adults who are critically ill.

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.

Identification of acute kidney injury subphenotypes

PURPOSE OF REVIEW

AKI is a complex clinical syndrome with many causes and there is a broad range of clinical presentations that vary according to duration, severity and context. Established consensus definitions of AKI are nonspecific and limited to kidney function. This reduces treatment options to generic approaches rather than individualized, cause-based strategies that have limited both understanding and management of AKI.

RECENT FINDINGS

The context and the temporal phase of kidney injury are critical features in the course of AKI and critical to timing-relevant intervention. These features are missing in generic definitions and terms used to describe AKI. Subphenotypes of AKI can be identified from novel damage biomarkers, from functional changes including creatinine trajectories, from the duration of change and from associated clinical characteristics and comorbidities. Subphenotype parameters can be combined in risk scores, or by association strategies ranging from a simple function-damage matrix to complex methods, such as machine learning. Examples of such strategies are reviewed along with tentative proposals for a revised nomenclature to facilitate description of AKI subphenotypes.

SUMMARY

Appropriate intervention requires refinement of the nomenclature of AKI to identify subphenotypes that facilitate correctly timed and selectively targeted intervention.

Acute Kidney Injury in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

To describe the incidence of and risk factors for acute kidney injury (AKI) in children with acute respiratory distress syndrome (ARDS) and study the effect of AKI on patient outcomes.

DESIGN

A single-center retrospective study.

SETTING

A tertiary care children's hospital.

PATIENTS

All patients less than 18 years of age who received invasive mechanical ventilation (MV) and developed ARDS between July 2010 and July 2013 were included. Acute kidney injury was defined using p-RIFLE (risk, injury, failure, loss, and end-stage renal disease) criteria.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

One hundred fifteen children met the criteria and were included in the study. Seventy-four children (74/115, 64%) developed AKI. The severity of AKI was risk in 34 (46%) of 74, injury in 19 (26%) of 74, and failure in 21 (28%) of 74. The presence of AKI was associated with lower Pao ₂ to Fio ₂ (P/F) ratio (P = .007), need for inotropes (P = .003), need for diuretics (P = .004), higher oxygenation index (P = .03), higher positive end-expiratory pressure (PEEP; P = .01), higher mean airway pressure (P = .008), and higher Fio ₂ requirement (P = .03). Only PEEP and P/F ratios were significantly associated with AKI in the unadjusted logistic regression model. Patients with AKI had a significantly longer duration of hospital stay, although there was no significant difference in the intensive care unit stay, duration of MV, and mortality. Recovery of AKI occurred in 68% of the patients. A multivariable model including PEEP, P/F ratio, weight, need for inotropes, and need for diuretics had a better receiver operating characteristic (ROC) curve with an AUC of 0.75 compared to the ROC curves for PEEP only and P/F ratio only for the prediction of AKI.

CONCLUSIONS

Patients with ARDS have high rates of AKI, and its presence is associated with increased morbidity and mortality.

Acute Kidney Injury and Fluid Overload in Pediatric Cardiac Surgery

PURPOSE OF REVIEW

Acute kidney injury (AKI) and fluid overload affect a large number of children undergoing cardiac surgery, and confers an increased risk for adverse complications and outcomes including death. Survivors of AKI suffer long-term sequelae. The purpose of this narrative review is to discuss the short and long-term impact of cardiac surgery associated AKI and fluid overload, currently available tools for diagnosis and risk stratification, existing management strategies, and future management considerations.

RECENT FINDINGS

Improved risk stratification, diagnostic prediction tools and clinically available early markers of tubular injury have the ability to improve AKI-associated outcomes. One of the major challenges in diagnosing AKI is the diagnostic imprecision in serum creatinine, which is impacted by a variety of factors unrelated to renal disease. In addition, many of the pharmacologic interventions for either AKI prevention or treatment have failed to show any benefit, while peritoneal dialysis catheters, either for passive drainage or prophylactic dialysis may be able to mitigate the detrimental effects of fluid overload.

SUMMARY

Until novel risk stratification and diagnostics tools are integrated into routine practice, supportive care will continue to be the mainstay of therapy for those affected by AKI and fluid overload after pediatric cardiac surgery. A viable series of preventative measures can be taken to mitigate the risk and severity of AKI and fluid overload following cardiac surgery, and improve care.