The impact of fluid balance on outcomes in premature neonates: a report from the AWAKEN study group

Continuous Kidney Replacement Therapy and Survival in Children and Young Adults: Findings From the Multinational WE-ROCK Collaborative

RATIONALE & OBJECTIVE

There are limited studies describing the epidemiology and outcomes in children and young adults receiving continuous kidney replacement therapy (CKRT). We aimed to describe associations between patient characteristics, CKRT prescription, and survival.

STUDY DESIGN

Retrospective multicenter cohort study.

SETTING & PARTICIPANTS

980 patients aged from birth to 25 years who received CKRT between 2015 and 2021 at 1 of 32 centers in 7 countries participating in WE-ROCK (Worldwide Exploration of Renal Replacement Outcomes Collaborative in Kidney Diseases).

EXPOSURE

CKRT for acute kidney injury or volume overload.

OUTCOMES

Death before intensive care unit (ICU) discharge.

ANALYTICAL APPROACH

Descriptive statistics.

RESULTS

Median age was 8.8 years (IQR, 1.6-15.0), and median weight was 26.8 (IQR, 11.6-55.0) kg. CKRT was initiated a median of 2 (IQR, 1-6) days after ICU admission and lasted a median of 6 (IQR, 3-14) days. The most common CKRT modality was continuous venovenous hemodiafiltration. Citrate anticoagulation was used in 62%, and the internal jugular vein was the most common catheter placement location (66%). 629 participants (64.1%) survived at least until ICU discharge. CKRT dose, filter type, and anticoagulation were similar in those who did and did not survive to ICU discharge. There were apparent practice variations by institutional ICU size.

LIMITATIONS

Retrospective design; limited representation from centers outside the United States.

CONCLUSIONS

In this study of children and young adults receiving CKRT, approximately two thirds survived at least until ICU discharge. Although variations in dialysis mode and dose, catheter size and location, and anticoagulation were observed, survival was not detected to be associated with these parameters.

PLAIN-LANGUAGE SUMMARY

In this large contemporary epidemiological study of children and young adults receiving continuous kidney replacement therapy in the intensive care unit, we observed that two thirds of patients survived at least until ICU discharge. However, patients with comorbidities appeared to have worse outcomes. Compared with previously published reports on continuous kidney replacement therapy practice, we observed greater use of continuous venovenous hemodiafiltration with regional citrate anticoagulation.

Diuresis-led volume replacement strategy in extremely low birth weight infants

AIM

In extremely low birth weight infants, fluid overload has been associated with bronchopulmonary dysplasia and death. Excessive weight loss may increase the risk of meconium obstruction and intestinal perforation. As these infants display oliguria followed by polyuria, we embarked on a diuresis-led volume replacement strategy as of January 2020.

METHODS

This single-centre analysis presents data of infants <1000 g birth weight surviving for more than 3 days admitted 2017-2019 (n = 217, daily volume increase) versus 2020-2022 (n = 2022, diuresis-led volume replacement).

RESULTS

The second cohort had lower gestational age (median [interquartile range]: 253/7 [243/7-264/7] vs. 263/7 [251/7-282/7] weeks), less antenatal steroids (58% vs. 69%), more indomethacin (66% vs. 47%) and higher initial diuresis (5.6 [4.9-6.8] vs. 4.8 [4.2-5.5] mL/kg/h) but did not differ by relative weight loss at Day 7 of life. Employing binary logistic regression with gestational age, antenatal steroids and indomethacin as covariates, the cohorts did not differ by rates of patent ductus arteriosus, abdominal surgery or severe retinopathy of prematurity, while there were significant declines in sepsis (from 32% to 19%), bronchopulmonary dysplasia (from 26% to 23%) and mortality (from 13% to 7%).

CONCLUSION

Diuresis-led volume replacement appears to be safe and maybe beneficial.

Advocating for the inclusion of kidney health outcomes in neonatal research: best practice recommendations by the Neonatal Kidney Collaborative

Acute kidney injury (AKI) occurs in nearly 30% of sick neonates. Chronic kidney disease (CKD) can be detected in certain populations of sick neonates as early as 2 years. AKI is often part of a multisystem syndrome that negatively impacts developing organs resulting in short- and long-term pulmonary, neurodevelopmental, and cardiovascular morbidities. It is critical to incorporate kidney-related data into neonatal clinical trials in a uniform manner to better understand how neonatal AKI or CKD could affect an outcome of interest. Here, we provide expert opinion recommendations and rationales to support the inclusion of short- and long-term neonatal kidney outcomes using a tiered approach based on study design: (1) observational studies (prospective or retrospective) limited to data available within a center's standard practice, (2) observational studies involving prospective data collection where prespecified kidney outcomes are included in the design, (3) interventional studies with non-nephrotoxic agents, and (4) interventional studies with known nephrotoxic agents. We also provide recommendations for biospecimen collection to facilitate ancillary kidney specific research initiatives. This approach balances the costs of AKI and CKD ascertainment with knowledge gained. We advocate that kidney outcomes be included routinely in neonatal clinical study design. Consistent incorporation of kidney outcomes across studies will increase our knowledge of neonatal morbidity.

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).

Correlation between early postnatal body weight changes and lung ultrasound scores as predictors of bronchopulmonary dysplasia in preterm infants: A secondary analysis of a prospective study

Recent research links early weight changes (EWC) with bronchopulmonary dysplasia (BPD) in preterm neonates, while lung ultrasound score (LUS) has shown promise in predicting BPD. We aimed to explore the correlation between LUS and EWC as markers of extravascular lung edema and to investigate the correlation between LUS and EWC in preterm infants with respiratory distress syndrome regarding future BPD development. This secondary analysis of a prospective study involved infants ≤ 28 weeks gestation. Enrolled infants underwent lung ultrasound assessment on postnatal days 3, 7 and 14, measuring LUS. EWC was computed on the same time points. Infants were classified as either having BPD or not. Descriptive statistics, correlation coefficient, and area under the receiver operating characteristic (AUROC) curve analysis were utilized. Of 132 infants, 70 (53%) had BPD. Univariate analysis revealed statistically significant differences in LUS and EWC at days 3, 7, and 14 between BPD and no-BPD groups (p < 0.001). A statistically significant but weak positive correlation existed between LUS and EWC (r0.37, r0.29, r0.24, and p < 0.01) at postnatal days 3, 7, and 14, respectively. AUROC analysis indicated LUS having superior predictive capacity for the need for invasive mechanical ventilation at day 14 as well as the later BPD development compared to EWC (p < 0.0001).

CONCLUSION

In a cohort of extreme preterm infants, our study revealed a positive yet weak correlation between LUS and EWC, suggesting that EWC was not the major contributing to the evolving chronic lung disease.

WHAT IS KNOWN

• Recent evidence links Early Weight-Changes with bronchopulmonary dysplasia in preterm neonates. • Lung ultrasound score has shown promise in early prediction of the subsequent development of bronchopulmonary dysplasia in preterm infants. No studies have examined the correlation between Early Weight-Changes and Lung ultrasound score in preterm infants during first 2 weeks after birth.

WHAT IS NEW

• Our study demonstrated a positive and statistically significant correlation between early LUS and EWC, indicating their potential role as early predictors for the subsequent development of BPD in extreme preterm infants. • The weak correlation between the two parameters may stem from the possible restricted influence of EWC, given that it may not be the primary factor contributing to the evolving chronic lung disease.

Fluid and electrolyte management in the neonate and what can go wrong

PURPOSE OF REVIEW

This review highlights recent advances in understanding fluid and electrolyte homeostasis during the newborn period, including heightened recognition of fluid overload and acute kidney injury contributing to poor clinical outcomes. Particular attention is given towards the care of extremely preterm infants.

RECENT FINDINGS

Emerging data demonstrate (i) disproportionally large transepidermal water loss in the extremely preterm population, (ii) the relationship between postnatal weight loss (negative fluid balance) and improved outcomes, (iii) the frequency and negative effects of dysnatremias early in life, (iv) the role of sodium homeostasis in optimizing postnatal growth, and (v) the deleterious effects of fluid overload and acute kidney injury.

SUMMARY

As clinicians care for an increasing number of preterm infants, understanding progress in approaches to fluid and electrolyte management and avoidance of fluid overload states will improve the care and outcomes of this vulnerable population. Further translational and clinical studies are needed to address remaining knowledge gaps and improve current approaches to fluid and electrolyte management.

Recent Advances in Kidney Replacement Therapy in Infants: A Review

Kidney replacement therapy (KRT) is used to treat children and adults with acute kidney injury (AKI), fluid overload, kidney failure, inborn errors of metabolism, and severe electrolyte abnormalities. Peritoneal dialysis and extracorporeal hemodialysis/filtration can be performed for different durations (intermittent, prolonged intermittent, and continuous) through either adaptation of adult devices or use of infant-specific devices. Each of these modalities have advantages and disadvantages, and often multiple modalities are used depending on the scenario and patient-specific needs. Traditionally, these therapies have been challenging to deliver in infants due the lack of infant-specific devices, small patient size, required extracorporeal volumes, and the risk of hemodynamic stability during the initiation of KRT. In this review, we discuss challenges, recent advancements, and optimal approaches to provide KRT in hospitalized infants, including a discussion of peritoneal dialysis and extracorporeal therapies. We discuss each specific KRT modality, review newer infant-specific devices, and highlight the benefits and limitations of each modality. We also discuss the ethical implications for the care of infants who need KRT and areas for future research.

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.

Time to Continuous Renal Replacement Therapy Initiation and 90-Day Major Adverse Kidney Events in Children and Young Adults

Importance

In clinical trials, the early or accelerated continuous renal replacement therapy (CRRT) initiation strategy among adults with acute kidney injury or volume overload has not demonstrated a survival benefit. Whether the timing of initiation of CRRT is associated with outcomes among children and young adults is unknown.

Objective

To determine whether timing of CRRT initiation, with and without consideration of volume overload (VO; <10% vs ≥10%), is associated with major adverse kidney events at 90 days (MAKE-90).

Design, Setting, and Participants

This multinational retrospective cohort study was conducted using data from the Worldwide Exploration of Renal Replacement Outcome Collaborative in Kidney Disease (WE-ROCK) registry from 2015 to 2021. Participants included children and young adults (birth to 25 years) receiving CRRT for acute kidney injury or VO at 32 centers across 7 countries. Statistical analysis was performed from February to July 2023.

Exposure

The primary exposure was time to CRRT initiation from intensive care unit admission.

Main Outcomes and measures

The primary outcome was MAKE-90 (death, dialysis dependence, or persistent kidney dysfunction [>25% decline in estimated glomerular filtration rate from baseline]).

Results

Data from 996 patients were entered into the registry. After exclusions (n = 27), 969 patients (440 [45.4%] female; 16 (1.9%) American Indian or Alaska Native, 40 (4.7%) Asian or Pacific Islander, 127 (14.9%) Black, 652 (76.4%) White, 18 (2.1%) more than 1 race; median [IQR] patient age, 8.8 [1.7-15.0] years) with data for the primary outcome (MAKE-90) were included. Median (IQR) time to CRRT initiation was 2 (1-6) days. MAKE-90 occurred in 630 patients (65.0%), of which 368 (58.4%) died. Among the 601 patients who survived, 262 (43.6%) had persistent kidney dysfunction. Of patients with persistent dysfunction, 91 (34.7%) were dependent on dialysis. Time to CRRT initiation was approximately 1 day longer among those with MAKE-90 (median [IQR], 3 [1-8] days vs 2 [1-4] days; P = .002). In the generalized propensity score-weighted regression, there were approximately 3% higher odds of MAKE-90 for each 1-day delay in CRRT initiation (odds ratio, 1.03 [95% CI, 1.02-1.04]).

Conclusions and Relevance

In this cohort study of children and young adults receiving CRRT, longer time to CRRT initiation was associated with greater risk of MAKE-90 outcomes, in particular, mortality. These findings suggest that prospective multicenter studies are needed to further delineate the appropriate time to initiate CRRT and the interaction between CRRT initiation timing and VO to continue to improve survival and reduce morbidity in this 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.

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.

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.

Improving acute peritoneal dialysis outcome with use of soft peritoneal dialysis catheter (Cook Mac-Loc Multipurpose Drainage catheter®) among infants < 1500 g in a low resource setting

BACKGROUND

Despite its utility, uncertainty exists on the feasibility of acute peritoneal dialysis (PD) and optimal PD catheter type for very low birth weight (VLBW < 1500 g) and extremely low birth weight (ELBW < 1000 g) infants. We hereby report our experience of acute PD among these high-risk infants and compare the outcome between stylet-based rigid catheter (SRC) and Cook Mac-Loc Multipurpose Drainage catheters® (CMMDC).

METHODS

Case notes of infants < 1500 g undergoing PD between 2012 and 2021 in a network of five participating neonatal units supported by a tertiary paediatric nephrology centre in Kolkata, India, were retrospectively reviewed. PD was conducted either with SRC or after 2018 with CMMDC. Outcome parameters included complications, survival during PD, and survival to discharge.

RESULTS

24 infants (VLBW: n = 13 and ELBW: n = 11) underwent PD at median age 4.5 days (IQR 3-6) with either CMMDC (n = 14) or SRC (n = 10). Significant improvement in biochemical parameters and fluid removal was seen in both ELBW and VLBW infants. CMMDC was associated with significantly fewer PD-related complications 7/14 (50%) vs. 9/10 (90%) (p = 0.04) and higher survival during PD 13/14 (93%) vs. 5/10 (50%) (p = 0.02), without significant difference in survival to hospital discharge 8/14 (57%) vs. 3/10 (30%) (p = 0.25). CMMDC also enabled longer duration of PD, higher ultrafiltration, and better control of acidosis. Consumable cost was higher for CMMDC (USD$60) than SRC (USD$14).

CONCLUSIONS

In a low resource setting, CMMDC had lower PD complications and superior short-term survival among ELBW/VLBW infants. A higher resolution version of the Graphical abstract is available as Supplementary information.

Positive fluid balance and diuretic therapy are associated with mechanical ventilation and mortality in preterm neonates in the first fourteen postnatal days

BACKGROUND

Fluid overload leads to poor neonatal outcomes. Diuretics may lower the rates of mechanical ventilation (MV) and mortality in neonates with fluid overload.

METHODS

This is a retrospective study of preterm neonates ≤ 36 weeks of gestational age (GA) in the first 14 postnatal days in a level IV NICU in 2014-2020. We evaluated the epidemiology of fluid balance in the first 14 postnatal days and its association with MV and mortality and studied the association of diuretics with fluid balance, MV, and mortality.

RESULTS

In 1383 included neonates, the overall median lowest and peak fluid balances were - 7.8% (IQR: - 11.7, - 4.6) and 8% (3, 16) on days 3 (2, 5) and 13 (5, 14), respectively. Fluid balance distribution varied significantly by GA. Peak fluid balance of ≥ 10% was associated with increased odds of MV on days 7 and 14 with highest odds ratios (OR) of MV in neonates with fluid balance ≥ 15%. Peak fluid balance of ≥ 15% was associated with the greatest odds of mortality. Diuretics were used more frequently in neonates with younger GA, smaller birthweight, positive fluid balance, and those on MV.

CONCLUSIONS

Positive fluid balance negatively impacts pulmonary status. The odds of MV and death increase significantly as peak fluid balance percentage increases in all GA groups. The impact of diuretics on MV and death in preterm neonates needs further evaluation. A higher resolution version of the Graphical abstract is available as Supplementary information.

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 and electrolyte management in preterm infants with patent ductus arteriosus

Optimal fluid management of preterm babies with suspected or confirmed diagnosis of patent ductus arteriosus (PDA) is frequently challenging for neonatal care physician because of paucity of clinical trials. There is wide variation in practice across neonatal units, resulting in significant impact on outcomes in Extremely Low Birth Weight (ELBW) babies with hemodynamically significant PDA. A delicate balance is required in fluid management to reduce mortality and morbidity in this population. The purpose of this review is to lay out the current understanding about fluid and electrolyte management in ELBW babies with hemodynamically significant PDA and highlight areas for future research.

Association of Fluid Balance With Short- and Long-term Respiratory Outcomes in Extremely Premature Neonates: A Secondary Analysis of a Randomized Clinical Trial

IMPORTANCE

Extremely low gestational age neonates are at risk of disorders of fluid balance (FB), defined as change in fluid weight over a specific period. Few data exist on the association between FB and respiratory outcomes in this population.

OBJECTIVE

To describe FB patterns and evaluate the association of FB with respiratory outcomes in a cohort of extremely low gestational age neonates.

DESIGN, SETTING, AND PARTICIPANTS

This study is a secondary analysis of the Preterm Erythropoietin Neuroprotection Trial (PENUT), a phase 3 placebo-controlled randomized clinical trial of erythropoietin in extremely premature neonates conducted in 30 neonatal intensive care units in the US from December 1, 2013, to September 31, 2016. This analysis included 874 extremely premature neonates born at 24 to 27 weeks' gestation who were enrolled in the PENUT study. Secondary analysis was performed in November 2021.

EXPOSURES

Primary exposure was peak FB during the first 14 postnatal days. The FB was calculated as percent change in weight from birth weight (BW) as a surrogate for FB.

MAIN OUTCOMES AND MEASURES

The primary outcome was mechanical ventilation on postnatal day 14. The secondary outcome was a composite of severe bronchopulmonary dysplasia (BPD) or death.

RESULTS

A total of 874 neonates (449 [51.4%] male; mean [SD] BW, 801 [188] g; 187 [21.4%] Hispanic, 676 [77.3%] non-Hispanic, and 11 [1.3%] of unknown ethnicity; 226 [25.9%] Black, 569 [65.1%] White, 51 [5.8%] of other race, and 28 [3.2%] of unknown race) were included in this analysis. Of these 874 neonates, 458 (52.4%) received mechanical ventilation on postnatal day 14, and 291 (33.3%) had severe BPD or had died. Median peak positive FB was 11% (IQR, 4%-20%), occurring on postnatal day 13 (IQR, 9-14). A total of 93 (10.6%) never decreased below their BW. Neonates requiring mechanical ventilation at postnatal day 14 had a higher peak FB compared with those who did not require mechanical ventilation (15% above BW vs 8% above BW, P < .001). On postnatal day 3, neonates requiring mechanical ventilation were more likely to have a higher FB (5% below BW vs 8% below BW, P < .001). The median time to return to BW was shorter in neonates who received mechanical ventilation (7 vs 8 days, P < .001) and those with severe BPD (7 vs 8 days, P < .001). After adjusting for confounding variables, for every 10% increase in peak FB during the first 14 postnatal days, there was 103% increased odds of receiving mechanical ventilation at postnatal day 14 (adjusted odds ratio, 2.03; 95% CI, 1.64-2.51).

CONCLUSIONS AND RELEVANCE

In this secondary analysis of a randomized clinical trial, peak FB was associated with mechanical ventilation on postnatal day 14 and severe BPD or death. Fluid balance in the first 3 postnatal days and time to return to BW may be potential targets to help guide management and improve respiratory outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01378273.

Association of early dysnatremia with mortality in the neonatal intensive care unit: results from the AWAKEN study

OBJECTIVE

To determine the association of dysnatremia in the first postnatal week and risk of acute kidney injury (AKI) and mortality.

STUDY DESIGN

A secondary analysis of 1979 neonates in the AWAKEN cohort evaluated the association of dysnatremia with (1) AKI in the first postnatal week and (2) mortality, utilizing time-varying Cox proportional hazard models.

RESULT

Dysnatremia developed in 50.2% of the cohort and was not associated with AKI. Mortality was associated with hyponatremia (HR 2.15, 95% CI 1.07-4.31), hypernatremia (HR 4.23, 95% CI 2.07-8.65), and combined hypo/hypernatremia (HR 6.39, 95% CI 2.01-14.01). In stratified models by AKI-status, hypernatremia and hypo/hypernatremia increased risk of mortality in neonates without AKI.

CONCLUSION

Dysnatremia within the first postnatal week was associated with increased risk of mortality. Hypernatremia and combined hypo/hypernatremia remained significantly associated with mortality in neonates without AKI. This may reflect fluid strategies kidney injury independent of creatinine and urine-output defined AKI, and/or systemic inflammation.

Fluid bolus administration in children, who responds and how? A systematic review and meta-analysis

BACKGROUND

Fluid boluses are frequently utilized in children. Despite their frequency of use, there is little objective data regarding the utility of fluid boluses, who they benefit the most, and what the effects are.

AIMS

This study aimed to conduct pooled analyses to identify those who may be more likely to respond to fluid boluses as well as characterize clinical changes associated with fluid boluses.

METHODS

A systematic review of the literature and meta-analysis was conducted to identify pediatric studies investigating the response to fluid boluses and clinical changes associated with fluid boluses.

RESULTS

A total of 15 studies with 637 patients were included in the final analyses with a mean age of 650 days ± 821.01 (95% CI 586 to 714) and a mean weight of 10.5 kg ± 7.19 (95% CI 9.94 to 11.1). The mean bolus volume was 12.14 ml/kg ± 4.09 (95% CI 11.8 to 12.5) given over a mean of 19.55 min ± 10.16 (95% CI 18.8 to 20.3). The following baseline characteristics were associated with increased likelihood of response [represented in mean difference (95% CI)]: greater age [207.2 days (140.8 to 273.2)], lower cardiac index [-0.5 ml/min/m² (-0.9 to -0.3)], and lower stroke volume [-5.1 ml/m² (-7.9 to -2.3)]. The following clinical parameters significantly changed after a fluid bolus: decreased HR [-5.6 bpm (-9.8 to -1.3)], increased systolic blood pressure [7.7 mmHg (1.0 to 14.4)], increased mean arterial blood pressure [5.5 mmHg (3.1 to 7.8)], increased cardiac index [0.3 ml/min/m² (0.1 to 0.6)], increased stroke volume [4.3 ml/m² (3.5 to 5.2)], increased central venous pressure [2.2 mmHg (1.1 to 3.3)], and increased systemic vascular resistance [2.1 woods units/m² (0.1 to 4.2)].

CONCLUSION

Fluid blouses increase arterial blood pressure or cardiac output by 10% in approximately 56% of pediatric patients. Fluid blouses lead to significant decrease in HR and significant increases in cardiac output, stroke volume, and systemic vascular resistance. Limited published data are available on the effects of fluid blouses on systemic oxygen delivery.

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.

Low albumin levels are independently associated with neonatal acute kidney injury: a report from AWAKEN Study Group

BACKGROUND

Data from adult and pediatric literature have shown an association between albumin levels and AKI. Whether hypoalbuminemia and neonatal AKI are associated has not been studied.

METHODS

We evaluated the association of albumin with early (during the first postnatal week) and late (after the first postnatal week) AKI for 531 neonates from the Assessment of Worldwide AKI Epidemiology in Neonates (AWAKEN) database and for 3 gestational age (GA) subgroups: < 29, 29 to < 36, and ≥ 36 weeks GA.

RESULTS

Low albumin levels were associated with increased odds of neonatal AKI; for every 0.1 g/dL decrease in albumin, the odds of late AKI increased by 12% on continuous analysis. After adjustment for potential confounders, neonates with albumin values in the lowest quartiles (< 2.2 g/dL) had an increased odds of early [Adjusted Odd Ratio (AdjOR) 2.5, 95% CI = 1.1-5.3, p < 0.03] and late AKI [AdjOR 13.4, 95% CI = 3.6-49.9, p < 0.0001] compared to those with albumin in the highest quartile (> 3.1 g/dL). This held true for albumin levels 2.3 to 2.6 g/dL for early [AdjOR 2.5, 95% CI = 1.2-5.5, p < 0.02] and late AKI [AdjOR 6.4, 95% CI = 1.9-21.6, p < 0.01]. Albumin quartiles of (2.7 to 3.0 g/dL) were associated with increased odds of late AKI. Albumin levels of 2.6 g/dL and 2.4 g/dL best predicted early (AUC = 0.59) and late AKI (AUC = 0.64), respectively. Analysis of albumin association with AKI by GA is described.

CONCLUSIONS

Low albumin levels are independently associated with early and late neonatal AKI. Albumin could be a potential modifiable risk factor for neonatal AKI.

Recurrent acute kidney injury in preterm neonates is common and associated with worse outcomes and higher mortality

BACKGROUND

Acute kidney injury (AKI) in preterm neonates is associated with poor outcomes that may worsen in the setting of recurrent episodes of AKI. This study defines and studies the incidence, risk factors, and outcomes of recurrent AKI (rAKI).

METHODS

Retrospective chart review of the neonates born at a gestational age of ≤28 weeks admitted to the neonatal intensive care unit (NICU) between January 2014 and December 2018. We identified AKI based on the serum creatinine (Scr) concentrations using the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. rAKI was defined as the occurrence of AKI after Scr from the prior AKI had returned to baseline.

RESULTS

Forty-nine of the 205 (24%) preterm neonates developed rAKI. An earlier diagnosis (<7 days old) and a higher KDIGO stage (stage 3) at the initial episode of AKI was associated with rAKI (p = 0.03). Preterm neonates with rAKI had higher mortality as compared to those with a single episode of AKI (sAKI) (adjusted odds ratio (aOR) 4.55, 95% confidence interval (CI), 1.12-18.51). Length of stay (LOS) was longer among neonates with rAKI as compared to those with sAKI by 36 days (95% CI 24.9-47.1).

CONCLUSIONS

Recurrent AKI in preterm neonates was associated with earlier episodes and higher KDIGO stage of the initial AKI episode. Neonates with rAKI had higher mortality and longer LOS compared to those with sAKI.

IMPACT

Definition and study of the incidence of rAKI and its associated outcomes among preterm neonates. Recurrent AKI is common among preterm neonates and may contribute to worse outcomes for premature neonates in the NICU. Early recognition of the risk factors for AKI, and effective management of initial AKI and early phase of recurrent AKI may improve outcomes of these preterm neonates.

Human Stem Cell and Organoid Models to Advance Acute Kidney Injury Diagnostics and Therapeutics

Acute kidney injury (AKI) is an increasingly common problem afflicting all ages, occurring in over 20% of non-critically ill hospitalized patients and >30% of children and >50% of adults in critical care units. AKI is associated with serious short-term and long-term consequences, and current therapeutic options are unsatisfactory. Large gaps remain in our understanding of human AKI pathobiology, which have hindered the discovery of novel diagnostics and therapeutics. Although animal models of AKI have been extensively studied, these differ significantly from human AKI in terms of molecular and cellular responses. In addition, animal models suffer from interspecies differences, high costs and ethical considerations. Static two-dimensional cell culture models of AKI also have limited utility since they have focused almost exclusively on hypoxic or cytotoxic injury to proximal tubules alone. An optimal AKI model would encompass several of the diverse specific cell types in the kidney that could be targets of injury. Second, it would resemble the human physiological milieu as closely as possible. Third, it would yield sensitive and measurable readouts that are directly applicable to the human condition. In this regard, the past two decades have seen a dramatic shift towards newer personalized human-based models to study human AKI. In this review, we provide recent developments using human stem cells, organoids, and in silico approaches to advance personalized AKI diagnostics and therapeutics.

Association between fluid overload and mortality in newborns: a systematic review and meta-analysis

Fluid overload (FO) is associated with higher rates of mortality and morbidity in pediatric and adult populations. The aim of this systematic review and meta-analysis was to investigate the association between FO and mortality in critically ill neonates. Systematic search of Ovid MEDLINE, EMBASE, Cochrane Library, trial registries, and gray literature from inception to January 2021. We included all studies that examined neonates admitted to neonatal intensive care units and described FO and outcomes of interest. We identified 17 observational studies with a total of 4772 critically ill neonates who met the inclusion criteria. FO was associated with higher mortality (OR, 4.95 [95% CI, 2.26-10.87]), and survivors had a lower percentage of FO compared with nonsurvivors (WMD, - 4.33 [95% CI, - 8.34 to - 0.32]). Neonates who did not develop acute kidney injury (AKI) had lower FO compared with AKI patients (WMD, - 2.29 [95% CI, - 4.47 to - 0.10]). Neonates who did not require mechanical ventilation on postnatal day 7 had lower fluid balance (WMD, - 1.54 [95% CI, - 2.21 to - 0.88]). FO is associated with higher mortality, AKI, and need for mechanical ventilation in critically ill neonates in the intensive care unit. Strict control of fluid balance to prevent FO is essential. A higher resolution version of the Graphical abstract is available as Supplementary information.

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.

Management of Acute Kidney Injury in Extremely Low Birth Weight Infants

Acute kidney injury (AKI) is a common problem in the neonatal intensive care unit (NICU). Neonates born at <1,000 g (extremely low birth weight, ELBW) are at an increased risk of secondary associated comorbidities such as intrauterine growth restriction, prematurity, volume restriction, ischaemic injury, among others. Studies estimate up to 50% ELBW infants experience at least one episode of AKI during their NICU stay. Although no curative treatment for AKI currently exists, recognition is vital to reduce potential ongoing injury and mitigate long-term consequences of AKI. However, the definition of AKI is imperfect in this population and presents clinical challenges to correct identification, thus contributing to under recognition and reporting. Additionally, the absence of guidelines for the management of AKI in ELBW infants has led to variations in practice. This review summarizes AKI in the ELBW infant and includes suggestions such as close observation of daily fluid balance, review of medications to reduce nephrotoxic exposure, management of electrolytes, maximizing nutrition, and the use of diuretics and/or dialysis when appropriate.

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.

Neonatal acute kidney injury: a case-based approach

Neonatal acute kidney injury (AKI) is increasingly recognized as a common complication in critically ill neonates. Over the last 5-10 years, there have been significant advancements which have improved our understanding and ability to care for neonates with kidney disease. A variety of factors contribute to an increased risk of AKI in neonates, including decreased nephron mass and immature tubular function. Multiple factors complicate the diagnosis of AKI including low glomerular filtration rate at birth and challenges with serum creatinine as a marker of kidney function in newborns. AKI in neonates is often multifactorial, but the cause can be identified with careful diagnostic evaluation. The best approach to treatment in such patients may include diuretic therapies or kidney support therapy. Data for long-term outcomes are limited but suggest an increased risk of chronic kidney disease (CKD) and hypertension in these infants. We use a case-based approach throughout this review to illustrate these concepts and highlight important evidence gaps in the diagnosis and management of neonatal AKI.

Weight gain in the first week of life and its association with morbidity and mortality in extremely low birthweight (ELBW) infants

BACKGROUND

Weight gain in the first week of life is indicative of fluid excess in preterm neonates.

AIMS

To determine if morbidity and/or mortality of extremely low birthweight (ELBW) infants was lower in those who did not have excess weight gain in the first week of life, compared with those who did.

STUDY DESIGN

Retrospective cohort study.

SUBJECTS

ELBW infants born from 1st May 2014 - 31st May 2019.

EXCLUSIONS

major congenital abnormalities (including hydrops), died within the first 7 days, no recorded weight on day 6, 7 or 8.

OUTCOME MEASURES

We compared infants whose weight was greater than birthweight by day 7 and infants whose weight remained at, or below, birthweight by day 7.

RESULTS

There were 312 ELBW infants in the study population: 15 (5%) died before discharge from hospital. Holding birthweight and gestational age (GA) constant, the odds of death in neonates with day 7 weight >birthweight was about 3 times the odds of death in neonates with day 7 weight ≤birthweight (adjusted odds ratio 3.18, 95% confidence interval 0.66-15.26, p = 0.15). Neonates with day 7 weight >birthweight were more likely to have had a PDA that required treatment than those with day 7 weight ≤birthweight (65% versus 43% respectively; p <0.001).

CONCLUSIONS

ELBW infants who gain weight in the first week of postnatal life, have a greater risk of PDA requiring treatment and may have a higher risk of mortality than infants who lose weight in the first week of life.

Neonatal Acute Kidney Injury: Understanding of the Impact on the Smallest Patients

The study of neonatal acute kidney injury (AKI) has transitioned from small, single-center studies to the development of a large, multicenter cohort. The scope of research has expanded from assessment of incidence and mortality to analysis of more specific risk factors, novel urinary biomarkers, interplay between AKI and other organ systems, impact of fluid overload, and quality improvement efforts. The intensification has occurred through collaboration between the neonatology and nephrology communities. This review discusses 2 case scenarios to illustrate the clinical presentation of neonatal AKI, important risk factors, and approaches to minimize AKI events and adverse long-term outcomes.

Fluid status in the first 10 days of life and death/bronchopulmonary dysplasia among preterm infants

OBJECTIVE

To investigate the association between fluid and sodium status in the first 10 postnatal days and death/bronchopulmonary dysplasia (BPD) among infants born <29 weeks' gestation.

STUDY DESIGN

Single center retrospective cohort study (2015-2018) of infants born 23-28 weeks'. Three exposure variables were evaluated over the first 10 postnatal days: cumulative fluid balance (CFB), median serum sodium concentration, and maximum percentage weight loss. Primary outcome was death and/or BPD. Multivariable logistic regression adjusting for patient covariates was used to assess the association between exposure variables and outcomes.

RESULTS

Of 191 infants included, 98 (51%) had death/BPD. Only CFB differed significantly between BPD-free survivors and infants with death/BPD: 4.71 dL/kg (IQR 4.10-5.12) vs 5.11 dL/kg (IQR 4.47-6.07; p < 0.001). In adjusted analyses, we found an association between higher CFB and higher odds of death/BPD (AOR 1.56, 95% CI 1.11-2.25). This was mainly due to the association of CFB with BPD (AOR 1.60, 95% CI 1.12-2.35), rather than with death (AOR 1.08, 95% CI 0.54-2.30).

CONCLUSION

Among preterm infants, a higher CFB in the first 10 days after delivery is associated with higher odds of death/BPD.

IMPACT

Previous studies suggest that postnatal fluid status influences survival and respiratory function in neonates. Fluid balance, serum sodium concentration, and daily weight changes are commonly used as fluid status indicators in neonates. We found that higher cumulative fluid balance in the first 10 days of life was associated with higher odds of death/bronchopulmonary dysplasia in neonates born <29 weeks. Monitoring of postnatal fluid balance may be an appropriate non-invasive strategy to favor survival without bronchopulmonary dysplasia. We developed a cumulative fluid balance chart with corresponding thresholds on each day to help design future trials and guide clinicians in fluid management.

Fluid Balance in the Critically Ill Child Section: "How Bad Is Fluid in Neonates?"

Fluid overload (FO) in neonates is understudied, and its management requires nuanced care and an understanding of the complexity of neonatal fluid dynamics. Recent studies suggest neonates are susceptible to developing FO, and neonatal fluid balance is impacted by multiple factors including functional renal immaturity in the newborn period, physiologic postnatal diuresis and weight loss, and pathologies that require fluid administration. FO also has a deleterious impact on other organ systems, particularly the lung, and appears to impact survival. However, assessing fluid balance in the postnatal period can be challenging, particularly in extremely low birth weight infants (ELBWs), given the confounding role of maternal serum creatinine (Scr), physiologic weight changes, insensible losses that can be difficult to quantify, and difficulty in obtaining accurate intake and output measurements given mixed diaper output. Although significant FO may be an indication for kidney replacement therapy (KRT) in older children and adults, KRT may not be technically feasible in the smallest infants and much remains to be learned about optimal KRT utilization in neonates. This article, though not a meta-analysis or systematic review, presents a comprehensive review of the current evidence describing the effects of FO on outcomes in neonates and highlights areas where additional research is needed.

Respiratory Variation in Aortic Blood Flow Velocity in Hemodynamically Unstable, Ventilated Neonates: A Pilot Study of Fluid Responsiveness

OBJECTIVES

To assess whether respiratory variation in aortic blood flow peak velocity can predict preload responsiveness in mechanically ventilated and hemodynamically unstable neonates.

DESIGN

Prospective observational diagnostic accuracy study.

SETTING

Third-level neonatal ICU.

PATIENTS

Hemodynamically unstable neonates under mechanical ventilation.

INTERVENTIONS

Fluid challenge with 10 mL/kg of normal saline over 20 minutes.

MEASUREMENTS AND MAIN RESULTS

Respiratory variation in aortic blood flow peak velocity and superior vena cava flow were measured at baseline (T0), immediately upon completion of the fluid infusion (T1), and at 1 hour after fluid administration (T2). Our main outcome was preload responsiveness which was defined as an increase in superior vena cava flow of at least 10% from T0 to T1. Forty-six infants with a median (interquartile range) gestational age of 30.5 weeks (28-36 wk) were included. Twenty-nine infants (63%) were fluid responders, and 17 (37%) were nonresponders Fluid responders had a higher baseline (T0) respiratory variation in aortic blood flow peak velocity than nonresponders (9% [8.2-10.8] vs 5.5% [3.7-6.6]; p < 0.001). Baseline respiratory variation in aortic blood flow peak velocity was correlated with the increase in superior vena cava flow from T0 to T1 (rho = 0.841; p < 0.001). The area under the receiver operating characteristic curve of respiratory variation in aortic blood flow peak velocity to predict preload responsiveness was 0.912 (95% CI, 0.82-1). A respiratory variation in aortic blood flow peak velocity cut-off point of 7.8% provided a 90% sensitivity (95% CI, 71-97), 88% specificity (95% CI, 62-98), 7.6 positive likelihood ratio (95% CI, 2-28), and 0.11 negative likelihood ratio (95% CI, 0.03-0.34) to predict preload responsiveness.

CONCLUSIONS

Respiratory variation in aortic blood flow velocity may be useful to predict the immediate response to a fluid challenge in hemodynamically unstable neonates under mechanical ventilation. If our results are confirmed, this measurement could be used to guide safe and individualized fluid resuscitation in critically ill neonates.

Low hemoglobin levels are independently associated with neonatal acute kidney injury: a report from the AWAKEN Study Group

BACKGROUND

Studies in adults showed a relationship between low hemoglobin (Hb) and acute kidney injury (AKI). We performed this study to evaluate this association in newborns.

METHODS

We evaluated 1891 newborns from the Assessment of Worldwide AKI Epidemiology in Neonates (AWAKEN) database. We evaluated the associations for the entire cohort and 3 gestational age (GA) groups: <29, 29-<36, and ≥36 weeks' GA.

RESULTS

Minimum Hb in the first postnatal week was significantly lower in neonates with AKI after the first postnatal week (late AKI). After controlling for multiple potential confounders, compared to neonates with a minimum Hb ≥17.0 g/dL, both those with minimum Hb ≤12.6 and 12.7-14.8 g/dL had an adjusted increased odds of late AKI (aOR 3.16, 95% CI 1.44-6.96, p = 0.04) and (aOR 2.03, 95% CI 1.05-3.93; p = 0.04), respectively. This association was no longer evident after controlling for fluid balance. The ability of minimum Hb to predict late AKI was moderate (c-statistic 0.68, 95% CI 0.64-0.72) with a sensitivity of 65.9%, a specificity of 69.7%, and a PPV of 20.8%.

CONCLUSIONS

Lower Hb in the first postnatal week was associated with late AKI, though the association no longer remained after fluid balance was included.

IMPACT

The current study suggests a possible novel association between low serum hemoglobin (Hb) and neonatal acute kidney injury (AKI). The study shows that low serum Hb levels in the first postnatal week are associated with increased risk of AKI after the first postnatal week. This study is the first to show this relationship in neonates. Because this study is retrospective, our observations cannot be considered proof of a causative role but do raise important questions and deserve further investigation. Whether the correction of low Hb levels might confer short- and/or long-term renal benefits in neonates was beyond the scope of this study.

Improving the quality of neonatal acute kidney injury care: neonatal-specific response to the 22nd Acute Disease Quality Initiative (ADQI) conference

With the adoption of standardized neonatal acute kidney injury (AKI) definitions over the past decade and the concomitant surge in research studies, the epidemiology of and risk factors for neonatal AKI have become much better understood. Thus, there is now a need to focus on strategies designed to improve AKI care processes with the goal of reducing the morbidity and mortality associated with neonatal AKI. The 22nd Acute Dialysis/Disease Quality Improvement (ADQI) report provides a framework for such quality improvement in adults at risk for AKI and its sequelae. While many of the concepts can be translated to neonates, there are a number of specific nuances which differ in neonatal AKI care. A group of experts in pediatric nephrology and neonatology came together to provide neonatal-specific responses to each of the 22nd ADQI consensus statements.

Impact of Acute Kidney Injury on Critically Ill Children and Neonates

Acute kidney injury (AKI) is a clinical syndrome that manifests as an abrupt impairment of kidney function. AKI is common in critically ill pediatric patients admitted to the pediatric intensive care units. AKI is a deleterious complication in critically ill children as it is associated with increased morbidity and mortality. This review provides an overview of the incidence, morbidity, and mortality of AKI in critically ill children in general and specific cohorts such as post-cardiac surgeries, sepsis, critically ill neonates, and post stem cell transplantation.

Preterm birth and neonatal acute kidney injury: implications on adolescent and adult outcomes

As a result of preterm birth, immature kidneys are exposed to interventions in the NICU that promote survival, but are nephrotoxic. Furthermore, the duration of renal development may be truncated in these vulnerable neonates. Immaturity and nephrotoxic exposures predispose preterm newborns to acute kidney injury (AKI), particularly in the low birth weight and extremely preterm gestational age groups. Several studies have associated preterm birth as a risk factor for future chronic kidney disease (CKD). However, only a few publications have investigated the impact of neonatal AKI on CKD development. Here, we will review the evidence linking preterm birth and AKI in the NICU to CKD and highlight the knowledge gaps and opportunities for future research. For neonatal intensive care studies, we propose the inclusion of AKI as an important short-term morbidity outcome and CKD findings such as a reduced glomerular filtration rate in the assessment of long-term outcomes.

Renal Precision Medicine in Neonates and Acute Kidney Injury: How to Convert a Cloud of Creatinine Observations to Support Clinical Decisions

Renal precision medicine in neonates is useful to support decision making on pharmacotherapy, signal detection of adverse (drug) events, and individual prediction of short- and long-term prognosis. To estimate kidney function or glomerular filtration rate (GFR), the most commonly measured and readily accessible biomarker is serum creatinine (S_cr). However, there is extensive variability in S_cr observations and GFR estimates within the neonatal population, because of developmental physiology and superimposed pathology. Furthermore, assay related differences still matter for S_cr, but also exist for Cystatin C. Observations in extreme low birth weight (ELBW) and term asphyxiated neonates will illustrate how renal precision medicine contributes to neonatal precision medicine. When the Kidney Disease Improving Global Outcome (KDIGO) definition of acute kidney injury (AKI) is used, this results in an incidence up to 50% in ELBW neonates, associated with increased mortality and morbidity. However, urine output criteria needed adaptations to broader time intervals or weight trends, while S_cr and its trends do not provide sufficient detail on kidney function between ELBW neonates. Instead, we suggest to use assay-specific centile S_cr values to better describe postnatal trends and have illustrated its relevance by quantifying an adverse drug event (ibuprofen) and by explaining individual amikacin clearance. Term asphyxiated neonates also commonly display AKI. While oliguria is a specific AKI indicator, the majority of term asphyxiated cases are non-oliguric. Asphyxia results in a clinical significant-commonly transient-mean GFR decrease (-50%) with a lower renal drug elimination. But there is still major (unexplained) inter-individual variability in GFR and subsequent renal drug elimination between these asphyxiated neonates. Recently, the Baby-NINJA (nephrotoxic injury negated by just-in-time action) study provided evidence on the concept that a focus on nephrotoxic injury negation has a significant impact on AKI incidence and severity. It is hereby important to realize that follow-up should not be discontinued at discharge, as there are concerns about long-term renal outcome. These illustrations suggest that integration of renal (patho)physiology into neonatal precision medicine are an important tool to improve contemporary neonatal care, not only for the short-term but also with a positive health impact throughout life.

AWAKEN-Ing a New Frontier in Neonatal Nephrology

In 2013, literature about the epidemiology of neonatal acute kidney injury (AKI) was limited to primarily retrospective, single center studies that suggested that AKI was common and that those with AKI had higher rates of mortality. We developed a 24-center retrospective cohort of neonates admitted to the NICU between January 1 and March 31, 2014. Analysis of the Assessment of Worldwide Acute Kidney Epidemiology in Neonates (AWAKEN) cohort, has allowed us to describe the prevalence, risk factors and impact of neonatal AKI for different gestational age cohorts. The ample sample size allows us to provide convincing data to show that those with AKI have an increase independent higher odds of death and prolonged hospitalization time (1). This data mirrors similar studies in pediatric (2) and adult (3) critically ill populations which collectively suggest that patients do not just die with AKI, but instead, AKI is directly linked to hard clinical outcomes. This study has allowed us to answer multiple other questions in the field which has expanded our understanding of the risk factors, complications, impact of fluid overload, the definition of neonatal AKI and suggests interventions for improving outcomes. Furthermore, this project brought together neonatologist and nephrologist within and across centers. Finally, the AWAKEN project has enabled us to build relationships and infrastructure that has launched the Neonatal Kidney Collaborative http://babykidney.org/ on its way to accomplish its stated mission to improve the health of newborns with or at risk for kidney disease through multidisciplinary collaborative research, advocacy, and education.