Neonatal and maternal serum creatinine levels during the early postnatal period in preterm and term infants

Perinatal asphyxia leads to acute kidney damage and increased renal susceptibility in adulthood

Perinatal asphyxia (PA) poses a significant threat to multiple organs, particularly the kidneys. Diagnosing PA-associated kidney injury remains challenging, and treatment options are inadequate. Furthermore, there is a lack of long-term follow-up data regarding the renal implications of PA. In this study, 7-day-old male Wistar rats were exposed to PA using a gas mixture (4% O2; 20% CO2 in N2 for 15 min) to investigate molecular pathways linked to renal tubular damage, hypoxia, angiogenesis, heat shock response, inflammation, and fibrosis in the kidney. In a second experiment, adult rats with a history of PA were subjected to moderate renal ischemia-reperfusion (IR) injury to test the hypothesis that PA exacerbates renal susceptibility. Our results revealed an increased gene expression of renal injury markers (kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin), hypoxic and heat shock factors (hypoxia-inducible factor-1α, heat shock factor-1, and heat shock protein-27), proinflammatory cytokines (interleukin-1β, interleukin-6, tumor necrosis factor-α, and monocyte chemoattractant protein-1), and fibrotic markers (transforming growth factor-β, connective tissue growth factor, and fibronectin) promptly after PA. Moreover, a machine learning model was identified through random forest analysis, demonstrating an impressive classification accuracy (95.5%) for PA. Post-PA rats showed exacerbated functional decline and tubular injury and more intense hypoxic, heat shock, proinflammatory, and profibrotic response after renal IR injury compared with controls. In conclusion, PA leads to subclinical kidney injury, which may increase the susceptibility to subsequent renal damage later in life. In addition, the parameters identified through random forest analysis provide a robust foundation for future biomarker research in the context of PA.NEW & NOTEWORTHY This article demonstrates that perinatal asphyxia leads to subclinical kidney injury that permanently increases renal susceptibility to subsequent ischemic injury. We identified major molecular pathways involved in perinatal asphyxia-induced renal complications, highlighting potential targets of therapeutic approaches. In addition, random forest analysis revealed a model that classifies perinatal asphyxia with 95.5% accuracy that may provide a strong foundation for further biomarker research. These findings underscore the importance of multiorgan follow-up for perinatal asphyxia-affected patients.

Population pharmacokinetics of vancomycin in term neonates with perinatal asphyxia treated with therapeutic hypothermia

AIMS

Little is known about the population pharmacokinetics (PPK) of vancomycin in neonates with perinatal asphyxia treated with therapeutic hypothermia (TH). We aimed to describe the PPK of vancomycin and propose an initial dosing regimen for the first 48 h of treatment with pharmacokinetic/pharmacodynamic target attainment.

METHODS

Neonates with perinatal asphyxia treated with TH were included from birth until Day 6 in a multicentre prospective cohort study. A vancomycin PPK model was constructed using nonlinear mixed-effects modelling. The model was used to evaluate published dosing guidelines with regard to pharmacokinetic/pharmacodynamic target attainment. The area under the curve/minimal inhibitory concentration ratio of 400-600 mg*h/L was used as target range.

RESULTS

Sixteen patients received vancomycin (median gestational age: 41 [range: 38-42] weeks, postnatal age: 4.4 [2.5-5.5] days, birth weight: 3.5 [2.3-4.7] kg), and 112 vancomycin plasma concentrations were available. Most samples (79%) were collected during the rewarming and normothermic phase, as vancomycin was rarely initiated during the hypothermic phase due to its nonempirical use. An allometrically scaled 1-compartment model showed the best fit. Vancomycin clearance was 0.17 L/h, lower than literature values for term neonates of 3.5 kg without perinatal asphyxia (range: 0.20-0.32 L/h). Volume of distribution was similar. Published dosing regimens led to overexposure within 24 h of treatment. A loading dose of 10 mg/kg followed by 24 mg/kg/day in 4 doses resulted in target attainment.

CONCLUSION

Results of this study suggest that vancomycin clearance is reduced in term neonates with perinatal asphyxia treated with TH. Lower dosing regimens should be considered followed by model-informed precision dosing.

Incidence, Risk Factors and Outcomes of Acute Kidney Injury in Neonates Undergoing Open-heart Surgeries: Single Center Experience

Background

Incidence and outcomes of acute kidney injury (AKI) among neonates who underwent open-heart surgery are not well highlighted in the literature. We aim to assess the incidence, risk factors, and outcome of AKI among neonates undergoing open-heart surgery.

Methods

This is a retrospective cohort study between 2016 and 2021 for all neonates requiring open heart surgery. The cases were divided into 2 groups: the AKI (index) group and the non-AKI (control) group. The two groups were statistically compared for risk factors, needs for dialysis, and outcomes.

Results

100 patients fulfilled the inclusion criteria. Among them, 74 (74%) developed AKI, including 41 (55%), 15 (21%), and 18 (24%) patients in KDIGO stages 1, 2, and 3, respectively. Multivariate analysis comparing both groups demonstrated that low pre-operative creatinine (p = 0.01), prolonged bypass time (p = 0.0004) and high vasoactive inotropic score (VIS), (p = 0.0008) were risk factors for developing AKI post-operatively. Furthermore, in the AKI group, 17 (23%) neonates required renal replacement therapy in the form of peritoneal dialysis. The length of stay was higher in the AKI index group (p = 0.015). Patients who had AKI recovered their kidney function at discharge. There was no difference in mortality between both groups.

Conclusion

The AKI occurred in 74% of neonates undergoing open-heart surgery, with 23% of them needing peritoneal dialysis. Low pre-operative creatinine, high VIS score, and prolonged bypass time are potential risk factors for AKI development after neonatal open-heart surgery. AKI may lead to prolonged hospitalization, though most affected patients recovered their normal kidney function at discharge.

Relationship between the serum creatinine concentrations of preterm neonates within 24 h of birth and their mothers before delivery

BACKGROUND

Neonatal serum creatinine (n-sCr) concentrations during the first few days of life have been reported to correlate with the maternal serum Cr (m-sCr) concentrations. We aimed to derive a regression equation to describe the relationship between n-sCr within 24 h of birth in preterm neonates and m-sCr before delivery, and to perform multiple regression analysis to identify factors related to n-sCr and the difference between n-sCr and m-sCr.

METHODS

We recruited preterm neonates who were treated at the University of the Ryukyus Hospital between March 2012 and October 2022. Patients with underlying diseases or conditions that might affect hemodynamics were excluded, as were patients whose n-sCr and m-sCr were not measured in pairs. A total of 278 cases were included in the analysis.

RESULTS

The median (interquartile range) gestational age, birth weight, n-sCr, and m-sCr were 33.9 weeks (32.0-35.1 weeks), 1901 g (1579-2284 g), 0.55 mg/dL (0.48-0.64 mg/dL), and 0.47 mg/dL (0.42-0.57 mg/dL), respectively. The regression equation derived was n-sCr = 0.092 + 0.970 × m-sCr (R2 = 0.768, p < 0.001). The multiple regression analysis showed that m-sCr was the most potent influencer of n-sCr, and the ratio of placental weight to birth weight (PW/BW ratio) was the most potent influencer of the difference between n-sCr and m-sCr.

CONCLUSIONS

We have obtained an approximate equation of n-sCr = 0.1 + m-sCr for preterm neonates. In addition, the high PW/BW ration may reduce the difference between n-sCr and m-sCr.

Ototoxic and nephrotoxic drugs in neonatal intensive care units: results of a Spanish and Italian survey

Neonates face heightened susceptibility to drug toxicity, often exposed to off-label medications with dosages extrapolated from adult or pediatric studies. Premature infants in Neonatal Intensive Care Units (NICUs) are particularly at risk due to underdeveloped pharmacokinetics and exposure to multiple drugs. The study aimed to survey commonly used medications with a higher risk of ototoxicity and nephrotoxicity in Spanish and Italian neonatal units. A prospective cross-sectional study was conducted in Italian and Spanish neonatal units using a web-based survey with 43 questions. A modified Delphi method involved experts refining the survey through online consensus. Ethical approval was obtained, and responses were collected from January to July 2023. The survey covered various aspects, including drug-related ototoxic and nephrotoxic management, hearing screening, and therapeutic drug monitoring. Responses from 131 participants (35.9% from Spain and 64.1% from Italy) revealed awareness of drug toxicity risks. Varied practices were observed in hearing screening protocols, and a high prevalence of ototoxic and nephrotoxic drug use, including aminoglycosides (100%), vancomycin (70.2%), loop diuretics (63.4%), and ibuprofen (62.6%). Discrepancies existed in guideline availability and adherence, with differences between Italy and Spain in therapeutic drug monitoring practices.

CONCLUSIONS

The study underscores the need for clinical guidelines and uniform practices in managing ototoxic and nephrotoxic drugs in neonatal units. Awareness is high, but inconsistencies in practices indicate a necessity for standardization, including the implementation of therapeutic drug monitoring and the involvement of clinical pharmacologists. Addressing these issues is crucial for optimizing neonatal care in Southern Europe.

WHAT IS KNOWN

• Neonates in intensive care face a high risk of nephrotoxicity and ototoxicity from drugs like aminoglycosides, vancomycin, loop diuretics, and ibuprofen. • Therapeutic drug monitoring is key for managing these risks, optimizing dosing for efficacy and minimizing side effects.

WHAT IS NEW

• NICUs in Spain and Italy show high drug toxicity awareness but differ in ototoxic/nephrotoxic drug management. • Urgent need for standard guidelines and practices to address nephrotoxic risks from aminoglycosides, vancomycin, loop diuretics, and ibuprofen.

Mother-child correlation of kidney function: data from the Yamanashi Adjunct Study of Japan Environment and Children's Study (JECS)

BACKGROUND

Individual variation in kidney function can be affected by both congenital and acquired factors, and kidney function in children is possibly correlated with that in their mothers. However, the mother-child correlation in kidney function remains directly unconfirmed.

METHODS

We conducted a cross-sectional study of 655 healthy pairs of 7- or 8-year-old children and their mothers as an adjunct study of a nationwide epidemiological study (Japan Environment and Children's Study).

RESULTS

Both serum creatinine level (all children, r = 0.324, p < 0.001; girls, r = 0.365, p < 0.001; boys, r = 0.278, p < 0.001) and estimated glomerular filtration rate (eGFR) (r = 0.274, p < 0.001; r = 0.352, p < 0.001; r = 0.195, p < 0.001, respectively) in children were weakly associated with their maternal values. In the single linear regression analyses, maternal values of serum creatinine and eGFR were significantly associated with the children's values. Moreover, several body composition values in children, such as weight-SDS, fat (%), and predicted muscle weight, were also significantly associated with kidney function values in children. In the multiple linear regression analysis for serum creatinine levels in children, in which weight-SDS and predicted muscle weight in children were selected as adjustment factors, maternal serum creatinine level showed a significant positive association (B = 0.214, p < 0.001 in the adjusted model). Moreover, in the multiple linear regression analysis for eGFR value in children, in which fat (%) and predicted muscle weight in children were selected as adjustment factors, maternal eGFR values showed a significant positive association (B = 0.319, p < 0.001).

CONCLUSIONS

We directly confirmed mother-child correlations in both serum creatinine levels and eGFR values, particularly in girls. Graphical abstract A higher resolution version of the Graphical abstract is available as Supplementary information.

An Exploratory Review on the Potential of Artificial Intelligence for Early Detection of Acute Kidney Injury in Preterm Neonates

A preterm birth is a live birth that occurs before 37 completed weeks of pregnancy. Approximately 15 million babies are born preterm annually worldwide, indicating a global preterm birth rate of about 11%. Up to 50% of premature neonates in the gestational age (GA) group of <29 weeks' gestation will develop acute kidney injury (AKI) in the neonatal period; this is associated with high mortality and morbidity. There are currently no proven treatments for established AKI, and no effective predictive tool exists. We propose that the development of advanced artificial intelligence algorithms with neural networks can assist clinicians in accurately predicting AKI. Clinicians can use pathology investigations in combination with the non-invasive monitoring of renal tissue oxygenation (rSO2) and renal fractional tissue oxygenation extraction (rFTOE) using near-infrared spectroscopy (NIRS) and the renal resistive index (RRI) to develop an effective prediction algorithm. This algorithm would potentially create a therapeutic window during which the treating clinicians can identify modifiable risk factors and implement the necessary steps to prevent the onset and reduce the duration of AKI.

Evaluation of an Empiric Vancomycin Dosing Protocol on Goal Troughs and Acute Kidney Injury in a Neonatal Intensive Care Unit

OBJECTIVE

Review the efficacy and safety of an updated empiric vancomycin dosing protocol in a neonatal intensive care unit (NICU).

METHODS

Retrospective chart review including neonates with postmenstrual age (PMA) less than 40 weeks without renal dysfunction who received vancomycin per protocol at a single institution's NICU before and after implementation of an updated dosing protocol. The primary outcome is the proportion of initial therapeutic troughs. Secondary outcomes include average trough, achievement of a therapeutic trough, number of days before attainment of a therapeutic trough, and proportion of acute kidney injury (AKI) during therapy.

RESULTS

The 2 groups were similar in gestational age, race, birth weight, PMA, and weight at time of vancomycin initiation. The post-implementation group had a higher proportion of initial therapeutic troughs (33.0% vs 55.1%) and a lower proportion of a subtherapeutic (58.7% vs 43.8%) and supratherapeutic (8.3% vs 1.1%) initial troughs (p = 0.002). The median trough was not different (9.20 vs 10.50 mg/L; p = 0.092). There was no difference in the proportions of achieving a therapeutic trough throughout therapy (69% vs 76%; p = 0.235); however, the post-implementation group achieved a therapeutic trough 1 day earlier (3 vs 2 days; p < 0.001). There was no difference in proportions of AKI developing between the pre-implementation vs post-implementation groups (10.1% vs 5.6%; p = 0.251).

CONCLUSIONS

Implementation of an updated vancomycin dosing protocol yielded a higher percentage of initial therapeutic vancomycin troughs and patients reached the therapeutic range 1 day earlier without increasing the proportion of AKI.

An Electronic Algorithm to Identify Vancomycin-Associated Acute Kidney Injury

Background

The burden of vancomycin-associated acute kidney injury (V-AKI) is unclear because it is not systematically monitored. The objective of this study was to develop and validate an electronic algorithm to identify cases of V-AKI and to determine its incidence.

Methods

Adults and children admitted to 1 of 5 health system hospitals from January 2018 to December 2019 who received at least 1 dose of intravenous (IV) vancomycin were included. A subset of charts was reviewed using a V-AKI assessment framework to classify cases as unlikely, possible, or probable events. Based on review, an electronic algorithm was developed and then validated using another subset of charts. Percentage agreement and kappa coefficients were calculated. Sensitivity and specificity were determined at various cutoffs, using chart review as the reference standard. For courses ≥48 hours, the incidence of possible or probable V-AKI events was assessed.

Results

The algorithm was developed using 494 cases and validated using 200 cases. The percentage agreement between the electronic algorithm and chart review was 92.5% and the weighted kappa was 0.95. The electronic algorithm was 89.7% sensitive and 98.2% specific in detecting possible or probable V-AKI events. For the 11 073 courses of ≥48 hours of vancomycin among 8963 patients, the incidence of possible or probable V-AKI events was 14.0%; the V-AKI incidence rate was 22.8 per 1000 days of IV vancomycin therapy.

Conclusions

An electronic algorithm demonstrated substantial agreement with chart review and had excellent sensitivity and specificity in detecting possible or probable V-AKI events. The electronic algorithm may be useful for informing future interventions to reduce V-AKI.

Population Pharmacokinetics and Dosing Optimization of Ceftazidime in Term Asphyxiated Neonates during Controlled Therapeutic Hypothermia

Ceftazidime is an antibiotic commonly used to treat bacterial infections in term neonates undergoing controlled therapeutic hypothermia (TH) for hypoxic-ischemic encephalopathy after perinatal asphyxia. We aimed to describe the population pharmacokinetics (PK) of ceftazidime in asphyxiated neonates during hypothermia, rewarming, and normothermia and propose a population-based rational dosing regimen with optimal PK/pharmacodynamic (PD) target attainment. Data were collected in the PharmaCool prospective observational multicenter study. A population PK model was constructed, and the probability of target attainment (PTA) was assessed during all phases of controlled TH using targets of 100% of the time that the concentration in the blood exceeds the MIC (T>MIC) (for efficacy purposes and 100% T>4×MIC and 100% T>5×MIC to prevent resistance). A total of 35 patients with 338 ceftazidime concentrations were included. An allometrically scaled one-compartment model with postnatal age and body temperature as covariates on clearance was constructed. For a typical patient receiving the current dose of 100 mg/kg of body weight/day in 2 doses and assuming a worst-case MIC of 8 mg/L for Pseudomonas aeruginosa, the PTA was 99.7% for 100% T>MIC during hypothermia (33.7°C; postnatal age [PNA] of 2 days). The PTA decreased to 87.7% for 100% T>MIC during normothermia (36.7°C; PNA of 5 days). Therefore, a dosing regimen of 100 mg/kg/day in 2 doses during hypothermia and rewarming and 150 mg/kg/day in 3 doses during the following normothermic phase is advised. Higher-dosing regimens (150 mg/kg/day in 3 doses during hypothermia and 200 mg/kg/day in 4 doses during normothermia) could be considered when achievements of 100% T>4×MIC and 100% T>5×MIC are desired.

The impact of intrauterine growth restriction and prematurity on nephron endowment

In humans born at term, maximal nephron number is reached by the time nephrogenesis is completed - at approximately 36 weeks' gestation. The number of nephrons does not increase further and subsequently remains stable until loss occurs through ageing or disease. Nephron endowment is key to the functional capacity of the kidney and its resilience to disease; hence, any processes that impair kidney development in the developing fetus can have lifelong adverse consequences for renal health and, consequently, for quality and length of life. The timing of nephrogenesis underlies the vulnerability of developing human kidneys to adverse early life exposures. Indeed, exposure of the developing fetus to a suboptimal intrauterine environment during gestation - resulting in intrauterine growth restriction (IUGR) - and/or preterm birth can impede kidney development and lead to reduced nephron endowment. Furthermore, emerging research suggests that IUGR and/or preterm birth is associated with an elevated risk of chronic kidney disease in later life. The available data highlight the important role of early life development in the aetiology of kidney disease and emphasize the need to develop strategies to optimize nephron endowment in IUGR and preterm infants.

Predictive Performance of Population Pharmacokinetic Models for Amikacin in Term Neonates

BACKGROUND AND OBJECTIVE

Amikacin is preferred in treating Gram-negative infections in neonates and it has a narrow therapeutic window. The population pharmacokinetic modeling approach can aid in designing optimal dosage regimens for amikacin in neonates. In this study, we attempted to identify the suitable population pharmacokinetic model from the published reports for the study population from an Indian setting.

METHODS

Published population pharmacokinetic studies for amikacin in neonates were identified. Data on structural models and typical pharmacokinetic parameters were extracted from the studies. For the clinical study, neonates who met the inclusion criteria were enrolled in the study from the NICU, Kasturba Medical College, Manipal, during Jan 2020 to March 2022. Drug concentrations were estimated, and demographic and clinical data were collected. Identified population pharmacokinetic models were used to predict the amikacin concentrations in neonates. Predicted concentrations were compared against the observed concentrations. Differences between predicted and observed concentrations were quantified using statistical measures. The population pharmacokinetic model, which was able to predict the data well, is considered a suitable model for the study population. Dosing regimens were suggested for neonates using the pharmacometric simulation approach generated by the selected model.

RESULTS

A total of 43 plasma samples were collected from 31 neonates. Twelve population pharmacokinetic models were found for amikacin in neonates. The predictive performance of the 12 studies was performed using clinical data. A two-compartment model reported by Illamola et al. predicted the amikacin concentrations better than other models. Illamola et al. reported creatinine clearance and body weight as the significant covariates impacting the pharmacokinetic parameters of amikacin. This model was able to predict the clinical data with 29.97% and 0.686 of relative median absolute prediction error and relative root mean square error, respectively, which is the best among the published models. The Illamola et al. model was selected as the final model to perform pharmacometric simulations for the subjects with different combinations of creatinine clearance and body weight. Dosage regimens were designed to attain target therapeutic concentrations for the virtual subjects and a nomogram was developed.

CONCLUSIONS

The population pharmacokinetic model reported by the Illamola et al. model was selected as the final model to explain the clinical data with the lowest relative median absolute prediction error and relative root mean square error when compared with other models. An amikacin nomogram was developed for the neonates whose creatinine clearance and body weight ranged between 10 and 90 mL/min and between 2 and 4 kg, respectively. A developed nomogram can assist clinicians to design an optimal dosage regimen of amikacin for term neonates.

Evaluation of Neonatal and Paediatric Vancomycin Pharmacokinetic Models and the Impact of Maturation and Serum Creatinine Covariates in a Large Multicentre Data Set

BACKGROUND AND OBJECTIVE

Infants and neonates present a clinical challenge for dosing drugs with high interindividual variability due to these patients' rapid growth and the interplay between maturation and organ function. Model-informed precision dosing (MIPD), which can account for interindividual variability via patient characteristics and Bayesian forecasting, promises to improve individualized dosing strategies in this complex population. Here, we assess the predictive performance of published population pharmacokinetic models describing vancomycin in neonates and infants, and analyze the robustness of these models in the face of clinical uncertainty surrounding covariate values.

METHODS

The predictive precision and bias of nine pharmacokinetic models were compared in a large multi-site data set (N = 2061 patients, 5794 drug levels, 28 institutions) of patients aged 0-365 days. The robustness of model predictions to errors in serum creatinine measurements and gestational age was assessed by using recorded values or by replacing covariate values with 0.3, 0.5 or 0.8 mg/dL or with 40 weeks, respectively.

RESULTS

Of the nine models, two models (Dao and Jacqz-Aigrain) resulted in predicted concentrations within 2.5 mg/L or 15% of the measured values for at least 60% of population predictions. Within individual models, predictive performance often 2 differed in neonates (0-4 weeks) versus older infants (15-52 weeks). For preterm neonates, imputing gestational age as 40 weeks reduced the accuracy of model predictions. Measured values of serum creatinine improved model predictions compared to using imputed values even in neonates ≤1 week of age.

CONCLUSIONS

Several available pharmacokinetic models are suitable for MIPD in infants and neonates. Availability and accuracy of model covariates for patients will be important for guiding dose decision-making.

Physiologically-based pharmacokinetic modelling and dosing evaluation of gentamicin in neonates using PhysPK

Each year, infections caused around the 25% of neonatal deaths. Early empirical treatments help to reduce this mortality, although optimized dosing regimens are still lacking. The aims were to develop and validate a gentamicin physiologically-based pharmacokinetic (PBPK) model and then potentially explore dosing regimens in neonates using pharmacokinetic and pharmacodynamic criteria. The PBPK model developed consisted of 2 flow-limited tissues: kidney and other tissues. It has been implemented on a new tool called PhysPK, which allows structure reusability and evolution as predictive engine in Model-Informed Precision Dosing (MIPD). Retrospective pharmacokinetic information based on serum levels data from 47 neonates with gestational age between 32 and 39 weeks and younger than one-week postnatal age were used for model validation. The minimal PBPK model developed adequately described the gentamicin serum concentration-time profile with an average fold error nearly 1. Extended interval gentamicin dosing regimens (6 mg/kg q36h and 6 mg/kg q48h for term and preterm neonates, respectively) showed efficacy higher than 99% with toxicity lower than 10% through Monte Carlo simulation evaluations. The gentamicin minimal PBPK model developed in PhysPK from literature information, and validated in preterm and term neonates, presents adequate predictive performance and could be useful for MIPD strategies in neonates.

Long-term follow-up of patients after acute kidney injury in the neonatal period: abnormal ambulatory blood pressure findings

Background

Data on the long-term effects of neonatal acute kidney injury (AKI) are limited.

Methods

We invited 302 children who had neonatal AKI and survived to hospital discharge; out of 95 patients who agreed to participate in the study, 23 cases were excluded due to primary kidney, cardiac, or metabolic diseases. KDIGO definition was used to define AKI. When a newborn had no previous serum creatinine, AKI was defined as serum creatinine above the mean plus two standard deviations (SD) (or above 97.5^th percentile) according to gestational age, weight, and postnatal age. Clinical and laboratory features in the neonatal AKI period were recorded for 72 cases; at long-term evaluation (2–12 years), kidney function tests with glomerular filtration rate (eGFR) by the Schwartz formula, microalbuminuria, office and 24-h ambulatory blood pressure monitoring (ABPM), and kidney ultrasonography were performed.

Results

Forty-two patients (58%) had stage I AKI during the neonatal period. Mean age at long-term evaluation was 6.8 ± 2.9 years (range: 2.3–12.0); mean eGFR was 152.3 ± 26.5 ml/min/1.73 m². Office hypertension (systolic and/or diastolic BP ≥ 95^th percentile), microalbuminuria (> 30 mg/g creatinine), and hyperfiltration (> 187 ml/min/1.73 m²) were present in 13.0%, 12.7%, and 9.7% of patients, respectively. ABPM was performed on 27 patients, 18.5% had hypertension, and 40.7% were non-dippers; 48.1% had abnormal findings. Female sex was associated with microalbuminuria; low birth weight (< 1,500 g) and low gestational age (< 32 weeks) were associated with hypertension by ABPM. Twenty-three patients (33.8%) had at least one sign of microalbuminuria, office hypertension, or hyperfiltration. Among 27 patients who had ABPM, 16 (59.3%) had at least one sign of microalbuminuria, abnormal ABPM (hypertension and/or non-dipping), or hyperfiltration.

Conclusion

Even children who experienced stage 1 and 2 neonatal AKI are at risk for subclinical kidney dysfunction. Non-dipping is seen in four out of 10 children. Long-term follow-up of these patients is necessary.

Urinary beta-2 microglobulin as an early predictive biomarker of acute kidney injury in neonates with perinatal asphyxia

To evaluate the role of urinary beta-2 microglobulin (B2mG) as an early predictive biomarker of acute kidney injury (AKI) in neonates with perinatal asphyxia. In this prospective cohort study, 80 term infants with perinatal asphyxia were included. The neonates were divided into AKI and no-AKI groups. Urinary B2mG levels were measured at 24 h of life. The diagnostic efficacy of the biomarker was determined using receiver operating characteristic (ROC) curves. Compared to infants without AKI, infants with AKI had higher levels of urinary B2mG (mean 6.8 versus 2.6 mg/L, p < 0.001). Area under the receiver operating characteristic curve (ROC curve) was 0.944. The balanced sensitivity/specificity trade-off was found at a cut-off value of 3.8 mg/L (81% sensitive and 81.6% specific).Conclusion Urinary B2mG can be useful to predict AKI early in term neonates with perinatal asphyxia. What is Known: • AKI is seen in 20-40% of neonates with asphyxia. • AKI affects the treatment plan and the prognosis of such neonates. What is New: • Urinary biomarkers are the easiest way to diagnose AKI in asphyxiated neonates. • Beta 2 microglobulin is the cheapest and readily available one such urinary biomarker with good sensitivity and specificity.

Quantification of Fetal Renal Function Using Fetal Urine Production Rate and Its Reflection on the Amniotic and Fetal Creatinine Levels During Pregnancy

Adequate prediction of fetal exposure of drugs excreted by the kidney requires the incorporation of time-varying renal function parameters into a pharmacokinetic model. Published data on measurements of fetal urinary production rate (FUPR) and creatinine at various gestational ages were collected and integrated for prediction of the fetal glomerular filtration rate (GFR). The predicted GFR values were then compared to neonatal values recorded at birth. Collected data for FUPR across different gestational ages using both 3D (N = 517) and 2D (N = 845) ultrasound methods showed that 2D techniques yield significantly lower estimates of FUPR than 3D (p < 0.0001). A power law function was shown to best capture the change in FUPR with fetal age (FA) for both 2D ( F U P R 2 D ( m L min ) = 0 . 000169     FA 2 . 19 ); and 3D ( F U P R 3 D   ( m L min ) =   3 . 21 × 1 0 - 7   FA 4 . 21 ) data. The predicted FUPR based on the observed 3D data was shown to be strongly linearly related (R ² = 0.95) to measured values of amniotic creatinine concentration (N = 664). The FUPR_3D data together with creatinine levels in the fetal urine and serum resulted in median predicted fetal GFR values of 0.47, 1.2, 2.5, and 4.9 ml/min at 23, 28, 33, and 38 weeks of fetal age (50% CV), respectively. These values are in good agreement with neonatal values observed immediately at birth. The derived FUPR and creatinine functions can be utilized to assess fetal renal maturation and predict fetal renal clearance.

Serum Creatinine Patterns in Neonates Treated with Therapeutic Hypothermia for Neonatal Encephalopathy

INTRODUCTION

There is large variability in kidney function and injury in neonates with neonatal encephalopathy (NE) treated with therapeutic hypothermia (TH). Acute kidney injury (AKI) definitions that apply categorical approaches may lose valuable information about kidney function in individual patients. Centile serum creatinine (SCr) over postnatal age (PNA) may provide more valuable information in TH neonates.

METHODS

Data from seven TH neonates and one non-TH-treated, non-NE control cohorts were pooled in a retrospective study. SCr centiles over PNA, and AKI incidence (definition: SCr ↑≥0.3 mg/dL within 48 h, or ↑ ≥1.5 fold vs. the lowest prior SCr within 7 days) and mortality were calculated. Repeated measurement linear models were applied to SCr trends, modeling SCr on PNA, birth weight or gestational age (GA), using heterogeneous autoregressive residual covariance structure and maximum likelihood methods. Findings were compared to patterns in the control cohort.

RESULTS

Among 1,136 TH neonates, representing 4,724 SCr observations, SCr (10th-25th-50th-75th-90th-95th) PNA centiles (day 1-10) were generated. In TH neonates, the AKI incidence was 132/1,136 (11.6%), mortality 193/1,136 (17%). AKI neonates had a higher mortality (37.2-14.3%, p < 0.001). Median SCr patterns over PNA were significantly higher in nonsurvivors (p < 0.01) or AKI neonates (p < 0.001). In TH-treated neonates, PNA and GA or birth weight explained SCr variability. Patterns over PNA were significantly higher in TH neonates to controls (801 neonates, 2,779 SCr).

CONCLUSIONS

SCr patterns in TH-treated NE neonates are specific. Knowing PNA-related patterns enable clinicians to better assess kidney function and tailor pharmacotherapy, fluids, or kidney supportive therapies.

Population Model of Serum Creatinine as Time-Dependent Covariate in Neonates

Serum creatinine (sCr) is a commonly measured biomarker to estimate glomerular filtration rate (GFR) and therefore widely used as a covariate in population pharmacokinetic models of renally excreted drugs. In neonates, sCr dynamically changes during the first few weeks after birth. Missing covariates are a common problem in pharmacokinetic modeling of neonates due to the limited availability of blood sampling in number and volume. The objective of this work is to develop a parsimonious population model describing time courses of sCr in neonates with the intent to be incorporated into pharmacokinetic models of various drugs where sCr values are sparse or missing. The data for model development consisted of sCr measurements in 1080 newborns with a gestational age of 24-42 weeks. The model is based on a pharmacokinetic model of sCr that involves GFR, backflow of creatinine from the renal tubules, and urinary flow. Gestational age is the only covariate explaining between-subject variability of sCr. The model adequately describes distinct features of the sCr time course such as a peak and decline to a plateau. For a neonate with a GA of 35 weeks, the typical value of sCr at birth was 0.584 mg/dL, the peak (0.794 mg/dL) occurred 2.3 days after birth, to reach a plateau of 0.255 mg/dL approximately after 24.7 days. Model simulations reveal that in neonates with a similar postnatal age, sCr decreases with increasing GA. In summary, our model is designed to be a part of full random effects pharmacokinetic models where sCr is a significant covariate.

Creatinine Trends and Patterns in Neonates Undergoing Whole Body Hypothermia: A Systematic Review

Many neonates undergoing whole body hypothermia (WBH) following moderate to severe perinatal asphyxia may also suffer from renal impairment. While recent data suggest WBH-related reno-protection, differences in serum creatinine (Scr) patterns to reference patterns were not yet reported. We therefore aimed to document Scr trends and patterns in asphyxiated neonates undergoing WBH and compared these to centiles from a reference Scr data set of non-asphyxiated (near)term neonates. Using a systematic review strategy, reports on Scr trends (mean ± SD, median or interquartile range) were collected (day 1-7) in WBH cohorts and compared to centiles of an earlier reported reference cohort of non-asphyxia cases. Based on 13 papers on asphyxia + WBH cases, a pattern of postnatal Scr trends in asphyxia + WBH cases was constructed. Compared to the reference 50th centile Scr values, mean or median Scr values at birth and up to 48 h were higher in asphyxia + WBH cases with a subsequent uncertain declining trend towards, at best, high or high-normal creatinine values afterwards. Such patterns are valuable for anticipating average changes in renal drug clearance but do not yet cover the relevant inter-patient variability observed in WBH cases, as this needs pooling of individual Screa profiles, preferably beyond the first week of life.

The Impact of Erythropoietin on Short- and Long-Term Kidney-Related Outcomes in Neonates of Extremely Low Gestational Age. Results of a Multicenter, Double-Blind, Placebo-Controlled Randomized Clinical Trial

OBJECTIVE

To evaluate whether extremely low gestational age neonates (ELGANs) randomized to erythropoietin have better or worse kidney-related outcomes during hospitalization and at 22-26 months of corrected gestational age (cGA) compared with those randomized to placebo.

STUDY DESIGN

We performed an ancillary study to a multicenter double-blind, placebo-controlled randomized clinical trial of erythropoietin in ELGANs.

RESULTS

The prevalence of severe (stage 2 or 3) acute kidney injury (AKI) was 18.2%. We did not find a statistically significant difference between those randomized to erythropoietin vs placebo for in-hospital primary (severe AKI) or secondary outcomes (any AKI and serum creatinine/cystatin C values at days 0, 7, 9, and 14). At 22-26 months of cGA, 16% of the cohort had an estimated glomerular filtration rate (eGFR) <90 mL/min/1.73 m², 35.8% had urine albumin/creatinine ratio >30 mg/g, 23% had a systolic blood pressure (SBP) >95th percentile for age, and 40% had a diastolic blood pressure (DBP) >95th percentile for age. SBP >90th percentile occurred less often among recipients of erythropoietin (P < .04). This association remained even after controlling for gestational age, site, and sibship (aOR 0.6; 95% CI 0.39-0.92). We did not find statistically significant differences between treatment groups in eGFR, albumin/creatinine ratio, rates of SBP >95th percentile, or DBP >90th or >95th percentiles at the 2 year follow-up visit.

CONCLUSIONS

ELGANs have high rates of in-hospital AKI and kidney-related problems at 22-26 months of cGA. Recombinant erythropoietin may protect ELGANs against long-term elevated SBP but does not appear to protect from AKI, low eGFR, albuminuria, or elevated DBP at 22-26 months of cGA.

Risk factors for in-hospital mortality and acute kidney injury in neonatal-pediatric patients receiving extracorporeal membrane oxygenation

BACKGROUND

Acute kidney injury (AKI) is the most frequent complication in critically ill neonatal and pediatric patients receiving extracorporeal membrane oxygenation (ECMO) support. This study analyzed risk factors for in-hospital mortality and the incidence of AKI in neonatal and pediatric patients received ECMO support.

METHODS

We reviewed the medical records of 105 neonatal and 171 pediatric patients who received ECMO support at the intensive care unit (ICU) of a tertiary care university hospital between January 2008 and December 2015. Demographic, clinical, and laboratory data were retrospectively collected as survival and AKI predictors, utilizing the Kidney Disease Improving Global Outcome (KDIGO) consensus definition for AKI.

RESULTS

In the 105 neonatal and 171 pediatric patients, the overall in-hospital mortality rate were 58% and 55% respectively. The incidence of AKI at post-ECMO 24 h were 64.8% and 61.4%. A greater KDIGO_24-h severity was associated with a higher in-hospital mortality rate (chi-square test; p < 0.01) and decreased survival rate (log-rank tests, p < 0.01). In univariate logistic regression analysis of in-hospital mortality, the CVP level at post ECOMO 24-h increased odds ratio (OR) (OR = 1.27 [1.10-1.46], p = 0.001) of in-hospital mortality in neonatal group; as for pediatric group, elevated lactate (OR = 1.12 [1.03-1.20], p = 0.005) and PT (OR = 1.86 [1.17-2.96], p = 0.009) increased OR of in-hospital mortality. And the KDIGO_24h stage 3 had the strongest association with in-hospital mortality in both neonatal (p = 0.005) and pediatric (p = 0.001) groups. In multivariate OR of neonatal and pediatric groups were 4.38 [1.46-13.16] (p = 0.009) and 3.76 [1.70-8.33] (p = 0.001), respectively.

CONCLUSIONS

AKI was a significant risk factor for in-hospital mortality in the neonatal and pediatric patients who received ECMO support. A greater KDIGO24-h severity was associated with higher mortality rates and decreased survival rate in both neonatal and pediatric groups. Of note, KDIGO24h can be an easy and early tool for the prognosis of AKI in the neonatal and pediatric patients.

Characterizing dynamics of serum creatinine and creatinine clearance in extremely low birth weight neonates during the first 6 weeks of life

BACKGROUND

Characterizing the dynamics of serum creatinine concentrations (Scr) and associated creatinine clearance (CLcr) as a measure of kidney function in extremely low birth weight (≤ 1000 g; ELBW) neonates remains challenging.

METHODS

We performed a retrospective study that included longitudinal Scr (enzymatic assay) data from 148 ELBW neonates up to 6 weeks after birth. Change of Scr and inter-individual variability was characterized with nonlinear mixed-effect modeling. Key covariates such as gestational age (GA), mode of delivery (MOD), and treatment with ibuprofen or inotropic agents were investigated.

RESULTS

A total of 2814 Scr concentrations were analyzed. GA was associated with Scr at birth (higher with advancing GA), and GA and MOD showed an association with postnatal maturation of CLcr (faster clearance increase with advancing GA and after C-section). Small CLcr decrease (≤ 5%) was quantified during ibuprofen treatment. For a GA of 27 weeks, mean Scr (estimated CLcr) at birth was 0.61 mg/dl (0.23 ml/min), increasing to 0.87 mg/dl (0.27 ml/min) at day three, and decreasing to 0.36 mg/dl (0.67 ml/min) at day 42 after birth.

CONCLUSIONS

We report the first mathematical model able to characterize Scr and CLcr in ELBW neonates during the first 6 weeks of life in a quantitative manner as a function of GA, MOD, and ibuprofen treatment. This model allows the derivation of GA-adjusted reference ranges for ELBW neonates and provides a rationale for normative Scr concentrations, and as such will help clinicians to further optimize monitoring and treatment decisions in this vulnerable patient population.

Prevalence of acute kidney injury (AKI) in extremely low gestational age neonates (ELGAN)

BACKGROUND

To determine the prevalence and severity of acute kidney injury (AKI) at different time frames in relation to gestational age (GA) and birthweight (BW) in extremely low gestational age neonates (ELGAN). Our hypothesis is that ELGAN with lower GA and lower BW have higher AKI rates.

METHODS

A total of 923 ELGAN enrolled in the Preterm Erythropoietin Neuroprotection Trial were evaluated from birth until death or hospital discharge. AKI was defined according to kidney disease: improving global outcomes (KDIGO) definition from clinically-derived serum creatinine (SCr) measurements. Severe AKI was defined as stage 2 or higher.

RESULTS

For the entire cohort, 351/923 (38.0%, CI = 34.8-41.3%) had at least one episode of stage 1 or higher AKI and 168/923 (18.2%, CI = 15.7-20.7%) had at least one episode of severe (stage 2 or higher) AKI. The prevalence of AKI stage 1 or higher for the entire cohort during the early (days 3-7), middle (days 8-14), and late follow-up period (after day 14) was 112/923 (12.1%, CI = 10.0-14.3%), 142/891 (15.9%, CI = 13.5-18.4%), and 249/875 (28.5%, CI = 25.4-31.5%), respectively. The rates of severe AKI during the hospital course were 27.8%, 21.9%, 13.6%, and 9.4% for the 24-, 25-, 26-, and 27-week GA groups, respectively. AKI rates were significantly higher with decreasing GA and decreasing BW for stated time trends (all p < 0.01 using tests for trend).

CONCLUSIONS

AKI is relatively common in ELGAN during their initial hospital course and is associated with lower GA and BW.

Challenges in developing a consensus definition of neonatal sepsis

Sepsis remains a leading cause of morbidity and mortality in the neonatal population, and at present, there is no unified definition of neonatal sepsis. Existing consensus sepsis definitions within paediatrics are not suited for use in the NICU and do not address sepsis in the premature population. Many neonatal research and surveillance networks have criteria for the definition of sepsis within their publications though these vary greatly and there is typically a heavy emphasis on microbiological culture. The concept of organ dysfunction as a diagnostic criterion for sepsis is rarely considered in neonatal literature, and it remains unclear how to most accurately screen neonates for organ dysfunction. Accurately defining and screening for sepsis is important for clinical management, health service design and future research. The progress made by the Sepsis-3 group provides a roadmap of how definitions and screening criteria may be developed. Similar initiatives in neonatology are likely to be more challenging and would need to account for the unique presentation of sepsis in term and premature neonates. The outputs of similar consensus work within neonatology should be twofold: a validated definition of neonatal sepsis and screening criteria to identify at-risk patients earlier in their clinical course. IMPACT: There is currently no consensus definition of neonatal sepsis and the definitions that are currently in use are varied.A consensus definition of neonatal sepsis would benefit clinicians, patients and researchers.Recent progress in adults with publication of Sepsis-3 provides guidance on how a consensus definition and screening criteria for sepsis could be produced in neonatology.We discuss common themes and potential shortcomings in sepsis definitions within neonatology.We highlight the need for a consensus definition of neonatal sepsis and the challenges that this task poses.

Creatinine filtration kinetics in critically Ill neonates

BACKGROUND

Creatinine values are unreliable within the first weeks of life; however, creatinine is used most commonly to assess kidney function. Controversy remains surrounding the time required for neonates to clear maternal creatinine.

METHODS

Eligible infants had multiple creatinine lab values and were admitted to the neonatal intensive care unit (NICU). A mathematical model was fit to the lab data to estimate the filtration onset delay, creatinine filtration half-life, and steady-state creatinine concentration for each subject. Infants were grouped by gestational age (GA) [(1) 22-27, (2) >27-32, (3) >32-37, and (4) >37-42 weeks].

RESULTS

A total of 4808 neonates with a mean GA of 34.4 ± 5 weeks and birth weight of 2.34 ± 1.1 kg were enrolled. Median (95% confidence interval) filtration onset delay for Group 1 was 4.3 (3.71, 4.89) days and was significantly different than all other groups (p < 0.001). Creatinine filtration half-life of Groups 1, 2, and 3 were significantly different from each other (p < 0.001). There was no difference in steady-state creatinine concentration among the groups.

CONCLUSIONS

We quantified the observed kidney behavior in a large NICU population as a function of day of life and GA using creatinine lab results. These results can be used to interpret individual creatinine labs for infants to detect those most at risk for acute kidney injury.

IMPACT

One of the largest cohorts of premature infants to describe the evolution of kidney development and function over their entire hospitalization. New concept introduced of the kidney filtration onset delay, the time needed for the kidney to begin clearance of creatinine, and that it can be used as an early indicator of kidney function. The smallest premature infants from 22 to 27 weeks gestation took the longest time to begin and complete maternal creatinine clearance. Clinicians can easily compare the creatinine level of their patient to the normative curves to improve understanding of kidney function at the bedside.

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.

Renal function in small for gestational age preterm infants

OBJECTIVE

The objective of this study is to compare glomerular and tubular functions in small for gestational age (SGA) and appropriate for gestational age (AGA) preterm infants.

STUDY DESIGN

A prospective controlled study was conducted on SGA and AGA infants with gestational ages between 32^0/7 and 36^6/7 weeks, who received gentamycin in the first 72 h of life. Glomerular and tubular functions were assessed on days 1 and 5.

RESULTS

Fifty (25 SGA and 25 AGA) infants were included. On day of life 1, SGA group had higher serum sodium, serum urea, and urinary creatinine. On day 5, SGA infants had significant increase in serum creatinine (p = 0.04). Urinary NAG and FeNa were comparable among the two groups on days 1 and 5.

CONCLUSIONS

Glomerular functions were compromised in SGA preterm infants. Tubular functions were comparable.