Renal consequences of preterm birth

BRAzil magnesium (BRAMAG) trial: a double-masked randomized clinical trial of oral magnesium supplementation in pregnancy

Background

There is conflicting evidence about the role of oral magnesium supplementation in the prevention of preterm birth and related adverse outcomes. The objective of this study was to compare magnesium citrate with placebo in the prevention of adverse perinatal and maternal outcomes among women at higher risk.

Methods

This multicenter, double-masked, placebo-controlled randomized superiority clinical trial compared oral magnesium citrate 300 mg to matched placebo, from 12 to 20 weeks’ gestation until delivery. This trial was completed in three centers in northeastern Brazil. Eligible women were those with a singleton pregnancy and ≥ 1 risk factor, such as prior preterm birth or preeclampsia, or current chronic hypertension or pre-pregnancy diabetes mellitus, age > 35 years or elevated body mass index. The primary perinatal composite outcome comprised preterm birth < 37 weeks’ gestation, stillbirth > 20 weeks, neonatal death or NICU admission < 28 days after birth, or small for gestational age birthweight < 3rd percentile. The co-primary maternal composite outcome comprised preeclampsia or eclampsia < 37 weeks, severe gestational hypertension < 37 weeks, placental abruption, or maternal stroke or death during pregnancy or ≤ 7 days after delivery.

Results

Analyses comprised 407 women who received magnesium citrate and 422 who received placebo. The perinatal composite outcome occurred among 75 (18.4%) in the magnesium arm and 76 (18.0%) in the placebo group – an adjusted odds ratio (aOR) of 1.10 (95% CI 0.72–1.68). The maternal composite outcome occurred among 49 (12.0%) women in the magnesium arm and 41 women (9.7%) in the placebo group – an aOR of 1.29 (95% CI 0.83–2.00).

Conclusions

Oral magnesium citrate supplementation did not appear to reduce adverse perinatal or maternal outcomes in high-risk singleton pregnancies.

Trial registration

ClinicalTrials.gov NCT02032186, registered January 9, 2014.

Variables of interest to predict glomerular filtration rate in preterm newborns in the first days of life

BACKGROUND

Measurement of neonatal renal function is challenging, and accurate, easy-to-use markers to estimate glomerular filtration rate (eGFR) are lacking. This study aimed to evaluate principal determinants of GFR in neonates and develop a predictive equation.

METHODS

GFR was measured, using single injection inulin clearance, at median day 3 of life in 48 newborns. Associations of clearance with height, gestational age, weight, creatinine, and cystatin C were explored and a multivariable model to estimate GFR developed. We also evaluated preexisting GFR equations (Schwartz, Zappitelli, combined Zappitelli).

RESULTS

Forty-four clearances were measured, 36 very preterm neonates (28-32 weeks); 5 extremely preterm (< 28 weeks), and 3 term newborns. No patient presented acute renal insufficiency. Median inulin clearance in preterm infants was 18.83 ml/min/1.73 m² (IQ 15.29; 24.99). Inulin clearance correlated with weight (ρ 0.74), gestational age (ρ 0.72), height (ρ 0.49), and creatinine (ρ - 0.42), but not cystatin C. In the multivariable model, predicted GFR equation was 2.32* (weight (g))^0.64/(creatinine (mcmol/l))^0.62. Mean error in predicting clearance was - 0.8 ml/min/1.73 m² (- 3.0-1.4) ranging from - 14.9 to 13.3 ml/min/1.73 m². Mean prediction error with Zappitelli and combined Zappitelli equations were 28.5 ml/min/1.73 m² (95% CI 24.6-32.3) and 28.3 ml/min/1.73 m² (95% CI 24.9-31.7), respectively, and 2 ml/min/1.73 m² (95% CI - 0.6-4.6) for Schwartz equation.

CONCLUSIONS

Weight and gestational age are crucial determinants of GFR in neonates. The Zappitelli models were not validated in our population. Our predictive model and Schwartz models performed better. Our model should be evaluated in another preterm population, particularly in those presenting renal insufficiency.

Diuretic Use and Subsequent Electrolyte Supplementation in a Level IV Neonatal Intensive Care Unit

OBJECTIVES

To evaluate the relationship between diuretic use, serum electrolyte concentrations, and supplementation requirements in infants admitted to the neonatal intensive care unit.

METHODS

This was a single-center retrospective cohort study conducted in a freestanding children's hospital Level IV NICU. Data were collected for all infants younger than 6 months, admitted to the NICU between January 2015 and May 2017, who received 2 or more consecutive doses of furosemide, chlorothiazide, hydrochlorothiazide, and/or hydrochlorothiazide/spironolactone. The primary outcome was the composite of the incidence of electrolyte abnormalities and/or electrolyte supplementation requirement within 30 days of diuretic exposure.

RESULTS

A total of 72 patients met inclusion criteria, with a median gestational age of 30 weeks. Overall, 92% of patients exposed to diuretics experienced derangement in at least 1 serum electrolyte and/or required electrolyte supplementation during diuretic therapy. Patients born at 36 to 41 weeks' gestational age, receiving thiazide diuretics, experienced a significantly lower rate of the primary outcome (37%, p ≤ 0.001). The most common electrolytes affected by diuretic use were potassium and bicarbonate, with the highest incidence of the primary outcome for potassium occurring in patients receiving furosemide (p = 0.0196). Last, the median total daily dose of chlorothiazide in patients with an adverse event was 15 mg/kg/day, compared with 10 mg/kg/day in patients without an adverse event (p = 0.0041).

CONCLUSIONS

Use of diuretics in young infants is likely to cause electrolyte derangements and/or require electrolyte supplementation. Patients born at earlier gestational ages may be at higher risk for developing such adverse effects.

Shaping of the nephron - a complex, vulnerable, and poorly explored backdrop for noxae impairing nephrogenesis in the fetal human kidney

Background

The impairment of nephrogenesis is caused by noxae, all of which are significantly different in molecular composition. These can cause an early termination of nephron development in preterm and low birth weight babies resulting in oligonephropathy. For the fetal human kidney, there was no negative effect reported on the early stages of nephron anlage such as the niche, pretubular aggregate, renal vesicle, or comma-shaped body. In contrast, pathological alterations were identified on subsequently developing S-shaped bodies and glomeruli. While the atypical glomeruli were closely analyzed, the S-shaped bodies and the pre-stages received little attention even though passing the process of nephron shaping. Since micrographs and an explanation about this substantial developmental period were missing, the shaping of the nephron in the fetal human kidney during the phase of late gestation was recorded from a microanatomical point of view.

Results

The nephron shaping starts with the primitive renal vesicle, which is still part of the pretubular aggregate at this point. Then, during extension of the renal vesicle, a complex separation is observed. The medial part of its distal pole is fixed on the collecting duct ampulla, while the lateral part remains connected with the pretubular aggregate via a progenitor cell strand. A final separation occurs, when the extended renal vesicle develops into the comma-shaped body. Henceforth, internal epithelial folding generates the tubule and glomerulus anlagen. Arising clefts at the medial and lateral aspect indicate an asymmetrical expansion of the S-shaped body. This leads to development of the glomerulus at the proximal pole, whereas in the center and at the distal pole, it results in elongation of the tubule segments.

Conclusions

The present investigation deals with the shaping of the nephron in the fetal human kidney. In this important developmental phase, the positioning, orientation, and folding of the nephron occur. The demonstration of previously unknown morphological details supports the search for traces left by the impairment of nephrogenesis, enables to refine the assessment in molecular pathology, and provides input for the design of therapeutic concepts prolonging nephrogenesis.

Renal function in the third year among very low birth weight infants fed by supplemental proteins

Very Low Birth Weight (VLBW) infants have higher nutritional needs than term infants. Energy and protein are two important factors influencing their growth. Breastfeeding is not enough to meet VLBW infants’ needs, for this reason, complementary protein is required by them. Hence, the present study aimed at investigation of renal function among VLBW infants receiving complementary proteins. The study was conducted on two groups of intervention and control (n= 18 in each group) (Case study: VLBW infants born in Akbarabadi hospital of Tehran in 2014 2015). The intervention group includes 3-year-old children who weighting less than 1200 grams at birth and have received protein supplementation at the course of NICU hospitalization, protein was added to maternal milk when the amount of milk reaches to 100 cc/kg/day, at this time parenteral nutrition was discontinued and the volume of feeding was increased 20cc/kg/day until reached to 150-180cc/kg/day. We also added the fortifier to breast milk at this time. The fortification and the protein supplementation were stopped when the weight of the baby reached to 1500 grams. The control group was fed similar to the intervention group but had received no complementary protein . The renal function was evaluated by measuring such criteria as BUN, Cr, ALB and U/A. After data collection, a statistical analysis was performed using SPSS software Ver. 22. Following to BUN evaluation, a significant correlation was seen between BUN and received protein (p-value=0.010). However, there was no significant correlation between Cr and received protein as well as mean values of the two groups (p-value=0.0766). Similarly, an insignificant correlation was found between the two groups following to investigation of ALB (p-value=0/257), while the mean values of the two groups were similar. The both groups were also equal in U/A. The complementary protein increased the BUN with no effect on Cr, ALB and U/A, providing no impact on renal function. Therefore, complementary protein intake made no conflict in renal function.

Length of gestation and birth weight are associated with indices of combined kidney biomarkers in early childhood

Infants born prematurely or with low birth weights are more susceptible to kidney dysfunction throughout their lives. Multiple proteins measured in urine are noninvasive biomarkers of subclinical kidney damage, but few studies have examined the joint effects of multiple biomarkers. We conducted an exploratory study of 103 children in the Programing Research in Obesity, Growth, Environment, and Social Stressors (PROGRESS) longitudinal birth cohort, and measured nine proteins selected a priori in banked spot urine samples collected at ages 4-6. The goal of our study was to explore the combined effects of kidney damage biomarkers previously associated with birth outcomes. To do this, we generated kidney biomarker indices using weighted quantile sum regression and assessed associations with length of gestation or birth weight. A decile increase in each kidney biomarker index was associated with 2-day shorter gestations (β = -2.0, 95% CI: -3.2, -0.9) and 59-gram lower birth weights (β = -58.5, 95% CI: -98.3, -18.7), respectively. Weights highlighting the contributions showed neutrophil gelatinase-associated lipocalin (NGAL) (60%) and osteopontin (19%) contributed most to the index derived for gestational age. NGAL (66%) and beta-2-microglobulin (10%) contributed most to the index derived for birth weight. Joint analyses of multiple kidney biomarkers can provide integrated measures of kidney dysfunction and improved statistical assessments compared to biomarkers assessed individually. Additionally, shorter gestations and lower birth weights may contribute to subclinical kidney damage measurable in childhood.

Prematurity With Extrauterine Growth Restriction Increases the Risk of Higher Levels of Glucose, Low-Grade of Inflammation and Hypertension in Prepubertal Children

Introduction: An adipose tissue programming mechanism could be implicated in the extrauterine growth restriction (EUGR) of very preterm infants with morbidity in the cardiometabolic status later in life, as has been reported in intrauterine growth restriction. The aim of this study was to assess whether children with a history of prematurity and EUGR, but also with an adequate growth, showed alterations in the metabolic and inflammatory status. Methods: This was a case-control study. A total of 88 prepubertal children with prematurity antecedents were selected: 38 with EUGR and 50 with an adequate growth pattern (PREM group). They were compared with 123 healthy children born at term. Anthropometry, metabolic parameters, blood pressure (BP), C-reactive protein, hepatocyte growth factor (HGF), interleukin-6 (IL-6), IL-8, monocyte chemotactic protein type 1 (MCP-1), neural growth factor, tumour necrosis factor-alpha (TNF-α) and plasminogen activator inhibitor type-1 were analysed at the prepubertal age. Results: EUGR children exhibited higher BP levels and a higher prevalence of hypertension (46%) compared with both PREM (10%) and control (2.5%) groups. Moreover, there was a positive relationship between BP levels and values for glucose, insulin and HOMA-IR only in children with a EUGR history. The EUGR group showed higher concentrations of most of the cytokines analysed, markedly higher TNF-α, HGF and MCP-1 levels compared with the other two groups. Conclusion: EUGR status leads to cardiometabolic changes and a low-grade inflammatory status in children with a history of prematurity, and that could be related with cardiovascular risk later in life.

The use of fetal MRI for renal and urogenital tract anomalies

Fetal anomalies are detected in approximately 2% of all fetuses and, among these, genitourinary tract abnormalities account for 30% to 50% of all structural anomalies present at birth. Although ultrasound remains the first line diagnostic modality, fetal MRI provides important additional structural and functional information, especially with the development of faster sequences and the use of functional sequences. The added value of MRI-based imaging is three-fold: (a) improvement of diagnostic accuracy by adequate morphological examination, (b) detection of additional anomalies, and (c) in addition, MRI has the potential to provide information regarding renal function. In this review, we describe the role of fetal MRI in the anatomical evaluation of renal and urogenital tract anomalies, and we also touch upon the contribution of functional MRI to the diagnostic workup of these conditions.

Associated factors for acute kidney injury in preterm infants

ABSTRACT Objective: to analyze the prevalence and factors associated with acute kidney injury in preterm newborns. Method: a cross-sectional study based on records data of preterm newborns hospitalized in two neonatal units in northwest Paraná State in 2015. For data analysis, the logistic regression model was used by the stepwise forward method and Fisher’s Exact Test. Results: 132 preterm newborns, with a prevalence of 7.5% of acute kidney injury, were hospitalized. Majority of males, extremely preterm and very low birth weight. Associated factors were the use of non-nephrotoxic antibiotics and the presence of mechanical pulmonary ventilation, increasing the chance of developing acute kidney damage by 2.98 and 1.33/day, respectively. Hospitalization days constituted a protection factor. Conclusion: this study was able to identify the prevalence, and outline the variables associated with acute kidney injury in preterm newborns in a particular care situation.

In Search of Imprints Left by the Impairment of Nephrogenesis

Clinical aspects dealing with the impairment of nephrogenesis in preterm and low birth weight babies were intensely researched. In this context it was shown that quite different noxae can harm nephron formation, and that the morphological damage in the fetal kidney is rather complex. Some pathological findings show that the impairment leads to changes in developing glomeruli that are restricted to the maturation zone of the outer cortex in the fetal human kidney. Other data show also imprints on the stages of nephron anlage including the niche, the pretubular aggregate, the renal vesicle, and comma- and S-shaped bodies located in the overlying nephrogenic zone of the rodent and human kidneys. During our investigations it was noticed that the stages of nephron anlage in the fetal human kidney during the phase of late gestation have not been described in detail. To contribute, these stages were recorded along with corresponding images. The initial nephron formation in the rodent kidney served as a reference. Finally, the known imprints left by the impairment in both specimens were listed and discussed. In sum, the relatively paucity of data on nephron formation in the fetal human kidney during the late phase of gestation is a call to start with intense research so that concepts for a therapeutic prolongation of nephrogenesis can be designed.

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.

Pharmacokinetics and bioavailability of cefquinome and ceftriaxone in premature calves

The aim of this study was to evaluate the pharmacokinetics and bioavailability of cefquinome (CFQ) and ceftriaxone (CTX) following intravenous (IV) and intramuscular (IM) administrations in premature calves. Using a parallel design, 24 premature calves were randomly divided into the two antibiotic groups. Each of the six animals in the first group received CFQ (2 mg/kg) through IV or IM administration. The second group received CTX (20 mg/kg) via the same administration route. Plasma concentrations of the drugs were analyzed by high-performance liquid chromatography and noncompartmental methods. Mean pharmacokinetic parameters of CFQ and CTX following IV administration were as follows: elimination half-life (t_1/2λz ) 1.85 and 3.31 hr, area under the plasma concentration-time curve (AUC_0-∞ ) 15.74 and 174 hr * μg/ml, volume of distribution at steady-state 0.37 and 0.45 L/kg, and total body clearance 0.13 and 0.12 L hr^-1  kg^-1 , respectively. Mean pharmacokinetic parameters of CFQ and CTX after IM injection were as follows: peak concentration 4.56 and 25.04 μg/ml, time to reach peak concentration 1 and 1.5 hr, t_1/2λz 4.74 and 3.62 hr, and AUC_0-∞ 22.75 and 147 hr * μg/ml, respectively. The bioavailability of CFQ and CTX after IM injection was 141% and 79%, respectively. IM administration of CFQ (2 mg/kg) and CTX (20 mg/kg) can be recommended at 12-hr interval for treating infections caused by susceptible bacteria, with minimum inhibitory concentration values of ≤0.5 and ≤4 μg/ml, respectively, in premature calves. However, further research is indicated to assess the pharmacokinetic parameters following multiple doses of the drug in premature calves.

Neonatal hypertension: an educational review

Hypertension is encountered in up to 3% of neonates and occurs more frequently in neonates requiring hospitalization in the neonatal intensive care unit (NICU) than in neonates in newborn nurseries or outpatient clinics. Former NICU neonates are at higher risk of hypertension secondary to invasive procedures and disease-related comorbidities. Accurate measurement of blood pressure (BP) remains challenging, but new standardized methods result in less measurement error. Multiple factors contribute to the rapidly changing BP of a neonate: gestational age, postmenstrual age (PMA), birth weight, and maternal factors are the most significant contributors. Given the natural evolution of BP as neonates mature, a percentile cutoff of 95% for PMA has been the most common definition used; however, this is not based on outcome data. Common causes of neonatal hypertension are congenital and acquired renal disease, history of umbilical arterial catheter placement, and bronchopulmonary dysplasia. The treatment of neonatal hypertension has mostly been off-label, but as evidence accumulates, the safety of medical management has increased. The prognosis of neonatal hypertension remains largely unknown and thankfully most often resolves unless secondary to renovascular disease, but further research is needed. This review discusses important factors related to neonatal hypertension including BP measurement, determinants of BP, and management of neonatal hypertension.

The Extended Use of Eculizumab in Pregnancy and Complement Activation⁻Associated Diseases Affecting Maternal, Fetal and Neonatal Kidneys-The Future Is Now?

Excessive complement activation is involved in the pathogenesis of many diseases and the kidney is an organ with particular susceptibility to complement-mediated injury. Apart from paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome (aHUS), there are several other diseases with clear evidence of complement activation affecting both maternal and fetal kidneys during pregnancy and causing long-term adverse outcomes. Several novel drugs have been recently developed for blocking the complement cascade, including purified plasma proteins, new monoclonal antibodies, recombinant proteins, small molecules, and small interfering RNA agents. Eculizumab, the humanized monoclonal IgG2/4-antibody targeting C5 was approved by the United States Food and Drug Administration (FDA) and the European Medicines Agency (EMA) for treatment of two rare diseases: PNH in 2007 and aHUS in 2011. There is an increasing number of publications of successful use of eculizumab for off-label indications, e.g., in pregnant women with antiphospholipid syndrome, sickle-cell anemia, and HELLP syndrome. These severe diseases are associated with both high maternal and fetal morbidity and mortality rate and substantial prematurity. Eculizumab has considerably improved overall outcome of patients with PNH and aHUS, enabling safe pregnancy for many women. Prolongation of pregnancy and the use of eculizumab, even for only a few weeks, may protect not only maternal renal function, but also alleviate acute and long-term renal consequences of prematurity in offspring.

IL-6/Smad2 signaling mediates acute kidney injury and regeneration in a murine model of neonatal hyperoxia

Prematurity is linked to incomplete nephrogenesis and risk of chronic kidney diseases (CKDs). Oxygen is life-saving in that context but induces injury in numerous organs. Here, we studied the structural and functional impact of hyperoxia on renal injury and its IL-6 dependency. Newborn wild-type (WT) and IL-6 knockout (IL-6^-/-) mice were exposed to 85% O₂ for 28 d, followed by room air until postnatal d (P) 70. Controls were in room air throughout life. At P28, hyperoxia reduced estimated kidney cortex area (KCA) in WT; at P70, KCA was greater, number of glomeruli was fewer, fractional potassium excretion was higher, and glomerular filtration rate was slightly lower than in controls. IL-6^-/- mice were protected from these changes after hyperoxia. Mechanistically, the acute renal injury phase (P28) showed in WT but not in IL-6^-/- mice an activation of IL-6 (signal transducer and activator of transcription 3) and TGF-β [mothers against decapentaplegic homolog (Smad)2] signaling, increased inflammatory markers, disrupted mitochondrial biogenesis, and reduced tubular proliferation. Regenerative phase at P70 was characterized by tubular proliferation in WT but not in IL-6^-/- mice. These data demonstrate that hyperoxia increases the risk of CKD through a novel IL-6-Smad2 axis. The amenability of these pathways to pharmacological approaches may offer new avenues to protect premature infants from CKD.-Mohr, J., Voggel, J., Vohlen, C., Dinger, K., Dafinger, C., Fink, G., Göbel, H., Liebau, M. C., Dötsch, J., Alejandre Alcazar, M. A. IL-6/Smad2 signaling mediates acute kidney injury and regeneration in a murine model of neonatal hyperoxia.

Emergent Prophylactic, Reparative and Restorative Brain Interventions for Infants Born Preterm With Cerebral Palsy

Worldwide, an estimated 15 million babies are born preterm (<37 weeks' gestation) every year. Despite significant improvements in survival rates, preterm infants often face a lifetime of neurodevelopmental disability including cognitive, behavioral, and motor impairments. Indeed, prematurity remains the largest risk factor for the development of cerebral palsy. The developing brain of the preterm infant is particularly fragile; preterm babies exhibit varying severities of cerebral palsy arising from reductions in both cerebral white and gray matter volumes, as well as altered brain microstructure and connectivity. Current intensive care therapies aim to optimize cardiovascular and respiratory function to protect the brain from injury by preserving oxygenation and blood flow. If a brain injury does occur, definitive diagnosis of cerebral palsy in the first few hours and weeks of life is difficult, especially when the lesions are subtle and not apparent on cranial ultrasound. However, early diagnosis of mildly affected infants is critical, because these are the patients most likely to respond to emergent treatments inducing neuroplasticity via high-intensity motor training programs and regenerative therapies involving stem cells. A current controversy is whether to test universal treatment in all infants at risk of brain injury, accepting that some patients never required treatment, because the perceived potential benefits outweigh the risk of harm. Versus, waiting for a diagnosis before commencing targeted treatment for infants with a brain injury, and potentially missing the therapeutic window. In this review, we discuss the emerging prophylactic, reparative, and restorative brain interventions for infants born preterm, who are at high risk of developing cerebral palsy. We examine the current evidence, considering the timing of the intervention with relation to the proposed mechanism/s of action. Finally, we consider the development of novel markers of preterm brain injury, which will undoubtedly lead to improved diagnostic and prognostic capability, and more accurate instruments to assess the efficacy of emerging interventions for this most vulnerable group of infants.

Low Renal Oxygen Saturation at Near-Infrared Spectroscopy on the First Day of Life Is Associated with Developing Acute Kidney Injury in Very Preterm Infants

BACKGROUND

Acute kidney injury (AKI) is a frequent complication in preterm infants, and the identification of early markers of renal hypoperfusion is a chief challenge in neonatal intensive care units.

OBJECTIVES

To describe the association between early markers of cardiovascular function and renal perfusion with AKI occurrence in a cohort of preterm infants < 32 weeks' gestation.

METHODS

128 infants were prospectively included from birth to discharge. During the first day of life, we assessed cardiovascular function, systemic and organ blood flow by Doppler ultrasound, and monitored cerebral and renal regional oxygen saturation (rSO2) using near-infrared spectroscopy (NIRS). These measures were analyzed in relation to developing AKI and serum creatinine (SCr) peak from day 2 to 7 of life.

RESULTS

12 of 128 infants presented with AKI (9.4%). SCr peak was 155.3 ± 30.2 µmol/L in infants with AKI versus 82.0 ± 16.5 in non-AKI infants (p < 0.001). Among all measures of cardiovascular function and renal perfusion, low mean cerebral and renal rSO2 during the first day of life and a low resistive index at renal artery Doppler were significantly associated with developing AKI. After adjustment for possible confounding factors, low renal rSO2 on the first day of life remained associated with a high SCr peak from day 2 to 7 of life.

CONCLUSION

Low renal rSO2 values during the first day of life correlate with developing AKI in preterm infants < 32 weeks' gestation. NIRS monitoring of renal function during adaptation seems promising, and its very early use after birth to detect kidney hemodynamic dysfunction deserves further investigations.

Arterial flow patterns in healthy transitioning near-term neonates

OBJECTIVE

Significant haemodynamic changes occur at delivery impacting organ blood flow distribution. We aimed to characterise Doppler indices patterns over time in three different organs (brain, gut and kidney) and test them as measures of vascular resistance.

DESIGN

Observational cohort study. Serial Doppler interrogations of the anterior cerebral, superior mesenteric and renal arteries within 2 hours, 2-6, and 24 hours of life, in combination with central haemodynamic data.

PATIENTS

Healthy, near-term (>36 weeks of gestation) neonates.

OUTCOME MEASURES

Pulsatility (PI) and Resistance Indices (RI) patterns and organ-specific conductances, detailed echocardiographic haemodynamic measures.

RESULTS

Twenty-one babies were studied. Doppler morphology and adaptation patterns were distinctly different between the organs (brain, gut and kidney) supporting autonomous vascular regulatory effects. The PI differentiated especially between kidney and other organ flow consistently over time. PI and RI for all three organs decreased. The variance in organ conductance did not explain the variance in 1/PI, indicating that PI is not a measure of resistance. Superior mesenteric artery had the highest velocity with 72 cm/s. Non-invasively acquired pilot serial values in a normal population are given. Patent ductus arteriosus flow remained open at discharge for 36%.

CONCLUSIONS

Haemodynamic transitioning patterns assessed by serial Dopplers in healthy near-term neonates differ in brain, gut and kidney: Doppler waveform morphology differs, and PI differentiates renal Doppler morphology, compared with the other organs. While PI and RI decline for all organs, they do not measure resistance. Brain artery velocity increases, mesenteric perfusion is variable and renal Vmax decreases.

Efficacy and Safety of Intravenous Colistin in Very Low Birth Weight Preterm Infants

BACKGROUND

Given the severity and high mortality of multidrug-resistant Gram-negative bacilli (MDR-GNB) infections, the use of colistin will increase in patients with MDR-GNB infection.

OBJECTIVE

This study aims to assess the efficacy and safety of intravenous colistin in very low birth weight (VLBW; birth weight < 1500 g) preterm infants.

METHODS

We retrospectively analyzed the medical records of patients who received colistin between June 2016 and December 2017. The patients were assigned to two groups: the VLBW group and the non-VLBW group. Both groups were evaluated for response to treatment and adverse effects.

RESULTS

In total, 66 infants who received colistin therapy were included; of these, 28 infants were VLBW. All of our patients received standard colistin treatment of 5 mg/kg per day in three doses and the median duration of colistin treatment was 14 days. No significant differences were observed between the groups with respect to the efficacy of colistin (defined as showing microbiological clearance in control cultures and the absence of mortality during treatment) (89.3 vs 86.8%, p > 0.99). Serum magnesium and potassium levels were significantly lower in the VLBW group than in the non-VLBW group during colistin therapy (magnesium, 1.30 vs 1.70 mg/dL, p < 0.001; potassium, 3.6 vs 4.6 mEq/L, p < 0.001). Acute kidney injury was observed in four infants in the VLBW group and one in the non-VLBW group, without significant differences (p = 0.15).

CONCLUSIONS

Colistin administration appears to be efficacious in VLBW infants; however, renal function tests and serum electrolytes should be monitored more closely in these infants during treatment.

Association Between Early Caffeine Citrate Administration and Risk of Acute Kidney Injury in Preterm Neonates: Results From the AWAKEN Study

Importance

Acute kidney injury (AKI) occurs commonly in preterm neonates and is associated with increased morbidity and mortality.

Objectives

To examine the association between caffeine citrate administration and AKI in preterm neonates in the first 7 days after birth and to test the hypothesis that caffeine administration would be associated with reduced incidence and severity of AKI.

Design, Setting, and Participants

This study was a secondary analysis of the Assessment of Worldwide Acute Kidney Injury Epidemiology in Neonates (AWAKEN) study, a retrospective observational cohort that enrolled neonates born from January 1 to March 31, 2014. The dates of analysis were October 2016 to December 2017. The setting was an international, multicenter cohort study of neonates admitted to 24 participating level III or IV neonatal intensive care units. Participants met the original inclusion and exclusion criteria of the AWAKEN study. Additional exclusion criteria for this study included participants greater than or equal to 33 weeks' gestation at birth, admission after age 7 days, use of theophylline in the neonatal intensive care unit, or lack of data to define AKI. There were 675 preterm neonates available for analysis.

Exposure

Administration of caffeine in the first 7 days after birth.

Main Outcomes and Measures

The primary outcome was the incidence of AKI (based on the modified neonatal Kidney Disease: Improving Global Outcomes [KDIGO] definition) in the first 7 days after birth. The hypothesis that caffeine administration would be associated with reduced AKI incidence was formulated before data analysis.

Results

The study cohort (n = 675) was 55.4% (n = 374) male, with a mean (SD) gestational age of 28.9 (2.8) weeks and a mean (SD) birth weight of 1285 (477) g. Acute kidney injury occurred in 122 neonates (18.1%) in the first 7 days after birth. Acute kidney injury occurred less frequently among neonates who received caffeine than among those who did not (50 of 447 [11.2%] vs 72 of 228 [31.6%], P < .01). After multivariable adjustment, administration of caffeine remained associated with reduced odds of developing AKI (adjusted odds ratio, 0.20; 95% CI, 0.11-0.34), indicating that for every 4.3 neonates exposed to caffeine one case of AKI was prevented. Among neonates with early AKI, those receiving caffeine were less likely to develop stage 2 or 3 AKI (adjusted odds ratio, 0.20; 95% CI, 0.12-0.34).

Conclusions and Relevance

Caffeine administration in preterm neonates is associated with reduced incidence and severity of AKI. Further studies should focus on the timing and dosage of caffeine to optimize the prevention of AKI.

[Monitoring of kidney injury in preterm infants]

Acute kidney injury (AKI) is a common complication in the neonatal intensive care unit that causes a high mortality of preterm infants and various chronic kidney diseases in adulthood. Preterm infants have immature development of the kidneys at birth. The kidneys continue to develop within a specific time window after birth. However, due to various factors during pregnancy and after birth, preterm infants tend to develop AKI. At present, serum creatinine and urine volume are used for the assessment of kidney injury, and their early sensitivity and specificity have attracted increasing attention. In recent years, various new biomarkers have been identified for early recognition of AKI. This article reviews the features, risk factors, renal function assessment, and prevention/treatment of AKI of preterm infants, in order to provide a reference for improving early diagnosis and treatment of AKI in preterm infants and long-term quality of life.

Neonatal nephron loss during active nephrogenesis - detrimental impact with long-term renal consequences

Neonatal nephron loss may follow hypoxic-ischemic events or nephrotoxic medications. Its long-term effects on the kidney are still unclear. Unlike term infants, preterm neonates less than 36 weeks gestational age show ongoing nephrogenesis. We hypothesized that nephron loss during nephrogenesis leads to more severe renal sequelae than nephron loss shortly after the completion of nephrogenesis. Rats show nephrogenesis until day 10 of life resembling the situation of preterm infants. Animals were uninephrectomized at day 1 (UNX d1) resulting in nephron reduction during nephrogenesis and at day 14 of life (UNX d14) inducing nephron loss after the completion of nephrogenesis. 28 days after uninephrectomy the compensatory renal growth was higher in UNX d1 compared to UNX d14. Nephrin was reduced and collagen deposition increased in UNX d1. At 1 year of age, glomerulosclerosis and markers of tubulointerstitial damage were most prevalent in UNX d1. Moreover, the number of desmin-positive podocytes was higher and nephrin was reduced in UNX d1 indicating podocyte damage. Infiltration of inflammatory cells was heightened after UNX d1. Uninephrectomized animals showed no arterial hypertension. We conclude that neonatal nephron loss during active nephrogenesis leads to more severe glomerular and tubulointerstitial damage, which is not a consequence of compensatory arterial hypertension.

Prematurity disrupts glomeruli development, whereas prematurity and hyperglycemia lead to altered nephron maturation and increased oxidative stress in newborn baboons

BackgroundPremature birth occurs when nephrogenesis is incomplete and has been linked to increased renal pathologies in the adult. Metabolic factors complicating preterm birth may have additional consequences for kidney development. Here, we evaluated the effects of prematurity and hyperglycemia on nephrogenesis in premature baboons when compared with those in term animals.MethodsBaboons were delivered prematurely (67% gestation; n=9) or at term (n=7) and survived for 2-4 weeks. Preterm animals were classified by glucose control during the first 5 days of life: normoglycemic (PtN; serum glucose 50-100 mg/dl, n=6) and hyperglycemic (PtH; serum glucose 150-250 mg/dl, n=3). Kidneys were assessed histologically for glomeruli relative area, maturity, size, and overall morphology. Kidney lysates were evaluated for oxidative damage with 4-hydroxynonenal (4-HNE) antibody.ResultsHistological examination revealed decreased glomeruli relative area (P<0.05), fewer glomerular generations (P<0.01), and increased renal corpuscle area (P<0.001) in preterm compared with those in term animals. Numbers of apoptotic glomeruli were similar between groups. PtH kidneys exhibited reduced nephrogenic zone width (P<0.0001), increased numbers of mature glomeruli (P<0.05), and increased 4-HNE staining compared with those in PtN kidneys.ConclusionPrematurity interrupts normal kidney development, independent of glomerular cell apoptosis. When prematurity is complicated by hyperglycemia; kidney development shifts toward accelerated maturation and increased oxidative stress.

Urinary Biomarkers to Predict Neonatal Acute Kidney Injury: A Review of the Science

Acute kidney injury (AKI) occurs in approximately 30% of all infants hospitalized in the neonatal intensive care unit. About 40% of very low-birth-weight infants develop AKI, with an estimated mortality rate of 50% to 80%. Very low-birth-weight survivors have twice the risk of developing chronic renal disease later in life compared with their term counterparts. Current diagnostic modalities for AKI include serum creatinine and urine output; however, recent studies suggest that these measures are imprecise, as they may not change until 25% to 50% of renal function is lost. Urinary biomarkers may more accurately identify infants at risk for early AKI development. The purpose of this review is to discuss current research findings related to neonatal AKI risk factors, provide an overview of short- and long-term outcomes, describe innovative diagnostic approaches, and identify future research direction needed to improve prediction and intervention strategies associated with renal impairment.

Developmental Programming of Renal Function and Re-Programming Approaches

Chronic kidney disease affects more than 10% of the population. Programming studies have examined the interrelationship between environmental factors in early life and differences in morbidity and mortality between individuals. A number of important principles has been identified, namely permanent structural modifications of organs and cells, long-lasting adjustments of endocrine regulatory circuits, as well as altered gene transcription. Risk factors include intrauterine deficiencies by disturbed placental function or maternal malnutrition, prematurity, intrauterine and postnatal stress, intrauterine and postnatal overnutrition, as well as dietary dysbalances in postnatal life. This mini-review discusses critical developmental periods and long-term sequelae of renal programming in humans and presents studies examining the underlying mechanisms as well as interventional approaches to "re-program" renal susceptibility toward disease. Clinical manifestations of programmed kidney disease include arterial hypertension, proteinuria, aggravation of inflammatory glomerular disease, and loss of kidney function. Nephron number, regulation of the renin-angiotensin-aldosterone system, renal sodium transport, vasomotor and endothelial function, myogenic response, and tubuloglomerular feedback have been identified as being vulnerable to environmental factors. Oxidative stress levels, metabolic pathways, including insulin, leptin, steroids, and arachidonic acid, DNA methylation, and histone configuration may be significantly altered by adverse environmental conditions. Studies on re-programming interventions focused on dietary or anti-oxidative approaches so far. Further studies that broaden our understanding of renal programming mechanisms are needed to ultimately develop preventive strategies. Targeted re-programming interventions in animal models focusing on known mechanisms will contribute to new concepts which finally will have to be translated to human application. Early nutritional concepts with specific modifications in macro- or micronutrients are among the most promising approaches to improve future renal health.

Concepts for a therapeutic prolongation of nephrogenesis in preterm and low-birth-weight babies must correspond to structural-functional properties in the nephrogenic zone

Numerous investigations are dealing with anlage of the mammalian kidney and primary development of nephrons. However, only few information is available about the last steps in kidney development leading at birth to a downregulation of morphogen activity in the nephrogenic zone and to a loss of stem cell niches aligned beyond the organ capsule. Surprisingly, these natural changes in the developmental program display similarities to processes occurring in the kidneys of preterm and low-birth-weight babies. Although those babies are born at a time with a principally intact nephrogenic zone and active niches, a high proportion of them suffers on impairment of nephrogenesis resulting in oligonephropathy, formation of atypical glomeruli, and immaturity of parenchyma. The setting points out that up to date not identified noxae in the nephrogenic zone hamper primary steps of parenchyma development. In this situation, a possible therapeutic aim is to prolong nephrogenesis by medications. However, actual data provide information that administration of drugs is problematic due to an unexpectedly complex microanatomy of the nephrogenic zone, in niches so far not considered textured extracellular matrix and peculiar contacts between mesenchymal cell projections and epithelial stem cells via tunneling nanotubes. Thus, it remains to be figured out whether disturbance of morphogen signaling altered synthesis of extracellular matrix, disturbed cell-to-cell contacts, or modified interstitial fluid impair nephrogenic activity. Due to most unanswered questions, search for eligible drugs prolonging nephrogenesis and their reliable administration is a special challenge for the future.

Ultrasound Imaging of the Renal Parenchyma of Premature Neonates for the Assessment of Renal Growth and Glomerulomegaly

Evidence is increasingly showing that prematurity results in chronic kidney disease. We hypothesized that we could use ultrasound imaging to measure and monitor the growth of the renal parenchyma in premature neonates. We conducted a prospective, case-control study to compare renal parenchymal growth between neonates born prematurely and term neonates. The study patients underwent ultrasound assessment at 32 wk postmenstrual age (PMA) and 37 wk PMA. Term neonates (gestation >37 completed wk) admitted to the neonatal unit with minor neonatal conditions were recruited into the control group. Complete data sets were available in 91 premature neonates and during the same period, 56 term neonates were recruited as the control. The median birth weight (preterm babies) was 930 g (780-1220 g), and the mean gestational age was 27.0 wk (2.1 wk). Total renal volume (TRV) increased from 14.6 (4.3) cm³ to 20.5 (5.3) cm³ from 32 to 37 wk PMA. During the same period, the total renal parenchyma (TRP) thickness increased from 1.6 (0.3) cm to 1.8 (0.3) cm. At 37 wk PMA, ex-premature neonates have a significantly smaller total renal volume (20.5 [5.3] versus 25.9 [6.4] cm³; p < 0.001) and total renal parenchyma thickness (1.8 [0.3] versus 2.0 [0.2] cm; p = 0.015) compared with term (control) neonates. However, premature neonates at 37 wk PMA have a larger TRP:TRV ratio compared with term neonates (0.09 [0.02] versus 0.0 8 [0.02] cm^-2; p < 0.001). Reduced nephron endowment as a result of prematurity may cause the remaining nephrons to undergo compensatory glomerulomegaly and we postulate this is the reason for the observed differences. Ultrasound imaging of the renal parenchyma shows promise in assessing the effects of prematurity on the developing kidney.