A simple estimate of glomerular filtration rate in full-term infants during the first year of life

A new approach to define acute kidney injury in term newborns with hypoxic ischemic encephalopathy

BACKGROUND

Current definitions of acute kidney injury (AKI) are not sufficiently sensitive to identify all newborns with AKI during the first week of life.

METHODS

To determine whether the rate of decline of serum creatinine (SCr) during the first week of life can be used to identify newborns with AKI, we reviewed the medical records of 106 term neonates at risk of AKI who were treated with hypothermia for hypoxic ischemic encephalopathy (HIE).

RESULTS

Of the newborns enrolled in the study, 69 % showed a normal rate of decline of SCr to ≥50 % and/or reached SCr levels of ≤0.6 mg/dl before the 7th day of life, and therefore had an excellent clinical outcome (control group). Thirteen newborns with HIE (12 %) developed AKI according to an established neonatal definition (AKI-KIDGO group), and an additional 20 newborns (19 %) showed a rate of decline of SCr of <33, <40, and <46 % from birth to days 3, 5, or 7 of life, respectively (delayed rise in estimated SCr clearance group). Compared to the control group, newborns in the other two groups required more days of mechanical ventilation and vasopressor drugs and had higher gentamicin levels, more fluid overload, lower urinary epidermal growth factor levels, and a prolonged length of stay.

CONCLUSIONS

The rate of decline of SCr provides a sensitive approach to identify term newborns with AKI during the first week of life.

Evaluating renal function and age as predictors of amikacin clearance in neonates: model-based analysis and optimal dosing strategies

AIMS

We aimed to compare the performance of renal function and age as predictors of inter-individual variability (IIV) in clearance of amikacin in neonates through parallel development of population pharmacokinetic (PK) models and their associated impact on optimal dosing regimens.

METHODS

Amikacin concentrations were retrospectively collected for 149 neonates receiving amikacin (post-natal age (PNA) between 4-89 days). Two population PK models were developed in parallel, considering at least as predictors current body weight (WT), in combination with either creatinine clearance (CLcr ) or age descriptors. Using stochastic simulations for both renal function or age-based dosing, we identified optimal dosing strategies that were based on attainment of optimal peak- (PCC) and trough target concentration coverage (TCC) windows associated with efficacy and toxicity.

RESULTS

The CLcr and age-based population PK models both included current body weight (WT) on CL, central distribution volume and intercompartmental clearance, in combination with either CLcr or PNA as predictors for IIV of clearance (CL). The WT-CLcr model explained 6.9% more IIV in CL compared with the WT-PNA model. Both models successfully described an external dataset (n = 53) of amikacin PK. The simulation analysis of optimal dose regimens suggested similar performance of either CLcr or PNA based dosing.

CONCLUSION

CLcr predicted more IIV in CL, but did not translate into clinically relevant improvements of target concentrations. Our optimized dose regimens can be considered for further evaluation to optimize initial treatment with amikacin.

Correlation between cystatin C-based formulas, Schwartz formula and urinary creatinine clearance for glomerular filtration rate estimation in children with kidney disease

INTRODUCTION

Assessment of glomerular filtration rate (GFR) is an important tool for monitoring renal function.

OBJECTIVES

Regarding to limitations in available methods, we intended to calculate GFR by cystatin C (Cys C) based formulas and determine correlation rate of them with current methods.

PATIENTS AND METHODS

We studied 72 children (38 boys and 34 girls) with renal disorders. The 24 hour urinary creatinine (Cr) clearance was the gold standard method. GFR was measured with Schwartz formula and Cys C-based formulas (Grubb, Hoek, Larsson and Simple). Then correlation rates of these formulas were determined.

RESULTS

Using Pearson correlation coefficient, a significant positive correlation between all formulas and the standard method was seen (R(2) for Schwartz, Hoek, Larsson, Grubb and Simple formula was 0.639, 0.722, 0.705, 0.712, 0.722, respectively) (P<0.001). Cys C-based formulas could predict the variance of standard method results with high power. These formulas had correlation with Schwarz formula by R(2) 0.62-0.65 (intermediate correlation). Using linear regression and constant (y-intercept), it revealed that Larsson, Hoek and Grubb formulas can estimate GFR amounts with no statistical difference compared with standard method; but Schwartz and Simple formulas overestimate GFR.

CONCLUSION

This study shows that Cys C-based formulas have strong relationship with 24 hour urinary Cr clearance. Hence, they can determine GFR in children with kidney injury, easier and with enough accuracy. It helps the physician to diagnosis of renal disease in early stages and improves the prognosis.

Acute Kidney Injury in Neonates in the PICU

OBJECTIVES

Acute kidney injury is an independent risk factor for morbidity and mortality in critically ill children in the PICU. Neonates are a particularly vulnerable subgroup regarding acute kidney injury. The objectives were to define the prevalence of acute kidney injury to assess independent risk factors, for the development of acute kidney injury, and to determine the impact of acute kidney injury on outcomes in critically ill neonates without history of cardiac surgery.

DESIGN

A retrospective study of neonates (≤ 28 d old and ≥ 32 wk of gestational age) admitted to a tertiary PICU was conducted. Acute kidney injury was classified using the Kidney Disease: Improving Global Outcomes definition.

SETTING

PICU in a tertiary children's hospital.

PATIENTS

A total of 80 neonates (62% male neonates) with a median gestational age of 38 weeks (interquartile range, 37-39 wk) were reviewed.

INTERVENTION

None.

MEASUREMENT AND MAIN RESULTS

Acute kidney injury was found in 35% (n = 28) of neonates. Fourteen (50%) reached stage I, 8 (29%) stage II, and 6 (21%) stage III acute kidney injury. Younger age was associated with acute kidney injury (p = 0.016; odds ratio, 0.93; CI, 0.88-0.98). In regression analysis adjusted for age and gender, bacteremia (p = 0.014; odds ratio, 5.4; CI, 1.4-20.4) and maximum sodium concentration (p = 0.02; odds ratio, 1.12; CI, 1.02-1.24) were associated with acute kidney injury. Mortality (p = 0.03) and length of mechanical ventilation (p = 0.001) were significantly higher in neonates with acute kidney injury compared with those without acute kidney injury. In an adjusted regression model, stages 2 and 3 combined were associated with increased mortality (p = 0.02; odds ratio, 5.64; CI, 1.33-23.8), length of ventilation (p = 0.016; β, 12.2; CI, 2.39-22.0), and length of stay (p = 0.049; β, 12.2; CI, 0.073-24.3).

CONCLUSIONS

Acute kidney injury is common in neonates not requiring cardiac surgery and is associated with increased morbidity and mortality. Age, bacteremia, and maximum sodium concentration are independently associated with the development of acute kidney injury in this population.

Vancomycin Therapeutic Targets and Nephrotoxicity in Critically Ill Children With Cancer

To obtain pharmacokinetic and pharmacodynamic data for vancomycin in a cohort of critically ill pediatric oncology patients, we analyzed 256 measurements of vancomycin concentrations in 94 patients. Variables were tested as possible risk factors for vancomycin-related nephrotoxicity or death for 28 days. We found the following: mean vancomycin trough serum concentration, 15.6 ± 12.4 μg/mL; mean vancomycin clearance, 0.16 ± 0.098 L/h/kg; and mean vancomycin distribution volume, 1.04 ± 0.11 L/kg. Only 13.6% of serum trough level measurements were between 15 and 20 μg/mL. The trough levels showed a strong correlation with the AUC (area under the curve of serum concentrations vs. time over 24 h to the minimum inhibitory concentration ratio), with a 94% positive predictive value for AUC/MIC ≥ 400, but only for MIC=1. The doses that are currently used (60 mg/kg/d) attained the therapeutic target (AUC/MIC ≥ 400) in only 56% of measurements, considering MIC=1. A serum trough level of ≥ 20 μg/mL was an independent risk for nephrotoxicity (P = 0.0008; odds ratio = 17.83). Vancomycin-related nephrotoxicity was a predictor of death for up to 28 days (P = 0.003, odds ratio = 7.68). Currently administered doses of vancomycin do not reach the therapeutic target for critical cancer patients, particularly if staphylococci isolates have a MIC>1.

Effect of vitamin A supplementation on the urinary retinol excretion in very low birth weight infants

Despite high-dose vitamin A supplementation of very low birth weight infants (VLBW, <1500 g), their vitamin A status does not improve substantially. Unknown is the impact of urinary retinol excretion on the serum retinol concentration in these infants. Therefore, the effect of high-dose vitamin A supplementation on the urinary vitamin A excretion in VLBW infants was investigated. Sixty-three VLBW infants were treated with vitamin A (5000 IU intramuscular, 3 times/week for 4 weeks); 38 untreated infants were classified as control group. On days 3 and 28 of life, retinol, retinol-binding protein 4 (RBP4), glomerular filtration rate, proteinuria, and Tamm-Horsfall protein were quantified in urine. On day 3 of life, substantial retinol and RBP4 losses were found in both groups, which significantly decreased until day 28. Notwithstanding, the retinol excretion was higher (P < 0.01) under vitamin A supplementation as compared to infants of the control group. On day 28 of life, the urinary retinol concentrations were predictive for serum retinol concentrations in the vitamin A treated (P < 0.01), but not in the control group (P = 0.570).

CONCLUSION

High urinary retinol excretion may limit the vitamin A supplementation efficacy in VLBW infants. Advanced age and thus postnatal kidney maturation seems to be an important contributor in the prevention of urinary retinol losses.

[Acute kidney injury after pediatric cardiac surgery: risk factors and outcomes. Proposal for a predictive model]

OBJECTIVES

To characterize the epidemiology and risk factors for acute kidney injury (AKI) after pediatric cardiac surgery in our center, to determine its association with poor short-term outcomes, and to develop a logistic regression model that will predict the risk of AKI for the study population.

METHODS

This single-center, retrospective study included consecutive pediatric patients with congenital heart disease who underwent cardiac surgery between January 2010 and December 2012. Exclusion criteria were a history of renal disease, dialysis or renal transplantation.

RESULTS

Of the 325 patients included, median age three years (1 day-18 years), AKI occurred in 40 (12.3%) on the first postoperative day. Overall mortality was 13 (4%), nine of whom were in the AKI group. AKI was significantly associated with length of intensive care unit stay, length of mechanical ventilation and in-hospital death (p<0.01). Patients' age and postoperative serum creatinine, blood urea nitrogen and lactate levels were included in the logistic regression model as predictor variables. The model accurately predicted AKI in this population, with a maximum combined sensitivity of 82.1% and specificity of 75.4%.

CONCLUSIONS

AKI is common and is associated with poor short-term outcomes in this setting. Younger age and higher postoperative serum creatinine, blood urea nitrogen and lactate levels were powerful predictors of renal injury in this population. The proposed model could be a useful tool for risk stratification of these patients.

Renal Function Descriptors in Neonates: Which Creatinine-Based Formula Best Describes Vancomycin Clearance?

Growth and maturational changes have been identified as significant covariates in describing variability in clearance of renally excreted drugs such as vancomycin. Because of immaturity of clearance mechanisms, quantification of renal function in neonates is of importance. Several serum creatinine (SCr)-based renal function descriptors have been developed in adults and children, but none are selectively derived for neonates. This review summarizes development of the neonatal kidney and discusses assessment of the renal function regarding estimation of glomerular filtration rate using renal function descriptors. Furthermore, identification of the renal function descriptors that best describe the variability of vancomycin clearance was performed in a sample study of a septic neonatal cohort. Population pharmacokinetic models were developed applying a combination of age-weight, renal function descriptors, or SCr alone. In addition to age and weight, SCr or renal function descriptors significantly reduced variability of vancomycin clearance. The population pharmacokinetic models with Léger and modified Schwartz formulas were selected as the optimal final models, although the other renal function descriptors and SCr provided reasonably good fit to the data, suggesting further evaluation of the final models using external data sets and cross validation. The present study supports incorporation of renal function descriptors in the estimation of vancomycin clearance in neonates.

Extrapolation of Valacyclovir Posology to Children Based on Pharmacokinetic Modeling

BACKGROUND

Valacyclovir is a prodrug of acyclovir. Although acyclovir is approved for children in Europe, valacyclovir is not approved, despite being used off-label. The aim of the study was to extrapolate the approved dosages of acyclovir, to valacyclovir dosages, in children using Monte Carlo simulations based on the population pharmacokinetic (PopPK) models of valacyclovir and acyclovir.

METHODS

Assuming that the recommended dosages of acyclovir are efficacious, a PopPK model of acyclovir was used to perform simulations to determine a critical concentration (Ccrit) for which a target criterion is fulfilled, ie, 90% of the simulated patients have acyclovir levels above Ccrit for at least half the time. The same was done for a secondary target, drug exposure, determining a critical area under the curve in 24 hours at steady state. Then a PopPK model of valacyclovir was used to determine by simulations, dosage regimens that fulfill the criteria for both targets. This was repeated for various indications and age groups.

RESULTS

Indicatively, for the treatment of varicella zoster virus, in ages 2-12 years, Ccrit and critical area under the curve in 24 hours at steady state were found to be 0.39 mg/L and 9.6 mg/L × h, respectively, using the acyclovir approved doses 20 mg/kg 4 times daily. For these breakpoints, a 20 mg/kg, 3 times daily, valacyclovir dose achieves the targets in 97% and 100% of the patients, respectively. We found that some patients receive higher than the ideal doses of acyclovir.

CONCLUSIONS

Simulations were used to determine the appropriate doses of valacyclovir in children to support a pediatric investigation plan targeting a paediatric-use marketing authorization application in the European Medicines Agency.

Chronic Kidney Disease in Children: Recent Update

The incidence of end stage of renal disease (ESRD) in US children age 0-19 years is 12.9 per million/year (2012). The economic and social burden of diagnosing, treating and preventing chronic kidney disease (CKD) in children and adults remains substantial. Advances in identifying factors that predict development of CKD and its progression, as well as advances in the management of co-morbid conditions including anemia, cardiovascular disease, growth, mineral and bone disorder, and neurocognitive function are discussed. Despite recent reports from retrospective registry data analysis and multi-center prospective studies which have significantly advanced our knowledge of CKD, and despite advances in the understanding of the pathogenesis, diagnosis and treatment of CKD much work remains to be done to improve the long term outcome of this disease.

Prospective Cohort Study of Nephrogenic Systemic Fibrosis in Patients With Stage 3-5 Chronic Kidney Disease Undergoing MRI With Injected Gadobenate Dimeglumine or Gadoteridol

OBJECTIVE

The purpose of this study was to determine the incidence of nephrogenic systemic fibrosis (NSF) in patients with chronic kidney disease (CKD) and moderate-to-severe impairment of kidney function who had not previously been exposed to gadolinium-based contrast agents (GBCAs) or referred to undergo contrast-enhanced MRI with gadobenate dimeglumine or gadoteridol.

SUBJECTS AND METHODS

Two multicenter prospective cohort studies evaluated the incidence of unconfounded NSF in patients with stage 3 CKD (estimated glomerular filtration rate [eGFR] in cohort 1, 30-59 mL/min/1.73 m(2)) or stage 4 or 5 CKD (eGFR in cohort 2, < 30 mL/min/1.73 m(2)) after injection of gadobenate dimeglumine (study A) or gadoteridol (study B). A third study (study C) determined the incidence of NSF in patients with stage 4 or 5 CKD who had not received a GBCA in the 10 years before enrollment. Monitoring for signs and symptoms suggestive of NSF was performed via telephone at 1, 3, 6, and 18 months, with clinic visits occurring at 1 and 2 years.

RESULTS

For studies A and B, the populations evaluated for NSF comprised 363 and 171 patients, respectively, with 318 and 159 patients in cohort 1 of each study, respectively, and with 45 and 12 patients in cohort 2, respectively. No signs or symptoms of NSF were reported or detected during the 2 years of patient monitoring. Likewise, no cases of NSF were reported for any of the 405 subjects enrolled in study C.

CONCLUSION

To our knowledge, and consistent with reports in the literature, no association of gadobenate dimeglumine or gadoteridol with unconfounded cases of NSF has yet been established. Study data confirm that both gadoteridol and gadobenate dimeglumine properly belong to the class of GBCAs considered to be associated with the lowest risk of NSF.

Impact of ventricular assist device placement on longitudinal renal function in children with end-stage heart failure

BACKGROUND

Although ventricular assist devices (VADs) restore hemodynamics in those with heart failure, reversibility of end-organ dysfunction with VAD support is not well characterized. Renal function often improves in adults after VAD placement, but this has not been comprehensively explored in children.

METHODS

Sixty-three children on VAD support were studied. Acute kidney injury (AKI) was defined by Kidney Disease: Improving Global Outcomes criteria. Estimated glomerular filtration rate (eGFR) was determined by the Schwartz method. Generalized linear mixed-effects models compared the pre-VAD and post-VAD eGFR for the cohort and sub-groups with and without pre-VAD renal dysfunction (pre-VAD eGFR < 90 ml/min/1.73 m(2)).

RESULTS

The pre-VAD eGFR across the cohort was 84.0 ml/min/1.73 m(2) (interquartile range [IQR] 62.3-122.7), and 55.6% (34 of 63) had pre-VAD renal dysfunction. AKI affected 60.3% (38 of 63), with similar rates in those with and without pre-existing renal dysfunction. Within the cohort, the nadir eGFR occurred 1 day post-operatively (62.9 ml/min/1.73 m(2); IQR, 51.2-88.9 ml/min/1.73 m(2); p < 0.001). By Day 5, however, the eGFR exceeded the baseline (99.0 ml/min/1.73 m(2); IQR, 59.3-146.7 ml/min/1.73 m(2); p = 0.03) and remained significantly higher through the first post-operative week. After adjusting for age, gender, and AKI, the eGFR continued to increase throughout the entire 180-day study period (β = 0.0025; 95% confidence interval, 0.0015-0.0036; p < 0.001). Patients with pre-VAD renal dysfunction experienced the greatest improvement in the eGFR (β = 0.0051 vs β = 0.0013, p < 0.001).

CONCLUSIONS

Renal dysfunction is prevalent in children with heart failure undergoing VAD placement. Although peri-operative AKI is common, renal function improves substantially in the first post-operative week and for months thereafter. This is particularly pronounced in those with pre-VAD renal impairment, suggesting that VADs may facilitate recovery and maintenance of kidney function in children with advanced heart failure.

Acute Kidney Injury in Premature, Very Low-Birth-Weight Infants

The epidemiology of neonatal acute kidney injury (AKI) is not well established, partly due to lack of a consensus definition. Preterm neonates are likely especially vulnerable to AKI. We performed a retrospective review to assess the incidence of and risk factors for AKI in very low-birth-weight (VLBW), premature infants admitted to a level 4 NICU (2006-2007). AKI was classified using a standardized definition based on changes in serum creatinine (SCr). AKI incidence varied inversely with gestational age (GA): 65% (22-25 weeks), 25% (26-28 weeks), 9% (29-32 weeks) as did severity (p < 0.001). Stage 1 AKI was most common in each cohort. Stages 2 and 3 AKI comprised approximately 60% of AKI in the 22- to 25-week cohort but 20% or less in the older cohorts. By univariate analysis, factors associated with AKI included younger GA, lower BW, lower Apgar scores, hypotension, more frequent treatment with nephrotoxic antimicrobials, longer-duration mechanical ventilation, and higher incidence of patent ductus arteriosus (PDA) requiring treatment. By multiple logistic regression analysis, only GA, hypotension, PDA, and longer duration of mechanical ventilation were independently associated with AKI. AKI was not independently associated with risk of death. Our study suggests that small increases (≥ 0.3 mg/dL) in SCr occur frequently in premature, VLBW infants, and are associated with increased morbidity but not mortality. AKI incidence and severity were highest in the youngest GA cohort. Understanding the epidemiology, risk factors, and impact of neonatal AKI is crucial as long-term premature infant survival continues to improve.

Special population considerations and regulatory affairs for clinical research

Special populations, including women (non-pregnant and pregnant), pediatrics, and the elderly, require additional consideration with regard to clinical research. There are very specific regulatory laws, which protect these special populations, that need to be understood and adhered to in order to perform clinical research. This review provides a broad overview of some of the physiological differences in special populations and discusses how these differences may affect study design and regulatory considerations. These various special populations, with respect to regulatory affairs, are clearly defined within the Code of Federal Regulations. The definition of "special population" exists to provide enhanced awareness of their vulnerabilities, thereby allowing the creation of regulatory guidance aimed to decrease injury or outright harm. Currently, progress is being made to be more inclusive of special populations in clinical trials. This reflects changing attitudes towards drug information, with it being more representative of those patients that will ultimately be prescribed or exposed to the therapy. However, all research undertaken in these populations should be performed in a manner that ensures all protections of each participant are upheld.

Antenatal Determinants of Long-Term Kidney Outcome in Boys with Posterior Urethral Valves

Background: Posterior urethral valves (PUV) are the most important cause of end-stage renal disease (ESRD) in young boys. The objective of this report was to define the antenatal determinants of long-term postnatal renal outcome in this condition. Design: This was a retrospective cohort analysis. The primary outcome was the development of ESRD defined as starting dialysis or receiving a preemptive kidney transplant. Results: Eighty-two cases of PUV were identified, with 17 (21%) developing ESRD at 6.1 ± 7.1 years. Cases developing ESRD were more likely diagnosed antenatally (41 vs. 19%, p = 0.05), had a younger gestational age (35.5 ± 3.4 weeks vs. 37.3 ± 2.1 weeks, p = 0.02), and on antenatal ultrasound scan were more likely to have oligohydramnios (60 vs. 26%, p = 0.02), renal cortical cysts (47 vs. 17%, p = 0.02), and the combination of oligohydramnios, renal cortical cysts, and increased renal echogenicity (47 vs. 9%, p = 0.002). Conclusions: In boys with PUV, decreased gestational age, oligohydramnios, renal cysts, and the combination of oligohydramnios, cortical cysts, and echogenic kidneys were associated with ESRD, while the combination was an independent predictor of poor long-term postnatal kidney function.

Practical considerations to drug dosing in children with acute kidney injury

Medication dosing for children with acute kidney injury (AKI) needs to be individualized based on pharmacokinetic and pharmacodynamic principles of the prescribed drugswhenever possible to optimize therapeutic outcome and to minimize toxicity. The pediatric RIFLE criteria should be prospectively utilized to identify patients at highest risk of developing AKI. Serum creatinine and urine output along with volume status should be utilized to guide drug dosing when urinary biomarkers including kidney injury molecule 1, interleukin-18, or neutrophil gelatinase-associated lipocalin are not readily available. Because of the presence of a positive fluid balance in early stages of AKI, the dosing regimen for many drugs, especially antimicrobial agents, should be initiated at a larger loading dose based on the expected volume of distribution to achieve target serum concentrations.When possible, therapeutic drug monitoring should be utilized for those medications where serum drug concentrations can be obtained in a clinically relevant time frame. For these medications, close monitoring of serum drug concentrations is highly recommended. This review addresses drug-dosing strategies in pediatric patients with AKI including the roles of therapeutic drug monitoring and newer kidney injury biomarkers.

Assessment of kidney function in children by enzymatic determination of 2- or 24-h creatinine clearance: comparison with inulin clearance

BACKGROUND

Although renal inulin clearance (Cin) is the gold standard for evaluation of kidney function, it cannot be measured easily. Therefore, creatinine clearance (Ccr) is often used clinically to evaluate kidney function. Enzymatically measured Ccr was recently found to be much higher than Cin because of the tubular secretion of creatinine (Cr). This study compared three measures of renal clearance, inulin, 2-h Ccr, and 24-h Ccr, in children.

METHODS

Kidney function was evaluated in 76 children (51 males and 25 females) aged 1 month to 18 years with chronic kidney disease (CKD) by three renal clearance methods at almost the same time.

RESULTS

Correlations between each pair of three renal clearance measurements were determined. Approximate glomerular filtration rate (GFR) was equal to 62 % of 2-h Ccr or 76 % of 24-h Ccr.

CONCLUSION

Cr secretion by renal tubules was approximately 50 % of the GFR. In this study, we indicate that the measurements of 2-h Ccr or 24-h Ccr do not show true GFR but we could infer approximate GFR from the values. The use of 2- or 24-h Ccr might contribute to the treatment of pediatric CKD patients.

The impact of small kidneys

BACKGROUND

Small kidneys due to renal hypodysplasia (RHD) result from a decrease in nephron number. The objectives of this study were to identify clinical variables that determine long-term renal outcome in children with RHD and to define the role of kidney size as a predictor of developing end-stage renal disease (ESRD).

METHODS

This was a single-center retrospective cohort analysis. The primary outcome was development of ESRD. We identified 202 RHD cases, with 25 (12%) reaching ESRD at mean age of 8.9 (±6.6) years.

RESULTS

Children with RHD with a known genetic syndrome had the smallest kidneys while those with posterior urethral valves (PUV) had the largest kidneys at diagnosis. Cases with bilateral RHD were most likely to develop ESRD. Younger gestational age (OR 0.8, CI 0.69-0.99, p = 0.05), smaller kidney size at diagnosis (OR 0.13, CI 0.03-0.47, p = 0.002), lower best-estimated glomerular filtration rate (eGFR) (OR 0.74, CI 0.58-0.93, p = 0.01), proteinuria (OR 1.03, CI 1.01-1.05, p < 0.001) and high blood pressure (OR 1.02, CI 1.01-1.04, p = 0.01) were associated with development of ESRD, while kidney size at diagnosis was independently associated with ESRD (HR 0.03, CI 0.01-0.72, p = 0.043).

CONCLUSIONS

In children with RHD, kidney size at diagnosis predicts the likelihood of developing ESRD.

Treatment of methylmalonic acidemia by liver or combined liver-kidney transplantation

OBJECTIVE

To assess biochemical, surgical, and long-term outcomes of liver (LT) or liver-kidney transplantation (LKT) for severe, early-onset methylmalonic acidemia/acid (MMA).

STUDY DESIGN

A retrospective chart review (December 1997 to May 2012) of patients with MMA who underwent LT or LKT at Lucile Packard Children's Hospital at Stanford.

RESULTS

Fourteen patients underwent LT (n = 6) or LKT (n = 8) at mean age 8.2 years (range 0.8-20.7). Eleven (79%) were diagnosed during the neonatal period, including 6 by newborn screening. All underwent deceased donor transplantation; 12 (86%) received a whole liver graft. Postoperative survival was 100%. At a mean follow-up of 3.25 ± 4.2 years, patient survival was 100%, liver allograft survival 93%, and kidney allograft survival 100%. One patient underwent liver re-transplantation because of hepatic artery thrombosis. After transplantation, there were no episodes of hyperammonemia, acidosis, or metabolic decompensation. The mean serum MMA at the time of transplantation was 1648 ± 1492 μmol/L (normal <0.3, range 99-4420). By 3 days, post-transplantation levels fell on average by 87% (mean 210 ± 154 μmol/L), and at 4 months, they were 83% below pre-transplantation levels (mean 305 ± 108 μmol/L). Developmental delay was present in 12 patients (86%) before transplantation. All patients maintained neurodevelopmental abilities or exhibited improvements in motor skills, learning abilities, and social functioning.

CONCLUSIONS

LT or LKT for MMA eradicates episodes of hyperammonemia, results in excellent long-term survival, and suggests stabilization of neurocognitive development. Long-term follow-up is underway to evaluate whether patients who undergo early LT need kidney transplantation later in life.

Open-Label Study To Evaluate the Single-Dose Pharmacokinetics, Safety, and Tolerability of Doripenem in Infants Less than 12 Weeks in Chronological Age

Doripenem, a parenteral carbapenem with broad-spectrum activity against aerobic Gram-negative and Gram-positive and anaerobic pathogens, is currently approved for use in adults in the United States and European Union. Single-dose doripenem pharmacokinetics in 52 infants <12 weeks in chronological age were investigated in this phase 1 study. Hospitalized, medically stable infants <12 weeks in chronological age were stratified into 6 groups based on chronological and gestational age designed to reflect increasing renal maturation and decreasing volume of distribution (Vz) for β-lactam antimicrobials during the first 3 months of life. Subjects received single-dose doripenem (5 mg/kg of body weight for <8 weeks and 8 mg/kg for ≥8 weeks in chronological age) administered intravenously over 1 h. Plasma samples were obtained immediately before the end of the infusion and 1.5, 3, and 7 h after the start of the infusion. Urine was obtained by indwelling catheter during the 8 h following infusion. Doripenem showed linear pharmacokinetics across the 6 age groups. Neonates (<4 weeks in chronological age) had increased mean exposure (area under the plasma concentration-time curve from time zero to infinite time [AUC∞], 45.7 versus 32.4 μg · h/ml), longer elimination half-life (2.98 versus 1.79 h), and lower clearance (2.03 versus 3.03 ml/min/kg) compared with infants >4 weeks. Mean Vz was highest in subjects with the earliest gestational age (<32 weeks): 0.564 liter/kg for neonates and 0.548 liter/kg for infants. Single-dose pharmacokinetics of doripenem administered as a 1-hour infusion in term and preterm infants <12 weeks in chronological age were similar to what has been observed in neonates and very young infants with other carbapenems. Single-dose doripenem was generally safe and well tolerated. (This study has been registered with ClinicalTrials.gov under registration no. NCT01381848 and with EudraCT under registration no. 2009-014387-20.).

Population pharmacokinetics of valganciclovir prophylaxis in paediatric and adult solid organ transplant recipients

AIM

Our aims were to quantify ganciclovir pharmacokinetics in paediatric and adult kidney, liver and lung transplant patients taking a range of valganciclovir doses to prevent herpes virus infections, including a 450 mg regimen, and to identify sources of pharmacokinetic variability.

METHOD

Plasma samples were collected at 2, 4, 8 and 12 weeks post-transplant and at 4, 6, 8 and 12 months post-transplant in subjects prescribed longer courses. Ganciclovir was measured by liquid chromatography/ultraviolet detection. Non-linear mixed effects modelling was used to analyze the concentration-time data and evaluate demographic and transplant-related covariates.

RESULTS

A two compartment model with first order absorption best described the data. Given the range of body sizes, clearance and volume of distribution terms were scaled using standard weight-based allometric exponents. Creatinine clearance was included on apparent oral clearance. Final estimates in a standard 70 kg individual for apparent oral clearance, central volume of distribution, intercompartmental clearance and peripheral volume of distribution were 14.5 l h(-1) , 87.5 l, 4.80 l h(-1) and 42.6 l, respectively. The median terminal half-life for kidney, liver and lung transplant recipients was 9.4, 9.5 and 8.2 h, respectively. Median exposure (i.e. AUC(0,∞) in subjects taking valganciclovir 900 mg or 450 mg once daily was 57.4 and 34.3 μg ml(-1)  h, respectively.

CONCLUSION

Allometric scaling allowed simultaneous analysis of data from children and adults. Ganciclovir pharmacokinetics were similar among kidney, liver and lung transplant recipients. Ganciclovir exposure after valganciclovir 450 mg once daily may be suboptimal in some individuals and requires evaluation along with virologic outcomes data.

Renal replacement therapy in children

Acute kidney injury (AKI) affects 3.9/1000 at-risk children in the United States, a number that has been increasing as critically ill and injured children have access to improved care and the diagnosis of AKI is being made more accurately. Children with AKI have a higher mortality and hospital length of stay as compared to children without AKI. Renal replacement therapy can improve outcomes in these patients. This article reviews the pathophysiology of AKI and the modalities, indications, and outcomes of renal replacement for children with AKI.

Clinical pharmacokinetics and pharmacodynamics of ganciclovir and valganciclovir in children with cytomegalovirus infection

INTRODUCTION

Among infants and immunocompromised children cytomegalovirus (CMV) is associated with significant morbidity and mortality.

AREAS COVERED

This review describes the clinical pharmacokinetics and pharmacodynamics of ganciclovir and valganciclovir for the treatment and prevention of CMV infection in children.

EXPERT OPINION

A 24-h ganciclovir area under the concentration versus time curve (AUC₀₋₂₄) of 40 - 60 μg h/ml decreased the risk of CMV infection for adults undergoing CMV prophylaxis. For adults undergoing treatment for active CMV disease, a target AUC₀₋₁₂ of 40 - 60 μg h/ml has been suggested. The applicability of these targets to children remains uncertain; however, with the most sophisticated dosing regimens developed to date only 21% of patients are predicted to reach these targets. Moving forward, identification of optimal pediatric ganciclovir and valganciclovir dosing regimens may involve the use of an externally validated pediatric population pharmacokinetic model for empirical dosing, an optimal sampling strategy for collecting a minimal number of blood samples for each patient and Bayesian updating of the dosing regimen based on an individual patient's pharmacokinetic profile.

Factors Associated With Acute Kidney Injury in Children Receiving Vancomycin

Background: As higher vancomycin doses have been used in children, concern for acute kidney injury (AKI) has increased. Data describing factors associated with AKI, particularly dose-related factors, are limited. Objective: To determine the incidence of AKI in children receiving intravenous vancomycin and to identify factors associated with increased odds of AKI. Methods: A retrospective review of patients admitted to a tertiary academic pediatric hospital from February 2009 to September 2010 was performed. Patients 3 months to <19 years old with normal kidney function, receiving vancomycin for at least 48 hours were included. Incidence of AKI was assessed as defined by the Pediatric-Modified RIFLE criteria. Patients with and without AKI were compared to determine factors associated with increased odds of AKI, focusing on vancomycin dose. Results: Of 175 patients included, 24 (13.7%) met AKI criteria. In a multivariate regression, likelihood of AKI increased with each 5 mg/kg increase in vancomycin dose (odds ratio [OR] = 1.16; 95% CI = 1.01-1.33). Odds of AKI increased with each additional day of therapy (OR = 1.11; 95% CI = 1.01-1.22) and use of concomitant nephrotoxic medications (OR = 5.02; 95% CI = 1.09-23.19). The study was limited by small sample size and retrospective design. Conclusions: AKI was common in children receiving vancomycin. Higher doses of vancomycin were associated with increased odds of AKI. The risks and benefits of higher vancomycin dosing should be considered for each patient. Patients should be monitored closely for AKI, especially with higher doses, extended durations of therapy, or concomitant use of nephrotoxic medications.

Prevalence and outcomes of acute kidney injury in term neonates with perinatal asphyxia

BACKGROUND

The kidney is the most damaged organ in asphyxiated full-term infants. The severity of its damage is correlated with the severity of neurological damage. We determined the prevalence of perinatal asphyxia-associated acute kidney injury (AKI).

METHODS

We conducted a prospective cohort study including 60 full-term neonates admitted at the Kenyatta National Hospital newborn unit (NBU) in Nairobi with hypoxic ischaemic encephalopathy (HIE) from June 2012 to November 2012. Renal function was assessed by measuring serum creatinine on day 3 of life. AKI was defined by a level of creatinine above 133 µmol/l. The degree of neurological impairment was determined daily until patient discharge, death or day 7 of life.

RESULTS

Of the 60 infants 36.6% had HIE I, 51.6% HIE II and 11.8% HIE III. The prevalence of AKI was 11.7 %. There was a 15 fold increase risk of developing AKI in HIE III versus HIE I, p=0.034. Mortality rate in perinatal asphyxia associated AKI was 71.4 % with a 24 fold increase risk of death in neonates with AKI, p=0.001.

CONCLUSIONS

AKI is common and associated with poorer outcomes in perinatal asphyxia. Larger studies need to be done to correlate maternal factors and perinatal asphyxia-associated AKI.

A novel treatment regimen for BK viremia

BACKGROUND

BK viremia, a prerequisite for BK virus nephropathy (BKVN), affects 5% to 16% of pediatric renal transplant recipients (PRTR). We evaluated the safety and efficacy of a novel approach to treating BK viremia using fluoroquinolones and leflunomide in PRTR.

METHODS

We studied 230 PRTR at Mattel Children's Hospital, UCLA, who underwent renal transplantation between January 2003 and October 2010. Nineteen patients were found to have BK viremia. Ciprofloxacin was started when the BK viral load was greater than 625 copies/mL, and patients were switched to leflunomide if BK viral load did not decrease after 2 months of ciprofloxacin therapy. All patients underwent transplant kidney biopsy, and their estimated glomerular filtration rate (eGFR) and BK PCR was measured serially. The side effects of ciprofloxacin and leflunomide were recorded in each patient.

RESULTS

There was a significant decrease in BK viral load in patients treated with ciprofloxacin and leflunomide (P<0.001) with only a small reduction in immunosuppression. BK viremia was associated with a significantly decreased eGFR (P<0.001), and treatment with ciprofloxacin and leflunomide was associated with improved eGFR (P<0.001). This approach resulted in a BKVN rate of only 1%.

CONCLUSIONS

This analysis demonstrates for the first time that, used in a stepwise fashion, ciprofloxacin and leflunomide are effective and safe treatments for BK viremia in PRTR.

IgA nephropathy with minimal change disease

BACKGROUND AND OBJECTIVES

Patients with IgA nephropathy typically present with hematuria and subnephrotic proteinuria. Nephrotic syndrome is uncommon in IgA nephropathy, and when present, it is usually associated with severe histologic features, such as endocapillary proliferation, segmental sclerosis, and crescent formation. Rarely, patients with IgA nephropathy present with nephrotic syndrome and only mild mesangial disease. This study sought to better characterize these patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A retrospective review of cases of IgA nephropathy diagnosed from 2004 to 2011 identified patients with nephrotic range proteinuria and histologically mild IgA nephropathy. Specifically, using the Oxford Classification of IgA Nephropathy, we identified cases that lacked endocapillary proliferation or segmental sclerosis.

RESULTS

The cohort consisted of 17 patients, including 10 men and 15 adults. The median serum creatinine was 0.9 mg/dl (range=0.7-3.1), median 24-hour urine protein was 8.0 g/d (3.0-18.0 g), and 14 patients were fully nephrotic, whereas the remaining 3 patients fulfilled two of three criteria for nephrotic syndrome. Biopsies revealed IgA-dominant or codominant deposits accompanied by mesangial proliferation in 14 patients (82.4%). Electron microscopy showed mesangial deposits and extensive foot process effacement (median=90%). Initial treatment consisted of corticosteroids, although many patients required additional agents to maintain remission status. Over a median follow-up of 20 months (2.2-82 months), 14 patients experienced a complete response, and 3 patients showed a partial response, with a median response time of 2 months (0.5-27 months). At least one relapse of nephrotic syndrome occurred in nine patients (53%). All patients exhibited stable or improved renal function over the follow-up period.

CONCLUSIONS

The findings in this cohort and previous studies suggest that rare cases of mild IgA nephropathy with nephrotic range proteinuria exhibit a clinical presentation, biopsy findings, treatment response, and outcome more typical of IgA nephropathy with superimposed minimal change disease. This study favors the view that such cases represent a dual glomerulopathy.

Lowe syndrome: a single center's experience in Korea

Purpose

Lowe syndrome is a rare, X-linked recessive disorder caused by mutations in the OCRL gene. It involves multiple anatomic systems, particularly the eyes, central nervous system, and kidneys, and leads to profound growth failure and global developmental delay. This study evaluated the clinical and genetic characteristics of Korean patients with Lowe syndrome.

Methods

The clinical findings and results of genetic studies were reviewed for 12 male patients diagnosed with Lowe syndrome at a single medical institution.

Results

The mean age of the patients at presentation was 2.2 months (range, 0-4 months), although the diagnosis was delayed by a mean of 2.8 years (range, 0-9.7 years). The mean follow-up period was 9.0 years (range, 0.6-16.7 years). Nine mutations in OCRL were identified in 11 patients (92%), with three novel mutations. The main presentation was congenital cataract in both eyes necessitating early cataract removal in the 11 patients with impaired visual acuity. Profound short stature and developmental delay were observed in all patients, and seizures occurred in 50% of the patients. All patients suffered from proximal renal tubular dysfunction, and one patient developed chronic renal failure. Other manifestations included pathologic fracture (50%), cutaneous cysts (42%), and cryptorchidism (42%). However, there was no bleeding tendency, and none of the patients died during the study period.

Conclusion

This study describes the clinical and genetic characteristics of Korean patients with Lowe syndrome. The observations are helpful for understanding the natural courses of Lowe syndrome and for appropriate genetic counseling.

New algorithm for valganciclovir dosing in pediatric solid organ transplant recipients

CMV infections are common after SOT. v-GCV is increasingly used in children. The aim of this study was to evaluate presently used dosing algorithms. Data from 104 pediatric SOT recipients (kidney, liver, and heart) aged 0.3-16.9 yr and receiving v-GCV once a day were used for model development and validation with the Pmetrics package for R. Monte Carlo simulations were performed to compare the probability of a GCV AUC 40-60 mg*h/L with the different algorithms across a range of ages, weights, and GFRs. GCV pharmacokinetics was well described by the non-parametric model. Clearance was dependent on GFR and Cockcroft-Gault estimates improved the model fit over Schwartz. Simulations showed that our new algorithm, where v-GCV dose is: Weight [kg]*(0.07*GFR [mL/min]+k), where k = 5 for GFR ≤ 30 mL/min, k = 10 for GFR > 30 mL/min and weight > 30 kg and k = 15 for GFR > 30 mL/min and weight ≤ 30 kg, outperformed the other algorithms. Thirty-three percent of all patients achieve an exposure above and 21% within the therapeutic window. We propose a simple algorithm for initial v-GCV dosing that standardizes plasma drug exposure better than current algorithms. Subsequent TDM is strongly suggested to achieve individual drug levels within the therapeutic window.

Cystatin C-based equation for estimating glomerular filtration rate in Japanese children and adolescents

BACKGROUND

Renal inulin clearance is the gold standard for evaluation of kidney function, but is compromised by problems of collecting urine samples in children, especially those <6 years or with a bladder dysfunction. Therefore, we should utilize the serum cystatin C (cysC)-based estimated glomerular filtration rate (eGFR) for measuring serum cysC. The purpose of the present study is to determine the applicability of the new serum cysC-based eGFR in Japanese children and adolescents, including infants with chronic kidney disease (CKD), for evaluation of renal function.

METHODS

Inulin clearance and standardized serum cysC level determined by the colloidal gold immunoassay were measured in 135 pediatric CKD patients between the ages of 1 month and 18 years with no underlying disease that affects renal function except CKD, to determine serum cysC-based eGFR in Japanese children and adolescents.

RESULTS

We showed the inulin clearance by expression of 1/serum cysC in pediatric CKD patients, which resulted in the equation: inulin GFR (mL/min/1.73 m(2)) = 104.1 × 1/serum cysC (mg/L) - 7.80. We also validated the cysC-based eGFR formula for Japanese adults. eGFR values obtained with the adult formula significantly underestimated GFR by approximately 8 % in children with CKD.

CONCLUSION

We determined the new cysC-based eGFR formula is useful for clinical screening of renal function in Japanese children and adolescents, including infants.

Cystatin C-based equation for estimating glomerular filtration rate in Japanese children and adolescents

BACKGROUND

Renal inulin clearance is the gold standard for evaluation of kidney function, but is compromised by problems of collecting urine samples in children, especially those <6 years or with a bladder dysfunction. Therefore, we should utilize the serum cystatin C (cysC)-based estimated glomerular filtration rate (eGFR) for measuring serum cysC. The purpose of the present study is to determine the applicability of the new serum cysC-based eGFR in Japanese children and adolescents, including infants with chronic kidney disease (CKD), for evaluation of renal function.

METHODS

Inulin clearance and standardized serum cysC level determined by the colloidal gold immunoassay were measured in 135 pediatric CKD patients between the ages of 1 month and 18 years with no underlying disease that affects renal function except CKD, to determine serum cysC-based eGFR in Japanese children and adolescents.

RESULTS

We showed the inulin clearance by expression of 1/serum cysC in pediatric CKD patients, which resulted in the equation: inulin GFR (mL/min/1.73 m(2)) = 104.1 × 1/serum cysC (mg/L) - 7.80. We also validated the cysC-based eGFR formula for Japanese adults. eGFR values obtained with the adult formula significantly underestimated GFR by approximately 8 % in children with CKD.

CONCLUSION

We determined the new cysC-based eGFR formula is useful for clinical screening of renal function in Japanese children and adolescents, including infants.

Assessment of renal function; clearance, the renal microcirculation, renal blood flow, and metabolic balance

Historically, tools to assess renal function have been developed to investigate the physiology of the kidney in an experimental setting, and certain of these techniques have utility in evaluating renal function in the clinical setting. The following work will survey a spectrum of these tools, their applications and limitations in four general sections. The first is clearance, including evaluation of exogenous and endogenous markers for determining glomerular filtration rate, the adaptation of estimated glomerular filtration rate in the clinical arena, and additional clearance techniques to assess various other parameters of renal function. The second section deals with in vivo and in vitro approaches to the study of the renal microvasculature. This section surveys a number of experimental techniques including corticotomy, the hydronephrotic kidney, vascular casting, intravital charge coupled device videomicroscopy, multiphoton fluorescent microscopy, synchrotron-based angiography, laser speckle contrast imaging, isolated renal microvessels, and the perfused juxtamedullary nephron microvasculature. The third section addresses in vivo and in vitro approaches to the study of renal blood flow. These include ultrasonic flowmetry, laser-Doppler flowmetry, magnetic resonance imaging (MRI), phase contrast MRI, cine phase contrast MRI, dynamic contrast-enhanced MRI, blood oxygen level dependent MRI, arterial spin labeling MRI, x-ray computed tomography, and positron emission tomography. The final section addresses the methodologies of metabolic balance studies. These are described for humans, large experimental animals as well as for rodents. Overall, the various in vitro and in vivo topics and applications to evaluate renal function should provide a guide for the investigator or physician to understand and to implement the techniques in the laboratory or clinic setting.

A pilot study of urinary fibroblast growth factor-2 and epithelial growth factor as potential biomarkers of acute kidney injury in critically ill children

BACKGROUND

Acute kidney injury (AKI) increases the morbidity of critically ill children. Thus, it is necessary to identify better renal biomarkers to follow the outcome of these patients. This prospective case-control study explored the clinical value of a urinary biomarker profile comprised of neutrophil gelatinase lipocalin (uNGAL), fibroblast growth factor-2 (uFGF-2), and epidermal growth factor (uEGF) to follow these patients.

METHODS

Urine samples were collected from 21 healthy children, and 39 critically ill children (mean age 7.5 years ± 6.97 SD) admitted to a pediatric intensive care unit with sepsis or requiring extra corporeal membrane oxygenation (ECMO). uNGAL, uFGF-2, and uEGF levels were measured using ELISA kits during the first 24 h of admission to PICU, at peak of illness, and upon resolution of the critical illness.

RESULTS

On admission, the uNGAL and uFGF-2 levels were increased, and the uEGF levels were decreased, in critically ill children with AKI (n = 19) compared to those without AKI (n = 20), and healthy controls. A biomarker score using the combined cut-off values of uNGAL, uFGF-2, and uEGF (AUC = 0.90) showed the highest specificity to identify children with AKI, relative to each biomarker alone. uNGAL and uFGF-2 on admission showed high sensitivity and specificity to predict mortality (AUC = 0.82).

CONCLUSIONS

The biomarker profile comprised of uNGAL, uFGF-2, and uEGF increased the specificity to detect AKI in critically ill children, when compared to each biomarker used alone. uNGAL and uFGF-2 may also predict the risk of death. Further validation of these findings in a large sample size is warranted.

A novel urinary biomarker profile to identify acute kidney injury (AKI) in critically ill neonates: a pilot study

BACKGROUND

The goal of this study was to assess the value of a urinary biomarker profile comprised of neutrophil gelatinase-associated lipocalin (NGAL), fibroblast growth factor-2 (FGF-2), and epidermal growth factor (EGF), to detect acute kidney injury (AKI) in critically ill neonates.

METHODS

We conducted a prospective cohort pilot study of at-risk neonates treated in a level IIIC neonatal intensive care unit (NICU) with therapeutic hypothermia (HT) (n = 25) or extracorporeal membrane oxygenation (ECMO) (n = 10). Urine was collected at baseline, 48 h of illness, and > 24 h post-recovery of their corresponding treatments. Control samples were collected from 27 healthy newborns. The data were expressed as urinary concentrations and values normalized for urinary creatinine. AKI was defined as the presence of oliguria >24 h and/or elevated serum creatinine (SCr), or the failure to improve the estimated creatinine clearance (eCCL) by >50% post-recovery. Non-parametric statistical tests and ROC analyses were used to interpret the data.

RESULTS

Fifteen at-risk newborns had AKI. In the first 48 h of illness, the urinary levels of NGAL and FGF-2 had high sensitivity but poor specificity to identify neonates with AKI. At recovery, low urinary EGF levels identified neonates with AKI with a sensitivity of 74% and specificity of 84%. Overall, in the early stages of a critical illness, the urinary levels of NGAL and FGF-2 were sensitive, but not specific, to identify neonates at risk of AKI. Low EGF levels post-recovery identified critically ill neonates with AKI.

CONCLUSIONS

These findings require validation in larger prospective studies.

Early initiation of peritoneal dialysis in neonates and infants with acute kidney injury following cardiac surgery is associated with a significant decrease in mortality

Association between early renal replacement therapy and better survival has been reported in adults with postoperative kidney injury, but not in children undergoing cardiac surgery. We conducted a retrospective cohort study of 146 neonates and infants requiring peritoneal dialysis following cardiac surgery in a tertiary referral hospital. A propensity score was used to limit selection bias due to timing of dialysis, and included baseline and intraoperative characteristics, requirement for postoperative extracorporeal membrane oxygenation, and creatinine clearance variation. Inverse probability of treatment weighting resulted in good balance between groups for all baseline and intraoperative variables. After weighting, 30-day and 90-day mortality were compared between the 109 patients placed on dialysis early, within the first day of surgery, and those with delayed dialysis, commencing on the second day of surgery or later, using logistic regression and survival analysis. Mortality was 28.1% at 30 days, and was 36.3% during follow-up. Early dialysis was associated with a 46.7% decrease in the 30-day and a 43.5% decrease in the 90-day mortality rate when compared with delayed dialysis. All other short-term outcome variables were similar. Thus, initiation of peritoneal dialysis on the day of or the first day following surgery was associated with a significant decrease in mortality in neonates and infants with acute kidney injury.

Population pharmacokinetics of tobramycin in patients with and without cystic fibrosis

BACKGROUND AND OBJECTIVES

While several studies have examined the pharmacokinetics of tobramycin in patients with cystic fibrosis (CF), there is no consensus on whether they differ in patients with and without CF. The objectives of this study were to identify covariates which explain pharmacokinetic variability and to examine whether having the disease CF in itself alters these relationships and drug dose requirements.

METHODS

To investigate this issue, a population pharmacokinetic meta-analysis of data from eight centres was undertaken. NONMEM(®) 7.2 was used to analyse the data, which comprised 4,514 concentration-time measurements from 465 adults and children with CF and 1,095 concentration-time measurements from 267 adults and children without CF.

RESULTS

Tobramycin disposition was well described by a two-compartment model with first-order elimination. Patient age, fat-free mass, serum creatinine concentration and sex were identified as significant covariates in the final model. Fat-free mass was superior to total bodyweight as a descriptor of clearance, volume of distribution of the central and peripheral compartments and inter-compartmental clearance. CF as an independent disease-specific factor had no significant influence on the pharmacokinetics of tobramycin at any stage during covariate model building. An optimal dose of 11 mg/kg every 24 h was defined for CF patients using a utility function approach.

CONCLUSION

The pharmacokinetics of tobramycin do not differ significantly in CF patients compared with patients without CF when subject age, fat-free mass, sex and renal function are taken into consideration. Variations in tobramycin dosing between CF and non-CF patients should therefore reflect target concentrations or exposures based on differences in expected pathogen sensitivity and not the presence of CF.

Postasphyxial renal injury in newborns as a prognostic factor of neurological outcome

OBJECTIVE

To estimate if an acute postasphyxial renal injury in newborns could indicate a neurological outcome.

METHODS

We conducted a prospective clinical trial on 50 full-term newborns with 5-minute Apgar score <7 (asphyxiated group) and a control group of 50 full-term newborns with 5-min Apgar score ≥ 7 (non-asphyxiated group). Renal function was assessed on the third day of life by serum values of creatinine, cystatin C and β2-microglobulin (β2M) and glomerular filtration rate (GFR). All newborns had brain and renal ultrasonography at early stages and were followed by Amiel-Tison Neurological Assassment (ATNA) throughout the first year of life.

RESULTS

Mean GFR was significantly lower in asphyxiated than in non-asphyxiated group (22.08 ± 6.66 ml/min/1, 73 m(2) versus 35.42 ± 2.26 ml/min/1, 73 m(2); p < 0.001) and serum values of creatinine, cystatin C and β2M were significantly higher (1.13 versus 0.66 mg/dl; 3.92 versus 1.52 mg/l; 1.53 versus 0.99 mg/l; p < 0.001). In asphyxiated group ATNA results throughout the first year of life significantly correlated with renal function (p < 0.01). A correlation of ATNA with Apgar score at 5 min, Sarnat and Sarnat staging of hypoxic ischemic encephalopathy and brain and renal ultrasonography has also been significant (p < 0.01).

CONCLUSIONS

Our study showed a significant correlation between early impairment of renal function due to neonatal asphyxia with neurological outcome at the end of the first year of life.

Nonsteroidal anti-inflammatory drugs are an important cause of acute kidney injury in children

OBJECTIVE

To characterize nonsteroidal anti-inflammatory drug (NSAID)-associated acute kidney injury (AKI) in children.

STUDY DESIGN

We conducted a retrospective chart review of children diagnosed with AKI through the use of International Classification of Diseases, Ninth Revision diagnosis code 584.5 or 584.9 from January 1999 to June 2010. Medical records were reviewed to confirm the diagnosis of AKI and to quantify NSAID administration. Pediatric RIFLE criteria were used to codify AKI. Patients were not classified as having NSAID-associated AKI if they had a diagnosis explaining AKI or comorbid clinical conditions predisposing to AKI development.

RESULTS

Patients (N=1015) were identified through International Classification of Diseases, Ninth Revision screening. Twenty-one children had clinical, laboratory, and radiographic studies suggesting NSAID-associated acute tubular necrosis and 6 had findings suggesting NSAID-associated acute interstitial nephritis, representing 2.7% (27 of 1015) of the total cohort with AKI and 6.6% when excluding complex patients with multifactorial AKI. Children with NSAID-associated AKI had a median (range) age of 14.7 years (0.5-17.7 years); 4 patients (15%) were <5 years old. Fifteen of 20 children (75%) for whom dosing data were available received NSAIDs within recommended dosing limits. Patients<5 years old were more likely to require dialysis (100% vs 0%, P<.001), intensive care unit admission (75% vs 9%, P=.013), and a longer length of stay (median 10 vs 7 days, P=.037).

CONCLUSIONS

NSAID-associated AKI accounted for 2.7% of AKI in this pediatric population. AKI typically occurred after the administration of correctly dosed NSAIDs. Young children with NSAID-associated AKI may have increased disease severity.

De novo therapy with everolimus and reduced-exposure cyclosporine following pediatric kidney transplantation: a prospective, multicenter, 12-month study

Prospective data regarding the de novo use of everolimus following kidney transplantation in children are sparse. In a prospective, 12-month, single-arm, open-label study, pediatric kidney transplant patients received everolimus (target trough concentration ≥3 ng/mL) with reduced-exposure CsA and corticosteroids, with or without basiliximab induction. Sixteen of the 18 patients completed the study on-treatment. Age range was 2-16 yr (mean 10.9 yr); eight patients received a living donor graft. Mean (s.d.) everolimus level was 7.4 (3.1) ng/mL during the first 12 months post-transplant. There were no cases of BPAR, graft loss, or death during the study. Protocol biopsies were performed at month 12 in seven patients, with subclinical (untreated) acute rejection diagnosed in one case. Mean (s.d.) estimated GFR (Schwartz formula) was 98 (34) mL/min/1.73 m(2) at month 12. Three patients experienced one or more serious adverse events with a suspected relation to study medication. One patient discontinued study medication due to post-transplant lymphoproliferative disease (5.6%). Everolimus with reduced-dose CsA and corticosteroids achieved good efficacy and renal function and was well tolerated in this small cohort of pediatric kidney transplant patients. Controlled trials are required to answer remaining questions about the optimal use of everolimus in this setting.

Reference intervals of serum cystatin C for determining cystatin C-based glomerular filtration rates in preterm neonates

OBJECTIVE

The aim of this study is to determine the reference values of serum Cystatin C (CysC) and CysC-based estimated glomerular filtration rate (GFR) on the 3rd and 30th day of life in comparison with serum creatinine (Cr) and Cr-based estimated GFR.

METHODS

This prospective study was performed on 52 preterm neonates whose gestational ages were between 28 and 34 weeks. Preterm neonates were divided into three groups according to the gestational age as follows: gestational week of 28-29 (group 1), gestational week of 30-32 (group 2) and gestational week of 33-34 (group 3). Blood samples were obtained on the 3rd and the 30th days of life. CysC was determined by particle-enhanced nephelometric immunoassay.

RESULTS

The group 1 preterm neonates have higher CysC values (1.34 ± 0.1 mg/L) on the 3rd day of life than the group 2 (1.28 ± 0.2 mg/L) and the group 3 (1.24 ± 0.2 mg/L) but the differences were not significant (p > 0.05, for each). CysC values were independent of gestational age, birth weight and gender (p > 0.05, for each). No correlation was found between CysC and Cr on the 3rd day of life (p > 0.05).

CONCLUSIONS

CysC is regarded as an alternative for assessing the renal function in preterm neonates.

Creatinine-based equations to estimate glomerular filtration rate in Japanese children aged between 2 and 11 years old with chronic kidney disease

BACKGROUND

Renal inulin clearance is the gold standard for glomerular filtration rate (GFR), but is compromised by problems of collecting urine samples in children, especially those <6 years of age or with a bladder dysfunction. Therefore, we should utilize the serum creatinine (Cr)-based estimated GFR (eGFR), measuring serum Cr by enzymatic method. The updated Schwartz formulae were reported by enzymatic Cr instead of by the Jaffe method in American children aged 1-16 years old. We believe it would be better to determine serum Cr-based eGFR by the enzymatic method in Japanese children for evaluation of renal function.

METHODS

Serum Cr-based eGFR was determined by measuring inulin clearance and serum Cr level in 76 pediatric chronic kidney disease (CKD) patients (49 males and 27 females) aged 2-11 years with no underlying disease that would affect renal function.

RESULTS

We showed the inulin clearance by expression of the body length/serum Cr ratio in pediatric CKD patients, which resulted in the equation: [Formula: see text]. Additionally, we suggest the following serum Cr-based eGFR formula passing through the origin: [Formula: see text], because it is simple and easy to remember, thus making it clinically useful.

CONCLUSION

The new eGFR formula derived from body length and serum Cr level is applicable for clinical screening of renal function in Asian as well as Japanese children aged between 2 and 11 years old.

Vancomycin serum concentrations in pediatric oncologic/hematologic intensive care patients

BACKGROUND

Usual treatment regimens with vancomycin often fail to provide adequate serum levels in patients with severe infections.

METHODS

Retrospective analysis of vancomycin trough serum measurements. The following parameters were calculated by Bayesian analysis: vancomycin clearance, distribution volume, and peak estimated concentrations. The area under the concentration curve (AUC) (total daily dose/24 h clearance of vancomycin) was used to determine the effectiveness of treatment through the ratio of AUC/minimum inhibitory concentration (MIC) above 400, using MIC=1 μg/mL, based on isolates of Staphylococci in cultures.

RESULTS

Sixty-one vancomycin trough measurements were analyzed in 31 patients. AUC/MIC>400 was obtained in 34 out of 61 dosages (55.7%), but the mean vancomycin dose required to achieve these levels was 81 mg/kg/day. In cases where the usual doses were administered (40-60 mg/kg/day), AUC/MIC>400 was obtained in nine out of 18 dosages (50%), in 13 patients. Trough serum concentrations above 15 mg/L presented a positive predictive value of 100% and a negative predictive value of 71% for AUC/MIC>400.

CONCLUSION

Higher than usual vancomycin doses may be required to treat staphylococcal infections in children with oncologic/hematologic diseases. Since the best known predictor of efficacy is the AUC/MIC ratio, serum trough concentrations must be analyzed in conjunction with MICs of prevalent Staphylococci and pharmacokinetic tools such as Bayesian analysis.

Pharmacokinetics of antibacterial agents in the CSF of children and adolescents

The adequate management of central nervous system (CNS) infections requires that antimicrobial agents penetrate the blood-brain barrier (BBB) and achieve concentrations in the CNS adequate for eradication of the infecting pathogen. This review details the currently available literature on the pharmacokinetics (PK) of antibacterials in the CNS of children. Clinical trials affirm that the physicochemical properties of a drug remain one of the most important factors dictating penetration of antimicrobial agents into the CNS, irrespective of the population being treated (i.e. small, lipophilic drugs with low protein binding exhibit the best translocation across the BBB). These same physicochemical characteristics determine the primary disposition pathways of the drug, and by extension the magnitude and duration of circulating drug concentrations in the plasma, a second major driving force behind achievable CNS drug concentrations. Notably, these disposition pathways can be expected to change during the normal process of growth and development. Finally, CNS drug penetration is influenced by the nature and extent of the infection (i.e. the presence of meningeal inflammation). Aminoglycosides have poor CNS penetration when administered intravenously. Intrathecal gentamicin has been studied in children with more promising results, often exceeding the minimum inhibitory concentration. There are very limited data with intrathecal tobramycin in children. However, in the few patients that have been studied, the CSF concentrations were highly variable. Penicillins generally have good CNS penetration. Aqueous penicillin G reaches greater concentrations than procaine or benzathine penicillin. Concentrations remain detectable for ≥ 12 h. Of the aminopenicillins, both ampicillin and parenteral amoxicillin reach adequate CNS concentrations; however, orally administered amoxicillin resulted in much lower concentrations. Nafcillin and piperacillin are the final two penicillins with pediatric data: their penetration is erratic at best. Cephalosporins vary greatly in regard to their CSF penetration. Few first- and second-generation cephalosporins are able to reach higher CSF concentrations. Cefuroxime is the only exception and is usually avoided due to its adverse effects and slower sterilization of the CSF than third-generation agents. Ceftriaxone, cefotaxime, ceftazidime, cefixime and cefepime have been studied in children and are all able to adequately penetrate the CSF. As with penicillins, concentrations are greatest in the presence of meningeal inflammation. Meropenem and imipenem are the only carbapenems with pediatric data. Imipenem reaches higher CSF concentrations; however, meropenem is preferred due to its lower incidence of seizures. Aztreonam has also demonstrated favorable penetration but only one study has been completed in children. Both chloramphenicol and sulfamethoxazole/trimethoprim (cotrimoxazole) penetrate into the CNS well; however, significant toxicities limit their use. The small size and minimal protein binding of fosfomycin contribute to its favorable CNS PK. Although rarely used, it achieves higher concentrations in the presence of inflammation and accumulation is possible. Linezolid reaches high CSF concentrations; however, more frequent dosing might be required in infants due to their increased elimination. Metronidazole also has very limited information but it demonstrated favorable results similar to adult data; CSF concentrations even exceeded plasma concentrations at certain time points. Rifampin (rifampicin) demonstrated good CNS penetration after oral administration. Vancomycin demonstrates poor CNS penetration after intravenous administration. When combined with intraventricular therapy, CNS concentrations are much greater. Of the antituberculosis agents, isoniazid, pyrazinamide and streptomycin have been studied in children. Isoniazid and pyrazinamide have favorable CSF penetration. Streptomycin appears to produce unpredictable CSF levels. No pediatric-specific data are available for clindamycin, daptomycin, macrolides, tetracyclines, and fluoroquinolones. Daptomycin, fluoroquinolones, and tetracyclines have demonstrated favorable CNS penetration in adults; however, data are limited due to their potential pediatric-specific toxicities and newness within the marketplace. Macrolides and clindamycin have demonstrated poor CNS penetration in adults and thus have not been studied in pediatrics.