Caffeine Exposure and Risk of Acute Kidney Injury in a Retrospective Cohort of Very Low Birth Weight Neonates

Caffeine and neonatal acute kidney injury

Acute kidney injury is one of the most threatening diseases in neonates, with complex pathogenesis and limited treatment options. Caffeine is a commonly used central nervous system stimulant for treating apnea in preterm infants. There is compelling evidence that caffeine may have potential benefits for preventing neonatal acute kidney injury, but comprehensive reports are lacking in this area. Hence, this review aims to provide a summary of clinical data on the potential benefits of caffeine in improving neonatal acute kidney injury. Additionally, it delves into the molecular mechanisms underlying caffeine's effects on acute kidney injury, with a focus on various aspects such as oxidative stress, adenosine receptors, mitochondrial dysfunction, endoplasmic reticulum stress, inflammasome, autophagy, p53, and gut microbiota. The ultimate goal of this review is to provide information for healthcare professionals regarding the link between caffeine and neonatal acute kidney injury and to identify gaps in our current understanding.

Population Pharmacokinetics of Caffeine in Neonates with Congenital Heart Disease and Associations with Acute Kidney Injury

Cardiac surgery-associated acute kidney injury (CS-AKI) occurs in approximately 65% of neonates undergoing cardiac surgery on cardiopulmonary bypass and contributes to morbidity and mortality. Caffeine may reduce CS-AKI by counteracting adenosine receptor upregulation after bypass, but pharmacokinetics (PK) in this population are unknown. The goal of our analysis is to address knowledge gaps in age-, disease-, and bypass-related effects on caffeine disposition and explore preliminary associations between caffeine exposure and CS-AKI using population PK modeling techniques and an opportunistic, electronic health record-integrated trial design. We prospectively enrolled neonates receiving preoperative caffeine per standard of care and collected PK samples. We retrospectively identified neonates without caffeine exposure undergoing surgery on bypass as a control cohort. We followed US Food and Drug Administration guidance for population PK model development using NONMEM. Effects of clinical covariates on PK parameters were evaluated. We simulated perioperative exposures and used multivariable logistic regression to evaluate the association between caffeine exposure and CS-AKI. Twenty-seven neonates were included in model development. A 1-compartment model with bypass time as a covariate on clearance and volume of distribution best fit the data. Twenty-three neonates with caffeine exposure and 109 controls were included in the exposure-response analysis. Over half of neonates developed CS-AKI. On multivariable analysis, there were no significant differences between CS-AKI with and without caffeine exposure. Neonates with single-ventricle heart disease without CS-AKI had consistently higher simulated caffeine exposures. Our results highlight areas for further study to better understand disease- and bypass-specific effects on drug disposition and identify populations where caffeine may be beneficial.

The Babyccino: The Role of Caffeine in the Prevention of Acute Kidney Injury in Neonates-A Literature Review

Acute kidney injury (AKI) in neonates is associated with increased morbidity and mortality. Theophylline (a methylxanthine) has been shown to prevent neonatal AKI but is seldom used due to its unfavorable profile. Caffeine, another methylxanthine, is utilized ubiquitously to treat apnea of prematurity, but there are no randomized trials evaluating its efficacy in preventing neonatal AKI. This literature review aims to summarize the existing research pertaining to the relationship between caffeine and neonatal AKI. The review was conducted using Pubmed, Embase, Google Scholar, and Cochrane. Inclusion criteria incorporated empirical studies, being published in English, and being available electronically. All eight studies identified were included. Seven studies found caffeine-exposed premature neonates had lower rates of AKI than caffeine-unexposed neonates. Four found reduced AKI severity with caffeine exposure. One study included term neonates and did not find a difference in the AKI rate between caffeine-exposed and non-exposed babies. Limitations include exclusively observational studies, short study periods, heterogenous definitions of prematurity, and a lack of assessment of dose-effect relationships. In conclusion, premature neonates exposed to caffeine appear to have lower rates and potentially less severe AKI. Further research is needed before caffeine can be considered for use in the primary prevention of neonatal AKI.

Early recognition and prevention of acute kidney injury in hospitalised children

Acute kidney injury is common in hospitalised children and is associated with poor patient outcomes. Once acute kidney injury occurs, effective therapies to improve patient outcomes or kidney recovery are scarce. Early identification of children at risk of acute kidney injury or at an early injury stage is essential to prevent progression and mitigate complications. Paediatric acute kidney injury is under-recognised by clinicians, which is a barrier to optimisation of inpatient care and follow-up. Acute kidney injury definitions rely on functional biomarkers (ie, serum creatinine and urine output) that are inadequate, since they do not account for biological variability, analytical issues, or physiological responses to volume depletion. Improved predictive tools and diagnostic biomarkers of kidney injury are needed for earlier detection. Novel strategies, including biomarker-guided care algorithms, machine-learning methods, and electronic alerts tied to clinical decision support tools, could improve paediatric acute kidney injury care. Clinical prediction models should be studied in different paediatric populations and acute kidney injury phenotypes. Research is needed to develop and test prevention strategies for acute kidney injury in hospitalised children, including care bundles and therapeutics.

Effects of photobiomodulation and caffeine treatment on acute kidney injury in a hypoxic ischemic neonatal rat model

Hypoxic ischemic encephalopathy (HIE) occurs in 2-5/1000 births, with acute kidney injury (AKI) occurring in 40%. AKI increases morbidity and mortality. Caffeine, an adenosine receptor antagonist, and photobiomodulation (PBM), working on cytochrome c oxidase, are potential treatments for AKI. To examine effects of caffeine and PBM on AKI in rats, Day 7 pups underwent a HIE intervention (Modified Rice-Vannucci model) replicating pathology observed in humans. Caffeine was administered for 3 days and/or PBM for 5 days following HIE. Weights and urine for biomarkers (NGAL, albumin, KIM-1, osteopontin) were collected prior to HIE, daily post intervention and at sacrifice. Both treatments reduced kidney injury seen on electron microscopy, but not when combined. HIE elevated urinary NGAL and albumin on Days 1-3 post-HIE, before returning to control levels. This elevation was significantly reduced by PBM or caffeine. KIM-1 was significantly elevated for 7 days post-HIE and was reduced by both treatments. Osteopontin was not altered by HIE or the treatments. Treatments, individually but not in combination, improved HIE-induced reductions in the enzymatic activity of mitochondrial complexes II-III. PBM and caffeine also improved weight gain. PBM and caffeine reduces AKI diagnosed by urinary biomarkers and confirmed by EM findings.

Neonatal acute kidney injury during indomethacin therapy: does it predict ductal closure?

BACKGROUND

Preterm newborns are at risk for patent ductus arteriosus, and non-steroidal anti-inflammatory drugs are often used to facilitate patent ductus arteriosus closure. Acute kidney injury is common in critically ill neonates and may be caused by non-steroidal anti-inflammatory drugs. We sought to describe the incidence of acute kidney injury among preterm infants receiving indomethacin and determine whether acute kidney injury during indomethacin therapy is associated with subsequent patent ductus arteriosus closure.

METHODS

Retrospective cohort including neonates < 33 weeks gestational age, admitted to two level IIIb neonatal intensive care units between November 2016 and November 2019, who received indomethacin in the first 2 weeks of life. Acute kidney injury in the 7-day period after treatment was defined by neonatal modified Kidney Disease Improving Global Outcomes (KDIGO) criteria. Patent ductus arteriosus closure was defined clinically and/or via echocardiogram. Clinical characteristics were extracted from medical records. Association between acute kidney injury during treatment and successful closure of patent ductus arteriosus was evaluated using chi-square tests and logistic regression.

RESULTS

One hundred fifty preterm infants were included; acute kidney injury occurred in 8% (all KDIGO Stage 1). Patent ductus arteriosus closed in 52.9% of the non-acute kidney injury group and 66.7% of the acute kidney injury group (p = 0.55). Serum creatinine was checked a mean of 3.1 times in the acute kidney injury group and 2.2 times in the non-acute kidney injury group. There was no difference in survival.

CONCLUSION

We found no association between acute kidney injury during indomethacin therapy and patent ductus arteriosus closure. Paucity of serum creatinine values likely underdiagnosed acute kidney injury. Surveillance of kidney function during indomethacin therapy using more sensitive renal biomarkers may better identify infants who develop acute kidney injury in the context of non-steroidal anti-inflammatory drug use.

Neonatal Acute Kidney Injury

Acute kidney injury (AKI) is a common occurrence in the neonatal intensive care unit (NICU). In recent years, our knowledge of the incidence and impact of neonatal AKI on outcomes has expanded exponentially. Neonatal AKI has been shown to be associated with adverse outcomes including increased length of mechanical ventilation, prolonged length of stay, and rise in mortality. There has also been increasing work suggesting that neonates with AKI are at higher risk of chronic kidney disease (CKD). In the past, AKI had been defined multiple ways. The utilization of the neonatal modified Kidney Disease: Improving Global Outcomes (KDIGO) criteria as the standard definition for neonatal AKI in research and clinical care has driven the advances in our understanding of neonatal AKI over the last 10 years. This definition has allowed researchers and clinicians to better understand the incidence, risk factors, and outcomes associated with neonatal AKI across populations through a multitude of single-center studies and the seminal, multicenter Assessment of Worldwide Acute Kidney Injury Epidemiology in Neonates (AWAKEN) study. As the impacts of neonatal AKI have become clear, a shift in efforts toward identifying those at highest risk, protocolizing AKI surveillance, improving prevention and diagnosis, and expanding kidney support therapy (KST) for neonates has occurred. These efforts also include improving risk stratification (identifying high risk populations, including those with nephrotoxic medication exposure) and diagnostics (novel biomarkers and diagnostic tools). Recent work has also shown that the targeted use of methylxanthines may prevent AKI in a variety of high-risk populations. One of the most exciting developments in neonatal AKI is the advancement in technology to provide KST to neonates with severe AKI. In this comprehensive review we will provide an overview of recent work and advances in the field of neonatal AKI. This will include a detailed review of (1) the definition of neonatal AKI, (2) the epidemiology, risk factors, and outcomes associated with neonatal AKI, (3) improvements in risk stratification and diagnostics, (4) mitigation and treatment, (5) advancements in the provision of KST to neonates, and (6) the incidence and risk of subsequent CKD.

Acute kidney injury in premature and low birth weight neonates: a systematic review and meta-analysis

BACKGROUND

Acute kidney injury (AKI) is common and it is associated with poor clinical outcomes in premature and low birth weight neonates. This systematic review and meta-analysis was performed to summarize the literature and evaluate the prevalence, risk factors, and mortality of premature and low birth weight neonates with AKI.

METHODS

A systematic search in PubMed, Embase, and the Cochrane Library was performed. Studies on the prevalence, risk factors, diagnosis, and outcomes of acute kidney injury in preterm neonates and neonates with low birth weight were included and analyzed.

RESULTS

Fifty articles of 10,744 patients were included in this study. The overall rate of AKI from the pooled results of all patients was 25% (95% CI 20-30%) with heterogeneity among studies (I² = 97%; P < 0.01). Patients with AKI had significantly higher rate of mortality than patients without AKI (odds ratio (OR) = 7.13; 95% CI 5.91-8.60; P < 0.01).

CONCLUSIONS

AKI was prevalent and was associated with high mortality rate among preterm and low birth weight neonates.

Renal tissue oxygenation after caffeine administration in preterm neonates

BACKGROUND

Caffeine has been associated with reduced rates of acute kidney injury (AKI) in preterm neonates. The effect of caffeine on preterm neonatal renal regional saturation of oxygen (RrSO₂) is unknown.

METHODS

RrSO₂ was recorded continuously in neonates < 32 weeks' gestation until 7 days of age with INVOS™ neonatal near-infrared spectroscopy (NIRS) sensors. Baseline RrSO₂ values were established by averaging the saturations in the 20 min prior to caffeine administration. Subgroup analysis was performed based on pre-caffeine RrSO₂ averages. Change in RrSO₂ was recorded at 0.5, 1, 2, 3, 4, 6, and 12 h after maintenance caffeine administration.

RESULTS

Of 35 eligible neonates, 31 (median gestational age 28.4 weeks) received 156 caffeine doses (median 8 mg/kg). Analysis of combined doses showed no significant changes in RrSO₂ after caffeine administration at any time. However, neonates with baseline 20-29.9% had significant increases from 1 to 12 h (range of increase 5.9-13.9%), and those with baseline 30-39.9 had significant increases at 1 h (8.06%, p < 0.05).

CONCLUSIONS

Maintenance caffeine dosing increased RrSO₂ in neonates with low RrSO₂ in the first week. Further research is needed to determine the effect of loading doses of caffeine and if increases in RrSO₂ correlate with improved clinical kidney outcomes.

IMPACT

Caffeine administration is associated with increased renal tissue oxygenation in preterm neonates with low baseline values under 40%. The most significant renal tissue oxygenation changes occur in the first 3 h after IV caffeine administration. With recent studies suggesting low RrSO₂ values in preterm neonates are associated with AKI, caffeine should be studied as a potential therapeutic for this common and complex morbidity in preterm neonates.

Advances in Neonatal Acute Kidney Injury

In this state-of-the-art review, we highlight the major advances over the last 5 years in neonatal acute kidney injury (AKI). Large multicenter studies reveal that neonatal AKI is common and independently associated with increased morbidity and mortality. The natural course of neonatal AKI, along with the risk factors, mitigation strategies, and the role of AKI on short- and long-term outcomes, is becoming clearer. Specific progress has been made in identifying potential preventive strategies for AKI, such as the use of caffeine in premature neonates, theophylline in neonates with hypoxic-ischemic encephalopathy, and nephrotoxic medication monitoring programs. New evidence highlights the importance of the kidney in "crosstalk" between other organs and how AKI likely plays a critical role in other organ development and injury, such as intraventricular hemorrhage and lung disease. New technology has resulted in advancement in prevention and improvements in the current management in neonates with severe AKI. With specific continuous renal replacement therapy machines designed for neonates, this therapy is now available and is being used with increasing frequency in NICUs. Moving forward, biomarkers, such as urinary neutrophil gelatinase-associated lipocalin, and other new technologies, such as monitoring of renal tissue oxygenation and nephron counting, will likely play an increased role in identification of AKI and those most vulnerable for chronic kidney disease. Future research needs to be focused on determining the optimal follow-up strategy for neonates with a history of AKI to detect chronic kidney disease.

Neonatal acute kidney injury: a case-based approach

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

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

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

Aminophylline for renal protection in neonatal hypoxic-ischemic encephalopathy in the era of therapeutic hypothermia

BACKGROUND

Neonates with hypoxic-ischemic encephalopathy (HIE) frequently develop acute kidney injury (AKI). Aminophylline has been shown to reduce severe renal dysfunction in neonates after perinatal asphyxia. However, the effect of aminophylline on renal function in neonates undergoing hypothermia has not been studied.

METHODS

A single-center, retrospective chart review of neonates cooled for moderate/severe HIE who received aminophylline for AKI was conducted to assess changes in urine output (UOP) and serum creatinine (SCr). Comparisons were also made to control neonates matched for hours of life who were cooled but unexposed to aminophylline.

RESULTS

Sixteen neonates cooled for HIE received aminophylline starting at 25 ± 14 h of life. Within 12 h of starting aminophylline, UOP increased by 2.6 ± 1.9 mL/kg/h. SCr declined by 0.4 ± 0.2 mg/dL in survivors over the first 4 days. When compared to control neonates, UOP increase was greater in the aminophylline group (p < 0.001). SCr declined in survivors in both groups, although baseline SCr was higher in the aminophylline group.

CONCLUSIONS

Aminophylline use in neonates with HIE undergoing hypothermia was associated with an increase in UOP and a decline in SCr. A randomized trial will be needed to establish a potential renal protective role of aminophylline.

IMPACT

The renal protective effect of aminophylline in neonates with HIE has not yet been studied in the context of therapeutic hypothermia. Aminophylline exposure in neonates cooled for HIE was associated with increased UOP and a similar decline in SCr when compared to control infants unexposed to aminophylline. Improved renal function after receiving aminophylline in this observational cohort study suggests the need for future randomized trials to establish the potential benefit of aminophylline in the HIE population undergoing hypothermia.

The effect of antenatal indomethacin on extremely preterm neonatal kidney function

Introduction/Objective: Indomethacin is an effective tocolytic to prevent extremely preterm birth. Prior studies have associated antenatal indomethacin exposure with adverse preterm neonatal intestinal and neurological outcomes. Indomethacin is a nephrotoxic medication that may also affect preterm neonatal kidneys. We sought to evaluate the effect of antenatal indomethacin on extremely preterm neonatal kidney function and acute kidney injury (AKI) in the first week of age.Methods: A retrospective cohort study was conducted on neonates born < 29 weeks at a level III neonatal intensive care unit (NICU) from January 2018-April 2019. Serum creatinine (sCr) values and urine output (UOP) in the first seven days of age and the neonate's peak serum creatinine within the first 30 days were evaluated. Neonatal AKI was defined by the modified neonatal Kidney Disease Improving Global Outcomes (KDIGO) definition including urine output.Results: 17 of the 55 neonates meeting criteria for this study were exposed to indomethacin. The average gestational age at birth was similar between study groups. Maternal preeclampsia was more common among women who did not receive indomethacin (p = 0.021). Indomethacin exposed neonates received more gentamicin (p = 0.024). Overall, staging of the neonatal AKI did not differ significantly between the study groups, regardless of how it was quantified (sCr or UOP) or the duration of time in which the injury developed (7 days or 30 days). Separate analysis of sCr and UOP in the first seven days also failed to show any statistically significant differences between the two groups.Conclusion: In this small cohort study of extremely preterm neonates, those born to mothers treated with indomethacin did not have an increased incidence of AKI compared to neonates born to unexposed mothers. Although no statistically significant differences in UOP or sCr were found, they deserve further evaluation in adequately powered prospective clinical trials. Future prospective studies with long-term follow-up utilizing advanced biomarkers are needed to determine how antenatal indomethacin affects extremely preterm neonatal kidney function in the NICU, during childhood, and as adults.

Nephrotoxic medications and acute kidney injury risk factors in the neonatal intensive care unit: clinical challenges for neonatologists and nephrologists

Neonatal acute kidney injury (AKI) is common. Critically ill neonates are at risk for AKI for many reasons including the severity of their underlying illnesses, prematurity, and nephrotoxic medications. In this educational review, we highlight four clinical scenarios in which both the illness itself and the medications indicated for their treatment are risk factors for AKI: sepsis, perinatal asphyxia, patent ductus arteriosus, and necrotizing enterocolitis. We review the available evidence regarding medications commonly used in the neonatal period with known nephrotoxic potential, including gentamicin, acyclovir, indomethacin, vancomycin, piperacillin-tazobactam, and amphotericin. We aim to illustrate the complexity of decision-making involved for both neonatologists and pediatric nephrologists when managing infants with these conditions and advocate for ongoing multidisciplinary collaboration in the development of better AKI surveillance protocols and AKI mitigation strategies to improve care for these vulnerable patients.

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

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

Caffeine Therapy in Preterm Infants: The Dose (and Timing) Make the Medicine

Caffeine is one of the most commonly utilized medications in the NICU. In preterm infants, short-term and long-term pulmonary and neurodevelopmental benefits of therapy are well documented in the literature. While robust evidence supports the use of standard doses of caffeine for apnea of prematurity or to facilitate successful extubation, much remains unknown regarding the boundaries of efficacy and safety for this common therapeutic agent. Escalating dosing regimens seem to provide additional benefit in select infants, but grave toxicity has also been documented with early utilization of high-dose caffeine. Conflicting data exist surrounding the ideal timing of initiation of therapy. Even the widely adhered to discontinuation point has been challenged by data supporting continued use. Until robust data definitively support change, practice should align with current evidence defining clear, safe, and efficacious dosing and timing of caffeine therapy.

Incidence and Risk Factors of Early Onset Neonatal AKI

BACKGROUND AND OBJECTIVES

Neonatal AKI is associated with poor short- and long-term outcomes. The objective of this study was to describe the risk factors and outcomes of neonatal AKI in the first postnatal week.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The international retrospective observational cohort study, Assessment of Worldwide AKI Epidemiology in Neonates (AWAKEN), included neonates admitted to a neonatal intensive care unit who received at least 48 hours of intravenous fluids. Early AKI was defined by an increase in serum creatinine >0.3 mg/dl or urine output <1 ml/kg per hour on postnatal days 2-7, the neonatal modification of Kidney Disease: Improving Global Outcomes criteria. We assessed risk factors for AKI and associations of AKI with death and duration of hospitalization.

RESULTS

Twenty-one percent (449 of 2110) experienced early AKI. Early AKI was associated with higher risk of death (adjusted odds ratio, 2.8; 95% confidence interval, 1.7 to 4.7) and longer duration of hospitalization (parameter estimate: 7.3 days 95% confidence interval, 4.7 to 10.0), adjusting for neonatal and maternal factors along with medication exposures. Factors associated with a higher risk of AKI included: outborn delivery; resuscitation with epinephrine; admission diagnosis of hyperbilirubinemia, inborn errors of metabolism, or surgical need; frequent kidney function surveillance; and admission to a children's hospital. Those factors that were associated with a lower risk included multiple gestations, cesarean section, and exposures to antimicrobials, methylxanthines, diuretics, and vasopressors. Risk factors varied by gestational age strata.

CONCLUSIONS

AKI in the first postnatal week is common and associated with death and longer duration of hospitalization. The AWAKEN study demonstrates a number of specific risk factors that should serve as "red flags" for clinicians at the initiation of the neonatal intensive care unit course.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Assessment of Worldwide AKI Epidemiology in Neonates (AWAKEN), NCT02443389.

Caffeine exposure and acute kidney injury in premature infants with necrotizing enterocolitis and spontaneous intestinal perforation

BACKGROUND

Acute kidney injury (AKI) is common in preterm infants, but specific therapies remain scarce. Recent studies have demonstrated an association between caffeine exposure and less frequent AKI in the first 7-10 days after birth. We hypothesized that patients with necrotizing enterocolitis (NEC) and spontaneous intestinal perforation (SIP) would provide a better natural model of AKI to evaluate this association.

METHODS

We reviewed all premature patients diagnosed with NEC or SIP at our institution from 2008 to 2014. AKI was defined by change in serum creatinine using the neonatal Kidney Disease: Improving Global Outcomes definition. Caffeine was prescribed for apnea of prematurity and caffeine exposure was determined by chart review.

RESULTS

A total of 146 patients with NEC/SIP were reviewed. Of these, 119 (81.5%) received caffeine, and 91 (62.3%) developed AKI. AKI occurred less frequently in patients who received caffeine than in those who did not (55.5% vs. 92.6%; odds ratio (OR) 0.10; 95% confidence interval (CI) 0.02-0.44). This association persisted in multivariable models after adjustment for potential confounders (adjusted OR 0.08; 95% CI 0.01-0.42; number needed to be exposed to caffeine to prevent one case of AKI = 2.6). Although baseline serum creatinine did not differ by caffeine exposure, patients receiving caffeine had lower peak creatinine (median 1.0 mg/dl vs. 1.5 mg/dl; p = 0.008) and absolute creatinine change (median 0.42 mg/dl vs. 0.68 mg/dl; p = 0.003) than those who did not.

CONCLUSIONS

Caffeine exposure in preterm infants with NEC/SIP is associated with decreased incidence and severity of AKI.

Incidence and Risk Factors of Early Onset Neonatal AKI

BACKGROUND AND OBJECTIVES

Neonatal AKI is associated with poor short- and long-term outcomes. The objective of this study was to describe the risk factors and outcomes of neonatal AKI in the first postnatal week.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The international retrospective observational cohort study, Assessment of Worldwide AKI Epidemiology in Neonates (AWAKEN), included neonates admitted to a neonatal intensive care unit who received at least 48 hours of intravenous fluids. Early AKI was defined by an increase in serum creatinine >0.3 mg/dl or urine output <1 ml/kg per hour on postnatal days 2-7, the neonatal modification of Kidney Disease: Improving Global Outcomes criteria. We assessed risk factors for AKI and associations of AKI with death and duration of hospitalization.

RESULTS

Twenty-one percent (449 of 2110) experienced early AKI. Early AKI was associated with higher risk of death (adjusted odds ratio, 2.8; 95% confidence interval, 1.7 to 4.7) and longer duration of hospitalization (parameter estimate: 7.3 days 95% confidence interval, 4.7 to 10.0), adjusting for neonatal and maternal factors along with medication exposures. Factors associated with a higher risk of AKI included: outborn delivery; resuscitation with epinephrine; admission diagnosis of hyperbilirubinemia, inborn errors of metabolism, or surgical need; frequent kidney function surveillance; and admission to a children's hospital. Those factors that were associated with a lower risk included multiple gestations, cesarean section, and exposures to antimicrobials, methylxanthines, diuretics, and vasopressors. Risk factors varied by gestational age strata.

CONCLUSIONS

AKI in the first postnatal week is common and associated with death and longer duration of hospitalization. The AWAKEN study demonstrates a number of specific risk factors that should serve as "red flags" for clinicians at the initiation of the neonatal intensive care unit course.

Renal Saturation and Acute Kidney Injury in Neonates with Hypoxic Ischemic Encephalopathy Undergoing Therapeutic Hypothermia

OBJECTIVE

To investigate the range of renal near-infrared spectroscopy (NIRS) measures in neonates undergoing therapeutic hypothermia for hypoxic ischemic encephalopathy (HIE) and to determine the association between renal NIRS measures and the development of acute kidney injury (AKI).

STUDY DESIGN

A retrospective chart review was conducted of neonates with moderate to severe HIE who received therapeutic hypothermia at a tertiary care center from 2014 to 2016. Neonates had routine continuous NIRS monitoring of cerebral and renal saturation (Rsat) as part of their clinical care for 72 hours of cooling and until 24 hours after rewarming. The outcome of AKI was defined by an abnormal rate of decline of serum creatinine over the first 5 days of life. Mixed effects models determined the association between renal NIRS measures and AKI over time.

RESULTS

Of 38 neonates with HIE undergoing cooling, 15 (39%) developed AKI. Rsat was lower than cerebral saturation during cooling (P < .01), but Rsat increased over time after rewarming, while renal oxygen extraction levels decreased (P < .0001). Neonates with AKI had higher Rsat levels (P < .01) compared with those without AKI after 24 hours of life. Using receiver operating characteristic curves, Rsat >75% by 24-48 hours predicted AKI with a sensitivity of 79% and specificity of 82% (area under the receiver operating characteristic curve = 0.76).

CONCLUSIONS

Throughout cooling, neonates with AKI had higher Rsat measures than those without AKI. These differences may reflect lower oxygen extraction by the injured kidney. NIRS monitoring of Rsat may identify neonates with HIE at risk of developing AKI.

Caffeine: an evidence-based success story in VLBW pharmacotherapy

Apnea of prematurity (AOP) is a common and pervasive problem in very low birth weight infants. Methylxanthines were reported >40 years ago to be an effective therapy and, by the early 2000s, caffeine had become the preferred methylxanthine because of its wide therapeutic index, excellent bioavailability, and longer half-life. A clinical trial to address unresolved questions and toxicity concerns, completed in 2004, confirmed significant benefits of caffeine therapy, including shorter duration of intubation and respiratory support, reduced incidence of chronic lung disease, decreased need for treatment of patent ductus arteriosus, reduced severity of retinopathy of prematurity, and improved motor and visual function. Cohort studies have now further delineated the benefits of initiation of therapy before 3 days postnatal age, and of higher maintenance doses to achieve incremental beneficial effects. This review summarizes the pivotal and in particular the most recent studies that have established the safety and efficacy of caffeine therapy for AOP and other respiratory and neurodevelopmental outcomes. Caffeine has a very favorable benefit-to-risk ratio, and has become one of the most prescribed and cost-effective pharmacotherapies in the NICU.

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.

Acute kidney injury in preterm infants with necrotizing enterocolitis

Purpose: Acute kidney injury (AKI) is an independent predictor of morbidity and mortality in critically ill infants and children. AKI develops in an estimated one-third of the neonatal intensive care unit (NICU) population; however, literature on the incidence of AKI in premature infants with a diagnosis of necrotizing enterocolitis (NEC) is limited. The objectives of this study were to describe the incidence of AKI in infants with radiographically confirmed NEC, assess these infants for independent risk factors associated with development of AKI and evaluate if the presence of AKI is associated with increased mortality. Study design: We conducted a retrospective chart review of premature infants, gestational age (GA) 23-34 weeks, who developed modified Bell's level 2 or 3 NEC while admitted to two tertiary NICUs within our health system between 2010 and 2015. AKI was defined and staged according to modified Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Results: 77 infants with Bell's level II (63.6%) and III (36.4%) NEC were studied. AKI occurred in 42.9% of infants (Stage 1: 18.2%; Stage 2: 13%; Stage 3: 11.7%). Bell's Stage III NEC, lower GA, maternal preeclampsia/eclampsia, gentamicin/vancomycin exposure, and empiric antibiotic use were independently associated with AKI. AKI was strongly associated with mortality (HR 20.3 95%CI 2.5-162.8, p = .005) in an adjusted Cox model. Conclusions: AKI is common in premature infants who develop NEC. More severe NEC was found to be an independent risk factor for AKI. Additionally, AKI in infants with NEC increases mortality risk significantly.

Intermittent hypoxia alters dose dependent caffeine effects on renal prostanoids and receptors in neonatal rats

Caffeine, one of the most commonly prescribed drugs in preterm neonates, is given in standard or suprapharmacologic doses. Although known as a diuretic, its effects in the neonatal kidneys are not well studied. We tested the hypothesis that neonatal intermittent hypoxia (IH) and high caffeine doses (HCD) alter renal regulators of vasomotor tone and water balance. Newborn rats were randomized to room air, hyperoxia, or IH and treated with standard or high caffeine doses; or placebo saline. Renal prostanoids; histopathology; and cyclooxygenase (COX), prostanoid receptor, and aquaporin (AQP) immunoreactivity were determined. HCD in IH caused severe pathological changes in the glomeruli and proximal tubules, consistent with acute kidney injury. This was associated with reductions in anthropometric growth, PGI_2, and IP, DP, and AQP-4 immunoreactivity, well as a robust increase in COX-2, suggesting that the use of HCD should be avoided in preterm infants who experience frequent IH episodes.

Risk of nonsteroidal anti-inflammatory drug-associated renal dysfunction among neonates diagnosed with patent ductus arteriosus and treated with gentamicin

OBJECTIVE

To evaluate the risk of nonsteroidal anti-inflammatory drug (NSAID) therapy-associated acute kidney injury (AKI) among neonates diagnosed with patent ductus arteriosus (PDA) who are treated with gentamicin.

STUDY DESIGN

Multicenter retrospective observational study of patients ⩽44 postmenstrual weeks of age diagnosed with PDA who received gentamicin during hospitalization between January 2006 and December 2014. Patients with and without NSAID exposure were matched on covariates associated with AKI and NSAID therapy. The primary end point, AKI, was defined according to Kidney Disease Improving Global Outcomes neonatal criteria.

RESULTS

The rate of AKI for the entire cohort (n=594) was 12% (n=71). Among neonates receiving NSAIDS, 14.8% (n=44) experienced an AKI as compared to 9.1% (n=27) for those who were not exposed (relative risk, 1.6; 95% confidence interval, 1.0 to 2.6). Therefore, the attributable risk of NSAID use was 5.7% (95% confidence interval, 0.5 to 11.0).

CONCLUSION

Among neonates with PDA and receiving gentamicin, NSAID therapy increases the risk of AKI by about 6%.

A review of caffeine use as a risk or protective factor for women's health and pregnancy

PURPOSE OF REVIEW

To provide a narrative synthesis of recently published studies on caffeine use as a risk or protective factor for health outcomes, with a focus on women's health and pregnancy.

RECENT FINDINGS

Based on predominantly observational studies, moderate caffeine intake has been shown to be a protective factor for liver cancer, certain bowel conditions, colorectal cancer, skin cancer, and regular menstrual cycle function. However, heavy consumption is a risk factor for osteoporosis, urinary incontinence, and poorer birth and child developmental outcomes. Residual confounding and issues surrounding retrospective self-reported intake are cited as key limitations in the majority of these studies. Moderate caffeine intake has been associated with lower risk of cardiovascular disease and metabolic syndrome; however, recent genetic epidemiology studies provide no evidence for a causal relationship.

SUMMARY

Greater inclusion of female participants in studies, and analysis of sex differences in the relationship between caffeine intake and certain health conditions, is necessary. The current literature suggests caffeine's role as a risk or protective factor differs across health conditions. Often, there are plausible biological mechanisms for this relationship. However, a continued precautionary stance is recommended until direct causal pathways are established. Review of recently published studies does not suggest that current intake guidelines for adults and for pregnant woman need to be modified.

The Impact of Kidney Development on the Life Course: A Consensus Document for Action

Hypertension and chronic kidney disease (CKD) have a significant impact on global morbidity and mortality. The Low Birth Weight and Nephron Number Working Group has prepared a consensus document aimed to address the relatively neglected issue for the developmental programming of hypertension and CKD. It emerged from a workshop held on April 2, 2016, including eminent internationally recognized experts in the field of obstetrics, neonatology, and nephrology. Through multidisciplinary engagement, the goal of the workshop was to highlight the association between fetal and childhood development and an increased risk of adult diseases, focusing on hypertension and CKD, and to suggest possible practical solutions for the future. The recommendations for action of the consensus workshop are the results of combined clinical experience, shared research expertise, and a review of the literature. They highlight the need to act early to prevent CKD and other related noncommunicable diseases later in life by reducing low birth weight, small for gestational age, prematurity, and low nephron numbers at birth through coordinated interventions. Meeting the current unmet needs would help to define the most cost-effective strategies and to optimize interventions to limit or interrupt the developmental programming cycle of CKD later in life, especially in the poorest part of the world.