A New Approach to Recognize Neonatal Impaired Kidney Function

Renal Oxygen Saturations and Acute Kidney Injury in the Preterm Infant with Patent Ductus Arteriosus

OBJECTIVE

 Decreased near-infrared spectroscopy (NIRS) measures of renal oxygen saturation (Rsat) have identified preterm infants with a hemodynamically significant patent ductus arteriosus (hsPDA). NIRS may further identify infants at risk for acute kidney injury (AKI) in a population with concern for hsPDA.

STUDY DESIGN

 Review of infants ≤29 weeks' gestation undergoing NIRS and echocardiography due to concern for hsPDA. The hsPDA was defined by two of the following: moderate-large size, left to right shunt, aortic flow reversal, left atrial enlargement. AKI was defined by neonatal modified Kidney Disease Improving Global Outcomes (KDIGO). Rsat and cerebral saturation (Csat), averaged over 1 hour, were evaluated for the 24-hour period around echocardiography.

RESULTS

 Among 77 infants, 29 (38%) had AKI by neonatal modified KDIGO criteria. hsPDA was found on echocardiography in 59 (77%). There were no differences in hsPDA in infants with and without AKI (p = 0.1). Rsat was not associated with AKI (p = 0.3). Infants on dopamine had less Rsat variability (p < 0.01).

CONCLUSION

 Rsat prior to echocardiography did not discriminate AKI in this cohort of preterm infants at risk for hsPDA; however, data may not capture optimal timing of Rsat measurement before AKI.

KEY POINTS

· No Rsat value was found to be associated with the development of AKI.. · The optimal timing of Rsat measurement should be evaluated in infants at risk for hsPDA.. · NIRS bedside monitoring of Csat and Rsat measures may be useful in trending perfusion patterns.. · Identification of those at high risk for AKI may allow for more careful kidney function monitoring..

Impact of preterm birth on kidney health and development

Preterm birth, defined as birth before the gestational age of 37 weeks, affects 11% of the newborns worldwide. While extensive research has focused on the immediate complications associated with prematurity, emerging evidence suggests a link between prematurity and the development of kidney disease later in life. It has been demonstrated that the normal course of kidney development is interrupted in infants born prematurely, causing an overall decrease in functional nephrons. Yet, the pathogenesis leading to the alterations in kidney development and the subsequent pathophysiological consequences causing kidney disease on the long-term are incompletely understood. In the present review, we discuss the current knowledge on nephrogenesis and how this process is affected in prematurity. We further discuss the epidemiological evidence and experimental data demonstrating the increased risk of kidney disease in these individuals and highlight important knowledge gaps. Importantly, understanding the intricate interplay between prematurity, abnormal kidney development, and the long-term risk of kidney disease is crucial for implementing effective preventive and therapeutic strategies.

Acute kidney injury in neonates with hypoxic ischemic encephalopathy based on serum creatinine decline compared to KDIGO criteria

BACKGROUND

Neonates with hypoxic ischemic encephalopathy receiving therapeutic hypothermia (HIE + TH) are at risk for acute kidney injury (AKI). The standardized Kidney Disease Improving Global Outcomes (KDIGO) criteria identifies AKI based on a rise in serum creatinine (SCr) or reduced urine output. This definition is challenging to apply in neonates given the physiologic decline in SCr during the first week of life. Gupta et al. proposed alternative neonatal criteria centered on rate of SCr decline. This study aimed to compare the rate of AKI based on KDIGO and Gupta in neonates with HIE and to examine associations with mortality and morbidity.

METHODS

A retrospective review was performed of neonates with moderate to severe HIE + TH from 2008 to 2020 at a single center. AKI was assessed in the first 7 days after birth by KDIGO and Gupta criteria. Mortality, brain MRI severity of injury, length of stay, and duration of respiratory support were compared between AKI groups.

RESULTS

Among 225 neonates, 64 (28%) met KDIGO, 69 (31%) neonates met Gupta but not KDIGO, and 92 (41%) did not meet either definition. Both KDIGO-AKI and GuptaOnly-AKI groups had an increased risk of the composite mortality and/or moderate/severe brain MRI injury along with longer length of stay and prolonged duration of respiratory support compared to those without AKI.

CONCLUSIONS

AKI in neonates with HIE + TH was common and varied by definition. The Gupta definition based on rate of SCr decline identified additional neonates not captured by KDIGO criteria who are at increased risk for adverse outcomes. Incorporating the rate of SCr decline into the neonatal AKI definition may increase identification of clinically relevant kidney injury in neonates with HIE + TH.

Does base excess predict kidney injury in neonates with hypoxic-ischemic encephalopathy?

In neonates with hypoxic-ischemic encephalopathy (HIE), we studied the correlation between cord blood base excess (BE) and kidney function. Among 225 infants, 29 % had oliguria. BE levels differed significantly between oliguric and non-oliguric infants (p < 0.01), with a negative correlation to kidney injury (r = -0.544, p < 0.01). BE < -18 had 85 % specificity and 76 % sensitivity in predicting kidney injury (AUC = 0.88). These findings suggest BE as a valuable indicator of impending kidney injury in HIE infants, though underlying mechanisms may vary.

Renal oximetry for early acute kidney injury detection in neonates with hypoxic ischemic encephalopathy receiving therapeutic hypothermia

BACKGROUND

Neonates with hypoxic ischemic encephalopathy (HIE) receiving therapeutic hypothermia are at high risk of acute kidney injury (AKI).

METHODS

We performed a two-site prospective observational study from 2018 to 2019 to evaluate the utility of renal near-infrared spectroscopy (NIRS) in detecting AKI in 38 neonates with HIE receiving therapeutic hypothermia. AKI was defined by a delayed rate of serum creatinine decline (< 33% on day 3 of life, < 40% on day 5, and < 46% on day 7). Renal saturation (Rsat) and systemic oxygen saturation (SpO2) were continuously measured for the first 96 h of life (HOL). Renal fractional tissue oxygen extraction (RFTOE) was calculated as (SpO2 - Rsat)/(SpO2). Using renal NIRS, urine biomarkers, and perinatal factors, logistic regression was performed to develop a model that predicted AKI.

RESULTS

AKI occurred in 20 of 38 neonates (53%). During the first 96 HOL, Rsat was higher, and RFTOE was lower in the AKI group vs. the no AKI group (P < 0.001). Rsat > 70% had a fair predictive performance for AKI at 48-84 HOL (AUC 0.71-0.79). RFTOE ≤ 25 had a good predictive performance for AKI at 42-66 HOL (AUC 0.8-0.83). The final statistical model with the best fit to predict AKI (AUC = 0.88) included RFTOE at 48 HOL (P = 0.012) and pH of the infants' first postnatal blood gas (P = 0.025).

CONCLUSIONS

Lower RFTOE on renal NIRS and pH on infant first blood gas may be early predictors for AKI in neonates with HIE receiving therapeutic hypothermia. A higher resolution version of the Graphical abstract is available as Supplementary information.

Patterns of acute kidney and hepatic injury and association with adverse outcomes in infants undergoing therapeutic hypothermia for hypoxic ischemic encephalopathy

OBJECTIVE

To describe patterns of renal and hepatic injury in infants with hypoxic ischemic encephalopathy (HIE).

STUDY DESIGN

Retrospective cohort of infants receiving therapeutic hypothermia for HIE was classified into groups based on organ injury: neither acute kidney injury (AKI) nor acute hepatic injury (AHI), isolated AKI, isolated AHI, or both AKI/AHI. Biomarkers and outcomes were described and analyzed.

RESULTS

Among 188 infants, 55% had no AKI nor AHI, 7% had only AKI, 22% had only AHI and 16% had both AKI and AHI. Infants with both AKI/AHI had the highest mortality (47%) and worse outcomes, compared to other injury groups, although AKI/AHI was not significantly associated with mortality (hazard ratio 2.5; 95% CI 0.9-6.9), after accounting for severity of HIE. For surviving infants, biomarkers of organ injury, on average, normalized by discharge.

CONCLUSION

Infants with HIE with both AKI/AHI have worse outcomes than infants with AKI or AHI alone.

Peritoneal dialysis in very low and extremely low birthweight infants: A pooled analysis

BACKGROUND

Peritoneal dialysis (PD) represents an important therapeutic option in neonatal acute kidney injury (AKI), although evidence regarding its effects in preterm neonates remains unclear. The present study aims to evaluate the feasibility of PD in very low birthweight (VLBW) and extremely low birthweight (ELBW) infants and clarify the association of catheter choice with clinical outcomes.

METHODS

Medline, Scopus, Web of Science, Clinicaltrials.gov and CENTRAL databases were systematically searched from inception to 15 January 2021. Studies reporting individual participant data of VLBW and ELBW infants treated with PD were selected.

RESULTS

Overall, 20 studies were included comprising 101 patients. Catheter-related complications were significantly more frequent among ELBW infants (odds ratio: 5.18, 95% confidence intervals (CI): 1.23-29.09). After inverse probability treatment weighting, compared to drainage catheters, death risk was significantly lower with the use of PD (hazard ratio: 0.42, 95% CI: 0.19-0.90) but not vascular catheters (hazard ratio: 0.58, 95% CI: 0.28-1.20). Similarly, kidney function loss was significantly lower only with the implementation of PD catheters (hazard ratio: 0.44, 95% CI: 0.21-0.94).

CONCLUSIONS

PD is a feasible kidney replacement therapy modality in VLBW and ELBW infants with AKI. The use of drainage catheters may be linked to significantly worse kidney recovery and overall survival rates, compared to PD catheters. Future cohorts should confirm the most appropriate catheter type and contribute to the standardisation of PD procedures.

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

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