Neonatal acute kidney injury (AKI) occurs in 52 to 64 percent of patients undergoing cardiac surgery (CS) and is associated with increased morbidity and mortality.
However, because CS-AKI rates vary widely between centers, it appears that interventions to prevent or mitigate the condition could reduce the overall rate.
Yet, noted Santiago Borasino, M.D., medical director of Children’s of Alabama’s Cardiovascular Intensive Care Unit (CVICU), “there are critical gaps in our understanding as to how to best define CS-AKI, who is at risk, and which patients could best benefit from interventions to prevent or mitigate the effects of CS-AKI.”
To improve understanding of CS-AKI in this population, Borasino is one of the leaders of the Neonatal and Pediatric Heart and Renal Outcomes Network (NEPHRON), composed of 22 children’s hospitals around the country. The consortium’s goals are to describe neonatal kidney injury epidemiology, evaluate variability in diagnosis and management, identify risk factors, investigate the impact of fluid overload and explore associations with outcomes. It involves multidisciplinary teams including clinicians from cardiac critical care, cardiology, nephrology, and cardiac surgery.
“NEPHRON is providing multicenter data on CS-AKI for the first time,” Borasino said. “The large size of the cohort will enable us to look at details that are not possible with single-center studies.”
NEPHRON published its preliminary results in April 2019, reporting an overall incidence of 54 percent among 2,240 patients in its database. In November 2019, NEPHRON presented additional results during the American Heart Association’s annual meeting, showing a threefold variation in rates among centers, from 27 percent to 86 percent, with significant variations in KDIGO stage (adult AKI definition) to identify AKI (65 percent by oligo oligo-anuria versus 35 percent by creatinine).
The results also showed that the use of cardiopulmonary bypass, but not time spent on bypass, increased the odds of CS-AKI, and that only KDIGO Stage 3 was associated with mortality. There was no impact of CS-AKI on the duration of mechanical ventilation or hospital length of stay.
“NEPHRON preliminary results highlight the limitations of the KDIGO definition and the need to better understand CS-AKI as it occurs with incredible variability among centers, opening the door for future quality improvement intervention,” Borasino said.
The next step is to develop an algorithm to predict which patients are more likely to develop AKI so physicians can intervene earlier. “Early recognition and proper management of AKI are at the forefront of critical care medicine,” said Children’s of Alabama pediatric nephrologist Tennille Webb, M.D. “However, most pediatric hospitals that perform cardiac surgeries do not have protocols in place for managing severe AKI post-operatively.” Webb is now working on developing a clinical pathway to identify patients at increased risk of AKI based on specific patient characteristics. “An advantage to developing this algorithm in the CVICU is that we are able to determine the exact timing and etiology of AKI development in individuals undergoing cardiopulmonary bypass,” she said. “If we can proactively identify risk factors that place these individuals at increased risk for AKI, we can provide earlier intervention, such as early initiation of renal replacement therapy, in an effort to mitigate some of the known severe consequences of AKI.”
“The work that we are doing is very important because we know that AKI post-cardiac surgery leads to worse outcomes and is associated with chronic kidney disease,” Webb said. “It’s great, and yet rare in other institutions, that we have been able to develop a strong relationship between the CVICU and nephrology to work as a cohesive team early AKI detection and prevention.”
 Gist KM, Blinder JJ, Bailly D, Neonatal and Paediatric Heart and Renal Outcomes Network: design of a multi-centre retrospective cohort study. Cardiol Young. 2019;29(4):511-518.
 Alten J, Cooper DS, Gist KM, et al. , Abstract 13177: Epidemiology of Neonatal Cardiac Surgery Induced Acute Kidney Injury From the Neonatal and Pediatric Heart and Renal Outcomes Network. Circulation. 2019;140(Suppl1).