ORIGINAL ARTICLE Acute kidney injury according to pediatric RIFLE criteria is associated with negative outcomes after heart surgery in children Michel Georges dos Santos El Halal & Paulo Roberto A. Carvalho Received: 29 January 2013 / Revised: 11 April 2013 / Accepted: 12 April 2013 / Published online: 22 May 2013 # IPNA 2013 Abstract Background The aim of this study was to investigate the association between the occurrence of acute kidney injury (AKI) according to pediatric RIFLE (pRIFLE) criteria and adverse outcomes in children after heart surgery. Methods Children undergoing heart surgery in a tertiary hospital in Southern Brazil were followed during their stay in the pediatric intensive care unit (PICU) or until death. The exposure variable was occurrence of AKI according to pRIFLE criteria which place AKI in three categories: R (risk), I (injury), and F (failure). The outcomes studied were death, length of mechanical ventilation (MV), and length of PICU stay. Results Eighty-five children were enrolled in the study. Of these, 47 (55.3 %) did not have AKI, while 22 (25.9 %), seven (8.2 %), and nine (10.6 %) were classified into pRI- FLE categories R, I, and F, respectively. The incidence of death was 18.4 and 4.2 % in patients with and without AKI, respectively. Compared to children who did not develop AKI, the adjusted odds ratio for death was 1.05 [95 % confidence interval (CI) 0.09–11.11], 8.36 (95 % CI 1.32– 52.63), and 7.85 (95 % CI 1.53–40.29) in the R, I, and F groups, respectively (p =0.022). Duration of MV and of PICU stay were significantly higher in those children with AKI. Conclusions The occurrence of AKI according to pRIFLE criteria is associated to adverse outcomes in children after heart surgery. Keywords Cardiac surgical procedures . Acute kidney injury . Child . Intensive care units . Mortality . Renal insufficiency Introduction Acute kidney injury (AKI) is common in critically ill patients hospitalized in intensive care units (ICUs). Over the years, the association between AKI and mortality in these patients has become evident. However, until recently, there were multiple definitions of AKI, which made it dif- ficult to compare results between different studies. The RIFLE criteria were published in 2004, and since this time these criteria have been used to define and stage AKI in most studies [1]. Studies have demonstrated an association between AKI defined by the RIFLE criteria and morbidity and mortality in hospitalized and critically ill patients. Patients who meet the RIFLE criteria of AKI have been shown to need longer periods of both mechanical ventilation (MV) and hospital and ICU stay. Therefore, a diagnosis of AKI based on the RIFLE criteria is an independent predictor of morbidity and mortality. To date, most of such studies have involved adult patients, and little data are currently available on children [2–7]. In 2007, Akcan-Arikan et al. proposed an adaptation of the RIFLE criteria for children, the “modified pediatric RIFLE criteria” (pRIFLE) (Table 1), which has been shown to be a good predictor of pediatric ICU (PICU) length of stay and hospital mortality [8]. This work was performed at Hospital da Criança Santo Antônio, Porto Alegre, RS, Brazil. M. G. dos Santos El Halal Faculdade de Medicina, Universidade Católica de Pelotas, Pelotas, RS, Brazil P. R. A. Carvalho Department of Pediatrics, Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil M. G. dos Santos El Halal (*) Hospital Universitário São Francisco de Paula, Universidade Católica de Pelotas, Rua Marechal Deodoro, 1123, Centro, CEP 96020-220, Pelotas, RS, Brazil e-mail: michelgeorges1981@hotmail.com Pediatr Nephrol (2013) 28:1307–1314 DOI 10.1007/s00467-013-2495-7