A classification system has been proposed to standardize the definition of acute kidney injury in adults. These criteria of risk, injury, failure, loss, and end-stage renal disease were given the acronym of RIFLE. We have modified the criteria based on 150 critically ill pediatric RIFLE (pRIFLE) patients to assess acute kidney injury incidence and course along with renal and/or non-renal comorbidities. Of these children, 11 required dialysis and 24 died. Patients without acute kidney injury in the first week of intensive care admission were less likely to subsequently develop renal Injury or Failure; however, 82% of acute kidney injury occurred in this initial week. Within this group of 123 children, 60 reached pRIFLEmax for Risk, 32 reached Injury, and 31 reached Failure. Acute kidney injury during admission was an independent predictor of intensive care; hospital length of stay and an increased risk of death independent of the Pediatric Risk of Mortality (PRISM II) score (odds ratio 3.0). Our results show that a majority of critically ill children develop acute kidney injury by pRIFLE criteria and do so early in the course of intensive care. Acute kidney injury is associated with mortality and may lead to increased hospital costs. We suggest that the pRIFLE criteria serves to characterize the pattern of acute kidney injury in critically ill children.

Acute kidney injury (AKI) is a frequent complication of cardiac surgery and increases morbidity and mortality. The identification of reliable biomarkers that allow earlier diagnosis of AKI in the postoperative period may increase the success of therapeutic interventions. Here, we conducted a prospective, multicenter cohort study involving 1219 adults undergoing cardiac surgery to evaluate whether early postoperative measures of urine IL-18, urine neutrophil gelatinase-associated lipocalin (NGAL), or plasma NGAL could identify which patients would develop AKI and other adverse patient outcomes. Urine IL-18 and urine and plasma NGAL levels peaked within 6 hours after surgery. After multivariable adjustment, the highest quintiles of urine IL-18 and plasma NGAL associated with 6.8-fold and 5-fold higher odds of AKI, respectively, compared with the lowest quintiles. Elevated urine IL-18 and urine and plasma NGAL levels associated with longer length of hospital stay, longer intensive care unit stay, and higher risk for dialysis or death. The clinical prediction model for AKI had an area under the receiver-operating characteristic curve (AUC) of 0.69. Urine IL-18 and plasma NGAL significantly improved the AUC to 0.76 and 0.75, respectively. Urine IL-18 and plasma NGAL significantly improved risk prediction over the clinical models alone as measured by net reclassification improvement (NRI) and integrated discrimination improvement (IDI). In conclusion, urine IL-18, urine NGAL, and plasma NGAL associate with subsequent AKI and poor outcomes among adults undergoing cardiac surgery. (Clinical Trials.gov number, NCT00774137).

Objective To determine the incidence, severity and risk-factors of AKI in children undergoing cardiac surgery for congenital heart defects. Design Prospective observational multicenter cohort study Setting Three pediatric intensive care units at academic centers. Patients 311 children between the ages of 1 month and 18 years undergoing pediatric cardiac surgery. Interventions None. Measurements and Main Results AKI was defined as a ≥ 50% increase in serum creatinine from the pre-operative value. Secondary outcomes were length of mechanical ventilation, length of ICU and hospital stays, acute dialysis, and in-hospital mortality. The cohort had an average age of 3.8 years with 45% females and was mostly white (82%). One third had prior cardiothoracic surgery, 91% of the surgeries were elective, and almost all patients required cardiopulmonary bypass (CPB). AKI occurred in 42% (130 patients) within 3 days after surgery. Children ≥ 2 years old and less than 13 years old had 72% lower likelihood of AKI (adjusted OR: 0.28, 95% CI: 0.16, 0.48), and patients 13 years and older had 70% lower likelihood of AKI (adjusted OR: 0.30, 95% CI: 0.10, 0.88) compared to patients less than 2 years old. Longer CPB time was linearly and independently associated with AKI. Development of AKI was independently associated with prolonged ventilation and with increased length of hospital stay. Conclusions AKI is common after pediatric cardiac surgery and is associated with prolonged mechanical ventilation and increased hospital stay. CPB time and age were independently associated with AKI risk. CPB time may be a marker for case complexity.

Objectives To test the hypothesis that, without diagnostic changes in serum creatinine, increased NGAL levels identify patients with subclinical acute kidney injury (AKI) and, therefore, worse prognosis. Background Neutrophil gelatinase-associated lipocalin (NGAL) detects subclinical AKI hours to days before increases in serum creatinine indicate manifest loss of renal function. Methods We analyzed pooled data from 2,322 patients with cardiorenal syndrome type 1 from ten prospective observational studies of NGAL. We used the terms NGAL(−) or NGAL(+) according to study-specific NGAL cut-off for optimal AKI prediction and the terms sCREA(−) or sCREA(+) to consensus diagnostic increases in serum creatinine defining AKI. A-priori-defined outcomes included need for renal replacement therapy (primary endpoint), hospital mortality, their combination and duration of stay in intensive care and in-hospital. Results Of study patients, 1,296 (55.8%) were NGAL(−)/sCREA(−), 445 (19.2%) NGAL(+)/sCREA(−), 107 (4.6%) NGAL(−)/sCREA(+) and 474 (20.4%) NGAL(+)/sCREA(+). According to the four study groups, there was a stepwise increase in subsequent renal replacement therapy initiation, (NGAL(−)/sCREA(−): 0.0015% vs. NGAL(+)/sCREA(−): 2.5% [odds ratio 16.4, 95% CI 3.6–76.9, P<0.001], NGAL(−)/sCREA(+): 7.5% and NGAL(−)/sCREA(−): 8.0%, respectively), hospital mortality (4.8%, 12.4%, 8.4%, 14.7%, respectively) and their combination (four-group comparisons: all P<0.001). There was a similar and consistent progressive increase in median number of intensive care and in-hospital days with increasing biomarker positivity: NGAL(−)/sCREA(−): 4.2 and 8.8 days; NGAL(+)/sCREA(−): 7.1 and 17.0 days; NGAL(−)/sCREA(+): 6.5 and 17.8 days; NGAL(+)/sCREA(+): 9.0 and 21.9 days; four-group comparisons: P=0.003 and P=0.040, respectively. Urine and plasma NGAL indicated a similar outcome pattern. Conclusions In the absence of diagnostic increases in serum creatinine, NGAL detects patients with subclinical AKI who have an increased risk of adverse outcomes. The concept and definition of AKI may need re-assessment.