Introduction: More than 30 Acute Kidney Injury (AKI) definitions exist in the published literature and there is no consensus especially in neonatal group. Chevalier and colleagues defined neonatal acute renal failure as serum creatinine values>1.5 mg/dL for at least 24 hours. Acute Renal Failure (ARF) affects approximately 1% to 24% of newborns in the Neonatal Intensive Care Units (NICUs). ARF is a significant factor of morbidity and mortality in critically ill children. The Acute Dialysis Quality Initiative (ADQI) group has recently proposed the RIFLE criteria for AKI in adults. The RIFLE acronym stands for risk, injury, failure, loss of kidney function and end-stage renal disease. This classification system to define AKI in neonatal group has not been performed. We hypothesized that critically ill neonates with ARF based on old definition (serum creatinine more than 1.5 mg/ dL) have decreased survival, independent of demographic characteristics, co-morbidities, clinical parameters, severity of illness and interventions variables known to predict infant survival.According to this hypothesis, we evaluated urine output, serum creatinine, and glomerular filtration rate in critically ill neonates and compared them to RIFLE scoring system.Methods: This cohort study was conducted at the neonatal intensive care units of Mofid and Mahdieh hospitals which are two of the largest referral neonatal hospitals in Tehran. There are about 4400 deliveries annually in the Mahdieh hospital and about 2000 admissions to the both neonatal intensive care units each year. Between March 2006 and May 2009 all neonates transferred to these NICUs were enrolled for the study in a prospective manner. We determined GFR, urine output, mortality, morbidity, and the RIFLE scorefor each neonate. We also evaluated CRIB, CRIB II, SNAP, SNAPII and SNAP-PE score for each neonate and the final scores were then obtained by the arithmetic sum of individual scores of these parameters. The predictive accuracy of these receivers were expressed as area under the receiver operative characteristic (ROC) curve for each score and help to compare the performance of different tests, by plotting sensitivity, specificity, PPV and NPV. All groups were statistically analyzed by the t test and logistic model was used to analyze the prediction of mortality. The ethics committee of the Shahid Beheshti medical university and pediatric infectious research center approved this study.Results: We evaluated 404 neonates of NICUs of Mofid and Mahdieh hospitals during 2007 to 2009. Based upon RIFLE scoring system, 22.5% (91 neonates) of our study group had normal renal function and 77.5% (313 neonates) of them had abnormal renal function at the second day of admission. Therefore 313 neonates (77.5%) developed AKI by RIFLE criteria and among them 43% (135 neonates) met the risk, 51% (161 neonates) the injury and about 6% (17 neonates) the failure criterion. Based on old definition of ARF in neonates the rate of ARF in our study group was 3.2% (13 out of 404 neonates had serum creatinine more than 1.5 mg/dL), P<.001. In this study, we detected an overall in-hospital mortality of 20.5% in critically ill neonates. Of those who died, 81.9% (68 of 83 patients) had AKI. In patients with normal renal function, the rate of mortality was 16.5% and in patients with AKI based on RIFLE scoring system the mortality rate was 21.7% (P<.31). In R (risk) group the mortality rate was 16.3%, in I (injury) group the mortality rate was 24.2% and in F (failure) group the mortality rate was 41.2%.In patients with ARF based on creatinine level definition (serum creatinine more than 1.5 mg/dL) the mortality rate was 61.5% (P<.001, OR=6.741).A progressive and significant elevation in mortality was correlated with increasing RIFLE classification severity among all patients. (OR=1.406, P=.042, CI=0.76 to 2.06). The patients who had any degree of AKI at the time of admission to the NICU as well as those who had normal renal function had statistically significant higher median CRIB, CRIB II, SNAP, SNAP II and SNAP-PE NICU scoring systems, lower levels of apgar score, serum PH, serum bicarbonate and platelet count and wereyounger and smaller. Injury group on admission was associated with higher mortality than Risk group on admission (P<.001) and patients who developed Failure criteria during NICU stay had higher mortality than those who developed Risk group criteria (OR=3.17) or Injury group (OR=1.84).Conclusions: We concluded that a RIFLE criterion is a practical method to define AKI in neonatal group and it will be a good predictive tool for morbidity and mortality in NICUs.

Background: Clinical Risk Index of Babies (CRIB), Score for Neonatal Acute Physiology (SNAP), an update of the Clinical Risk Index for Babies score (CRIB II) and Score for Neonatal Acute Physiology - Perinatal Extension (SNAP-PE) are scoring devices developed in neonatal intensive care units. This study reviewed these scoring systems in critically ill neonates to determine how well they could predict mortality.Methods: This prospective cohort study was conducted at the neonatal intensive care units of Mofid and Mahdieh hospitals between March 2006 and May 2009. We evaluated CRIB, CRIB II, SNAP, SNAPII and SNAP-PE score for each neonate and the final scores were then obtained. The predictive accuracy of these parameters were expressed as area under the receiver operative characteristic curve, sensitivity, specificity, positive predictive value and negative predictive value.Results: Of 404 neonate evaluated 53% were male. Primary diagnoses were respiratory distress syndrome, gastrointestinal obstruction, sepsis, prematurity, and neuromuscular diseases. The authors detected mortality in 20.5% and found a significant difference in scoring systems between survived and death groups. The mean CRIB score in survived neonates was 2.57±3.66 and in death neonates 8.43±4.66 (p value<0.001). We also found that the SNAP score had the highest area under the curve and the highest sensitivity, specificity, positive predictive value, negative predictive value and we had the lowest score for CRIB II.Conclusion: We concluded that the neonatal scoring systems could be a useful tool for prediction of mortality in NICUs and SNAP can predict the mortality better than the others.

One of the main mechanisms of emulsion formation in porous media is the SNAP-off; invasion of the wetting phase flowing adjacent to the pore wall within a constriction mostly occupied by the non-wetting phase, causing breakup into isolated drops of this phase. The current approaches to determine the occurrence of this phenomenon have been formulated for quasistatic flow conditions, where the mechanisms governing the flow are controlled by the geometry of the capillary. However, some studies suggest that the drop breakup does not occur above a capillary number threshold and given a certain viscosity ratio, even if the static breakup criteria are met. In this paper, we extend the current numerical analysis of the capillary number upper limit (Calim), in which the SNAP-off is inhibited, by considering the effect of viscosity ratio on the dynamics of immiscible two-phase flow through constricted circular capillaries. Based on the results of this study, empirical mathematical expressions that relate the main physical variables of the flow were established as breakup criteria for dynamic flow conditions. The dynamic breakup criteria takes into account, jointly: some aspects of rheology of the two-phase system, such as the viscosity ratio; the dynamic factors of the flow, encapsulated in the local capillary number; and an integral form of the capillary geometry, represented by a parameter that relates both radii and the distance between them.