The standard definition of pediatric acute kidney injury (AKI) is evolving, especially for critically ill in the PICU. We sought to validate the application of the Pediatric Reference Change Value Optimized for Acute Kidney Injury in Children (pROCK) criteria in critically ill children. DESIGN: Multicenter retrospective study.SETTING: Six PICUs in mainland China. PATIENTS:One thousand six hundred seventy-eight hospitalized children admitted to the PICU with at least two creatinine values within 7 days. INTERVENTIONS: None.MEASUREMENTS AND MAIN RESULTS: AKI was diagnosed and staged according to the Pediatric Risk, Injury, Failure, Loss, End-Stage Renal Disease (pRIFLE), the Kidney Disease Improving Global Outcomes (KDIGO), and the pROCK criteria. Multiple clinical parameters were assessed and analyzed along with 90-day follow-up outcomes. According to the definitions of pRIFLE, KDIGO, and pROCK, the prevalence of AKI in our cohort of 1,678 cases was 52.8% (886), 39.0% (655), and 19.0% (318), respectively. The presence of AKI, as defined by pROCK, was associated with increased number of injured organs, occurrence of sepsis, use of mechanical ventilation, use of continuous renal replace therapy (p < 0.05), higher Pediatric Risk of Mortality III score, and higher Pediatric Logistic Organ Dysfunction-2 score (p < 0.001). The survival curve of 90-day outcomes showed that pROCK was associated with shorter survival time (LogRank p < 0.001), and pROCK definition was associated with better separation of the different stages of AKI from non-AKI (p < 0.001). CONCLUSIONS:In this retrospective analysis of AKI criteria in PICU admissions in China, pROCK is better correlated with severity and outcome of AKI. Hence, the pROCK criteria for AKI may have better utility in critically ill children.

The analysis of urban spatial form is the basic research of urban development. Traditional fractal research often focuses on the urban spatial layout, which cannot visually express the specific form, change characteristics and development trend of urban architectural spaces.The urban architectural form is simplified and the basic architectural form templates are extracted, and then, the correlations between architecture form and fractal dimension are built. The results of the case study show that the architectural layout of Zhengzhou City exhibits obvious fractal characteristics, and the combination of the two-dimensional and three-dimensional fractal dimensions is helpful for comprehensively revealing the architectural layout information. Moreover, the fractal dimension of buildings shows that the gradient from the inner to outer ring decreases, similar to the ‘annual growth rings’ of trees. Obvious differences exist in the fractal dimensions of urban buildings in different directions, reflecting the urban expansion direction. This study promotes the visualization of fractal theory and the expression of fractal theory in spatial gradient, providing theoretical and data reference for urban spatial form optimization.

No abstract

Urban spatial form is a significant reference to getting to know cities and running the cities. The fractal theory is an effective means to quantify urban spatial form. Taking the buildings in the outer ring of Zhengzhou City as the research object, the basic architectural models are built by extracting their forms. The research site is subdivided into 199 regions. The distribution of architectural forms in Zhengzhou is analyzed by fractal theory and spatial autocorrelation from the perspective of two-dimensional(2D) and three-dimensional(3D). The results indicate that the architectural layout of Zhengzhou has distinct fractal characteristics; Both global spatial autocorrelation and local spatial autocorrelation show significant positive correlations; There are obvious spatial differences in architectural space forms in different regions. The refined grid analysis strengthens the understanding of the urban spatial structure and development rules in more detail. The study promotes the refinement and visualization of fractal theory effectively and improves the depth of urban spatial form cognition.